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NBSIR 84-1699

EXPERIMENTAL RESULTS FOR

FITNESS-FOR-SERVICE ASSESSMENT

OF HY130 WELDMENTS

National Bureau of Standards

U.S. Department of Commerce

Boulder, Colorado 80303

March 1984

ac

NBSIR 84-1699

.US'}

EXPERIMENTAL RESULTS FOR

^

FITNESS-FOR-SERVICE ASSESSMENTTt

OF HY130 WELDMENTS

D. T. Read

Fracture and Deformation Division

National Bureau of Standards

Boulder, Colorado 80303

March 1984

Sponsored by:

Naval Sea Systems Command (SEA 05R25)

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Contents

Page

1. Introduction 1

2. Materials 3

3. Techniques 3

4. Results and Discussion 6 4.1 Uncracked Weldment 6 4.2 Through Cracks 8 4.3 Surface Cracks 11

5. Conclusions 13

6. Acknowledgments 14

7. References 14

Experimental Results for Fi tness-for-Servi ce Assessment of HY130 Weldments

D. T. Read Rational Bureau of Standards, Boulder, Colorado

Applied J-integral values for through and surface cracks in HY130 weldments and for surface cracks in HY130 base metal have been measured using a previously developed

technique. The applied J-integral is taken as a measure of the crack driving force. The results confirmed previous conclusions, namely, the strong effect of deformation pattern on applied J-integral values, the utility of the J-integral estimation curve for

f i tness-for-servi ce assessment in cases of gross section yielding (crack size less than 1 percent of load-bearing cross-section), and the need to consider ligament yielding behind

surface cracks. Additional conclusions for surface cracks and for weldments were: surface-crack depth controls crack driving force; overmatching weld metal strength greatly

reduces crack driving force for strains above yield; the relationship between crack length

and crack driving force for cases of residual stress is similar to that for applied stress;

for a crack in a weld transverse to the tensile axis, gross section yielding occurs if the crack intercepts less than 1.5 percent of the load-bearing cross section; the effective

crack size for J-integral estimation is 0.75 of the actual crack depth for crack aspect

ratios of 12 or less, and is no larger than the crack depth for any crack length; the line

J-integral in the plane perpendicular to the surface crack root at the crack center is sufficiently path independent to allow direct experimental measurement of the J-integral.

Key words: design curve; elastic-plastic fracture mechanics; gross section

yielding; net section yielding; residual stress; surface crack.

1. Introduction

Indications of the presence of surface flaws can be found by non-destructive inspection of structures during construction and repair. Even if no indications are found, the existence of flaws

smaller than the detection threshold must be considered possible, especially in weldments. Structural

integrity in the presence of flaws is assured by a combination of sufficiently small flaws, sufficiently tough structural material, and sufficiently low applied stresses and strains. The needed

balance among flaw size, material toughness, and applied stress and strain has been obtained by the Navy in the past by accepting only excellent welding workmanship to minimize flaws, by using only the toughest available materials, and by controlling stress and strain levels according to experience,

model tests, and engineering judgment. Costs associated with material procurement and weld repair

provide incentive for using a more quantitative approach to selection of plate and weld quality, in order to ensure that as much construction as possible is accomplished with the available resources.

This report was prepared as part of the Fracture Control Technology program under the sponsorship of Dr. H. H. Vandervel dt , Naval Sea Systems Command (SEA 05R25). The effort, was directed by Mr. John P. Gudas, David Taylor Naval Ship R&D Center, under Program Element 62761N, Task Area SF-61-544- 504

.

1
During an investigation of Navy fracture control requirements [1], it was reported that rational

procedures are needed to provide answers to several recurring questions, including:

1. How much material toughness is sufficient for a given

appl ication?

2. How large a defect can be tolerated in a given structural

element, particularly in a weld?

Fitness for service assessment (FFSA) relates actual flaw sizes, fracture mechanics characterization

of material toughness, and quantitative levels of applied stress and strain. Therefore, FFSA allows

quantitative evaluation of the balance among flaw size, material toughness, and applied stress and strain. This is especially useful for decisions on new materials and applications where experience

is lacking. Unfortunately, no fully-developed f i tness-f or-service assessment method applicable to surface flaws in weldments exists.

This report describes experimental results in support of f itness-for-service assessment of HY130

weldments. It extends previous reports on FFSA for base metals [2, 3] to weldments and describes

additional results of experiments on surface flaws in both base metal and weldments.

The present approach uses the J-integral [4-7] as the measure of fracture toughness and of the driving force for fracture. Required toughness can be related to applied strain and flaw size in HY130 through the J-integral estimation curve for gross section yielding (Fig. 1), provided that net section yielding [2, 3] is avoided. The curve of figure 1 lies at the upper bound of experimental

results for applied J-integral as a function of strain for gross section yielding for a variety of through flaws in HY130 tensile panels. The curve is expressed algebraically as [3]:

j = 2e 2

, e^l (la)

j = 4(e-l) + 2 , e>l (lb)

In these equations, j denotes normalized J-integral, given by

j = EJ/Uaa 2) (2a)

where E is Young's modulus, J is applied J-integral, a is crack size (taken in the usual fracture

mechanics usage as crack length per crack tip for through cracks), and is material yield strength.

The normalized strain, e, is given as

e = e/£y (2b)

where e is applied tensile strain remote from the crack and e = a /E. The

y y J-integral estimation curve of eq (1) is at the upper bound of previously published estimation curves

[3, 8-10],

Both welds and surface flaws complicate the dependence of required fracture toughness on applied

stress and strain and on crack size. Weld metal generally has different tensile properties than base plate; welds can be overmatching (higher strength than base plate) or undermatching. In the HY130

weldments used in the present study the weld metal itself was overmatching, but an undermatching

heat-affected-zone (HAZ) occurred beside the welds. Weld over- or undermatching can have a strong

effect on the strain pattern in and around the weld. It, therefore, can have a strong effect on required toughness because of the close connection between strain patterns and required fracture

toughness. This connection was emphasized in the previous report on HY130 base plate [3]. Overmatched

welds tend to require lower toughness; but often less material toughness is available in overmatched

weld metal. Residual stresses in weldments can also contribute to the driving force for fracture,

and so must be accounted for in FFSA. For surface flaws, the zone of plasticity can spread from the

2
flaw root through the plate to the back face [3, 11-14], a process referred to as ligament yielding

(LY). Ligament yielding is an intermediate process between elastic behavior and full yielding, and requires explicit treatment in FFSA. Furthermore, gross section yielding (GSY) around surface flaws cannot be treated directly using the J-integral estimation curve for through flaws until the effective flaw size for surface flaws for GSY is defined.

Experimental results leading to a method for FFSA for through flaws in weldments and for surface

flaws in both base metal and weldments are described in this report.

2. Materials

The materials used in the present study were HY130 base metal and HY130 weldments. The base

metal is described in the previous report [3], The weldments were made using the GMAW process with

standard Naval shipyard procedures. A diagram showing the location of the weld passes is shown in Fig. 2a. The chemical composition of the weld metal as obtained from analysis of a specimen cut from

a weldment is given as Table 1. The weldment tensile properties are not identical with the base

metal. As shown by a test of an uncracked tensile panel with a weldment transverse to the tensile

axis, discussed below in the "Results" section, the heat affected zone (HAZ) has a lower yield

strength but a higher ultimate strength than the weld metal, and the weld metal itself has higher

yield and ultimate strengths than the base metal.

Table 1. Chemical composition by weight percent of HY130 weld metal used in the present study.

Nj_ Mn 4.8 1.4

Mo Cr C Cu Si

1.0 0.68 0.086 0.12 0.34

P $ 0.003 0.004V Ti Co

< 0.01 < 0.01 < 0.01

Fe

bal

The toughness of the weld metal used in the present study was tested by the J-R curve technique.

Comapct tensile specimens of the standard 1T-CT geometry were used. Crack growth was monitored by the compliance technique. The compliance measured crack growth values were rescaled linearly to agree with the actual final crack lengths for presentation in Fig. 2b. The three critical J-integral

values were scattered considerably, from 66.5 kN/m (380 lb/in.) to 161 kN/m (922 lb/in). The slopes

of the tearing portions of the R-curves were in good agreement, with values all approximately

37 MN/m? (5.3 ksi). The large intervals of crack growth between data points for two of the specimens

occurred because the tearing was only marginally stable. The compliance of the loading apparatus

used, exclusive of the specimen itself, was approximately 3 x 10' 5 mm/N (5 x 10' 6 in/lb).

3. Techni ques

The analytical approach and experimental techniques used in the present study for direct experimental measurement of the contour J-integral were described in detail in the previous report. The J-integral was given as [4]:

J = / Wdy - f • 3u/ax ds ,

3
where W is strain work density, /a^de^; o.^ and are the stress and strain tensors; t is the traction vector across the contour of integration, r, u is the displacement vector; ds is increment

of displacement along the contour of integration and x and y are Cartesian position coordinates, with

the crack perpendicular to the y direction propagating in the x direction. The integrand terms of the J-integral were obtained from strain gage and linear variable differential transformer (LVDT) measurements. The J-integral was computed by numerical integration. The analytical approach and experimental techniques used to obtain the J-integral were discussed at length in the previous report

[3], It was concluded that uncertainty in the measured J-integral values themselves was about ±10 percent, and that material variability could raise this uncertainty in specimen-to-specimen comparisons.

Use of the J-integral and other integrals for three-dimensional flaws has been discussed in the recent literature [15,16]. For surface flaws, the line integral form of J is not in general path

independent. The surface integral form of J is surface-independent, but it provides only an average

value over the whole crack front. By choosing a special surface enclosing a thin slice of the specimen penetrated by the crack front it can be shown that for contours in two special planes, one

in the surface of the plate enclosing the end of the crack and one perpendicular to the surface

cutting through the crack front, the line integral form of J is path-independent if an area integral

containing terms in is insignificant [16]. In the area integral, o

^ is a stress tensor component,

where k is the x, y, or z direction and the z direction is parallel to the crack front. The hypothesis that the area integral in question is insignificant is supported by arguments

based on: nearness of strain fields near the two special contours to plane-stress or plane-strain

fields, smallness of out-of-plane stress-displacement gradient products, similarity of strain fields

in the special planes to strain fields in face-cracked or center-cracked specimens, analogy of J-integral to crack-opening-displacement, and numerical evaluations of J-integrals.

The strain field near the side surfaces of a surface-cracked specimen must be nearly a plane-stress field, because no tractions exist at the side surfaces to create stress in the out-of-plane directions. Since J is path-independent under plane-stress conditions, it should be essentially path-independent for line contours in the surface of a surface-cracked specimen. The strain field near the center of a surface-cracked specimen must be nearly plane-strain near the crack, because of constraint provided by the specimen geometry. Away from the crack, plane-stress

conditions are expected because of the absence tractions at the specimen sides. But exactly the same conditions exist in specimens widely used for J-integral measurements. Therefore, path independence

should pose no more of a problem for surface cracks than it does for more usual specimens used for

J-integral measurements.

All terms inside the area integral involve the derivative with respect to the out-of-plane

direction (z direction) of the product a^

z u^

x (sum on k implied) where z is the crack propagation

direction. This product vanishes on both of the two special contours. It includes only out-of-plane

stresses, which are not driven directly by applied tractions. Therefore, the quantity 3/3z • (o^

u^

x

) should be insignificant on the two special planes. The strain field near the face of a surface-cracked specimen should be similar to the field near

the face of a through-cracked specimen with a crack of the same length. Therefore, the J-integral on the special contour in the specimen face should be as path-independent as the J-integral in a center- cracked panel. The strain field in the other special plane, the longitudinal mid-plane perpendicular

to the crack root in a surface-cracked specimen, should be similar to the strain field in the same plane in a specimen with a face crack, that is, a full width surface crack. Therefore, the J-integral

for integration paths in such a plane should be path-independent, as it is for the face-cracked

specimen.

