W31

W31

YP47 Steels and Brittle Crack Arrest Steels(Jan 2013)(Rev.1
1.
Scope
Sept 2015)(Rev.2
1.1 General
Dec 2019
Complete 1.1.1 This UR defines the requirements on YP47 steels and brittle crack arrest steels as
Revision) required by UR S33.
(Rev.3
Mar 2023) 1.1.2 Unless otherwise specified in this UR, UR W11 is to be followed.
1.2

YP47 steels

1.2.1 Steels designated as YP47 refer to steels with a specified minimum yield point of 460
N/mm2.
1.2.2 The YP47 steels can be applied to longitudinal structural members in the upper deck
region of container carriers (such as hatch side coaming, hatch coaming top and the attachedlongitudinals, etc.). Special consideration is to be given to the application of YP47 steels forother hull structures.
1.2.3 This UR gives the requirements for YP47 steels in thickness greater than 50mm andnot greater than 100mm intended for the upper deck region of container carriers. For YP47
steels outside scope of the said thickness range, special consideration is to be given by theClassification Society.

Notes:
1.

This UR is to be applied by IACS Societies on ships contracted for construction on orafter 1 January 2014.

2.

Revision 1 of this UR is to be applied by IACS Societies to ships contracted forconstruction on or after 1 January 2017.

3.

The “contracted for construction” date means the date on which the contract to build thevessel is signed between the prospective owner and the shipbuilder. For further details
regarding the date of “contract for construction”, refer to IACS Procedural Requirement(PR) No. 29.

4.

Revision 2 of this UR is to be uniformly implemented by IACS Societies on ships
contracted for construction on or after 01 January 2021.

5.

Revision 3 of this UR is to be uniformly implemented by IACS Societies when theapplication for certification of manufacturer approval is dated on or after 01 July 2024.

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1.3

Brittle crack arrest steels

1.3.1 The brittle crack designation can be assigned to YP36 and YP40 steels specified in UR
W11 and YP47 steels specified in this UR, which meet the additional brittle crack arrest
requirements and properties defined in this UR.
1.3.2 The application of brittle crack arrest steels is to comply with UR S33, which covers
longitudinal structural members in the upper deck region of container carriers (such as hatchside coaming, upper deck, hatch coaming top and the attached longitudinals, etc.).
1.3.3 The thickness range of brittle crack arrest steels is over 50mm and not greater than
100mm as specified in Table 3 of this UR.
2

Material specifications

2.1

YP47 steels

Material specifications for YP47 steels are specified in Table 1 and Table 2.
Table 1 Chemical composition and deoxidation practice for YP47 steels
without specified brittle crack arrest properties
Grade

EH47

Deoxidation Practice

Killed and fine grain treatedChemical Composition %(ladle samples)(6)(7)
C max.
Mn
Si max.
P max.
S max.
Al (acid soluble min)Nb
V
Ti max.
Cu max.
Cr max.
Ni max.
Mo max.
Ceq max.(4)Pcm max.(5)0.18
0.90 – 2.00
0.55
0.020
0.020
0.015 (1)(2)0.02 – 0.05 (2)(3)0.05 – 0.10 (2)(3)
0.02(3)
0.35
0.25
1.0
0.08
0.49
0.22

Notes:
1.

The total aluminium content may be determined instead of the acid soluble content. In
such cases the total aluminium content is to be not less than 0.020%.

2.

The steel is to contain aluminium, niobium, vanadium or other suitable grain refining
elements, either singly or in any combination. When used singly the steel is to containthe specified minimum content of the grain refining element. When used in combination,
the specified minimum content of a fine graining element is not applicable.

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3.

The total niobium, vanadium and titanium content is not to exceed 0.12%.

4.

The carbon equivalent Ceq value is to be calculated from the ladle analysis using thefollowing formula:
C eq = C +5.

Mn Cr + Mo + V Ni + Cu
(%)
+
+
6
5
15

Cold cracking susceptibility Pcm value is to be calculated using the following formula:Pcm = C +Si Mn Cu Ni Cr Mo V
+
+
+ + +
+ + 5B(%)
30 20 20 60 20 15 10

6.

Where additions of any other element have been made as part of the steelmaking
practice subject to approval by the Classification Society, the content is to be indicatedon product inspection certificate.

7.

Variations in the specified chemical composition may be allowed subject to approval ofClassification Society.
Table 2 Conditions of supply, grade and mechanical properties for
YP47 steels without specified brittle crack arrest properties (1)Tensile test

Supplycondition

TMCP(2)

Grad
e

EH47
t

Impact test

Yield
Strength(N/mm2)min.

TensileStrength(N/mm2)Elongation(%) min.

460

570 - 720

17

Test
Temp
.
(℃)
-40

Average Impact Energy(J) min.
50 < t ≤ 70
Longitudinal53

70 < t ≤ 85
Longitudinal64

85 < t ≤ 100
Longitudinal
75

thickness (mm)Notes:
1.

The additional requirements for YP47 steel with brittle crack arrest properties is
specified in 2.2 of this UR.

2.

Other conditions of supply are to be in accordance with the Classification Society’s
procedures.

2.2

Brittle crack arrest steels

2.2.1 Brittle crack arrest steels are defined as steel plate with the specified brittle crack arrest
properties measured by either the brittle crack arrest toughness Kca or Crack Arrest
Temperature (CAT).
2.2.2 In addition to the required mechanical properties of UR W11 for YP36 and YP40 and
Table 2 of this UR for YP47, brittle crack arrest steels are to comply with the requirements
specified in Table 3 and Table 4 of this UR.
2.2.3 The brittle crack arrest properties specified in Table 3 are to be evaluated for the
products in accordance with the procedure approved by the Classification Society. Test
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specimens are to be taken from each piece (means “the rolled product from a single slab or
ingot if this is rolled directly into plates” as defined in UR W11), unless otherwise agreed by
the Classification Society.
Table 3 Requirement of brittle crack arrest properties for brittle crack arrest steels
Suffix to thesteelgrade(1)Thickness
range
(mm)

BCA1

50 < t ≤ 100

BCA280 < t ≤ 100t:

Brittle crack arrest properties(2)(6)Crack Arrest
Brittle Crack Arrest Toughness
Temperature
Kca at -10 ℃ (N/mm3/2) (3)CAT (℃) (4)(7)

6,000 min.

-10 or below

8,000 min.

(5)

thickness (mm)Notes:
1.

Suffix “BCA1” or “BCA2” is to be affixed to the steel grade designation (e.g. EH40BCA1, EH47-BCA1, EH47-BCA2, etc.).

2.

Brittle crack arrest properties for brittle crack arrest steels are to be verified by either thebrittle crack arrest toughness Kca or Crack Arrest Temperature (CAT).

3.

Kca value is to be obtained by the brittle crack arrest test specified in Annex 3 of thisUR.

4.

CAT is to be obtained by the test method specified in Annex 4 of this UR.

5.

Criterion of CAT for brittle crack arrest steels corresponding to Kca=8,000 N/mm3/2 is tobe approved by the Classification Society

6.

Where small-scale alternative tests are used for product testing (batch release testing),
these test methods are to be approved by the Classification Society in accordance with
Annex 5 of this UR.

7.

Lower thicknesses may be approved at the discretion of the Classification Society.

Table 4 Chemical composition and deoxidation practice for brittle crack arrest steels
Grade

EH36BCA

Deoxidation
Practice

EH40BCAEH47-BCA

Killed and fine grain treatedChemicalComposition %(1)(7)(8)(ladle samples)
C max.
Mn
Si max.
P max.

0.18
0.90 – 2.00
0.50
0.020
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0.18
0.90 – 2.00
0.55
0.020
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S max.
Al (acid soluble
min)
Nb
V
Ti max.
Cu max.
Cr max.
Ni max.
Mo max.
Ceq max.(5)Pcm max.(6)W31(cont)

0.020
0.015 (2) (3)0.020
0.015 (2) (3)0.02 – 0.05 (3) (4)0.05 – 0.10 (3) (4)0.02(4)
0.50
0.25
2.0
0.08
0.47
0.49
-

0.02 – 0.05 (3) (4)0.05 – 0.10 (3) (4)0.02(4)
0.50
0.50
2.0
0.08
0.55
0.24

Notes:
1.

Chemical composition of brittle crack arrest steels shall comply with Table 4 of this UR,
regardless of chemical composition specified in UR W11 and Table 1 of this UR.

2.

The total aluminium content may be determined instead of the acid soluble content. In
such cases the total aluminium content is to be not less than 0.020%.

3.

The steel is to contain aluminium, niobium, vanadium or other suitable grain refining
elements, either singly or in any combination. When used singly the steel is to containthe specified minimum content of the grain refining element. When used in combination,
the specified minimum content of a fine graining element is not applicable.

4.

The total niobium, vanadium and titanium content is not to exceed 0.12%.

5.

The carbon equivalent Ceq value is to be calculated from the ladle analysis using thefollowing formula:
C eq = C +6.

Cold cracking susceptibility Pcm value is to be calculated using the following formula:Pcm = C +7.

Mn Cr + Mo + V
Ni + Cu
(%)
+
+
6
5
15

Si Mn Cu Ni Cr Mo V
+
+
+
+
+
+
+ 5 B (%)
30 20
20 60 20 15 10

Where additions of any other element have been made as part of the steelmaking
practice subject to approval by the Classification Society, the content is to be indicatedon product inspection certificate.

8.
Variations in the specified chemical composition may be allowed subject to approval ofClassification Society.

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3

Manufacturing approval scheme

3.1

YP47 steels

Manufacturing approval scheme for YP47 steels is to be in accordance with Annex 1 of thisUR.
3.2

Brittle crack arrest steels

Manufacturing approval scheme for brittle crack arrest steels is to be in accordance with
Annex 2 of this UR.
4

Welding procedure qualification test

4.1

YP47 steels

4.1.1 General
Approval test items, test methods and acceptance criteria not specified in this UR are to be inaccordance with the Classification Society’s procedures.
4.1.2 Approval range
UR W28 is to be followed for approval range.
4.1.3 Impact test
UR W28 is to be followed for impact test. 64J at -20℃ is to be satisfied.
4.1.4 Hardness
HV10, as defined in UR W28, is to be not more than 350. Measurement points are to include
mid-thickness position in addition to the points required by UR W28.
4.1.5 Tensile test
Tensile strength in transverse tensile test is to be not less than 570N/mm2.
4.1.6 Brittle fracture initiation test
Deep notch test or CTOD test may be required.
Test method and acceptance criteria are to be considered appropriate by the Classification
Society.
4.2

Brittle crack arrest steels

4.2.1 General
Where Welding Procedure Specification (WPS) for the non-BCA steels has been approved by
the Classification Society, the said WPS is applicable to the same welding procedure applied
to the same grade with suffix “BCA1” or “BCA2” specified in Table 3 of this UR except highheat input processes over 50kJ/cm.

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(cont)The requirements for welding procedure qualification test for brittle crack arrest steels is to bein accordance with the relevant requirements for each steel grade excluding suffix “BCA1” or“BCA2” specified in Table 3 of this UR, except for 4.2.2 below.
4.2.2 Hardness
For YP47 steels with brittle crack arrest properties, HV10, as defined in UR W28, is to be notmore than 380. Measurement, and measurement points are to include mid-thickness positionin addition to the points required by UR W28.
5

Production welding

5.1

YP47 steels

5.1.1 Welder
Welders engaged in YP47 welding work are to possess welder’s qualifications specified in
UR W32.
5.1.2 Short bead
Short bead length for tack and repairs of welds by welding are not to be less than 50mm.
In the case where Pcm is less than or equal to 0.19, 25mm of short bead length may be
adopted with approval of the Classification Society.
5.1.3 Preheating
Preheating is to be 50℃ or over when air temperature is 5℃or below.
In the case where Pcm is less than or equal to 0.19 and the air temperature is below 5℃ but
above 0℃, alternative preheating requirements may be adopted with approval of theClassification Society.
5.1.4 Welding consumables
Approval procedure, approval test items, test methods and acceptance criteria not specified
in this UR are to be in accordance with UR W17.
Specifications of welding consumables for YP47 steel plates are to be in accordance with
Table 5.
Table 5 Mechanical properties for deposited metal tests for welding consumables
Mechanical Properties
Yield
Strength(N/mm2) min.

TensileStrength(N/mm2)460

570 - 720

Impact test
Test
Elongation
Temp.
(%) min.
(℃)
19

-20

Average Impact
Energy(J) min.
64

Consumables tests for butt weld assemblies are to be in accordance with Table 6.

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Table 6 Mechanical properties for butt weld tests for welding consumables

W31(cont)

Tensile strength(N/mm2)570 - 720

Bend test ratio:
Dt4

Charpy V-notch impact tests
Test
temperature
Average absorbed
energy (J) min.
(℃)
- 20
64

5.1.5 Others
Special care is to be paid to the final welding so that harmful defects do not remain.
Jig mountings are to be completely removed with no defects in general, otherwise thetreatment of the mounting is to be accepted by the Classification Society.
5.2

Brittle crack arrest steels

Welding work (such as relevant welder’s qualification, short bead, preheating, selection of
welding consumables, etc.) for brittle crack arrest steels is to be in accordance with therelevant requirements for each steel grade excluding suffix “BCA1” or “BCA2” specified inTable 3 of this UR.

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Annex 1 Manufacturing Approval Scheme for YP47 Steels
A1.1.

Scope

A1.1.1 This Annex specifies, as given in 3.1 of this UR, the manufacturing approval scheme
for YP47 steels of grade EH47.
A1.1.2 Unless otherwise specified in this Annex, Appendix A2 of UR W11 is to be followed.
A1.2.

Approval tests

A1.2.1 Extent of the approval tests
A1.2.1.1 3.1 (c) and (d), Appendix A2 of UR W11 are not applied to manufacturing approval
of YP47 steels.
A1.2.1.2 The products for testing are to represent the maximum thickness for approval. If thetarget chemical composition changes with the thickness, the maximum thickness for eachspecified chemical composition specification shall be tested.
A1.2.2 Type of tests
A1.2.2.1

Brittle fracture initiation test

Deep notch test or Crack Tip Opening Displacement (CTOD) test is to be carried out. Test
method is to be in accordance with the Classification Society’s practice.
A1.2.2.2(a)Weldability test

Y-groove weld cracking test (Hydrogen crack test)

The test method is to be in accordance with recognized national standards such as JIS Z
3158-:2016 or, CB/T 4364-:2013 or ISO 17642-2:2005. Acceptance criteria are to be inaccordance with the Classification Society’s practice.
(b)

Brittle fracture initiation test

Deep notch test or CTOD test is to be carried out. Test method and results are to beconsidered appropriate by the Classification Society.
A1.2.2.3

Other tests

In addition to the requirement specified in A1.2.2.1 and A1.2.2.2 above, the approval tests
required for steels specified in Appendix A2 of UR W11 are to be carried out. Additional tests
may be required when deemed necessary by the Classification Society.

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Annex 2 Manufacturing Approval Scheme for Brittle Crack Arrest Steels
A2.1.

Scope

A2.1.1 This Annex specifies, as given in 3.2 of this UR, the manufacturing approval scheme
for brittle crack arrest steels.
A2.1.2 Unless otherwise specified in this Annex, Appendix A2 of UR W11 and/or Annex1 ofthis UR are to be followed.
A2.2.

Approval Application

A2.2.1 Documents to be submitted
The manufacturer is to submit to the Classification Society the following documents together
with those required in 2.1, Appendix A2 of UR W11:a) In-house test reports of the brittle crack arrest properties of the steels intended forapprovalb) Approval test program for the brittle crack arrest properties (see A2.3.1 below)c) Production test procedure for the brittle crack arrest properties.
A2.3.

Approval tests

A2.3.1 Extent of the approval tests
A2.3.1.1 The extent of the test program is specified in A2.3.2, A2.3.3 and A2.3.4 of thisAnnex. If the manufacturing process and mechanism to ensure the brittle crack arrest
properties for the steels intended for approval are same, 3.1, Appendix A2 of UR W11 is to befollowed for the extent of the approval tests. For YP47 steels with brittle crack arrest
properties, 3.1 (c) and (d), Appendix A2 of UR W11 are not applied.
3.1.2A2.3.1.2 The products for testing are to represent the maximum thickness for approval.
If the target chemical composition changes with the thickness, the maximum thickness foreach specified chemical composition specification shall be tested.
A2.3.1.3 The number of test samples and test specimens may be increased when deemednecessary by the Classification Society, based on the in-house test reports of the brittle crackarrest properties of the steels intended for approval specified in A2.2.1 a).
A2.3.2 Type of tests
A2.3.2.1 Brittle crack arrest tests are to be carried out in accordance with A2.3.3 of thisAnnex in addition to the approval tests specified in Appendix A2 of UR W11 and/or Annex 1of this UR.
A2.3.2.2 In the case of applying for addition of the specified brittle crack arrest properties for
YP36, YP40 and YP47 steels of which, manufacturing process has been approved by theClassification Society (i.e. The aim analyses, and method of manufacture and condition of
supply are similar and the steelmaking process, deoxidation and fine grain practice, casting
method and condition of supply are the same), brittle crack arrest tests, chemical analyses,
tensile test and Charpy V-notch impact test are to be carried out in accordance with Annex 2of this UR and Appendix A2 of UR W11.

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A2.3.3 Test specimens and testing procedure of brittle crack arrest tests
A2.3.3.1 The test specimens of the brittle crack arrest tests are to be taken with theirlongitudinal axis parallel to the final rolling direction of the test plates.
A2.3.3.2 The loading direction of brittle crack tests is to be parallel to the final rolling
direction of the test plates.
A2.3.3.3 The thickness of the test specimens of the brittle crack arrest tests is to be the fullthickness of the test plates.
A2.3.3.4 The test specimens and repeat test specimens are to be taken from the same steel
plate. Where the brittle crack arrest properties are evaluated by Kca, and the brittle crackarrest test result fails to meet the requirement, further brittle crack arrest tests may be carriedout. In this case, the judgment of acceptance is to be made on the arrest toughness value Kcaof all test specimens (results of the initial test, failed tests and additional tests shall be
included in the testing report.).
A2.3.3.5 The thickness of the test specimen is to be the maximum thickness of the steel
plate requested for approval.
A2.3.3.6 In the case where the brittle crack arrest properties are evaluated by Kca, the brittle
crack arrest test method is to be in accordance with Annex 3 of this UR. In the case where
the brittle crack arrest properties are evaluated by CAT, the test method is to be inaccordance with Annex 4 of this UR.
A2.3.4 Other tests
Additional tests may be required when deemed necessary by the Classification Society inaddition to the tests specified in A2.3.3.
A2.4.

Results

Appendix A2 of UR W11 is to be followed for the results.
Additionally, results of test items and the procedures shall comply with the test programapproved by the Classification Society. In the case where the brittle crack arrest properties
are evaluated by Kca or CAT, the manufacturer also is to submit to the Classification Society
the brittle crack arrest test reports in accordance with Annex 3 for Kca and Annex 4 for CAT
of this UR.
A2.5.

Approval and Certification

Upon satisfactory completion of the survey and tests, approval is granted by the Classification
Society with the grade designation having the suffix “BCA1” or “BCA2” (e.g. EH40-BCA1,
EH47-BCA1, EH47-BCA2, etc.).
A2.6.

Renewal of approval

The manufacturer is also to submit to the Classification Society actual manufacturing recordsof the approved brittle crack arrest steels within the term of validity of the manufacturing
approval certificate.
Note: Chemical composition, mechanical properties, brittle crack arrest properties (e.g. brittle
crack arrest test results or small-scale alternative test results) and nominal thickness are to
be described in the form of histogram or statistics.
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Annex 3 Test Method for Brittle Crack Arrest Toughness, Kca
Setting a temperature gradient in the width direction of a test specimen, and applying uniform
stress to the test specimen, strike the test specimen to initiate a brittle crack from themechanical notch at the side of the test specimen and causes crack arrest (temperature
gradient type arrest testing). Using the stress intensity factor, calculate the brittle crack arrest
toughness, Kca, from the applied stress and the arrest crack length. This value is the brittle
crack arrest toughness at the temperature of the point of crack arrest (arrest temperature). To
obtain Kca at a specific temperature followed by the necessary evaluation, the method
specified in Appendix A of this Annex 3 can be used.
As a method for initiating a brittle crack, a secondary loading mechanism can also be used(see Appendix B of this Annex 3 “Double tension type arrest test”).
1.

Scope

A3.1. Scope
ISO20064: 2019 provides a test method for the determination of brittle crack arrest toughnessof steel by using wide plates with a temperature gradient.
This Annex 3 specifies the test methodprocedures for brittle crack arrest toughness (i.e. Kca)of steel using fracture mechanics parameter and determination method of Kca at a specifictemperature which are specified in ISO 20064:2019. Additionally, this Annex 3 specifies theevaluation method of Kca of test plate. This Annex 3 is applicable to hull structural steels withthe thickness over 50mm and not greater than 100mm specified in UR W11 or this UR.
2.