4
The crack-opening-displacement 6 has been used extensively as a measure of the crack driving

force for surface cracks H3]. The J-integral obtained using the two special contours is closely

related to the crack-opening-displacement. For plastic strain aJ = a*A<5 where AJ is en increment of

J, A6 is an increment of 6, and o is material flow strength [3], Therefore, the J-integral obtained

on the two special contours should be as good a measure of the crack driving force as the crack-openingdisplacement, and so it should be essentially path independent.

Finite element analysis of model specimens containing surface cracks under elastic-plastic

conditions will soon be possible. Evaluation of the J-integral for such models should definitively

settle the question of the significance of the area term in the line J-integral in three-dimensional

strain fields. Indications of the relative size of the area integral can be found in current studies

of through cracks. It was found [15] that J, an integral equal to the sum of the line integral plus

the area term, was equal to the Merkl e-Corten expression for the J-integral for a compact specimen.

Since the Merkl e-Corten expression was intended to give the line integral part of J, it is indicated

that the area term was small for the case considered. If similar results occur for surface cracks,

the utility of the line J-integral for surface cracks will have been established.

For the present study it is assumed that the line J-integral for surface flaws is sufficiently

path-independent for practical purposes.

The path independence of J in weldments also requires consideration. Figure 3 shows some integration paths in a welded tensile panel with a through crack. The weld boundary remains at the same in-plane position through the whole thickness. One wishes to evaluate the J-integral on the major contour F'E'D'C'B' ABCDEF. Consider three minor contours, F'E'B'ABEF, EBCDE and E'D'C'B'E'.

Each of these minor contours is within a homogenous material, therefore, J-integrals on each of these

are path-independent. The relationship between the J-integral around contour F'E'B'ABEF, within the weld, around contour EBCDE, within the base metal, around contour E'D'C'B'E', within the base metal,

and J, on contour F ' E' D' C

' B' ABCDEF , is now sought. Let the notation J ( X Y ) indicate the J integral

along contour segment XY. Let the notation J w

(XY) indicate that the contour XY is traversed within

weld-metal; Jg(XY) indicates the J-integral within the base metal along contour segment XY. Path- independence has been established for the following integrals:

J w

= J w

(F ' E '> + Jw

(E ' B,) + J w(B ' AB) + J W(BE) + J W(EF) (4a)

J

B = J

b (EB) + JB (BC) + Jb (CD) + JB (DE) = 0 , (4b)

J B

. = J b .(E'D') + J

b ,(D'C') + Jb .(C'B') + Jb ,(B'E') = 0 . (4c)

The integrals Jg and Jg , are not only path-independent, but are also zero because they enclose no singularities. The sum of these integrals is formed:

J = J + J D + J D , ( 5a

w w B B

= J w

(F'E') + J B

, (E ' D

' ) + Jg , (D ' C' ) + J

B

( C

' B ' ) + J W (B'AB) +

J b (BC) + J

b (CD) + Jb (DE) + J w

(EF) + [J w( E' B

' ) + (5b)

J

b .(B'E')] + Cw

( BE ) + Jg(EB)

Consider the bracketed term:

J

r j = J w

( BE ) + J

b (EB) = 0 (6a)

This term is zero by mutual cancellation' because segment EB has no extent along the y direction,

outward tractions are opposite and displacements are equal along the weld-base metal interface, and

the increment of path length ds is positive for both segment integrals.

5
Similarly,

Jf

] = J w

( E

' B ' ) + Jg , ( B

' E ' ) = 0 (6b) But the resulting expression for J , from eq (5b) is just the segment-by-segment expression of J, the w J-integral around the major contour:

J = J (7) w

It is already well known that the J-integral retains path-independence as long as the material

properties are constant along the x direction. The derivation above indicates the correction terms needed if the fusion lines EB and E'B' do not lie along the x direction. This correction term is the difference between the J-integral measured on a remote contour, for instance ( F

' E' D'

1 B ' ABCDEF) , and

J . The bracketed terms J r i and J f n are the needed correction terms. Because the traction terms

w L j L 1 always cancel, the following holds:

E J[

] = / (Ww

- W

B

} ’ (8)

where IJ represents strain work density in weld metal and Wg is work density in base metal Figure 3b. A similar expression holds for J

1

j- -j. It is usual for weld metal to have elastic constants nearly

equal to those of the base metal. Therefore, for elastic strains the correction term would vanish. For large plastic strains, the strain in the weld metal, e , might be less than the strain in the

w base metal, Eg, (overmatching weld) for equal stress, a. In this case

'[ ] J

B a( V >)dy. (large plastic strains) (9)

and similarly for J

1

j- j. If the stress and strain along EB were constant, and the strains were

large, the correction term, AJ, for the J-integral would be given by

AJ = 2a( Eg-e w) Ay , (large plastic strains) (10)

where Ay is the total extent in the y direction of the fusion line, as illustrated in figure 3b. Returning to the case of a fusion line that does lie along the x direction, the actual form of

J (BE) would be J (BE) = / T du /dx dx. If u were constant alonq BE, as would be the case for a w w ts y y y very small crack, then J w

(BE) and its complement J ( B'

1 ) would be negligible and J w would be given

by

J = J (

1 E ' ) + J (B'AB) + J (EF) (11) w w w w

In the present study no correction terms like eq (10) were used. For through cracks eq (7) was used,

and for surface cracks eq (11) was used. In one specimen with a weld along the tensile axis, the flow properties of the weld metal were similar enough to those of the base metal that no corrections

to the J-integral were needed. The use of eq (11) for surface-cracked specimens implies that only

strains near the crack in the weld metal are considered to contribute to the J-integral. The strains

in the HAZ and BM are assumed to be the same on the front and back faces of the specimen, so that their effects on the J-integral mutually cancel. Figure 4 shows the general form of the instrumentation layout used on the surface-cracked specimens. In all cases the strain values from

the gages away from the crack supported the use of eq (11).

4. Results and Discussion

Tests on uncracked and through-cracked weldments, surface-cracked base metal tensile panels, and surface-cracked weldments were performed during this study. Table 2 lists the specimen types and dimensions and the crack dimensions used.4.1 Uncracked Weldment

The first specimen listed in Table 2, a transverse-wel ded uncracked tensile panel, was instrumented

with strain gages, as shown in figure 5, and a photoelastic coating. It was strained to failure with

6
periodic pauses to record strain gage readings, LVDT readings, and load. Individual strain gage readings representati ve of longitudinal strain in weld metal (WM), heat-affected-zone (HAZ), and base

metal (BM) are plotted against applied stress in Fig. 6. These strain values represent composite

weldment behavior, rather than behavior of homogenous specimens of WM, HAZ, or BM. These stress-strain

curves show that the WM was overmatched and the HAZ was initially undermatched to the BM. The photoelastic coating dramatically displayed the HAZ as a high-strain region. Fig. 7. (The

narrowing of the highly strained HAZ near the specimen edges was simply an edge effect, as confirmed

by finite element analysis and by a subsequent test of a wider tensile panel.) The photograph shown

as Fig. 7 was taken at a stress of 904 MPa (131.1 ksi). The strain in the HAZ reached a level of nearly 1.5 times the strain in the BM. Then strain hardening occurred in the HAZ, as shown in Fig.

_2

6, and the strain in the BM caught up with the HAZ at a value of 2.2x10 . The overmatched weld had

a strain of only 5.5x10 ^ at this stress level, 941 MPa (136.5 ksi).

Overmatched WM and undermatched HAZ were observed for all the tests of transverse-wel ded tensile

panels except one with a large crack in the weld, which restricted yielding in the BM and HAZ.

Table 2. HY130 specimens tests in the present study

Key: W HY130 weldment

T HY130 tensile panel

R HY130 welded plate for residual stress measurement

C Through crack in specimen center

F Full thickness crack

B HY130 base metal

S Surface crack

Specimen Specimen Crack Crack

Materi al Specimen Crack thickness width 1 ength depth

Type Type Type (mm) (mm) (mm) (mm)

U T 10 89 --

w R C 25 800 to 50 F w T C 10 89 8 F w T C 25 912 25 F

B T S 10 89 25 6

B T S 10 89 20 1.7

B T S 10 89 5 1.7 W T S 10 89 5 1.7

W T S 20 254 30 2.5

7
4.2 Through Cracks

The second weldment test was a measurement of residual J-integral, that is, J-integral produced

by residual stress. A large welded HY130 plate specimen, approximately 80 cm square and 2.5 cm

thick, was instrumented with strain gages near the weld. Fig. 8. Then a crack transverse to the weld

was started by drilling a hole 1.3 cm in diameter in the plate in the center of the weld, and was extended in both directions perpendicular to the weld by cutting with a saw. Cutting was interrupted

periodically so that strains around the cut could be recorded. Because the initial tensile residual

strains near the saw cut recovered toward a zero-strain state as the saw cut progressed, the recorded

strains were negative (compressive). The longitudinal strains along the crack center-line for saw

cut length 2.5 cm are plotted in Fig. 9. Analysis of the results of this test provided data on three

quantities: the magnitude of the initial residual stress, the magnitude of the residual J-integral,

and the width of the residually stressed area. Extrapolation of the measured strains to the edge of the hole used to start the saw cut indicated

_3

an initial strain of 1.9x10 , which converts to a stress of 380 MPa (55 ksi), about 40 percent of the nominal yield strength. This value represents the through-thickness-average residual stress in the weldment tested.

An expression for the J-integral in the presence of residual strains, J , was given by Chell

[17], His expression is

J r

= J + /AdAa

i j3Gi; ./3x , (12)

where J is the usual expression for the J-integral, given above as eq (3), and the second integral on the right is the residual stress correction. This integral is taken over the area enclosed by the contour used to evaluate J; is the stress tensor, 0^ is the residual strain and x is distance

from the crack center in the crack plane. Exact evaluation of eq (12) for an experimental situation

clearly would be a formidable task. However these simplifying assumptions allow progress:

only o and 0 are significant;

yy yy

s 0 increases from zero very far from the saw cut, and reaches a constant value far from the saw yy

J cut, Fig. 10;

0 is independent of y; the traction-bending term in J is insignificant because the integration contour extends to infinity in the y direction;

the work density along segment CD (Fig. 10) of the contour chosen for evaluation of J can be made to vanish by choosing CD far from the crack and the residually strained region.

The area integral in eq (12) is independent of y because the thermal strain was assumed to be independent of y and located far away from the crack, which is the only possible source of y-dependence in the residual stress term of eq (12). Near the crack, where the stress does depend on distance from the crack, the residual stress gradient 30 /ax is zero. The strains in the usual yy

J-integral expression for the first term on the right side of eq (12) are the actual strains along

the weld centerline, e (y); contributions from the other contour segments were dismissed in the assumptions listed above. Therefore we now have
Rewriting the area integral in the residual strain term as an integral over x and y, and assuming

that the stress in the region of the residual strain gradient and near the crack depends on the strain in the usual linear elastic fashion we have

where e is the tensile residual strain at the weld. This equation makes sense because if no yy*o

crack were present e yy(y) would be identical to

Q and so would be zero. If e (y) is relaxed

below e Q near a crack, will be positive. Evaluating the strain integrals we have

0

r

= (E/2) dy [tyy

(y)Z 21 'yy>o

(15)

As shown by the data plotted in Fig. 9, the measured strain relaxation values near the crack E yy(y)

can be represented as

e (Y) = -e exp(-y/y ) (16) yy yy,p o'

Where e

p and y Q are fitting parameters. The magnitude of the residual strain, e 0

, was calculated from eq (16) using the y value at the radius of the starter hole, y

n

:

e yy,o

£ yy,p

exp (-y

n /y

0

) (17)

The tensile residual stresses remaining in the plate along the y axis after partial saw cutting can

be deduced from the strain gage data and the fitting function, eq (16). Far from the saw-cut, the strains are constant at the residual strain value, e Q

. Near the

cut, the strains are relaxed as shown in Fig. 9. The residual strain can be expressed as a function

of saw cut length as

9
yy.o

e (y) = e yy

- e exp ( -y/y ) yy,p

K y J o'

= e [1 - (e /e ) exp (-y/y )]. yy,o yy,p yy,o' H J J o' J ( 18 )

When evaluating eq (18) only y values greater than y , the radius of the starter hole, correspond to actual strains. Substituting the strain function of ea (18) into eq (15) and evaluating the

i ntegral , one finds

i = 3 F 2

r 2 yy,o y . (19)

o

A plot of residual J-integrals calculated from eq (19) plotted against saw-cut length is shown in Fig.a 11. These values are well below the critical J value, J T , for HY13G. But, if the residual

Ic strain were near yield instead of less than half of yield, the residual J values would quadruple, and would then be approximately Jj

c for cracks several centimeters long. This implies that for residual

strains at their maximum value, yield strain, and cracks about 5 cm long, tearing could initiate in HY130 at sharp cracks under residual strain alone.

The residual J values plotted against crack length in Fig. 11 can be compared to J values J(K),

calculated using the usual expression for the stress intensity factor for a center-cracked panel,

with the saw cut length and the measured residual stress. At a saw cut length of 4.4 cm, for

example, the value for J(K) was 50kJ/m 2 (288 lb/in) which was 25 percent above the value calculated

by integrating strains. This difference probably indicates that the saw cut was approaching the region of the residual stress gradient. A stressed tensile panel has tensile stresses across its whole width. Residual stresses only part-way across a panel would be expected to produce lower

applied J-integral values. The breakdown of the near-linear dependence of J on saw-cut lengths

(Fig. 11) for cut lengths less than about 2 cm is attributed to: inadequacy of eq (16), for strain as

a function of position, near the hole, 1.3 cm in diameter, used to start the saw cut; variability of the actual residual strain along the saw cut; and breakdown of the assumptions, listed above, used in evaluating the residual J-integral.

It is concluded from the results discussed above that residual strains produce strain distributions of the same general character as those produced by mechanical strains, and that similar relationships among stress level, crack size, and applied J-integral should hold for residual and mechanical

stresses

The next through-cracked specimen tested was a trans verse-wel ded , center-cracked tensile panel. The through crack intercepted about 10 per cent of the cross-sectional area. Its instrumentation

layout is shown in Fig. 12. As shown by the the strain gage results and photoelastic coating.

Figs. 13 and 14, net section yielding occurred. Figures 15a-k verify the expected rapid increase of applied J-integral and crack mouth opening displacement with strain for net section yielding

behavior. This test showed that in weldments, as in base plate, net section yielding occurs when the crack intercepts 10 per cent or more of the specimen cross-section. The exact crack area separating

net section yielding from gross section yielding was pursued further for surface flaws in weldments,

as discussed below. Figures 16-19 depict the instrumentation layout and behavior of the third through-cracked

specimen, a much larger welded tensile panel with the weld along the tensile axis. The results of this test showed that residual stresses and size scaling have no first order effects on tensile panel

behavior for the crack sizes and strain levels considered here, namely, a crack intercepting 2.8 per cent of the specimen area. Net section yielding occurred as expected, Figs. 17-18. The residual

applied J-integral was about 20 kJ/m 2 (120 1 b/ in), as calculated from the crack size and the residual

10
stress measurement described above. This level of applied J-integral might be significant in a very brittle material, but it is insignificant for a crack growing toward HY130 base metal.

4.3 Surface Cracks

The goals of the tests of surface-cracked tensile panels were three: to verify the effects of gross and net section yielding on applied J-integral values, to locate more precisely the boundary

between NSY and GSY, and to determine effective crack sizes for several sets of crack lengths and depths.

The behavior of a large surface crack (17 percent of cross-section area) was reported

previously [3], The data are repeated here for completeness. The instrumentation layout is shown in Fig. 20, strain gage results are plotted in Fig. 21, strain patterns revealed by the brittle lacquer

coating are shown in Fig. 22, and the strain and stress dependence of J-integral and crack mouth

opening displacement are displayed in Figs. 23 a-k. This test showed that for surface cracks, as for

through cracks, net section yielding occurs and produces a rapid increase in applied J-ir.tegral with

applied strain. It also showed the necessity of accounting for ligament yielding in surface cracks.

Surface cracks, being geometrically more complex than through flaws, have an additional yielding

pattern, ligament yielding. As can be seen in Fig. 24, ligament yielding means that the plastic zone emanating from the crack root has reached the back face of the specimen, but has not reached the sides of the specimen. Ligament yielding is a sort of locat net section yielding, restrained by the elastic strain field between the specimen sides and the end of the crack's plastic zone. As might be expected, ligament yielding produces a rapid increase in crack driving force, but not as rapid as net section yielding at a through flaw. Two additional experiments on surface-cracked base metal specimens were conducted to locate the transition from NSY and GSY and to measure effective crack sizes for GSY for surface cracks. Instrumen

tation layouts for these two specimens are shown in Figs. 25 and 26. The behavior of these two surface-cracked base-metal panels was complicated by nonuniformity of tensile properties along the

panel tensile axis. For both specimens, one end had a lower flow strength than the remaining material;

strains in the soft end were much larger than elsewhere in the specimen, as indicated in Fig. 27. The qualitative strain asymmetry was revealed by the photoelastic coating on the specimens. Because

strain gages were present, by chance, only on the harder specimen end, the form of the strain on the softer end could only be estimated from the fringes in the photoelastic coating and from the total strain over the whole specimen, obtained from measured displacements. Because of this strain asymmetry

some of the data pertain only to the specimen end instrumented with strain gages, while others

pertain to the overall specimen length. Figures 28 and 29 show the strain gage strains and photoelastic strain patterns for the specimen with the longer crack, and Figs. 30 and 31 show these

data for the specimen with the shorter crack. Because the behaviors of the two ends of these

specimens were different, overal 1 -1 ength data cannot be combined with half-length data to give a complete description of specimen behavior. Instead, the two data sets must be separately considered

and compared. Quantities pertaining to the instrumented half-length are the contour J-integral, the remote strain as given by a strain gage away from the crack, the gage length strain as calculated by

integrating strains from individual gages, and the stress. Plots showing the interdependence of these quantities for the two base-metal, surface-cracked specimens are referred to as half-length

plots, and are presented in Figs. 32 and 34. Quantities relevant to the full length include crack

mouth opening displacement (CMOD), gage length strain from LVDTs, and stress. Plots relating these

quantities are called full-length plots. Figs. 33 and 35. On the 89 x 10 mm specimen with a surface crack 10 mm by 1.7 mm (crack intercepted 2 percent of cross section area), deformation patterns indicative of net section yielding were visible. This

confirmed the previous result that for cracks larger than 1 percent of the cross section area net section yielding can be expected.

The smallest surface crack tested in a base metal tensile panel, 1.7 mm deep by 5 mm long in a panel with a 10 x 89 mm cross section (crack intercepts 1 percent of cross section) showed no signs

of net section yielding. Gross section yielding occurred, followed by yielding to failure in the soft end.

11
For the through-cracked specimens covered by the previous report, the GSY part of the applied

J-integral was clearly distinguishable from the NSY part. However for surface cracks, deformation

bands extend from the crack root to the back surface for both ligament yielding and NSY. Therefore,

no clear distinction between the NSY and GSY parts of the applied J-integral is available. Therefore,

these base-metal surface-cracked specimens provided an upper bound to the effective crack size, but not a definitive value. The effective crack size is that value of the parameter a in the J-integral estimation curve

(eqs (1) and (2), above) that forces the estimated J values to be equal to the measured values for a specific case. Effective crack sizes for the base metal specimen with the longer surface crack were calculated from the plot of J-integral against remote strain (half-length data) and from the plot of CMOD against gage length strain (full-length data). The effective crack sizes were 0.92 and 0.77 of the actual crack depth. Because some NSY occurred in this test, these effective crack sizes are overestimates of the GSY part of the applied J-integral.

For the specimen with the shorter crack, the strain-gaged end of the specimen did not reach strains above yield. Therefore an effective crack length for this specimen was obtained from the full-length plot of CMOD against gage length strain. Fig. 34b. The J-integral was taken to be the product of CMOD and yield strength, a relationship provided by the previous series of tests [3]. Net section yielding at the crack did not occur in this specimen as shown by the photoelastic coating,

Fig. 30. Therefore the gage length strain provided a good measure of the average remote strain. The effective crack size was 0.5 of the actual crack depth. Two trans verse-wel ded surface-cracked tensile panels were tested, one 10 mm thick by 89 mm wide

(0.4 x 3.5 in) and one 20 mm thick by 250 mm wide (0.77 x 10 in). Instrumentation layouts for these

specimens are shown in Figs. 36 and 37. The CMOD for the smaller specimen was measured using a traveling microscope, because the crack was too small for a clip-on gage. Strain gage strains and photoelastic coating strain patterns are shown as Figs. 38, 39, 40 and 41. Stress and strain

dependences of the J-integral and crack mouth opening displacement are shown as Fig.s 42 and 43. The measured CMOD values for the smaller specimen contained a scatter of about ±0.03 mm because of the optical measurement method used. These tests clearly demonstrated the behavior of small surface

cracks in HY130 weldments. The key results are the importance of overmatching weld metal strength,

crack sizes small enough to ensure gross section yielding, and small crack depths in limiting crack driving force. Overmatching was expected because of the results of the test uncracked welded tensile

panel and confirmed by the strain vs position results and strain patterns from the surface-cracked

weldments. The cracks machined in these two tensile panels were 1 and 1.6 percent, respectively, of their cross-sectioned areas. The absence of NSY is evident from the strain vs position results and the strain patterns. The effect of crack depth can be seen from analysis of the J-integral results.

For the smaller tensile panel, the J-integral was obtained in the usual way. For the larger specimen

the measured strains were complicated by the presence of a natural flaw in the weld, in addition to the crack introduced intentionally. The complicated strains prevented contour J-integral measurement

for this specimen. The J-integral was estimated as the product of yield strength and CMOD. Effective crack sizes were obtained by requiring that the J-integral values given by the estimation

curve matched the measured values. The ratio of effective crack size to actual crack depth decreased

from 0.72 to 0.028, for the smaller specimen, and from 0.76 to 0.084 for the larger one as the strain

increased from 0.004, near yield, to 0.007, where the high weld metal flow strength prevented further

plastic strains in the weld metal. The ratios of effective crack size to actual crack depth in the elastic-plastic strain range in the two specimens were 0.72 and 0.76, even though the crack aspect

ratios (depth to total length) were 0.34 and 0.083, the crack depth to plate thickness ratios were

12
0.17 and 0.13, and the ratios of crack length to plate width were 0.06 and 0.12. The fact that the ratio of effective crack size to actual crack depth was not noticeably influenced by aspect ratio,

crack depth to plate thickness ratio, or crack length to panel width ratio indicates the predominant

effect of crack depth on effective crack size. Both of these tests demonstrated the conservatism of using the actual crack depth as the effective crack size. In fact these two tests, together with the results from the surface-cracked base-metal tests, indicate that for gross section yielding and for

surface cracks with aspect ratios greater than 0.08 the effective size for surface cracks can be taken as 0.75 of the actual crack depth. The aspect ratio restriction excludes very long cracks, for

which the effective size is the full depth.

A natural weld flaw in addition to the machined flaw in the larger surface-cracked specimen

provided the opportunity to draw another conclusion about the effects of weld defects: a weld defect

can cause unstable tearing in a tensile panel. The natural defect was a buried part-through crack in

a plane approximately perpendicular to the panel tensile axis. The. crack extended in the transverse direction from one edge of the specimen almost to its center line and was approximately 2 mm in depth

(plate thickness direction). This crack caused local yielding, evidenced by local strains revealed

by the photoelastic coating, Fig. 41, and eventually caused unstable tearing of half the panel width

at an applied remote strain of 0.013. The tearing arrested near the end of the natural flaw, at about the center of the specimen.

From the two experiments on surface cracks in transverse-wel ded tensile panels discussed here,

it was concluded that surface cracks in weldments can be treated using the J-integral estimation

curve previously reported for base metals. For surface cracks the effective crack size a for GSY should be taken as 0.75 of the crack depth for relatively short cracks (length to depth ratio 12 or less). For longer cracks the effective size is to be taken as the full depth.