Symbols and their significanceThe symbols and their significance used in this standard are shown in Table A3-1.
Table A3-1 Symbols and their significanceSymbolUnit

Significance

a
E
Ei
Es
Et
F
K
Kca
L
Lp
Lpc
Ltb
T
t

mm
N/mm2
J
J
J
MN
N/mm3/2
N/mm3/2
mm
mm
mm
mm
°C
mm

Crack length or arrest crack length
Modulus of longitudinal elasticity
Impact energy
Strain energy stored in a test specimen
Total strain energy stored in tab plates and pin chucks
Applied load
Stress intensity factor
Arrest toughness
Test specimen length
Distance between the loading pins
Pin chuck length
Tab plate length
Temperature or arrest temperature
Test specimen thickness

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Table A3-1 Symbols and their significance (cont’d)(cont)

Symbol

Unit

ttb

mm

Tab plate thickness

tpc
W

mm
mm

Pin chuck thickness
Test specimen width

Wtb
Wpc

mm
mm

Tab plate width
Pin chuck width

xa

mm

xbr

mm

ya

mm

ybr

mm

σ
σY0

N/mm2
N/mm2

Coordinate of a main crack tip in the width direction
Coordinate of the longest branch crack tip in the width
direction
Coordinate of a main crack tip in the stress loading
direction
Coordinate of the longest branch crack tip in the stressloading direction
Applied stress
Yield stress at room temperature

3.

Significance

Testing equipment

The following specifies the testing machine neededA3.2.

Test Procedures

The test procedures including testing equipment, test specimens, test methods, determinationof arrest toughness, reporting of test results, etc. are to be in accordance with ISO 20064: 2019.
As a method for conducting theinitiating a brittle crack arrest test. Testing machine, asecondary loading mechanism can be used in accordance with Annex D of ISO 20064: 2019,
except that the first sentence in Annex B.2.4 of ISO 20064: 2019 is used to apply tensile
forcerevised to an integrated specimen, and impact equipment is used to generate a brittle
crack on the test specimen.
3.1

Testing machine

3.1.1

Loading method

Tensile load to an integrated specimen shall be hydraulically applied.
The loading method to an integrated specimen using the testing machine shall be of a pin type.
The stress distribution in the plate width direction shall be made uniform by aligning the centresof the loading pins of both sides and the neutral axis of the integrated specimen.
3.1.2

Loading directions

The loading directions shall be either vertical or horizontal. In the case of the horizontal
direction, test specimen surfaces shall be placed either perpendicular to the ground.
3.1.3

Distance between the loading pins

The distance between the loading pins shall be approximately 3.4W or more, where W is thewidth of the test specimen. Since the distance between the loading pins sometimes has aneffect on the load drop associated with crack propagation, the validity of the test results isdetermined by the judgment method described in 7.1.
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Impact equipment

3.2.1

Impact methods

Methods to apply an impact load to an integrated specimen shall be of a drop weight type orof an air gun type.
The wedge shall be hard enough to prevent significant plastic deformation caused by the
impact. The wedge thickness shall be equal to or greater than that of the test specimen, andthe wedge angle shall be greater than that of the notch formed in the test specimen and havea shape capable of opening up the notch of the test specimen.
4.

Test specimens

4.1

Test specimen shapes

The standard test specimen shape is shown in Figure A3-1. Table A3-2 shows the ranges oftest specimen thicknesses, widths and width-to-thickness ratios.
The test specimen length shall be, in principle, equal to or greater than its width.

W=500

29

(cont)

3.2

2～5

29

W31

L=500

[mm]

Figure A3-1 Standard test specimen shape

Table A3-2 Dimensions of test specimens
Test specimen thickness, t
Test specimen width, W
Test specimen width/test specimen thickness, W/t

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350 mm ≤ W ≤ 1000 mm(Standard width: W = 500 mm)
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Shapes of tab plates and pin chucks

The definitions of the dimensions of the tab plates and pin chucks are shown in Figure A3-2.
Typical examples are shown in Figure A3-3.
Pin chuck (Thickness: tpc)

Wtb

Wpc

Lpc

SpecimenTab plate(Thickness: ttb) (Thickness: t)

Ltb

W

L
Lp

(a) Single-pin type
Pin chuck (Thickness: tpc)

SpecimenTab plateWtb (Thickness: t ) (Thickness: t)
tb

Wpc

Lpc

Ltb

W

L
Lp

(b) Double-pin type

Lpc

W

t ｔｂ

t

t pc

Figure A3-2 Definitions of dimensions of tab plates and pin chucks

Wtb(cont)

4.2

Wpc

W31

L

Ltb

Lp

(a) Example 1
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Lpc

t pc

W

Wtb

Wpc

(cont)

ttb

t

W31

ttb

W31

L
Lp

“Obtain

tpc

ttb

t

(b) Example 2

Lpc

W

Wtb

Wpc

Welds

Ltb

L
Lp

(c) Example 3
Figure A3-3 Examples of the shapes of tab plates and pin chucks

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ttb

t

t pc

W31

Lpc

W

Wtb

Wpc

(cont)

Ltb

L
Lp

ttb

W

Wtb

t

(d) Example 4

L

Ltb

Lp

(e) Example 5
Figure A3-3 Examples of shapes of tab plates and pin chucks (cont’d)4.2.1 Tab plates
The tolerances of tab plate dimensions are shown in Table A3-3. When the lengths of the tabplates attached to both ends of a test specimen are different, the shorter length shall be usedas the tab length, Ltb.
Table A3-3 Tolerances of tab plate dimensions
Tab plate thickness, ttb

0.8t ≤ ttb ≤ 1.5t

Tab plate width, Wtb
Total length of a test specimen and tab plates, L + 2Ltb
(Total length of a test specimen and a single tab plate L + Ltb)
Tab plate length (Lt)/Tab plate width, (W)W ≤ Wtb ≤ 2.0W
L + 2Ltb ≥ 3.0W
(L + Ltb ≥ 2.0W)
Ltb/W ≥ 1.0

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4.2.2 Pin chucks
The pin chuck width, Wpc, shall be in principle equal to or more than the tab plate width, Wtb.
The pin chucks shall be designed to have a sufficient load bearing strength. When pin chucks
attached to both ends of an integrated specimen are asymmetric, the length of the shorter
one shall be used as the pin chuck length, Lpc.
The distance between the pins, Lp, is obtained from the equation (1). In the case as shown in
Figure A3-3 (e), Example 5, Lp is obtained by setting Lpc = 0.

Lp = L + 2 Ltb + 2Lpc ························································ (1)4.3

Welding of test specimen and tab plates

Test specimen, tab plates, and pin chucks shall be connected by welding. The welds shallhave a sufficient force bearing strength.
As shown in Figure A3-4 (a), the flatness (angular distortion, linear misalignment) of the weld
between a test specimen and a tab plate shall be 4 mm or less per 1 m. In the case of
preloading, however, it is acceptable if the value after preloading satisfies this condition. As
shown in Figure A3-4 (b), the accuracy of the in-plane loading axis shall be 0.5% or less ofthe distance between the pins, and the accuracy of the out-of-plane loading axis shall be
0.4% or less of the distance between the pins.
≤4mm

1m

(a) Flatness of weld between test specimen and tab plate≤0.004Lp≤0.005Lp

Lp(b) Accuracy of in-plane and out-of-plane loading axes
Figure A3-4 Dimensional accuracy of weld between test specimen and tab plate

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5.

Test methods

The following specifies methods for conducting the arrest toughness test.
5.1

Temperature control methods

A predetermined temperature gradient shall be established across a test specimen width bysoldering at least nine thermocouples to the test specimen for temperature measurement andcontrol.
Temperature gradient shall be established in accordance with the following conditions (1)through (3).
(1) A temperature gradient of 0.25 - 0.35°C/mm shall be established in a test specimen
width range of 0.3W - 0.7W. When measuring the temperatures at the centre
position of the test specimen thickness, it shall be kept within ±2°C for 10 minutes
or more, whereas when measuring the temperatures on the front and back surface
positions of the test specimen, it shall be kept within ±2°C for (10＋0.1t [mm])minutes or more taking account of the time needed for soaking to the centre. If thetemperature gradient at 0,3W - 0,7W is less than 0.25°C/mm, crack arrest may
become difficult, and if the gradient is larger than 0.35°C/mm, the obtained arrest
toughness may be too conservative.
(2) At the test specimen width centre position (i.e., 0.5W), and in the range of ±100 mm
in the test specimen length direction, the deviation from the temperature at thecentre position in the length direction shall be controlled within ±5°C. However,when temperature measurement is not performed at the centre position in thelength direction, the average temperature at the closest position shall be used as
the temperature at the centre position in the length direction.
(3) At the same position in the width direction, the deviation of the temperature on thefront and back surfaces shall be controlled within ±5°C.
5.2

Crack initiation methods

Impact energy shall be applied to a test specimen to initiate a crack. However, if the energy isexcessive, it may influence on the test results. In that case, the results shall be treated as
invalid data in accordance with the judgment criteria specified in 7.2. It is desirable to use
equation (2) and Figure A3-5 as guides for obtaining valid data.

Ei≤ min (1.2σ − 40 , 200 ) ············································· (2)tWhere the variables have the following units: Ei [J], t [mm], and σ [N/mm2], and min means
the minimum of the two values.

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400

W31

350

(cont)

Ei /t [J/mm]

300
250
200
150
100

Recommendation

50
0
0

50

100

150
σ

200

250

300

[N/mm 2 ]Figure A3-5 Recommended range of impact energy
6.

Test procedures

The following specifies the procedures for testing brittle crack arrest toughness.
6.1

Pretest procedures(1) Install an integrated specimen in the testing machine.
(2) Mount a cooling device on the test specimen. A heating device may also be mounted on
the test specimen.
(3) Install an impact apparatus specified in 3.2, on the testing machine. Place an appropriate
reaction force receiver as necessary.
Note: The above procedures (1) through (3) do not necessarily specify the order of
implementation, and they may be completed, for example, on the day before
the test.
(4) After checking that all measured values of the thermocouples indicate room temperature,
start cooling. The temperature distribution and the holding time shall be as provided in thespecifications in 5.1.
(5) Set an impact apparatus, as specified in 3.2 so that it can supply predetermined energy
to the test specimen.
(6) Apply force to the test specimen until it reaches the predetermined value. This force isapplied after temperature control to prevent autonomous crack initiation during force
increase. Alternatively, temperature control may be implemented after loading. The
loading rate and applied stress shall satisfy the conditions (a) and (b) described below,
respectively.
(a) Loading rate
There is no specification of loading rate, but it shall be determined considering that an
excessively slow loading rate may prolong the temperature control period, thereby
allowing the temperature distribution to depart from the desired condition and an
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excessively fast loading rate may cause over-shooting of the load.
(b) Applied stress/yield stress ratio
Applied stress shall be within the range shown by equation.