For the HY130 weldments tested here, the post-yield strain in the weld increased much less than

the post-yield strain in the base metal, because of overmatching. While for the welds in this study

the effective crack size for GSY was definitely less 'than 10 percent and more than 1.6 of the actual crack depth for strains above 0.007, the specific fraction might depend on the exact weld process and weld chemistry used.

5. Conclusions

From tests of 3 surface-cracked HY130 base metal tensile panels and 6 uncracked, throughcracked, and surface-cracked HY130 wel dments, the following conclusions of the previous report [3] on base metal tests have been sustained:

1. Applied J-integral is controlled qualitatively by deformation pattern. Net section yielding

produces large applied J-integral values, while gross section yielding produces small applied

J-integral values.

2. Fitness-for-service assessment for contained plasticity and gross section yielding can be performed using a J-integral estimation curve to obtain applied J-integral as a function of applied strain and crack size. __

3. Met section yielding is intolerable. This yielding pattern can be avoided in tensile panels by

restricting crack size to 1 percent or less of load-bearing-cross-sectional area.

4. Estimation of applied J-integral values for surface flaws requires consideration of ligament

yielding as well as contained and gross section yielding. Contributions of each of these

yielding patterns to applied J-integral can be evaluated using estimation curves specific to each yielding pattern.

13
The following additional conclusions have been obtained for surface cracks generally and surface

cracks in weldments:

5. Surface-crack depth has a dominant effect on the crack driving force.

6. Overmatching weld metal flow strength is a powerful means of lowering crack driving forces for cracks in welds transverse to the tensile axis. A five percent strength overmatch can reduce

effective crack size by a factor of 10 in HY130, assuming that adequate weld toughness can be maintai ned

7. Residual stresses in HY130 weldments produce applied J-integrals at cracks within the stress

fields. The residual stress field measured in this study had a magnitude of slightly less than half yield, and could have initiated tearing in HY130 at a through-crack 12 cm long, if such a large residual stress field were possible.

8. Met section yielding from cracks in HY130 welds transverse to the tensile axis is prevented by

restricting crack size to 1.5 percent of the load-bearing-cross-sectional area. This restriction

applies for welds ground flush. The presence of a weld crown might allow further relaxation of this restriction.

9. For surface flaws in HY130 base- and weld-metal tensile panels, the effective crack size for

gross section yielding can safely be taken as 0.75 of the actual crack depth for cracks with

length to depth ratio 12 or less; the effective size can be taken as the full crack depth for

longer cracks.

10. The applied J-integral at the crack root is the appropriate measure of crack driving force in surface cracks in base plates and in weldments. The usual line J-integral in the plane perpen- dicular to the crack root at the crack center is sufficiently path independent for practical purposes

6. Acknowledgments

Financial support from the Fracture Control Technology Program of the Naval Sea Systems Command

is gratefully acknoledged.

The contributions of J. D. McColskey as technician on this project are gratefully acknowledged.

Helpful discussions with J. P. Gudas, H. I. McHenry, R. B. King, and Y. W. Cheng, assistance in data plotting by B. Gunther, and manuscript preparation by J. Wilken are appreciated.

7. References

[1] R. W. Judy, Jr., T. W. Crooker, J. A. Corrods, J. E. Beach, J. A. Hauser, Review of Fracture

control technology in the U.S. Navy. Presented at the Second Program Review, Fracture

Control Technology for Ships and Submarines; 1979 November 30; Annapolis, MD.

[2] D. T. Read and H. I. McHenry, Interim Progress Report: J-Integral Method for Fitness-forService Assessment, National Bureau of Standards Interagency Report NBSIR 81-1648, May 1981.

[3] D. T. Read, Applied J-Integral in HY130 Tensile Panels and Implications for Fitness-forService Assessment, National Bureau of Standards Interagency Report NBSIR 82-1670, July 1982.

[4] J. R. Rice, A Path Independent Integral and Approximate Analysis of Strain Concentration by

Notches and Cracks, Journal of Applied Mechanics 35 , 1968, pp. 379-386.

14
[5] W. A. Logsdon, Elastic Plastic (Jj ) Fracture Toughness Values: Their Experimental Determination and Comparison with Conventional Linear Elastic (Kj ) Fracture Toughness Values for

five Materials, Mechanics of Crack Growth STP 560 , American Society for Testing and Materials,

Philadelphia, 1976, pp. 43-60.

[6] J. A. Begley and J. D. Landes, The J Integral as a Fracture Criterion, Fracture Toughness,

STP 514 , American Society for Testing and Materials, Philadelphia, 1972, pp. 1-20.

[7] J. D. Landes and J. A. Begley, The Effect of Specimen Geometry on J

c

, Fracture Toughness,

STP 514 , American Society for Testing and Materials, Philadelphia, 1972, pp. 24-39.

[8] M. G. Dawes, The COD Design Curve, in Advances in El ast.o-Pl asti c Fracture Mechanics , edited

by L. H. Larsson, Applied Science Publishers, London, 1980, pp. 279-300.

[9] J. A. Begley, J. D. Landes, and W. K. Wilson, An Estimation Model for the Application of the J-Integral, Fracture Analysis, STP 560 , American Society for Testing and Materials,

Philadelphia, 1974, pp. 155-169.

[10] C. E. Turner, Elastic-Plastic Aspects of Fracture Stress Analysis: Methods for other than Standardized Test Conditions, in Fracture Mechanics in Design and Service, Phil. Trans. R. Soc. Lond. A299 , 1981, pp. 73-92.

[11] H. I. McFlenry, .D T. Read, and J. A. Begley, Fracture Mechanics Analysis of Pipeline

Girthwelds, Elastic-Plastic Fracture, STP 668, American Society for Testing and Materials,

Philadelphia, 1979, pp. 155-169.

[12]

, R. deWit and J. H. Smith, Development of Some Analytical Fracture Mechanics Models for

Pipeline Girth Welds, Fracture Mechanics, STP 700 , American Society for Testing and Materials, Philadelphia, 1980, pp. 513-528.

[13] Y. W. Cheng, H. I. McHenry, and D. T. Read, Crack-opening Displacement of Surface Cracks in Pipeline Steel Plates, Proceedings of the Fourteenth national Symposium on Fracture Mechanics, June 30-July 2, 1981, Los Angeles, CA. [14] Y. W. Cheng, R. B. King, D. T. Read, and H. I. McHenry, Post-yield Crack-opening Displacement

of Surface Cracks in Steel Weldments. Proceedings of the Fifteenth National Symposium on Fracture Mechanics. July 7-9, 1982, College Park, MD. [15] K. Kishimoto, S. Aoki, and M. Sakata, On the Path Independent Integral J, Engineering

Fracture Mechanics 13, 1980, pp. 841-850.

[16] R. B. King, Y. W. Cheng, D. T. Read, and H. I. McHenry, J-Integral Analysis of Surface Cracks

in Pipeline Steel Plates. Proceedings of second International Symposium on Elastic-Plastic

Fracture Mechanics, October 6-9, 1981, Philadelphia, PA. [17] G. G. Chell, Elastic-Plastic Fracture Mechanics, in Developments in Fracture Mechanics-1 , edited by G. G. Chell, Applied Science Publishers, London, 1979, p. 97.

15
Normalized

J-Integral

25

Normalized Strain:

20 1- e /€

y

Normalized J-Integral:

JE

15 |- 7rao-2

10 Gross Section

Yielding

2 3 4

Normalized Strain

Figure 1. Experimentally derived J-integral estimation curve for contained

yielding and gross section yielding in HY130 in tension.

16
Figure 2a. Weld bead placement in HY130 GMAW-process butt weld used in the

present study.

17
CRACK

EXTENSION,

in

3

u ! / q i ui ‘ivao3iNi-r

o o o o O o o o o o o

00 o CD CM o o

CM CM CM T— oo

oo

CD

CM

CO CO CM

3 ui/r>i “ivaoaiNi-r

Figure 2b. J-R curves for the weld metal of the present study.

18

CRACK

EXTENSION,

mm
Figure 3.

Load

\

Load

Integration paths for the J-integral for a crack in a weldment.

19
Figure 4.

Load

1

1

Load

Schematic diagram of surface-cracked tensile panel instrumented

with strain gages and LVDTs for direct measurement of the

contour J- i ntegral .

20
CO

O

Figure 5. Instrumentation layout for transverse-wel ded uncracked HY130

tensile panel .

21
STRESS,

MPa

1000

900

800

700-

600-

500-

400-

A 1 A A flA

O A

O A OA

OCA

cx>

CA Q

140

120

a Axial strains measuredat

Q tensile panel centerline

Q o Weld Metal

aa

a

A Heat Affected Zone

Base Metal

HY130 Welded Tensile Panel

No Crack

Width 90 mm

Thickness 10 mm

i 0.004

100

80

60

0.008 0.012

STRAIN

Figure 6. Longitudinal strai-n in weld metal (WM), heat-affected-zone

(HAZ), and base metal (BM) plotted against stress for transversewelded uncracked HY130 tensile panel.

22

STRESS,

ksi
HY130

Welded

Tensile

Panel

No

Crack

Width

90

mm

Thickness

10

mm

Stress

904

MPa

23

Figure

7.

Photograph

showing

highly

strained

HAZ

of

transverse-wel

ded

uncracked

HY130

tensile

panel,

ata

stress

of

904

MPa
DISTANCE

FROM

CRACK

PLANE,

cm

HY-130 Welded Plate

Residual J measurement by

cutting instrumented plate

Plate size lOOx 100 cm

Plate thickness 25 mm

Saw-cut starter hole at center of plate

Weld metal

Small strain gages (4)

Strain gage

:::i Path of saw-cut

(symmetric about weld)

Figure 8. Instrumentation layout for large welded HY130 plate specimen for

residual J-integral measurement.

24
00

-

co

co

01. x ine-us pejnseejAi

b

ro 4-* Z3 fO “O =3

Z5 -r- O

U) fD U

fO L0J 4-> 4- Z O

CT>

CL) L25

Distance

from

Crack

Plane,

x

cm
Figure 10. Diagram showing location of contour for J-integral evaluation in

a plate with residual strains.

26
-cut

length,

in

uj/qi-u; ‘|BJ68iU!-p lenpjsau

CD

S~3

CD

,w/p>i |enp|sey

27

Experimentally

obtained

residual

J-integral

values

plotted

against

total

saw-cut

length

for

HY130

weldment

with

residual

strains

.
HY

130

Welded

Tensile

Panel

s~

+->

o • >^rfO CD

.— C

<T5 C CL

S- o -4-> co

28

i=i

Transverse

strain

gage

LVDT

Displacement

gage

•

LVDT

attachment

point
HY

130

Welded

Tensile

Panel

Center-Cracked

Nivais oCO

TD

CDU

rD

CJI s-<Dc to

CD r—

CJ CD>

TD CD

CD i—

“O

r—C

CD •«- ^ CO I S- CD -M

<J) to

CD “O > CD to -i— C= r—

ro cl

s- CL

+->

a3 C CD

•r- (1) c _c O 4->

Z3 ro -Q

S- CDC

i/i ro

•i- CL

"O

CD

ro to

SC

+-> CD Ul -M

CD

Z3cn

NlVdlS

29
HY130

Welded

Tensile

Panel

Center

-Cracked

30

Figure

14.

Transverse-wel

ded

center-cracked

HY130

tensile

panel,

crack

half-length 4

mm,

with

photoelastic

coating

to

show

strain

pattern,

at

the

three

strain

values

used

for

figure

13.
-Integral,

kN/m

J-Integral,

kN/m

Figure 15a-k. Dependence of J-integral, stress, and crack mouth opening

displacement on strain for transverse-wel ded center-cracked

HY130 tensile panel

.

Gage Length Strain/Yield Strain

0 0.5 1 1.5 2 2.5

Figure 15a.

Remote Strain/Yield Strain

0.2 0.4 0.6 0.8 _L _ _L _L

1200 -

900 -

600 -

HY130 Welded Tensile Panel

Cen t e r-C r acked

Width 90 mm

Thickness 10 mm

Crack Half-Length 4 mm

o

o

o8

8

o

o

1.2

' - 8000

6000

- 4000

300 -

- 2000

« ym

1.0 nnooo° ooQOCOQO ocr 1“ 1 I

2.0 3.0 4.0 Remo t e Strain

o.o 5.0 M0'

Figure 1 5b.

Integral,

Ib/in

J-Integral,

Ib/i
Stress

Intensity

Factor,

MPa\

m

J—

Integral

kN/m

o 40

Stress, ksi

80 120

i

1200 -

900 -

600 -

300 -

HY130 Welded Tensile Panel

Center-Cracked

Width 90 mm

Thickness 10 mm

Crack Half-Length 4 mm

oo

8

o

o

o

|-|DOQOQCi OOOOOCDCOc£p

&

160 _i__

200

L

200 400 600 800 1000 Stress, MPa

T- 8000

6000

- 4000

-2000

CD

<DC

I

1200 — 0 1400

Figure 15c.

Stress, ksi

40 _L_

80 _J_120L_

200 -

150-

100 -

50-

HY130 Welded Tensile Panel

Cen t e r-C r acked

Width 90 mm

Thickness 10 mm

Crack Half-Length 4 mm

no

160 200 —4- 200

-150

200 —I

400 600 800

Stress, MPa

~r

-100

-50

1000 1200

0 1400

Fi gure 1 5d .

32

Stress

Intensity

Factor,

ksiv

in
Stress,

MPa

1400

1200

1000

800

600

400

200

0

1400

1200

1000

800

600

400

200

0

Gage Length Strain/Yield Stra

0.5 i 1.5 2.5 HY130 Welded Tensile Panel

Cen t e r-C r acked

Width 90 mm

Thickness 10 mm

Crack Half-Length 4 mm

-200

-160

/

o°°/

tP

d?°

6°

cP ( JO( >- 120

-80

-40

—r—

0.000 0.002 0.004 0.006 0.008 0.010 0.012 Gage Length Strain

Figure 1 5e

.

0.2

_i

Remote Strain/Yield Strain

0.4 0.8 1 _! 0.6

_i

.2-200

HY130 Welded Tensile Panel

Center — Cracked

Width 90 mm

Thickness 10 mm

Crack Half-Length 4 mm

-160

,cP -120

O

'

-80

-40

-I 0.0 4.0

“I

1.0 2.0 3.0 Remo t e Strain

5.0 M0~

:

Figure 1 5 f

.

33

Stress,

ksi

Stress,

ksi
Crack

Mouth

Opening

Displacement,

mm

Gage

Length

Strain

0.012-

o.oio0 . 008 -

0 . 006 -

0.004 -

0 . 002 -

0.000

0.2 _L

Remote Strain/Yield Strain

0.8 1 _L

0.4

J. 0.6_L HY130 Welded Tensile Panel

Cen t e r-C r acked

Width 90 mm

Thickness 10 mm

Crack Half-Length 4 mm

o.o T“

1.0 2.0 3.0 4.0 Remo t e Strain

1.2

- 2.5

- 2

1.5

-1

- 0.5

5.0 MO”'

Figure 15g.

Gage Length Strain/Yield Strain

0.5 1 1.5 2 2.5

- 0.08

- 0.06

0.04

- 0.02

0.00

Figure 1 5h

34

Crack

Mouth

Opening

Displacement,

in

Gage

Length

Strain/Yield

Strain
Crack

Mouth

Opening

Displacement,

mm

Crack

Mouth

Opening

Displacement,

Remote Strain/Yield Strain

0.2 0.4 0.6 0.8 1 -I

1.2

1.5

1 -

0 . 5

-

HY130 Welded Tensile Panel

Cen t e r-C r acked

Width 90 mm

Thickness 10 mm

Crack Half-Length 4 mm

o

0.0 pnooooo ooo 000000 ” 0 03001.0 2.0 3.0 4 5.0 MO”'

Figure 1 5 i

.

Stress, ks i 0 40 80 120 160 200

I

1 1

1 1

1 0 200 400 600 800 1000 1200 1400 Stress, MPa

Fi ' ~ I5j.

0.08

0.06

0.04

0.02

0.00

0.08

0.06

0.04

0.02

0.00

35

Crack

Mouth

Opening

Displacement,

in

Crack

Mouth

Opening

Displacement,

in
Crack Mouth Opening Displacement, in

0.00 0.02 0.04 0.06 0.08

cr> <u

1200 -

900 -

600 -

300 -

HY130 Welded Tensile Panel a o Q oo

o

^ Cen t e r-C r acked

Width 90 mm 0

° Thickness 10 mm

Crack Half-Length 4 mm _ °

o o

cf

cP o U8000

6000

-4000

- 2000

0 0.5 1 1.5 2 Crack Mouth Opening Displacement, mm

Figure 15k.

36

Integral,

I

b/i
<Do>

roX

<T3

CDcn

Sro

o • >)rro CD

<T5 C Q. O

•r- CD

fD *r-

-4—5 CO C C

CD CD

EE 4-> Z5

S- O -*-> CO

CO r—

I

37

•

LVDT

attachment

point

CMOD

Crack

mouth

opening

displacement

gage
C/5 X

COo

05co

0)c

<£

a>

t/5 c

<d

TJ

at 32

0) $o

CO>X z<

CL ° * *° u<a: u S §<uz< V CD

+-> c

00 ro

•r- Q.

"O

cd

C i

ro CO

SC

+-> CD LD +J

CD

S-Z5CD

38
HY130 Welded Tensile Panel Weld along Tensile Axis

Center-Cracked Width 910 mm

Thickness 25 mm Crack Half-Length 12.5 mm

Scan #35

Scan #45 Scan #49

Scan #45

Scan #49

Figure 18. Strain pattern as revealed by photoelastic coating on large

axial-welded center-cracked HY130 tensile panel.

39
Integral,

kN/m

j-lntegral,

kN/m

Figure 19a-k. Dependence of J-integral, stress, and crack mouth opening

displacement on strain for transverse-wel ded center-cracked

HY130 tensi 1 e panel

3000

2500

2000

1500

1000

500

0

3000 H

2500

2000

1500

| 1000

500

0

Gage Length Strain/Yield Strain

0.3 till 0.6 0.9 1.2 1.5

I HY130 Welded Tensile Panel

Weld along Tensile Axis

Cen t e r-C r acked

Width 912 mm

Thickness 25 mm

Crack Half-Length 12.5 mm

1.8 T 18000

-15000

-12000 \JD

-9000

-6000

CD

<D

)ooo i a

|

i i f unncoQ 0

"'

fP

-3000

0.0 1.0 T

- 2.0 3.0 4.0 5.0 6.0 Gage Length Strain

7.0 8.0 9.0 • 10

"

Figure 19a

Remote Strain/Yield Strain

0.2 0.4 0.6 0.8 HY130 Welded Tensile Panel

Weld along Tensile Axis

Cen t e r-C r acked

Width 912 mm

Thickness 25 mm

Crack Half-Length 12.5 mm

1.2

_j

1.4 18000

15000

-12000

-9000

-6000

freo.o 1.0

© o °

- 3000

0

7.0 MO'

3

-r

2.0

-I3.0

—i4.0 5.0 Remo t e Strain

6.0

Figure 19b.

40

-Integral,

Ib/in
Stress

Intensity

Factor,

MPavm

J-Integral,

kN/m

25 50 75 Stress, ksi100 125 150 175 200

a>c

I

Figure 1 9c

.

700 -

600 -

500 -

400 -

300 -

200 -

100

0**

Stress, ksi

25 50 75 100 125 150 —I I I I L L_

175 HY130 Welded Tensile Panel

Weld along Tensile Axis

Center-Cracked

Width 912 mm

Thickness 25 mm

Crack Half-Length 12.5 mm

o

o

o

ooo

JP

300 —I

1

600 900

Stress, MPa

200

l

c -eoo'y

-500

o

400 O

700

(/>

-300 '

-200

- 100

cn

1200 1500

Figure 1 9d

.

41
Stress,

MPa

1500

1200

900 -

600 -

300 -

o-P

Gage Length Strain/Yield Strain

0.3 0.6 0.9 1.2 1.5 1.8

I II I _J 1 HY130 Welded Tensile Panel

Weld along Tensile Axis

Cen t e r-C r acked

Width 912 mm

Thickness 25 mm

Crack Half-Length 12.5 mm

fP

ooo

I I I T— T- T—

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

-200

-175

-150

-125

100

-75

-50

-25

Gage Length Strain

o

9.0 MO'

3

Figure 19e.

1500 -

600 - ui

Remote Strain/Yield Strain

0.2 0.4 0.6 0.8 1 1.2

) 1— i L_ _l I

1200 -

o

9= 900 -

HY130 Welded Tensile Panel

Weld along Tensile Axis

Center— Cracked

Width 912 mm

Thickness 25 mm

Crack Half-Length 12.5 mm

fP

,cP

ooo o O o

1.4

-200

-175

- 150

-125 ox

i/) in

- 100 a)

on

- 75

300 - - 50

-25

0 #- -r—

1.0 5.0 “t 0

7.0 MO'

3 0.0 2.0 3.0 4.0 Remo t e Strain

i 6.0

Figure 1 9 f

42

Stress,

ksi
Crack

Mouth

Opening

Displacement,

*

c

D

01

.CCDC

a>

a)CDoO

9 . 0

-

Remote Strain/Yield Strain

0.2 0.4 0.6 0.8 1 1.2

I I -L _L _L _L

8 . 0

-

7 . 0

-

6 . 0

-

5 . 0

-

4 . 0

-

3 . 0

-

2 . 0

-

1 . 0

-

HY130 Welded Tensile Panel

Weld along Tensile Axis

Center-Cracked

Width 912 mm

Thickness 25 mm

Crack Half-Length 12.5 mm

cP

1.4

- 1.8

- 1.5

- 1.2

- 0.9

- 0.6

- 0.3

0.0 -i

1.0 —T“2.0 07.0 MO'

3 o.o 3.0 4.0 Remote Strain

5.0 6.0

Figure 1 9g

.

Gage Length Strain/Yield Strain

._ 0 0.3 0.6 0.9 1.2 1.5 1.8 t 3.5 1 ' 1 E

3

2.5

2

1.5

1

0.5

I I I I I I I I ^ 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 Gage Length Strain MO'

3

HY130 Welded Tensile Panel

Weld along Tensile Axis

Center-Cracked

Width 912 mm

Thickness 25 mm

Crack Half-Length 12.5 mm

- 0.12

- o.io

- 0.08

- 0.06

- 0.04

noo° 0 oooo 0 0°

- 0.02

n nn

Figure 1 9h

.

43

Crack

Mouth

Opening

Displacement,

in

Gage

Length

Strain/Yield

Strain
Crack

Mouth

Opening

Displacement,

mm

Crack

Mouth

Opening

Displacement,

0.2

3.5

3

-

2 . 5

-

Remote Strain/Yield Strain

0.4 0.6 0.8 1 _u_= HY130 Welded Tensile Panel

Weld along Tensile Axis

Cen t e r-C r acked

Width 912 mm

Thickness 25 mm

Crack Half-Length 12.5 mm

1.2 1.4 _L_

- 0.12

- 0.10

2

- 0.08

1 . 5

-

- 0.06

1-

0 . 5

-

0

> no°o°°°°°

0 °

, o o ° &

0.0 ~r

1.0 T

2.0 3.0 4.0 Remo t e Strain

5.0 6.0

- 0.04

0.02

0.00

7.0 M0

- '

Fi gure 1 9 i

3 . 5

-

3

-

2 . 5

-

Stress, ksi

25 50 _L_

75 100 __L_125 —L150 _L_

HY130 Welded Tensile Panel

Weld along Tensile Axis

Center — Cracked

Width 912 mm

Thickness 25 mm

Crack Half-Length 12.5 mm °

175 200

- 0.12

- 0.10

- 0.08

1 . 5

-

1-

0 . 5

-

0 a o 0 ococooao°'

I o o °

o

o

o

o

o

T

300 600 900

Stress, MPa

- 0.06

- 0.04

- 0.02

0.00 1200 1500

Figure 1 9 j

44

Crack

Mouth

Opening

Displacement,

in

Crack

Mouth

Opening

Displacement,

in
0.00 Crack Mouth Opening Displacement, in

0.02 0.04 0.06 0.08 0.10 0.12

Fi gure 19k.