σ ≤ 2 σ Y0 ····································································· (3)3As a guide, a value equal to 1/6 of σY0 or more is desirable. If applied stress is larger thanthat specified by equation (3), the test may give a non-conservative result.
(7) To initiate a crack, the notch may be cooled further immediately before impact on thecondition that the cooling does not disturb the temperature in the range of 0.3W - 0.7W.
The test temperature in this case shall be the measured temperature obtained from thetemperature record immediately before the further notch cooling.
(8) Record the force value measured by a force recorder.
6.2

Loading procedures(1) After holding a predetermined force for 30 seconds or more, apply an impact to thewedge using the impact apparatus. If a crack initiates autonomously and the exact force
value at the time of the crack initiation cannot be obtained, the test is invalid.
(2) After the impact, record the force value measured by the force recorder.
(3) When the force after the impact is smaller than the test force, consider that crack
initiation has occurred.
Note: An increase in the number of times of impact may cause a change in the
shape of the notch of the test specimen. Since the number of impact has noeffect on the value of brittle crack arrest toughness, no limit is specified for thenumber of impact. However, because the temperature gradient is often
distorted by impact, the test shall be conducted again, beginning fromtemperature control when applying repeated impact to the wedge.
(4) When crack initiation, propagation, and arrest are observed, remove the force.
6.3

Procedures after testing(1) Remove the impact apparatus.
(2) Remove the cooling device, thermocouples, and strain gauges.
(3) Return the temperature of the test specimen to room temperature. For that purpose, thetest specimen may be heat-tinted using a gas burner or the like. If it is necessary to
prevent heating of the fracture surface, this method shall be avoided.
(4) After gas-cutting an uncracked ligament, use the testing machine to cause ductile
fracture, as necessary. Alternatively, it is also possible to gas-cut the uncracked ligament
after using the testing machine to develop a ductile crack to a sufficient length.

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6.4

Observation of fracture surfaces(1) Photograph the fracture surfaces and propagation path.
(2)
Measure the longest length of the arrest crack tip in the plate thickness direction, andrecord the result as the arrest crack length. The arrest crack length shall include the notch
length. In the case where a crack deviates from the direction vertical to the loading direction,
the length projected to the plane vertical to the loading line is defined as the arrest crack length.
In the following cases, however, judge the results according to the methods described{Kca /[K0*exp(−c/TcaK)]} for each casedata point”.
(a) Crack re-initiation
In the case where a brittle crack has re-initiated from an arrested crack, the originalarrest position is defined as the arrest crack position. Here re-initiation is defined as
the case where a crack and re-initiated cracks are completely separated by astretched zone and brittle crack initiation from the stretched zone can be clearlyobserved. In the case where a crack continuously propagates partially in the
thickness direction, the position of the longest brittle crack is defined as the arrest
position.
(b) Crack branching
In the case where a crack deviates from the direction vertical to the loading
direction, the length projected to the plane vertical to the loading line is defined as
the arrest crack length. Similarly, in the case of crack branching, the length of thelongest branch crack projected to the plane vertical to the loading line is defined as
the branch crack length. More specifically, from the coordinates (xa, ya) of the arrest
crack tip position and the coordinates (xbr, ybr) of the branch crack tip position
shown in Figure A3-6, obtain the angle θ from the x-axis and define xa as the arrest
crack length, a. Here, x is the coordinate in the test specimen width direction, andthe side face of the impact side is set as x = 0; y is the coordinate in the test
specimen length direction, and the notch position is set as y = 0.
(3) Prepare a temperature distribution curve (line diagram showing the relation between thetemperature and the distance from the test specimen top side) from the thermocouple
measurement results, and obtain the arrest temperature T corresponding to the arrest
crack length.
yy(x a, y a)
Main crackθxBranching crack(x br, y br)

Test specimen width

W(a) Case of branching from notch
brittle crack propagation(x a, y a)
Main crackθxBranching crack(x br, y br)

Test specimen width

W(b) Case of branching during

Figure A3-6 Measurement methods of main crack and branch crack lengths
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7.

A3.3. Determination of arrest toughness

7.1

Judgment of arrested crack

When an arrested crack satisfies all of the conditions (a) through (d) below as shown in
Figure A3-7, the length of the arrested crack determined by 6.4 is valid. If any of theconditions is not met, the arrest toughness calculated from 7.3 is invalid.

Figure A3-7 Necessary conditions of arrest crack position(a)Conditions for crack propagation path:

All of the crack path from crack initiation to arrest shall be within the range shown in Figure
A3-8. However, in the case where a main crack tip lies within this range but a part of the maincrack passes outside the range, the arrest toughness may be assessed as valid if thetemperature at the most deviated position of the main crack in the y direction is lower thanthat at y = 0, and also K for the main crack falls within ± 5% of K for a straight crack of thesame a. The calculation method of Ks for the main crack and a straight crack is obtained fromequation (4).

φ  φ 
φ 
K = K I cos 3   + 3K II cos 2   sin   ································· (4)2 22

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Figure A3-8(b)Allowable range of main crack propagation path

Conditions for arrest crack length:a ≤ 0.7 ······························································· (5)W 

0.3 ≤ a  ≥1.5 ······································································ (6)
t
 a 
 ≤ 0.15 ···································································· (7) Lp 
Note: Equation (7) ensures minimal influence of force drop at the centre of thespecimen which might be caused by crack propagation and reflection of thestress wave at the two ends of the specimen. However, application of equation(7) is not necessarily required if the strain and the crack length have been
dynamically measured and the value of the strain at the time of arrest is 90% ormore of the static strain immediately before crack initiation.
(c)

Conditions for crack straightness:ya ≤ 50 mm ·································································· (8)In the case where 50 mm < ya ≤ 100 mm and θ ≤ 30°, the result is valid only when thetemperature at x = 0.5W and y = ±100 mm falls within ± 2.5°C of that at x = 0.5W and
y = 0.
(d)

Conditions for crack branching: xbr  ≤ 0.6(9)x··································································aPage 24 of 54

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7.2

Assessment of impact energy

Impact energy shall satisfy equation (10). If it does not satisfy the equation, the value of arrest
toughness calculated from the equations in 7.3 is invalid.
Conditions for impact energy:Ei5a − 1050 + 1.4W≤
Es + Et
0.7 W − 150

 a  ≤ 0.7 ·········· (10)W where 0.3≤ 

where the variables have the following units: a [mm], and W [mm]. Ei is impact energy
calculated from the equation (11). Es and Et are calculated from equations (12) and (13),respectively.
Note1: If equation (10) is not satisfied, the influence of impact energy on the stressintensity factor is too large to obtain an accurate arrest toughness.
Note2: In the case where the tab plates are multistage as shown in Figure A3-3 (b),calculate and total the strain energy of each tab plate using equation (12).
Note3: In the case where tab plate widths are tapered as shown in Figure A3-3 (d),calculate the strain energy based on elastostatics.

Ei = m g h ··································································· (11)Es =109 F 2 L····························································· (12)2E W tEt =Lpc 
10 9 F 2  Ltb
 ············································ (13)+E  Wtb t tb Wpc t pc where the variables have the following units: Es [J], Et [J], F [MN], E [N/mm2], L [mm], W[mm], and t [mm].
7.3

Calculation of arrest toughness

The arrest toughness, Kca, at the temperature, T, shall be calculated from equation (14) using
the arrest crack length, a, and the applied stress, σ, judged by 7.1. Calculate σ from equation
(15).
 2W
 π a  
K ca = σ π a tan
 2W   π aσ=

1/ 2············································ (14)10 6 F····································································· (15)Wt

where the variables have the following units: F [MN], W [mm], and t [mm].
If the conditions specified in 7.1 and 7.2 are not satisfied, the Kca calculated from equation (14)is invalid.

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8.

Reporting

Using Table A3-4, the following items shall be reported:(1) Test material: Steel type and yield stress at room temperature(2) Testing machine: Capacity of the testing machine(3) Test specimen dimensions: Thickness, width, length, angular distortion, and linear
misalignment(4) Integrated specimen dimensions: Tab plate thickness, tab plate width, integrated
specimen length including the tab plates, and distance between the loading pins
(5) Test conditions: Applied force, applied stress, temperature gradient, impact energy, andthe ratio of impact energy to the strain energy stored in the integrated specimen (sum of
test specimen strain energy and tab plate strain energy)(6) Test results(a) Judgment of arrest: Crack length, presence or absence of crack branching, maincrack angle, presence or absence of crack re-initiation, and arrest temperature(b) Arrest toughness value(7) Temperature distribution at moment of impact: Thermocouple position, temperature value,
and temperature distribution(8) Test specimen photographs: Crack propagation path (one side), and brittle crack fracturesurface (both sides)(9) Dynamic measurement results: History of crack propagation velocity, and strain change
at pin chucks
Note: Item (9) shall be reported as necessary.

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Table A3-4 Report sheet for brittle crack arrest test results
Item(1) Test material(2) Test
equipment(3) Test
specimen
dimensions(4) Integrated
specimen
dimensions(5) Test
conditions(6) Test results

Details

SymbolConditions/
Results

Unit

Valid/
Invalid

Steel type

－

－

－

Yield stress at room temperature

σY0

N/mm2

－

Testing machine capacity

－

MN

－

Thickness

t

mm

Width

W

mm

LengthLmm

Angular distortion ＋ linear
misalignment

－

mm/m

Tab plate thickness

ttb

mm

Tab plate width

Wtb

mm

L + Ltb

mm

Lp

mm

Applied forceF

MN

Applied stress

σ

N/mm2

Temperature gradient－°C /mmTest specimen length including a tab
plate
Distance between loading pins

Impact energy
Ei
Ratio of impact energy to strainenergy stored in integrated specimen Ei/(Es+Et)
Crack lengthaPresence/absence of－
crack branching
Ratio of branch
Judgment of
crack length to main
xbr/xacrack
crack
propagation/a
rrest
Main crack angleθ
Presence/absence of
crack re-initiation
Temperature at crackarrest position
Arrest toughness value

J
－
mm
－

－

－
degree
(°)

－

－

T

°C

Kca

N/mm3/2(7) Temperature
distribution
at moment of
impactTemperature measurement position
Temperature at each temperature
measurement position
Temperature distribution curve－

Attached－－－

Attached°C－－

Attached－(8) Test
specimenphotographs

Crack propagation path
Brittle crack fracture surface (bothsides)
History of crack propagation velocity－

Attached－－

Attached－－

Attached－－

Attached－(9) Dynamic
measuremen
Strain change at pin chuckst results
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Annex 3 - Appendix A
Method for obtaining Kca at a specific temperature and the evaluation
A
A3.3.1
GeneralMethod
This Appendix specifies the The method for conducting multiple tests specified in Annex 3 ofthis UR to obtain Kca value at a specific temperature TD. is to be in accordance with Annex B
of ISO 20064: 2019.
AA3.3.2

MethodA number of experimental data show dependency of Kca on arrest temperature, as expressedby equation (A.1), where TK [K] (= T [°C]＋273), c and K0 are constants.
 c 
K ca = K 0 exp
 TK  ·························································· (A.1)

The arrest toughness at a required temperature TD [K] can be obtained by following theprocedures below.
(1) Obtain at least four valid Kca data.
(2) Approximating log Kca by a linear expression of 1/TK, determine the coefficients log K0
and c for the data described in paragraph (1) by using the least square method.

log K ca = log K 0 + c

1
TK ················································· (A.2)(3) Obtain the value of (Kca/K0)exp(c/TK) for each data item. When the number of data
outside the range of 0.85 through 1.15 does not exceed, the least square method used inparagraph (2) is considered valid. Here is an integer obtained by rounding down thevalue of (number of all data divided by 6). If this condition is not met, conduct additional
tests to add at least two data and apply the procedure in paragraph (2) to the data.
(4) The value of K0 exp(c/TD) is defined as the estimated value of Kca at TD. The estimatedvalue for the temperature corresponding to a specific value of Kca can be obtained from
TK = c/log(Kca/K0). If the condition specified in paragraph (3) is not met, these estimatedvalues are treated as reference values.
A.3

Evaluation

The straight-line approximation of arrheniusArrhenius plot for valid Kca data by interpolation
method are to comply with either the following (1) or (2):(1) The evaluation temperature of Kca (i.e. - 10 degree C) is located between the upper andlower limits of the arrest temperature, with the Kca corresponding to the evaluation
temperature not lower than the required Kca (e.g. 6,000 N/mm3/2 or 8,000 N/mm3/2), as
shown in Fig. A3-A.1.