45

-Integral,

Ib/in
H Small strain gages (4)

] Strain gage

LVDT Displacement gage

» LVDT attachment point

CMOD Crack mouth opening

displacement gage

Figure 20. Instrumentation layout for surface-cracked tensile panel, crack depth 6 mm, crack

length 25 mm.

46
HY130

Tensile

Panel

Surface-Cracked

,th =

25

mm.

Crack

Depth =6

mm.

Specimen

Width =

90

mm.

II

(/)

l/) QJC ^ i— U CD

fOC

S_ fO CJ D_ eo

47

DISTANCE

ABOVE

CRACK

PLANE,

cm

DISTANCE

ABOVE

CRACK

PLANE,
~o0o

co

v. o0o

toD

C

0c

co D_0<t

C0 EE EE

CO CD

O

O

C\J T- CD

ii si ss es

U)a 0

cl 0 H

"O 0

_J 0 c Q * §c

'jz 0 o o H E CO CO O 6 £ o0

co CL X CO o

CO>X

48

Figure

22.

Surface-cracked

tensile

panel,

crack

depth 6

mm,

crack

length

25

mm,

with

brittle

lacquer

coating

to

show

strain

distribution

at

three

strain

levels.
Integral,

kN/m

J-Integral,

kN/m

Figure 23a-k. Strain and stress dependence of J-integral and crack mouth

opening displacement for surface-cracked HY130 base metal

tensile panel with crack length 25.4 mm and crack depth 6.4 mm.

Gage Length S tr a i n/Yi e I d Strain

0.3 0.6 0.9 1.2 1.5

Figure 23a

.

o.o 1000

800

600

400-

200 -

Remote Strain/Yield Strain

0.4 0.6

1 __j

0.2

_l HY130 Tensile Panel

Su rt ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 25.4 mm

Crack Depth 6.35 mm

0.8

_j

-5000

O

O

oo oo oooooo CO cP°

cP

4000

3000

-2000

-1000

0.0 1.0 2.0 Remo t e Strain

3.0 o

4.0 io'

s

Figure 23b.

49

Integral,

Ib/in

J-Integral,

Ib/i
Stress

Intensity

Factor,

MPaVm

J-Integral,

kN/m

Stress, ksi

1000

800

600-

400

200 -

25 —L— 50 _J_

75 _1_100

l HY130 Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 25.4 mm

Crack Depth 6.35 mm

125 _j

200

o

o

o

o

o

oo

oo

o

o

o

SD" pCD®.ccO 1 0

c?

""T"" 400 600 800

Stress, MPa

m

150 _J175

- 5000

4000 .-

-3000 o

cn

0)

2000 —

-1000

1000 — 0 1200

Figure 23c.

25 50 Stress, ksi

75 100 125 150 175

c

Figure 23d.

50

Stress

Intensity

Factor,

ksivi
Gage Length Strain/Yield Strain

0 0.3 0.6 0.9 1.2 1.5

Figure 23e.

Remote Strain/Yield Strain

0.0 0.2 0.4 0.6 0.8

Figure 23f.

51

Stress,

ksi
Crack

Mouth

Opening

Displacement,

mm

Gage

Length

Strain

o

*

Remote Strain/Yield Strain

o.o 0.2 0.4 0.6 0.8

o.o 1.0 2.0 Remo t e Strain

3.0

- 1.5

- 1.2

0.9

- 0.6

- 0.3

4.0 MCT

Figure 2 3 g

Gage Length Strain/Yield Strain

0.3 0.6 0.9 1.2 1.5

Figure 23h.

52

Crack

Mouth

Opening

Displacement,

in

Gage

Length

Strain/Yield

Strain
Crack

Mouth

Opening

Displacement,

mm

Crack

Mouth

Opening

Displacement,

Remote Strain/Yield Strain

0.0 0.2 0.4 0.6 0.8

Figure 2 3 i .

Stress, ksi

Fi gure 23j

.

53

Crack

Mouth

Opening

Displacement,

in

Crack

Mouth

Opening

Displacement,

in
1000

Crack Mouth Opening Displacement, in

0.00 0.01 0.02 0.03 0.04 0.05 __U 1 J_ J U—

800 -

600

HY130 Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 25.4 mm

Crack Depth 6.35 mm

a> 400 -

200-

T— i ——

T~ i I — r 0.2 0.4 0.6 0.8 1 1.2 Crack Mouth Opening Displacement, mm

Figure 23k.

- 5000

- 4000

- 3000

- 2000

-1000

0

54

-Integral,

Ib/in
Yielding Patterns (no bending)

(shading indicates yielding)

Through Cracks

Yielding Confined to Net Section

Crack Tip Region Yielding

Gross Section

Yielding

Surface Cracks

Front Back

Confined Yielding Ligament Yielding

Gross Section Yielding

Figure 24. Yielding patterns for surface cracks compared to those for

through cracks.

55
IBm

©

09

56

Section

Through

LVDT

Displacement

gage

Crack

Plane

•

LVDT

attachment

point

CMOD

Crack

mouth

opening

displacement

gage
in w ©

cn m

® co a O)

cO

_Qo • CO r-H >- d:

Cl “O CD

CD “O

CD

03 CD

S- 03 CD SI CD

CD

CD "

03 E

s-

=3 LO

S- -M O cn

13O

CD

03 03 r— S-CD Co •*

4-> CD 03 C

-4-> 03 C QCDE CD

CO C

C CD

CD

(XI

57

•

LVDT

attachment

point

CM0D

Crack

mouth

opening

displacement

gage
>* w

AAj ‘utgjig 9|JSU@1 ‘uibjjs ai;su@i

58

Figure

27.

Strain

asymmetry

produced

by

strength

asymmetry

of

surfacecracked

base-metal

tensile

panels.
~o

CD CJ

<0

<j s~. ro CJ

S-CJ -Oc

CD ro

CJ

rO EE

s-3 OCO *-H

S- _cz o +-> <+- cnc C CD O r—

4-> •r- CJ

CO ro o t- CL o

T3

0> E ? £

<D cn o c

03 0)

CO

l- o

0)c

CO Q. EE

r^

0)

in q. c CD £ q o

CO o

C3 > o X

roCHr—

ro CD

CJ "O ro CD CL

CL 00c

00 CD

ro i

S- ro

4-> 4-> 00 CDE E

CD E

cn (D ro on (\

cn ro _Q i—l C

•IO JC

ro CO -P

s~ t—i a.

•+->>- CD oo jc ~o

00

C\J

CD

s~

J3cn

NlVdlS

59
HY130

Tensile

Panel

Surfaee-Cracked

Width

90

mm

Thickness

10

mm

Crack

Length

10

mm

Crack

Depth

1.7

mm

60

Figure

29.

Strain

pattern

as

revealed

by

photoelastic

coating

on

surfacecracked

HY130

base

metal

tensile

panel

with

crack

length

10

mm

and

crack

depth

1.7

mm.
HY130

Tensile

Panel

Surface-Cracked

Specimen

Width

90mm

Crack

Depth

1.7mm

Crack

Length

5mm

N IVdiS

“O

CD CJ

CJ ro

rO

d

d

U

CJ TD

CD

d

CJ ro

ro E d E

Z5Ul LO d JZ O -t—> d CD O f—

-M ZL

•r- CJ

cn ro O d

CL CJ

CO 4-> d t-

•r- ^

roCHrro CDd

“O ro

CD CL

4->

+-> CD O r—

rains

pi

al

tensi E

+-> 4_>

(j CO CD • E E . CD E

UJ cn cd Z ro c/) r-~ < cn ro —l _Q r—l Q_ d

•rO _d

rO CO +-> CJ d r-H CL <

>« CD QCCJ co m “O

LJ>o o CD<

CO

CD

L*J

d

CJ =3 z cn <1

inQ

LU

N IVdiS

61
HY130 Welded Tensile Panel Surface-Cracked

Width 90 mm Thickness 10 mm

Crack Length 5mm Crack Depth 1.7 mm

Scan #29

Scan #33 Scan #40

Scan #77

Scan #48 Scan #61

Figure 31. Strain pattern as revealed by photoelastic coating on surfacecracked HY130 base metal tensile panel with crack length 5 mm

and crack depth 1.7 mm.

62
Scan #29

Scan #33 Scan #40

Scan #77

Fi gure 31 , conti nued

.

63
-Integral,

kN/m

J-Integral,

kN/m

Gage Length S tr a i n/Yi e I d Strain

0.5 1 1.5 2 2.5

Figure 32a.

120

90 -

60 -

30 -

Remote Strain/Yield Strain

0.5 1 1.5 2

i i i i 2.5

_J HY130 Tensile Panel

Surtace-Cracked

Width 90 mm

Thickness 10 mm

Crack Length 10 mm

Crack Depth 1.7 mm

cP_,d?

cP

aP0.000 0.002 0.004 0.006 Remo t e Strain

"i ~T~

0.008 0.010

-750

-600

-450

-300

-150

—r* 0

0.012

Figure 32b.

64

-Integral,

Ib/in

J-Integral,

Ib/i
Stress

Intensity

Factor,

MPaVm

J-Integral,

kN/m

120-

90-

60-

30-

30 Stress, ksi60 90 120 150 HY130 Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 10 mm

Crack Depth 1.7 mm

o

o

o

oo

o

oo

o

o

o

oooo oaf mr.,w Q;

:

OpO n ©ocp^ qOqoO ^

200 r—

400 600 800

Stress, MPa

1000

180

i 1200

750

-600 C

-450

- 300

-150

*- 0

: igure 32c.

200 -

150-

100 -

50-

30 _L_

Stress, ksi

60 90 120 _j i i HY130 Tensile Panel

Surface-Cracked

Width 90 mm

Thickness 10 mm

Crack Length 10 mm

Crack Depth 1.7 mm

150

i

giocP

n°°0

o§

,oO

o o

oooo —i r~

" 1

i 1—

200 400 600 800

Stress, MPa

1000

180 —1 r 200

-150

-100

-50

1200

Figure 32d.

65

Stress

Intensity

Factor,

ksiVin

J—

Integral,

Ib/i
1000

800

O

9= 600

(/) 400 -

200

0.5

_l

Gage Length Strain/Yield Stra i n

1.5 4

2.5 -h

3.5

§

Oo

o

o

o

o

o

o

o

oo

oo

o

o

o

o

o

oo

o

o

oo

o

HY130 Tensile Panel

Surface-Cracked

Width 90 mm

Thickness 10 mm

Crack Length 10 mm

Crack Depth 1.7 mm

4.5

0.000 0.004 0.008 0.012 0.016 Gage Length Strain

125

- 100

- 75

-50

-25

to

to

<o

a>

oo

—-r 0.020

Figure 32e.

c

o

lw.

C/0

CT> c

<K

a>cy> oO

0.012

0 . 010 -

0 . 008 -

0 . 006 -

0 . 004 -

0 . 002 -

0.000

Remote Strain/Yield Strain

0.5 1 1.5 2 HY130 Tensile Panel

Surface-Cracked

Width 90 mm

Thickness 10 mm

Crack Length 10 mm

Crack Depth 1.7 mm

2.5

,cP"

&

0.000

I 0.002 0.004 0.006 0.008 Remo t e Strain

—i

0.010

- 2.5

-2

- 1.5

- 1

- 0.5

—

1 0

0.012

Figure 32f.

66

Gage

Length

Strain/Yield

Strain
Crack

Mouth

Opening

Displacement,

mm

Crack

Mouth

Opening

Displacement,

Figure 33a-b. Ful 1 -1 ength-resul t plots showing the dependence of crack mouth

opening displacement on strain for surface-cracked HY130 base

metal tensile panel with crack length 10 mm and crack depth

1 . 7 mm

.

Gage Length Strain/Yield Strain

- 0.012

- o.oio

- 0.008

0.006

- 0.004

- 0.002

0.000

Fi gure 33a

.

0 . 30 -

0 . 25 -

0 . 20 -

0 . 15 -

0 . 10 -

0 . 05 -

0.00

25 _l_

Stress, ksi

50 75

i j 100 HY130 Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 10 mm

Crack Depth 1.7 mm

125

w-i n n O Q ° O o o o o O o o o o O O o O O

- 0.012

0.010

0.008

0.006

- 0.004

0.002

0.000 200 400 600

Stress, MPa

800 1000

Figure 33b.

67

Crack

Mouth

Opening

Displacement,

in

Crack

Mouth

Opening

Displacement,

in
Figure 34a-f. Hal f-1 ength-resul t plots showing the dependence of J-integral on strain for surface-cracked HY130 base metal tensile panel with

crack length 5 mm and crack depth 1.7 mm.

150

120 -

90 -

CT>

0)c— 60 -

30 -

Gage Length S tr a i n/Yi e I d Strai

0.4 0.8 HY130 Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

1.2 1.6

axxxtrrrtWj®.

oo

o

o

o

o

0.000 0.002 0.004 0.006 Gage Length Strain

-—f~“

0.008

-800

-Q 600 —

-400

-200

cn

0)c

I

0 0.010

Figure 34a.

a>©

150 -

120 -

90 -

60 -

30 -

Remote Strain/Yield Strain

0.2 0.4 0.6 0.8

1 1 1

i HY130 Tensile Panel

Surface-Cracked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

ooo oea nn n QQ o go oo ° ° ° ° oo o co

0.0 1.0 r

2.0 _r

__

3.0 4.0 Remote Strain

O oo

O O

o

o

c

- 800

OO

o

o

JO -600 —

400

-200

cn©

0

5.0 M0‘

:

Figure 34b.

68
Stress

Intensity

Factor,

MPa\

m

J—

Integral,

kN/m

150 -

120 -

90 -

60 -

30 -

40 S tr ess, ks i 80 120 160 200

HY130 Tensile Panel o®

Surface-Cracked (® Width 90 mm %

o Thickness 10 mm o Crack Length 5 mm o Crack Depth 1.7 mm oo

oo

0

8

1

cecd

51

nnnnnnnnOaaag°°222^ ..1°. ooo°®°

200 400 600

Stress, MPa

800

-800

-600

400

-200

L 0 1000

Figure 34c.

Stress, ksi

200 -

iso

100 -

50 -

o-l

40 _L_

80 _L_120

I 160 _J

200

HY130 Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

OQO

) 0°0 o° o° o°° o°oo

lQ oO'

200

150

-100

-50

L 0 200 400 600 800

Stress, MPa

1000

Figure 34d

.

69

Stress

Intensity

Factor,

ksivin

J-Integral,

Ib/in
1000 -

800-

O

CL

00

600-

400-

200 -

Gage Length Strain/Yield Str

oo

oo

o

o

o

o

o

o

o

o

o

oo

o

o

oo

o

o

oo

o

3

a i n

7

I

oooococdocdoocooococCi coco CDOcDCOo

HY130 Tensile Panel

Surface-Cracked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

1 0.000 0.005 —r —r

0.010 0.015 0.020 0.025 0.030 Gage Leng t h Strain

-i

0.035

t- 160

- 140

-120

-100 '

80

0.040

-60 00

- 40

-20

Figure 34e.

0.010 -i

0.008-

W 0.006-

a>c

a>

0)cnDo

0.004 -

0 . 002 -

0.000

Remote Strain/Yield Strain

0.2 0.4 0.6 0.8

i —i—__

HY130 Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

<§> cP

cP o° k

-r T"

0.0 1.0 2.0 3.0 Remo t e Strain

4.0

%

- 1.6

- 1.2

- 0.8

- 0.4

-*-0

5.0 MO'

Figure 34f.

70

Gage

Length

Strain/Yield

Strain
Crack

Mouth

Opening

Displacement,

Figure 35a-b. Ful 1 -1 ength-resul t plots showing the dependence of crack mouth

opening displacement on strain for surface-cracked HY130 base

metal tensile panel with crack length 5 mm and crack depth

1.7 mm

.

Gage Length Strain/Yield Strain

Figure 35a.

c

(DE

0)o

o

Q.

Crt

CT> C

c

0)Q. o

u

oa

0 . 30 -

0 . 25 -

0 . 20 -

0.15 -

0.10

0.05

0.00

20 _L_40 —1_

Stress, ksi

60 80 100 _j ' i HY130 Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

120

i 140I O

oo8

o

o

o

o °

p

o ° ° oOpPOQ 00001

( onOO

cPa?

200

T

400 600

Stress, MPa

800 1000

160

0.012

- 0.010

- 0.008

- 0.006

- 0.004

- 0.002

0.000

nnure 35b.

71

Crack

Mouth

Opening

Displacement,
inm©

o>«

a»c©

©

08

£0a 0c

CL

a> 'mc©T3©2©0

00>1 EEo0) ©

— 5 .* ^ o o O

•— CQ co

“O

CD "O

S- CD

CDC > CD

03

S4->

5-o

M—

=3 3: O

r—

03 CD i— C

03

sz q_ o

•r~ CD C C

CD CD

s- o E

+-> ro

I/)

H

N

VO

CO

72

LVDT

Displacement

gage •

LVDT

attachment

point

CMOD

Crack

mouth

opening

displacement

gage
c X3 CD _C

4-> U Q_

ro CD

S- “D UI CD O

CJ ro

03 S- 4- U

13 ID

CO

C

03 “O

CD E

-O E

CD

O^ CO I CD _CZ CO +-> cn

CD c > CD CO I c

03

su

4-> 03

5-

su oo

>>—

03 CD

03

C Q- O

•i- CD

-*-> i—

03 *r-

•4-J CO C C

CD CD E 4-> • Z3 E ^ O E 4-J ro

C0 i—I Lf) c >- • *—• m csj

ro

73
HY130

Welded

Tensile

Panel

Surface-Cracked

Width

90

OCO

i—H >-

=3= EE

“O

CD

CJ i—

rO

s- JZ

<J 4-> I CL

<U (L) (J “O

rO 9—

<J

Z5 <0

(/) S_CJ "O

CD TD

-o

C <— <0

CD^ E I E

CD

(/) LO

CD _£Z > +-> co cn

sz cz rO CD

S- r- ^ CJ O <o 4- S-<J c/) C JZ

•r— 4-> ro •<—

4->

(/) i

CD

CD CZ Cn ro

ro Q- CH

CD

ro CO

SC

+-> CD CO +->

CO

CO

CD

®P!S P9>f0BJ0Un OUO|B U|BJ1S

74
03 o

O h- CO CO 03 O o CO o o

GO CO

r- T- CM 03

CO o o

d o

CM o o

CO T* T- CO O o

o o

o CM

r- CO o o o CO o o CO o o

03 CO

•'T CO o o in CO o o CM o o

CO CO

co

O) o o 03

CM o o

o o

c

CO *

k_ w c E

-C CO z

JC O)c CO "co 0)

<13 *-* o

w. *

c

_l

03

03

03

03 O) E _c o CO 03 1 CO O cc ->

0P!S p9>|0BJ0 6U0|B UjBJIS

9P!S P9>|0BJ0 BuO|B U|BJ^S

75

Distance

above

Crack

Plane,

cm

Distance

above

Crack

Plane,

cm
HY130 Tensile Panel

Width 90 mm

Crack Length 5 mm

Surface-Cracked

Thickness 1 0 mm

Crack Depth 1.7 mm

Scan #35 Scan #52 Scan #59

Scan #35 Scan #52 Scan #59

Figure 39. Strain pattern as revealed by photoelastic coating on transverse-wel ded surface-cracked HY130 tensile panel with crack

length 5 mm and crack depth 1.7 mm.

76
HY130

Welded

Tensile

Panel

Surface-Cracked

Width

254

Thickness

20

mm

Crack

Length

30

mm

Crack

Depth

2.5 e e E E Eo

0)c

jo

CLO

CO

fc-= O

0)>on

co

CDoc

CO

+-» CO QEo

d)c

JO

Q-a

CO O

CD>O

X)

CO

<1> ac

CO Q oon

“O LO

CD • (XI V

<T3 sz d 4—1 CJ QCD

CD TD

CJ

05 M—

U

d rC

=3d

00 CJ “O “O

CDd

“D ro

"aj E

CD oon oo d

O) _d > +-> on cn d d

HD CD d —d CJ O ro d- d

CJ

ond Jd

•r- 4-> ro •!— d ^

4-> on .

CD CD d

cn 05

05 Q_ cn

CD

d I—

ro on d d

4-> CD on +-> O

CDd

Z5cn

77
HY130

Welded

Tensile

Panel

Surface-Cracked

78

Figure

41.

Strain

pattern

as

revealed

by

photoelastic

coating

on

transverse-wel

ded

surface

cracked

HY130

tensile

panel

with

crack

length

30

mm

and

crack

depth

2.5

mm.
-Integral,

kN/rn

J-Integral.

kN/m

Figure 42a-k. Strain and stress dependences of J-integral and crack mouth

opening displacement for transverse-wel ded surface cracked HY130

tensile panel with crack length 5 mm and crack depth 1.7 mm.

Gage Length Strain/Yield Strain

0 1 2 3 4 5 6

Figure 42a.

012345678 Remote Strain/Yield Strain

1 I I I I I I I 400

-350

300

250

200

150

100

50

0 0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 Remo t e Strain

70 -

60 -

50 -

40

30 -

20 -

10 -

cP

,cP

d7°',o°° o ° o O

d

3 o

o

o

o

o

o

o

/ o

(9

HY130 Welded Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

Figure 42b.

79

-Integral,

Ib/in

J-Integral,

Ib/i
Stress

Intensity

Factor,

MPavm

J-Integral,

kN/m

25 Stress, ksi50 75 100 125 150 70 -

60-

50-

40-

30-

20 -

10 -

HY130 Welded Tensile Panel

Surf ace-C racked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

i o o° oo l

.. . V. o~ ) o o 1

200 400

r 600 800

Stress, MPa

Figure 42c.

1000

175 _

-400

-350

-300

-250

-200

-150

-100

-50 —

1200

200 -

ISO

100 -

50-

25 _L_

Stress, ksi

50 75 100 HY130 Welded Tensile Panel

Su rf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

125L—

>o° oo o° o°‘

»o° ) 0 ° oo 1

150

1 " I I I I

200 400 600 800 1000 Stress, MPa

175-200

-150

- 100

-50

0 1200

Figure 42d.

80

Stress

Intensity

Factor,

ksiVin

J-Integral,

Ib/i
Stress,

MPa

1200

1000

800

600

400

200

0

1200

1000

800

600

400

200

0

Gage Length Strain/Yield Strain

1 2 3 4 5 175

O

o

o

oo

o

o

o

3

0000000000°00000000000

I 0.005

HY130 Welded Tensile Panel

Surface-Cracked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

i 0.025

-150

-125

(/> Moo

cT

CO

a> 75

-50

-25

CO

1— 0.000 0.010 0.015 0.020 0.030 Gage Length Strain

Figure 42e.

Remote Strain/Yield Strain

6 -175

O

o

oo

o

o

o

oo

o

oo

o

3

'CCOOqooOOo O o o o oo oo oooooooooooooo

HY130 Welded Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

0.000 0.005 0.010 0.015 0.020 0.025 Remo t e Strain —i 0.030

-150

-125

co -100

cov> <D -75

-50

-25

(/)

0.035

Figure 42f.