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Fig. A3-A.1 Example for evaluation of Kca at - 10 degree C(2) The temperature corresponding to the required Kca (e.g. 6,000 N/mm3/2 or 8,000 N/mm3/2)
is located between the upper and lower limits of the arrest temperature, with thetemperature corresponding to the required Kca not higher than the evaluation temperature(i.e. -10 degree C), as shown in Fig. A3-A.2.

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Fig. A3-A.2 Example for evaluation of temperature corresponding to the required
Kca
If both of (1) and (2) above are not satisfied, conduct additional tests to satisfy this condition.

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Annex 3 - Appendix B

W31

Double tension type arrest test(cont)

B.1

Features of this test method

A double tension type arrest test specimen consists of a main plate and a secondary loadingtab. The main plate is a test plate for evaluating brittle crack arrest toughness. The secondary
loading tab is a crack starter plate for assisting a brittle crack to run into the main plate. After
applying a predetermined tension force and a temperature gradient to the main plate, asecondary force is applied to the secondary loading tab by a secondary loading device tocause a brittle crack to initiate and run into the main plate. The arrest toughness is evaluatedfrom the arrest temperature and the crack length in the main plate.
The narrow connection part of the main plate and the secondary loading tab in this test
suppress the flow of the tension stresses of the secondary loading tab into the main plate.
The values of arrest toughness obtained by this method can be considered the same as theresults obtained by the brittle crack arrest toughness test specified in Annex 3 of this UR.
The specifications described in Annex 3 of this UR shall be applied to conditions not
mentioned in this Appendix B.
B.2

Test specimen shapes

The recommended shapes of the entire double tension type arrest test specimen and thesecondary loading tab are shown in Figures A3-B.1 and A3-B.2, respectively. Clause 4.2 ofAnnex 3 of this UR is applied to the shapes of the tab plates and pin chucks.
Note: Because of the narrowness of the connection part, slight crack deviation may leadto failure of the crack to enter the main plate. The optimum shape design of thesecondary loading tab depends on the type of steel and testing conditions.

460

Secondaryloading tab

320

5
500

[mm]

Shaped for stress deconcentration(e. g., large curvature radius)

Figure A3-B.1 Example of shape ofentire test specimen

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80

200

Main plate

75

500

Machined foreasy brittle crack
initiation[mm]Figure A3-B.2 Example of shape of
secondary loading tab

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B.3

Temperature conditions and temperature control methods

Establish a temperature gradient in the main plate in order to evaluate its brittle crack arrest
toughness. The specifications for temperature gradients and methods for establishing thetemperature gradient are described in clause 5, Annex 3 of this UR. In addition, in the double
tension type arrest test, the secondary loading tab must be cooled. The secondary loading
tab is cooled without affecting the temperature gradient of the main plate. As in the coolingmethod for test specimens described in Annex 3 of this UR, cooling may be applied using a
cooling box and a coolant. The temperature of the secondary loading tab can be measured
using thermocouples as described in Annex 3 of this UR.
B.4

Secondary loading method

A secondary loading device is used to apply force to the secondary loading tab. The
secondary loading device shall satisfy the conditions below.
B.4.1 Holding methods of secondary loading device
To avoid applying unnecessary force to the integrated specimen, the secondary loading
device must be held in an appropriate way. Suspension type or floor type holding methods
can be used. In the suspension type method, the secondary loading device is suspended andheld by using a crane or a similar device. In the floor type method, the secondary loading
device is lifted and held by using a frame or a similar device.
B.4.2 Loading system
A hydraulic type loading system is most suitable for applying a force to the secondary loadingtab. However, other methods may be used. Clause 4.2 of Annex 3 of this UR is applied to theshapes of the tab plates and pin chucks.
B.4.3 Loading method
The method of loading the secondary loading tab shall be a pin type loading method. A
loading method other than a pin type may be used by agreement among the parties
concerned. The loading rate is not specifically specified because it does not have a direct
influence on the crack arrest behavior of the main plate.

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Annex 4 Outline of requirements for undertaking isothermal Crack Arrest Temperature(CAT) test
A4.1

Scope of application

A4.1.1 Annex 4 is to be applied according to the scope defined in UR W31.
A4.1.2 Annex 4 specifies the requirements for test procedures and test conditions whenusing the isothermal crack arrest test to determine a valid test result under isothermal
conditions and in order to establish the crack arrest temperature (CAT). Annex 4 is applicableto steels with thickness over 50mm and not greater than 100mm.
A4.1.3 This method uses an isothermal temperature in the test specimen being evaluated.
Unless otherwise specified in this Annex 4, the other test parameters are to be in accordancewith Annex 3ISO 20064: 2019.
A4.1.4 Table 3 of UR W31 gives the relevant requirements for the brittle crack arrest
property described by the crack arrest temperature (CAT).
A4.1.5 The manufacturer is to submit the test procedure to the Classification Society forreview prior to testing.
A4.2

Symbols and their significanceA4.2.1 Table A4-1 supplements Table A3-1 in Annex 3ISO 20064: 2019 with specificsymbols for the isothermal test.

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Table A4-1

Nomenclature supplementary to Table A3-11 in ISO 20064: 2019

SymbolUnit

Significance

t
L
W
aMN
LSG

mm
mm
mm
mm
mm

dSG
LEB - minmmmm

Test specimen thickness
Test specimen length
Test specimen width
Machined notch length on specimen edge
Side groove length on side surface from the specimen edge.
LSG is defined as a groove length with constant depth except
a curved section in depth at side groove end.
Side groove depth in section with constant depth
Minimum length between specimen edge and electron beam
re-melting zone front

LEB-s1, -s2

mm

LLTG
aarrestTtargetTtest
TarrestLength between specimen edge and electron beam re-melting
zone front appeared on both specimen side surfaces

mm
mm
°C℃
°C℃
°C℃

Local temperature gradient zone length for brittle crack runway
Arrested crack length
Target test temperature
Defined test temperature
Target test temperature at which valid brittle crack arrest
behaviour is observed

σ
SMYS

N/mm2
N/mm2

Applied test stress at cross section of W x t
Specified minimum yield strength of the tested steel grade to
be approved

CAT

°C℃

Crack arrest temperature, the lowest temperature, Tarrest,
at which running brittle crack is arrested

A4.3

Testing equipment

A4.3.1 The test equipment to be used is to be of the hydraulic type of sufficient capacity toprovide a tensile load equivalent to ⅔ of SMYS of the steel grade to be approved.
A4.3.2 The temperature control system is to be equipped to maintain the temperature in thespecified region of the specimen within ±2oC2℃ from Ttarget.
A4.3.3 Methods for initiating the brittle crack may be of drop weight type, air gun type or
double tension tab plate type.
A4.3.4 The detailed requirements for testing equipment are specified in 3 of Annex 3to be inaccordance with ISO 20064: 2019.
A4.4

Test specimens

A4.4.1 Impact type crack initiation
A4.4.1.1 Test specimens are to be in accordance with 4 of Annex 3ISO 20064: 2019, unlessotherwise specified in this Annex.

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A4.4.1.2 Specimen dimensions are shown in Figure A4-1. The test specimen width, W shallbe 500mm. The test specimen length, L shall be equal to or greater than 500mm.
A4.4.1.3 V-shape notch for brittle crack initiation is machined on the specimen edge of the
impact side. The whole machined notch length shall be equal to 29mm with a tolerance rangeof ±1mm.
A4.4.1.4 Requirements for side grooves are described in A4.4.4.

Figure A4-1 Test specimen dimensions for an impact type specimen
NOTE: Saw cut notch radius may be machined in the range 0.1mmR and 1mmR in order
to control a brittle crack initiation at test.
A4.4.2 Double tension type crack initiation
A4.4.2.1 Reference shall be made to Appendix B in Annex 3D in ISO 20064: 2019 for the
shape and sizes in secondary loading tab and secondary loading method for brittle crack
initiation.
A4.4.2.2 In a double tension type test, the secondary loading tab plate may be subject tofurther cooling to enhance an easy brittle crack initiation.
A4.4.3 Embrittled zone setting
A4.4.3.1 An embrittled zone shall be applied to ensure the initiation of a running brittle crack.
Either Electron Beam Welding (EBW) or Local Temperature Gradient (LTG) may be
adopted to facilitate the embrittled zone.
A4.4.3.2 In EBW embrittlement, electron beam welding is applied along the expected initial
crack
propagation path, which is the centre line of the specimen in front of the machined
V- notch.
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theembrittled zone. One side EBW penetration is preferable, but dual sides EB
penetration may be also adopted when the EBW power is not enough to achievecomplete penetration by one side EBW.