81
Crack

Mouth

Opening

Displacement,

mm

Gage

Length

Strain

0.030

0.025

0.020

0.015

0.010

0.005

0.000

0.12

0.10

0.08

0.06

0.04

0.02

0.00

HY130 Welded Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

Remote Strain/Yield Strain

2 3 4 5 6 7

-.cP

,cP

-6

-5

-3

-2

-1

l i 0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 Remo t e Strain

Figure 42g.

Gage Length Strain/Yield Strain

o o o

o° ° o°o

d

3 o o

o

o o

?> o o

<§> ePr ooO

o

oo £

o

HY130 Welded Tensile Panel

Surf ace-C r acked

Widfh 90 mm

Thickness 10 mm

Crack Lengfh 5 mm

Crack Depth 1.7 mm

3 —

E

2.5 £

E

a>o

o

h 2 —

CL

1/1 o

1.5 cncc

<DCL

1 O

— -r 0.000 0.005

- 0.5

0.010 0.015 0.020 Gage Length Strain

0.025 0.030

o

oo

Figure 42h.

82

Gage

Length

Strain/Yield

Strain
Crack

Mouth

Opening

Displacement,

mm

Crack

Mouth

Opening

Displacement,

Remote Strain/Yield Strain

1 2 3 4 5 6 7

0.12

0 . 10 -

0 . 08 -

0. 06 -

0 . 04 -

0 . 02 -

0.00

o O o

o o

cP

§ °

o

o o o o o o

o o o

o

o o %

o'- CP HY130 Welded Tensile Panel

Surface-Cracked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm —

-

1

- i i i —i— - ~ r —— i 0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 Remote Strain

- 2.5

-2

- 1.5

0.5

Ft gure 42 i .

0.12

0.10

0 . 08 -

0.06

0.04 -

0.02

0.00

25 _L_

Stress, ksi

50 75 100 HY130 Welded Tensile Pane

Su rf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

o O

o

O O

o

125 150

QD

a?

o °ocf

o

o. %

OO

OO

Oo

oo

,

O O

o —I

1

1

1—

200 400 600 800

Stress, MPa

1000

175

- 2.5

-2

1.5

-1

- 0.5

1200

Figure 42 j

.

83

Crack

Mouth

Opening

Displacement,

mils

Crack

Mouth

Opening

Displacement,

mils
70 -

60 -

50 -

- 40 -

cn

<D 30 -

20 -

10 -

0

Crack Mouth Opening Displacement, mils

0.5 1 1.5 2 2.5 3 - I 1 _J I HY130 Welded Tensile Panel

Surf ace-C r acked

Width 90 mm

Thickness 10 mm

Crack Length 5 mm

Crack Depth 1.7 mm

8 °

cP° CD

400

-350

300

250

-200

-150

-100

-50

0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 Crack Mouth Opening Displacement, mm

Figure 42k.

84

-Integral,

I

b/i
-Integral,

kN/m

J-Integral,

kN/m

Figure 43a-k. Strain and stress dependences of J-integral and crack mouth

opening displacement for transverse-wel ded surface-cracked HY130

tensile panel with crack length 30 mm and crack depth 2.5 mm.

100-

80

60

40-

20 -

Gage Length Strain/Yield Strain

0.5 1.5 HY130 Welded Tensile Panel

Surf ace-Cracked

Width 254 mm

Thickness 20 mm

Crack Length 30 mm o Crack Depth 2.5 mm

CP

0

.OO

0.000 —I 0.002 0.004 0.006 0.008 Gage Length Strain —f0.010

2.5 600

500

400 \-O

-300

- 200

-100

cn

<L>

0.012

Figure 43a.

100 J

80-

60-

40-

20 -

Remote Strain/Yield Strain

0.5 1 1.5 2 2.5

OO

&

o

o

o

o

o

oo

o

cf3

0

t ,cP

HY130 Welded Tensile Panel

Surf ace-C r acked

Width 254 mm

Thickness 20 mm

Crack Length 30 mm

Crack Depth 2.5 mm

T

0.0000 0.0025

1 1

1

I 0.0050 0.0075 0.0100 0.0125 Remo t e Strain

600

-500

-400

-300

200

-100

0

Figure 43b.

-Integral,

Ib/in
Stress

Intensity

Factor,

MPa

Vm

J—

Integral,

kN/m

100-

80-

60-

40-

20 -

Stress, ks

25 _L_

50 75 —L100 —I

125 —1—

150 _J

HY130 Welded Tensile Panel

Su r f ace-C r acked

Width 254 mm

Thickness 20 mm

Crack Length 30 mm

Crack Depth 2.5 mm

ooo

o

oo

o 0§

oo

o

o

0 » o ; . O

O O °

O o T=

200

-T -r 400 600 800

Stress, MPa

1000

175600

-500

- 400

-300

-200

-100

—jo

1200

Figure 43c.

150-

100 -

50-

o ^

25 Stress, ksi50 75 100 125

200 400 600 800

Stress, MPa

150

1000

175 HY130 Welded Tensile Pane 1 Surf ace-C r acked

Width 254 mm

Thickness 20 mm 1

Crack Length 30 mm

Crack Depth 2.5 mm LJ xP

o

Cr O

o°

o o°

°°

o

0 o

O

o

o o o o

o

o o

0

o o

o

150

100

-50

1200

Figure 43d.

86

Stress

Intensity

Factor,

ksivin

J-Integral,

Ib/in
Stress,

MPa

Stress,

MPa

1200

1000-

800

600-

400-

200 -

0 <

Gage Length Strain/Yield Strain

0.5 1.5 2.5

.cP,o° 1 O O OOOoOOCBO O

T

0.000 0.002

HY130 Welded Tensile Panel

Surface-Cracked

Width 254 mm

Thickness 20 mm

Crack Length 30 mm

Crack Depth 2.5 mm —,————

i ——i 0.004 0.006 0.003 Gage Length Strain

o.oio

175

- 150

-125

- 100

-75

-50

-25

0 0.012

Figure 43e.

1200

1000 -

800-

600

400

200 -

0

Remote Strain/Yield Strain

0.5

_i

1.5

_l 2.5

_J

§

o

oo

o

rP oooo O O o ooo o

HY130 Welded Tensile Panel

Surface-Cracked

Width 254 mm

Thickness 20 mm

Crack Length 30 mm

Crack Depth 2.5 mm

T

r 175

-150

-125

-100

-75

-50

-25

0.0000 0.0025 0.0050 0.0075 0.0100 Remo t e Strain

0.0125

Figure 43f

.

87

Stress,

ksi

Stress,

ksi
Crack

Mouth

Opening

Displacement,

Remote Strain/Yield Strain

0.5 1.5

co

in

_cCDC

a)

a>cnoO

0.012

0.010

0 . 008 -

0 . 006 -

0.004

0.002 -

0.000

2.5 HY130 Welded Tensile Panel

Surface-Cracked

Width 254 mm

Thickness 20 mm

Crack Length 30 mm

Crack Depth 2.5 mm

&

if

<9

_,cP

- 2.5

-r 0.0000 0.0025 0.0050 0.0075 0.0100 Remo t e Strain

1.5

-1

0.5

—i—

0.0125

Figure 43g.

Gage Length Strain/Yield Strain

0.5 _j__

1.5

_l HY130 Welded Tensile Panel

Su rf ace-C r acked

o.25-| Width 254 mm

Thickness 20 mm

Crack Length 30 mm

0 . 20 H Crack Depth 2.5 mm

2.5

7.5

- 4.5

0 . 15 - ©P

0 . 10 -

- 3

0 . 05 -

rP

0.00 0.000 0.002 0.004 0.006 0.008 0.010 Gage Length Strain

- 1.5

0.012

Figure 4 3 h

Crack

Mouth

Opening

Displacement,

mils

Gage

Length

Strain/Yield

Strain
Crack

Mouth

Opening

Displacement,

mm

Crack

Mouth

Opening

Displacement,

E

E

0.25

0.20

0.15

0.10

0.05

0.00

0.25

0.20

0 . 15 -

0 . 10 -

0.05

0.00

Remote Strain/Yield Strain

0.5 1 1.5 2 2.5

- 7.5 HY130 Welded Tensile Panel

Su rf ace-C r acked

Width 254 mm

Thickness 20 mm

Crack Length 30 mm

Crack Depth 2.5 mm oo

Jp

cP

cP jSP

,cP— , 0.0000 0.0025

-6

- 4.5

- 3

- 1.5

0 0.0050 0.0075 0.0100 Remo t e Strain

0.0125

Figure 43 i

.

Stress, ksi

25 50 75 100 125 150 —1 I

i

l 1 1 175 -+ 7.5 HY130 Welded Tensile Panel

Surf ace-Cr acked

Width 254 mm

Thickness 20 mm

Crack Length 30 mm

Crack Depth 2.5 mm

3cP

—i 1 1 1

200 400 600 800

Stress, MPa

- 4.5

-3

- 1.5

—

V

0 1000 1200

Figure 43 j .

89

Crack

Mouth

Opening

Displacement,

mils

Crack

Mouth

Opening

Displacement,

mils
Crack Mouth Opening Displacement, mils

0 1.5 3 4.5 6 7.5

I l — 1 —— 1 i- 600

CD

0)

100

80

60

40

20

HY130 Welded Tensile Panel

Surf ace-C r acked

Width 254 mm

Thickness 20 mm

Crack Length 30 mm

Crack Depth 2.5 mm

0 -£•6*

<7ccP

CP cP

0.00 0.05 0.10 0.15 0.20 0.25 Crack Mouth Opening Displacement, mm

-500

-400

300

-200

-100

Figure 43k.

90

-Integral,

Ib/in
U.S. DEPT. OF COMM. 1. PUBLICATION OR 2. Performing Organ. Report No. 3. Publication D ate BIBLIOGRAPHIC DATA

SHEET (See instructions)

REPORT NO.

NBSIR 84-1699 March 1984

4. TITLE AND SUBTITLE

Experimental Results for Fi tness-for-Service Assessment of HY130 Weldments

5. AUTHOR(S)

D. T. Read

6. PERFORMING ORGANIZATION (If joint or other than N BS. see instructions) 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State, ZIP)

8 . Type of Report & Period Covered

Final - 10/81 - 9/82

Naval Sea Systems Command (SEA 05R25)

under direction of:

David Taylor Naval Ship R&D Center, Annapolis, MD 21402

10.

SUPPLEMENTARY NOTES

FT] Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. I f document includes a significant

bi bliography or literature survey, mention it here)

Applied J- i ntegral values for through and surface cracks in HY130 weldments and for

surface cracks in HY130 base metal have been measured using a previously developed

technique. The applied J-integral is taken as a measure of the crack driving force.

The results confirmed previous conclusions, namely, the strong effect of deformation

pattern on applied J-integral values, the utility of the J-integral estimation curve

for fi tness-for-service assessment in cases of gross section yielding (crack size less

than 1 percent of 1 oad-jbeari ng cross-section), and the need to consider ligament

yielding behind surface cracks. Additional concl usionsfor surface cracks and for

weldments were: surface-crack depth controls crack driving force; overmatching weld

metal strength greatly reduces crack driving force for strains above yield; the

relationship between crack length and crack driving force for cases of residual stress

is similar to that for applied stress; for a crack in a weld transverse to the tensile

axis, gross section yielding occurs if the crack intercepts less than 1.5 percent of

the load-bearing cross section; the effective crack size for J-integral estimation is

0.75 of the actual crack depth for crack aspect ratios of 12 or less, and is no larger

than the crack depth for any crack length; the line J-integral in the plane perpendicular to the surface crack root at the crack center is sufficiently path independent

to allow direct experimental measurement of the J-integral.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

design curve; elastic-plastic fracture mechanics; gross section yielding; net

section yielding; residual stress; surface crack.

13.

AVAILABILITY

£><$[ Uni imited aFor Official Distribution. Do Not Release to NTIS

Order From Superintendent of Documents, U.S. Government Printing Office, Washington,

20402.

[XJ Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

93

15. Price

$ 11.50

USCOMM-DC 6043-P 80

U.S. GOVERNMENT PRINTING OFFICE: 1 984—778-992 9262 REGION NO. 8