A4.4.3.4 The EBW embrittlement is recommended to be prepared before specimen contour
machining.
A4.4.3.5 In EBW embrittlement, zone shall be of an appropriate quality.
Note: EBW occasionally behaves in an un-stable manner at start and end points. EBWline is recommended to start from the embrittled zone tip side to the specimen edge withan increasing power control or go/return manner at start point to keep the stable EBW.
A4.4.3.6 In LTG system, the specified local temperature gradient between machined notchtip
and isothermal test region is regulated after isothermal temperature control. LTG
temperature control is to be achieved just before brittle crack initiation,nevertheless the steady temperature gradient through the thickness shall be ensured.
A4.4.4 Side grooves
A4.4.4.1 Side grooves on side surface can be machined along the embrittled zone to keep
brittle crack propagation straight. Side grooves shall be machined in the specified cases as
specified in this section.
A4.4.4.2 In EBW embrittlement, side grooves are not necessarily mandatory. Use of EBW
avoids the shear lips. However, when shear lips are evident on the fractured specimen, e.g.
shear lips over 1mm in thickness in either side then side grooves should be machined tosuppress the shear lips.
A4.4.4.3 In LTG embrittlement, side grooves are mandatory. Side grooves with the same
shape and size shall be machined on both side surfaces.
A4.4.4.4 The length of side groove, LSG shall be no shorter than the sum of the required
embrittled zone length of 150mm.
A4.4.4.5 When side grooves would be introduced, the side groove depth, the tip radius andthe open angle are not regulated, but are adequately selected in order to avoid any shear
lips over 1mm thickness in either side. An example of side groove dimensions are shown in
Figure A4-2.
A4.4.4.6 Side groove end shall be machined to make a groove depth gradually shallow
with a curvature larger than or equal to groove depth, dSG. Side groove length, LSG is defined
as a groove length with constant depth except a curved section in depth at side groove end.

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Figure A4-2 Side groove configuration and dimensions
A4.4.5 Nominal length of embrittled zone
A4.4.5.1 The length of embrittled zone shall be nominally equal toat least 150mm in both
systems of EBW and LTG.

Figure A4-3 Definition of EBW length
A4.4.5.2 EBW zone length is regulated by three measurements on the fracture surface after
test as shown in Figure A4-3, LEB-min between specimen edge and EBW front line, and LEB-s1
and LEB-s2.

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A4.4.5.3 The minimum length between specimen edge and EBW front line, LEB-min should be
no smaller than 150mm. However, it can be acceptable even if LEB-min is no smaller than
150mm-0.2t, where t is specimen thickness. When LEB-min is smaller than 150mm, a
temperature safety margin shall be considered into Ttest (See A4.8.1.2).
A4.4.5.4 Another two are the lengths between specimen edge and EBW front appeared on
both side surfaces, as denoted with LEB-s1 and LEB-s2. Both of LEB-s1 and LEB-s2 shall be nosmaller than 150mm.
A4.4.5.5 In LTG system, LLTG is set as 150mm.
A4.4.6 Tab plate / pin chuck details and welding of test specimen to tab plates
A4.4.6.1 The configuration and size of tab plates and pin chucks shall be referred to 4.2 ofAnnex 3ISO 20064: 2019. The welding distortion in the integrated specimen, which is weldedwith specimen, tab plates and pin chucks, shall be also within the requirement in 4.3 of Annex
3ISO 20064: 2019.
A4.5

Test method

A4.5.1 Preloading
A4.5.1.1 Preloading at room temperature can be applied to avoid unexpected brittle crack
initiation at test. The applied load value shall be no greater than the test stress. Preloading
can be applied at higher temperature than ambient temperature when brittle crack initiation is
expected at preloading process. However, the specimen shall not be subjected totemperature higher than 100oC100℃.
A4.5.2 Temperature measurement and control
A4.5.2.1 Temperature control plan showing the number and position of thermocouples is to
be in accordance with this section.
A4.5.2.2 Thermocouples are to be attached to both sides of the test specimen at a
maximum interval of 50mm in the whole width and in the longitudinal direction at the test
specimen centre position (0.5 W) within the range of ±100mm from the centreline in thelongitudinal direction, refer to Figure A4-4.

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Figure A4-4 Locations of temperature measurement

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A4.5.2.3

For EBW embrittlement

A4.5.2.3.1 The temperatures of the thermocouples across the range of 0.3W~0.7W in bothwidth and longitudinal directions are to be controlled within ± 2°C℃ of the target test
temperature, Ttarget.
A4.5.2.3.2 When all measured temperatures across the range of 0.3W~0.7W havereached Ttarget, steady temperature control shall be kept at least for 10 + 0.1 x t [mm]minutes to ensure a uniform temperature distribution into mid-thickness prior to applying test
load.
A4.5.2.3.3 The machined notch tip can be locally cooled to easily initiate brittle crack.
Nevertheless, the local cooling shall not disturb the steady temperature control across therange of 0.3W~0.7W.
A4.5.2.4

For LTG embrittlement:

A4.5.2.4.1 In LTG system, in addition to the temperature measurements shown in Figure A44, the additional temperature measurement at the machine notch tip, A0 and B0 is required.
Thermocouples positions within LTG zone are shown in Figure A4-5.

Figure A4-5 Detail of LTG zone and additional thermocouple A0
A4.5.2.4.2 The temperatures of the thermocouples across the range of 0.3W~0.7W in bothwidth and longitudinal directions are to be controlled within ± 2oC 2℃of the target test
temperature, Ttarget. However, the temperature measurement at 0.3W (location of A3 and B3)
shall be in accordance with A4.5.2.4.6 below.
A4.5.2.4.3 Once the all measured temperatures across the range of 0.3W~0.7W havereached Ttarget, steady temperature control shall be kept at least for 10 + 0.1 x t [mm] minutes
to ensure a uniform temperature distribution into mid-thickness, then the test load is applied.
A4.5.2.4.4 LTG is controlled by local cooling around the machined notch tip. LTG profile shallbe recorded by the temperature measurements from A0 to A3 shown in Figure A4-6.
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A4.5.2.4.5 LTG zone is established by temperature gradients in three zones, Zone I, Zone II
and Zone III. The acceptable range for each temperature gradient is listed Table A4-2.
Two temperatureA4.5.2.4.6 Temperature measurements at A2, B2 and A3, B3 shall besatisfied the following requirements:
T at A3, T at B3 < Ttarget – 2oC2℃
T at A2 < T at A3 – 5oC
T at B2 < T at B3 – 5oC
A4.5.2.4.7 No requirements for T at A0 and T at A1 temperatures when T at A3 and T at A2
satisfy the requirements above. Face B is the same.
A4.5.2.4.8 The temperatures from A0, B0 to A3, B3 should be decided at test planningstage refer to Table A4-2 which gives the recommended temperature gradientsin three zones, Zone I, Zone II and Zone III in LTG zone.

Figure A4-6 Schematic temperature gradient profile in LTG zone
Zone
Zone I
Zone II
Zone III1)

Table A4-2 Acceptable LTG range
Location from edge
Acceptable range of temperature gradient29mm – 50mm
2.00 °C℃/mm – 2.30 °C℃/mm
50mm – 100mm
0.25 °C℃/mm – 0.60 °C℃/mm
100mm – 150mm
0.10 °C℃/mm – 0.20 °C℃/mm

Note 1: The Zone III arrangement is mandatory
A4.5.2.4.9 The temperature profile in LTG zone mentioned above shall be ensured after
holding time at least for 10 + 0.1 x t [mm] minutes to ensure a uniform temperature
distribution into mid-thickness before brittle crack initiation.
A4.5.2.4.10 The acceptance of LTG in the test shall be decided from Table A4-2 based on
the measured temperatures from A0 to A3.

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A4.5.2.5

For double tension type crack initiation specimen:

A4.5.2.5.1 Temperature control and holding time at steady state shall be the same as thecase of EBW embrittlement specified in 5.2.3 or the case of LTG embrittlement specified in
Section A4.5.2.4.
A4.5.3 Loading and brittle crack initiation
A4.5.3.1

Prior to testing, a target test temperature (Ttarget) shall be selected.

A4.5.3.2 Test procedures are to be in accordance with 6 of Annex 3ISO 20064: 2019
except that the applied stress is to be ⅔ of SMYS of the steel grade tested.
A4.5.3.3
seconds

The test load shall be held at the test target load or higher for a minimum of 30
prior to crack initiation.

A4.5.3.4
theBrittle crack can be initiated by impact or secondary tab plate tension after all of
temperature measurements and the applied force are recorded.

A4.6

Measurements after test and test validation judgement

A4.6.1 Brittle crack initiation and validation
A4.6.1.1 If brittle crack spontaneously initiates before the test force is achieved or the
specified hold time at the test force is not achieved, the test shall be invalid.
A4.6.1.2 If brittle crack spontaneously initiates without impact or secondary tab tension
but after the specified time at the test force is achieved, the test is considered as a valid
initiation. The following validation judgments of crack path and fracture appearance shall be
examined.
A4.6.2 Crack path examination and validation
A4.6.2.1 When brittle crack path in embrittled zone deviates from EBW line or side groovein LTG system due to crack deflection and/or crack branching, the test shall be considered as
invalid.
A4.6.2.2 All of the crack path from embrittled zone end shall be within the range shown in
Figure A4-7. If not, the test shall be considered as invalid.

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Figure A4-7 Allowable range of main crack propagation path
A4.6.3Fracture surface examination, crack length measurement and their validation

A4.6.3.1 Fracture surface shall be observed and examined. The crack “initiation” and“propagation” are to be checked for validity and judgements recorded. The crack “arrest”
positions are to be measured and recorded.
A.4.6.3.2 When crack initiation trigger point is clearly detected at side groove root, otherthan the V-notch tip, the test shall be invalid.
A4.6.3.3
In EBW embrittlement setting, EBW zone length is quantified by threemeasurements of LEB-s1, LEB-s2 and LEB-min, which are defined in A4.4.5. When either or both of LEBs1 and LEB-s2 are smaller than 150mm, the test shall be invalid. When LEB-min is smaller than
150mm-0.2t, the test shall be invalid.
A4.6.3.4 When the shear lip with thickness over 1mm in either side near side surfaces ofembrittled zone are visibly observed independent of the specimens with or without side
grooves, the test shall be invalid.
A4.6.3.5 In EBW embrittlement setting, the penetration of brittle crack beyond the EBW
front line shall be visually examined. When any brittle fracture appearance area continued
from the EB front line is not detected, the test shall be invalid.
A4.6.3.6 The weld defects in EBW embrittled zone shall be visually examined. If detected,
it shall be quantified. A projecting length of defect on the thickness line through EB weld
region along brittle crack path shall be measured, and the total occupation ratio of the
projected defect part to the total thickness is defined as defect line fraction (See Figure A48). When the defects line fraction is larger than 10 %, the test shall be invalid.

Fig. A4-8 Counting procedure of defect line fraction
A4.6.3.7 In EBW embrittlement by dual sides’ penetration, a gap on embrittled zone
fracture surface which is induced by miss meeting of dual fusion lines is visibly detected at an
overlapped line of dual side penetration, the test shall be invalid.
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A4.7

Judgement of “arrest” or “propagate”

A4.7.1 The final test judgment of “arrest”, “propagate” or “invalid” is decided by the following
requirements of A4.7.2 through A4.7.6.
A4.7.2 If initiated brittle crack is arrested and the tested specimen is not broken into twopieces, the fracture surfaces should be exposed with the procedures specified in 6.3 and 6.4of Annex 3ISO 20064: 2019.
A4.7.3 When the specimen was not broken into two pieces during testing, the arrested
crack length, aarrest shall be measured on the fractured surfaces. The length from thespecimen edge of impact side to the arrested crack tip (the longest position) is
defined as aarrest.
A4.7.4 For LTG and EBW, aarrest shall be greater than LLTG and LEB-s1, LEB-s2 or LEB-min. If not,the test shall be considered as invalid.
A4.7.5 Even when the specimen was broken into two pieces during testing, it can beconsidered as “arrest” when brittle crack re-initiation is clearly evident. Even in the fracturesurface all occupied by brittle fracture, when a part of brittle crack surface from embrittled
zone is continuously surrounded by thin ductile tear line, the test can be judged as reinitiation behaviour. If so, the maximum crack length of the part surrounded tear line can bemeasured as aarrest. If re-initiation is not visibly evident, the test is judged as “propagate”.
A4.7.6 The test is judged as “arrest” when the value of aarrest is no greater than 0.7W. If not,the test is judged as “propagate”.
A4.8

Ttest, Tarrest and CAT determination

A4.8.1 Ttest determination
A4.8.1.1 It shall be ensured on the thermocouple measured record that all temperature
measurements across the range of 0.3W ~ 0.7W in both width and longitudinal direction are
in the range of Ttarget ±2°C℃ at brittle crack initiation. If not, the test shall be invalid. However,
the temperature measurement at 0.3W (location of A3 and B3) in LTG system shall be
exempted from this requirement.
A4.8.1.2 If LEB-min in EBW embrittlement is no smaller than 150mm, Ttest can be defined toequal with Ttarget. If not, Ttest shall be equaled with Ttarget + 5˚C5℃.
A4.8.1.3

In LTG embrittlement, Ttest can be equaled with Ttarget.

A4.8.1.4 The final arrest judgment at Ttest is concluded by at least two tests at the sametest condition which are judged as “arrest”.
A4.8.2

Tarrest determination

A4.8.2.1
arrestWhen at least repeated two “arrest” tests appear at the same Ttarget, brittle crack
behaviour at Ttarget will be decided (Tarrest = Ttarget).When a “propagate” test result is
included in the multiple test results at the same Ttarget, the Ttarget cannot to be
as Tarrest.

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A4.8.3CAT determination

A4.8.3.1 When CAT is determined, one “propagate” test is needed in addition to two “arrest”
tests. The target test temperature, Ttarget for “propagate” test is recommended to
select
5oC5℃ lower than Tarrest. The minimum temperature of Tarrest is determined as CAT.
A4.8.3.2 With only the “arrest” tests, without “propagation” test, it is decided only that CAT islower than Ttest in the two “arrest” tests, i.e. not deterministic CAT.
A4.9

Reporting

The following items are to be reported:(i)

Test material: grade and thickness(ii)

Test machine capacity(iii)

Test specimen dimensions: thickness t; width W and length L; notch details andlength aMN, side groove details if machined;(iv)

Embrittled zone type: EBW or LTG embrittlement(v)

Integrated specimen dimensions: Tab plate thickness, tab plate width, integrated
specimen unit length including the tab plates, and distance between the loading
pins, angular distortion and linear misalignment(vi)

Brittle crack trigger information: impact type or double tension. If impact type, drop
weight type or air gun type, and applied impact energy.

(vii)

Test conditions; Applied load; preload stress, test stress- Judgements for preload stress limit, hold time requirement under steady teststress.

(viii)

Test temperature: complete temperature records with thermocouple positions formeasured temperatures (figure and/or table) and target test temperature.
- Judgements for temperature scatter limit in isothermal region.
- Judgement for local temperature gradient requirements and holding timerequirement after steady local temperature gradient before brittle crack trigger, if
LTG system is used.

(ix)

Crack path and fracture surface: tested specimen photos showing fracturesurfaces on both sides and crack path side view; Mark at “embrittled zone tip” and“arrest” positions.
- Judgment for crack path requirement.
- Judgment for cleavage trigger location (whether side groove edge or V-notchedge).

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(x)

Embrittled zone information:
When EBW is used: LEB-s1, LEB-s2 and LEB-min(cont)- Judgement for shear lip thickness requirement- Judgment whether brittle fracture appearance area continues from the EBW
front line
- Judgement for EBW defects requirement- Judgement for EBW lengths, LEB-s1, LEB-s2 andLEB-min requirements
When LTG is used: LLTG
- Judgment for shear lip thickness requirement
Test results:
When the specimen did not break into two pieces after brittle crack trigger,arrested crack length aarrest
When the specimen broke into two pieces after brittle crack trigger,- judgement whether brittle crack re-initiation or not.
If so, arrested crack length aarrest:- Judgement for aarrest in the valid range (0.3W < aarrest ≤ 0.7W)- Final judgement either “arrest”, “propagate” or “invalid”
(xi)
A4.10

Dynamic measurement results: History of crack propagation velocity, and strainchange at pin chucks, if needed
Use of test for material qualification testing

Where required, the method can also be used for determining the lowest temperature atwhich a steel can arrest a running brittle crack (the determined CAT) as the material property
characteristic in accordance with A4.8.3.

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Annex 5 Approval Scheme of Small-scale Test Methods for Brittle Crack Arrest
Steels
A5.1.

Scope

A5.1.1 This Annex specifies the approval scheme of small-scale test methods which areused for product testing (batch release testing) of brittle crack arrest steels specified as Table
3 of this UR.
A5.1.2 Unless otherwise specified in this Annex, Annex 1 of this UR and/or Annex 2 of this
UR are to be followed.
A5.2.

Approval Application

A5.2.1 The manufacturer is to submit to the Classification Society the following documents:
a)
b)

c)
d)
e)
f)
g)

Application for approval of small-scale test procedure specification
Small-scale test procedure specification including the following items at least:・ Applicable material grades, thickness range, deoxidation practice, heat treatment,etc.
・ Types and methods of small-scale tests
・ Sampling positions in plate thickness direction and final rolling direction of test
specimens
・ Size and dimension of test specimens
・ Number of test specimens
・ Test conditions, such as test temperature
・ Acceptance criterion
・ Example of format of test report・ Example of product inspection certificate including small-scale test results
・ Handling of the products when small-scale test results do not satisfy the criterion
Mechanism of achieving the brittle crack arrest properties of brittle crack arrest steels
Technical background for enabling the evaluation of brittle crack arrest properties bysmall-scale test methods considering the mechanism specified in above c).
Procedure of the evaluation for the brittle crack arrest properties of brittle crack arrest
steels by small-scale test results.
Data records which validate the correlation between small-scale test results and the large
brittle crack arrest test results of brittle crack arrest steels whose number can satisfy therequirement for minimum data number given in A5.3.3
Proposed test plan for approvalA5.2.2 Small-scale test procedure specification is to be prepared in accordance with A5.3 ofthis Annex.
A5.2.3 Where the manufacturer proposes to change any part of the approved small-scale
test procedure specification, then the manufacturer is to submit to the Classification Society
the documents which can cover all items specified in Annex A5.2.1 of this UR.
A5.2.4 The documents confirming the reason for the change shall be submitted to identify
the impact of those changes on the existing procedure, and the proposed actions to address
any such impacts.

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A5.3.

Establishment of Procedure Specification for Small-scale TestingA5.3.1 General
A5.3.1.1 Small-scale test methods are to be determined based on the manufacturer’s own
technical philosophy with regard to achieving the brittle crack arrest properties of brittle crackarrest steels. Furthermore, description of an appropriate correlation between large scale
brittle crack arrest properties and small-scale test results is to be required, and theacceptance criterion of the small-scale test are to be determined, based on the followings:
・
・
・
・
・
・

Mechanism of achieving the suitable brittle crack arrest properties
Sampling position and direction
Frequency of sampling
Small-scale test methodology
Demonstrated correlation between brittle crack arrest test results and small-scale test
results
Derivation of small scale testing acceptance criterion based on the statistical analysis

A5.3.1.2 The manufacturer shall prepare the small-scale test procedure specification inaccordance with the following A5.3.2 through A5.3.5.
A5.3.2 Types and Methods of TestingA5.3.2.1 Types, methods, dimension and positions as well as direction of test specimens,
etc. of small-scale tests are to be specified by the manufacturer, and approved in accordancewith this UR.
A5.3.2.2 In general, the test method should reproduce the crack initiation, propagation andarrest feature by such as the following test method.
・・Combination of test methods, e.g. NRL drop weight test and V-notch Charpy impact test
One test method, e.g. press-notch Charpy impact test or side-section drop weight test

A5.3.2.3 In general, brittle crack arrest properties of brittle crack arrest steels are to bepredicted using a regression equation on the relationship between small scale test result (e.g.
transition temperature obtained by small scale tests) and large scale brittle crack arrest test
result (e.g. Kca or temperature corresponding to the specific brittle crack arrest properties).
Other approaches can be used subject to the approval of the Classification Society.
NOTE: Table A5-1, Table A5-2 and Table A5-3 give the examples of small scale test
methods.
A5.3.2.4 For determination of test methods, the manufacturer should confirm theapplicability of these test methods to their brittle crack arrest steels theoretically taking into
account the methodology of test methods, their own mechanism of achieving the brittle crackarrest properties, and sampling positions of test specimens (See A5.3.1.1). Then, themanufacturer should also submit the technical background for determination of small-scale
test methods to the Classification Society as given in A5.2.1.
A5.3.3 Testing Data
A5.3.3.1 Selection of test plates

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A5.3.3.1.1 Brittle crack arrest tests and small-scale tests are to be conducted for eachmaterial grade (including all suffixes) of brittle crack arrest steels in accordance with A5.3.3 ofthis Annex.
A5.3.3.1.2 Brittle crack arrest tests and small-scale tests are to be carried out on at least 12
test plates, in accordance with A5.3.3.1.3, by which these test results can reliably estimate
brittle crack arrest properties of brittle crack arrest steels.
NOTE: “One test plate” means “the rolled product from a single slab or ingot if this isrolled directly into plates” as defined in URW11.
A5.3.3.1.3 In order to ensure appropriate correlation between small-scale test results andbrittle crack arrest properties with various manufacturing conditions of steel plates, the steel
plates should be representative for each combination of thickness range and heat sample toinclude:・・The intended maximum and minimum plate thickness;
Different heats are to be chosen for each thickness.

Furthermore, the above test plates are to include a fixed number of steel plate(s) whosebrittle crack arrest properties (i.e. brittle crack arrest test results) do not comply with therequirements specified in Table 3 of this UR. Such a number should be at least one, but notexceeding one quarter of all test plates. Manufacturing process of these test plates can bedifferent (or intentionally altered from the approved manufacturing process) from that of thebrittle crack arrest steels to which the small-scale test method is applied. It is recommended
that the strength grade of these test plates (non-compliant with the relevant requirements ofbrittle crack arrest properties) are similar to that of the brittle crack arrest steels.
Where the manufacturer has requested approval for only a single thickness, the thickness oftest plates can be only a single thickness. In this case, at least four steel plates for eachcombination of thickness (single thickness) and heats (three different heats) should be used,
and the applicable thickness of the small scale test is only that single thickness condition.
A5.3.3.1.4 Brittle crack arrest steels used for the approval test of manufacturing process ofthese steels (and its approval test results) can also be used as the test plates specified inA5.3.3.1.3
A5.3.3.1.5 Brittle crack arrest test specimens and small-scale test specimens are to be takenfrom the same test plate.
A5.3.3.1.6 A decrease of the total of the indicated number of test plates may be accepted by
the Classification Society in the following (a) or (b) cases:(a) When the manufacturer applies a small-scale test procedure specification to multiple
material grades, and the manufacturing process and mechanism to ensure the brittle crackarrest properties of these different material grades are the same.
(b) When a small-scale test procedure specification is already approved by the Classification
Society for one or some material grades, and the manufacturer applies similar small-scale
test procedure specification to the other material grade(s), and the manufacturing process
and mechanism to ensure the brittle crack arrest properties of these different material
grades are same.
A5.3.3.2

Brittle crack arrest tests

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A5.3.3.2.1 Brittle crack arrest tests are to be carried out for each test plate in accordancewith A2.3.3, Annex 2 of this UR.
A5.3.3.2.2 Where brittle crack arrest tests are carried out for evaluation of Kca, Kca at a
specific temperature is to be obtained in accordance with A3.3 of Annex 3.
A5.3.3.2.3 Where brittle crack arrest tests are carried out for evaluation of CAT, deterministic(actual) CAT is to be obtained in accordance with A4.8.3 of Annex 4.
A5.3.3.3

Small-scale tests

A5.3.3.3.1 Small-scale tests are to be carried out in accordance with small-scale test
procedure specification to be approved for each test plate.
A5.3.3.3.2 In general, the test specimens of small-scale tests are to be taken with theirlongitudinal axis parallel to the final rolling direction of the test plates.
A5.3.3.3.3 The test specimens of small-scale tests are to be taken from the specified
positions in plate thickness direction of the test plates, as given in A5.3.2.3.
A5.3.4 Validation of Correlation
A5.3.4.1 A regression equation on the relationship between brittle crack arrest property
obtained from brittle crack arrest test and single or multiple small-scale test results is to beestablished. For brittle crack arrest properties, a specific temperature (e.g. TKca6000 in BCA1,
TKca8000 in BCA2 or CAT) or the Kca value at -10℃ may be used.
A5.3.4.2 The validity of the regression equation shall be examined to predict brittle crackarrest properties with enough accuracy. The correlation in brittle crack arrest properties
between the calculated values from small scale tests and the brittle crack arrest test results
shall be assured by using the value of twice the standard deviation (2σ). When using
temperature for brittle crack arrest property, 2σ shall not be greater than 20℃. In other cases(e.g. Kca value at -10℃), an upper limit of 2σ shall be established with the agreement of theClassification Society.
NOTE：
Calculation procedure of the standard deviation (σ) is given as follows:σ=n1( yi − xi )2∑(n − 1) i =1

n: number of test plates
yi: brittle crack arrest property obtained from brittle crack arrest test for one test platexi: brittle crack arrest property estimated from small scale tests for one test plateA5.3.5 Acceptance Criterion
A5.3.5.1 Acceptance criterion of brittle crack arrest steels by the small-scale tests is to be
proposed by the manufacturer based on the regression equation which is assured in thecorrelation with brittle crack arrest properties in A5.3.4 above. The criterion is to be
determined so that regression equation can predict brittle crack arrest properties on safety
side, considering the scatter of brittle crack arrest properties from the predicted value by the
regression equation.

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A5.3.5.2 Unless otherwise agreed by the Classification Society, an acceptance criterion ofsmall-scale tests is to be determined by following procedures:(a) For correlation by means of temperature(i) The required temperature (see Fig A5-1) is obtained by subtracting 2σ (℃) from thebrittle crack arrest steel specification in Table 3 of this UR, that is -10-2σ (℃), where 2σ
is given in A5.3.4.2.
TKca6000 and TKca8000 in Fig. A5-1 are the temperatures at which the Kca value of steel plates
equals 6,000N/mm3/2 and 8,000N/mm3/2, respectively.
(ii) The temperature predicted from the small-scale test results through the regression
equation shall be no higher than the value of -10-2σ(℃).

Fig. A5-1 Example for determination of acceptance criterion of small-scale test forcorrelation by means of temperature(Note: This is only a schematic and may not represent the actual data obtained)(b)

For correlation by means of brittle crack arrest toughness (Kca):(i) The required Kca (see Fig. A5-2) is obtained by adding 2σ (N/mm3/2) to the brittle crackarrest steel specification in Table 3 of this UR, that is either 6,000+2σ(N/mm3/2) in BCA1 or
8,000+2σ(N/mm3/2) in BCA2, where 2σ is given in A5.3.4.2.
(ii) The Kca value predicted from the small-scale test results through the regression
equation shall be no smaller than the value of 6000+2σ(N/mm3/2) for BCA1, or
8000+2σ(N/mm3/2) for BCA2.

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Fig. A5-2

Example for determination of acceptance criteria of small-scale test forcorrelation by means of brittle crack arrest toughness (Kca)(Note: This is only a schematic and may not represent the actual data obtained)

A5.4.

Approval Tests

A5.4.1 General
A5.4.1.1 In order to confirm the validity of the submitted technical documents specified inA5.2.1, approval tests are to be carried out.
A5.4.1.2

Approval test plan is to be approved by the Classification Society prior to testing.

A5.4.1.3 Considering the contents of the submitted technical documents specified inA5.2.1, the Classification Society may require additional tests in the following cases:a)When the Classification Society determines that the number of brittle crack arrest
tests or small-scale tests is too few to adequately confirm the validity of the acceptancecriterion of small-scale tests (See A5.3.3.1);b)
When the Classification Society determines that the testing data obtained for setting
the acceptance criterion of small-scale tests varies too widely (See A5.3.4.2), or that the data
is clustered producing a biased correlation curve;c)When the Classification Society determines that the validity of brittle crack arrest test
results or small-scale test results for setting the acceptance criterion of small-scale tests is
insufficient, or has some flaws during tests and/or for test results (See A5.3.3.2 and A5.3.3.3);
andd)Others as deemed necessary by the Classification Society.
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A5.4.2 Extent of the approval tests
A5.4.2.1 Extent of the approval tests is to be in accordance with 2.1, Annex 1 and 3.1,
Annex 2 of this UR.
A5.4.3 Type of tests
A5.4.3.1

Brittle crack arrest tests

A5.4.3.1.1 Brittle crack arrest tests are to be carried out in accordance with A2.3.3, Annex 2of this UR.
A5.4.3.1.2 Where brittle crack arrest tests are carried out for evaluation of Kca, Kca at a
specific temperature (TKca6000 or TKca8000) is to be obtained in accordance with A3.3 of Annex
3.
A5.4.3.1.3 Where brittle crack arrest tests are carried out for evaluation of CAT, deterministic
CAT is to be obtained in accordance with A4.8.3 of Annex 4.
A5.4.3.2

Small-scale tests

A5.4.3.2.1 Small-scale tests are to be carried out in accordance with A5.3.3.3.
A5.5.

Results

A5.5.1Results of test items and the procedures shall comply with the test programapproved by the Classification Society.
A5.5.2For the brittle crack arrest test results, the manufacturer is to submit to theClassification Society the brittle crack arrest test reports in accordance with Annex 3 of thisUR for Kca and Annex 4 of this UR for CAT.
A5.5.3For small-scale test results, the manufacturer is to submit to the Classification
Society the small-scale test reports in accordance with the example of format of test reports
submitted as specified in A5.2.1 b) of this Annex.
A5.6.

Approval

Upon satisfactory completion of the survey and tests, and satisfactory confirmation of thesubmitted technical documents, the approval for small scale test procedure specification is
granted by the Classification Society.

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Table A5-1 Example of small-scale test method
using NRL drop weight test and V-notch Charpy impact test (Informative)
Test type：
NRL drop weight test and V-notch Charpy impact test
Standard：
ASTM E208:2020 and ISO 148-1:2016
Sampling positions NRL drop weight test: at surfaceof test specimens： V-notch charpy impact test: 1/4 of thickness
Length direction of
Parallel to the final rolling direction of test plate
test specimen：

TKca = α・ ( NDTT + 10) + β・ vTrs + 153(t − 5)1/13 − 170.5
Regression
equation：

Notes：

Test type：
Standard：
Sampling
position of
test
specimen：
Lengthdirection of
test
specimen：

Regression
equation：

Notes：

TKca：Temperature at Kca of 6,000N/mm3/2 or Kca of 8,000N/mm3/2, (℃)
NDTT： Nil-ductility transition temperature (℃)
vTrs：Transition temperature of the absorbed energy (℃)
t：thicknessα, β(1)：constant(1) α and β are determined by comparing small-scale test results withbrittle crack arrest test results.

Table A5-2 Example of small-scale test method
using pressed-notch Charpy impact test (Informative)
Pressed-notch Charpy impact test
Dimension, shape, introducing method of notch: Manufacturer’s proposal
Others: ISO148-1:2016
1/2 of thickness

Parallel to the final rolling direction of test plate

TKca =α pTEγJ + β
TKca：Temperature at Kca of 6,000N/mm3/2 or Kca of 8,000N/mm3/2, (℃)
pTEγJ：Test temperature at absorbed energy of γ (J), (℃)
α and β：Constantγ：Absorbed energy at brittle fracture surface ratio of δ (%),(J)(1) α, β, γ and δ are determined by comparing small-scale test resultswith brittle crack arrest test results.

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Test type：
Standard：

Table A5-3 Example of small-scale test method
using Side-section drop weight test (Informative)
Side-section drop weight test
Dimension: P-2 type of ASTM E 208 2020
Others: ASTM E 208:2020
1/2 of thickness and side-section

Sampling positionsof test specimens：

Length direction oftest specimen：

Parallel to the final rolling direction of test plateside
TKca = α + β・ TNDT
+ γ・ t 1.5

Regression
equation：

Notes：

TKca：Temperature at Kca of 6,000N/mm3/2 or Kca of 8,000N/mm3/2, (℃)
side
TNDT
: Nil-ductility transition temperature obtained by side-section drop
weight test, (℃)
t : thickness
α, β,γ(1)：constant(1) α, β and γ are to be determined by comparing small-scale test
results with brittle crack arrest test results.

End ofDocument

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