The certification of the absorbed energy (80 J nominal) of Charpy V-notch reference test pieces for tests at 20 °C : ERM®-FA015aa.
Date: 2017-02-23
Institutions: Institute for Reference Materials and Measurements
Subjects: approval, metrology, physical sciences, research method, research report, resistance of materials

CERTIFICATION REPORT 

The certification of the absorbed energy 
(80 J nominal) of Charpy V-notch reference test 
pieces for tests at 20 °C:  
ERM®-FA015aa 

E
U
R
2
8
3
6
4

E
N
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2
0
1
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JRC-IRMM promotes a common and reliable European measurement 

provides reference measurements. 

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Joint Research Centre 
Directorate F – Health, Consumers and Reference Materials 

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JRC 104875 

EUR 28364 EN 

ISBN 978-92-79-64649-2 (PDF) 
ISSN 1831-9424 (online) 
doi: 10.2787/894362 

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Reproduction is authorised provided the source is acknowledged. 
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Abstract 

This certification report describes the processing and characterisation of ERM®-FA015aa, a batch of Charpy V-notch reference test pieces certified for 
the absorbed energy (KV). Sets of five of these test pieces are used for the verification of pendulum impact test machines according to ISO 148-2 
(Metallic materials - Charpy pendulum impact test – Part 2: Verification of testing machines).  
The absorbed energy (KV) is operationally defined and refers to the impact energy required to break a V-notched test piece of standardised 
dimensions, as defined in ISO 148-1. The certified value of ERM®-FA015aa is made traceable to the SI, via the SI-traceable certified value of the 
master batch ERM®-FA015v, by testing samples of ERM®-FA015aa and ERM®-FA015v under repeatability conditions on an impact pendulum verified 

and calibrated with SI-traceably calibrated tools. The certified value is valid only for strikers with a 2 mm tip radius and at (20 ± 2) °C. 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The certification of the absorbed energy 
(80 J nominal) of Charpy V-notch reference test 
pieces for tests at 20 °C:  
ERM®-FA015aa 

Ts. Gerganova, G. Roebben, A. Dean, T. Linsinger 

European Commission, Joint Research Centre 
Directorate F – Health, Consumers and Reference Materials 
Geel, Belgium 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Disclaimer 

Certain commercial equipment, instruments, and materials are identified in this paper to specify adequately the 
experimental  procedure.  In  no  case  does  such  identification  imply  recommendation  or  endorsement  by  the 
European Commission, nor does it imply that the material or equipment is necessarily the best available for the 
purpose.  

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Summary 

This  certification  report  describes  the  processing  and  characterisation  of  ERM®-
FA015aa,  a  batch  of  Charpy  V-notch  reference  test  pieces  certified  for  the  absorbed 
energy (KV). Sets of five of these test pieces are used for the verification of pendulum 
impact  test  machines  according  to  ISO  148-2  (Metallic  materials  -  Charpy  pendulum 
impact test – Part 2: Verification of testing machines [1]).  
The  absorbed  energy  (KV)  is  operationally  defined  and  refers  to  the  impact  energy 
required  to  break  a  V-notched  test  piece  of  standardised  dimensions,  as  defined  in 
ISO 148-1  [2].  The  certified  value  of  ERM®-FA015aa  is  made  traceable  to  the  SI,  via 
the SI-traceable certified value of the master batch ERM®-FA015v, by testing samples 
of  ERM®-FA015aa  and  ERM®-FA015v  under  repeatability  conditions  on  an  impact 
pendulum verified and calibrated with SI-traceably calibrated tools. The certified value is 
valid only for strikers with a 2 mm tip radius and at (20 ± 2) °C. 

The  certified  value  for  KV  (energy  required  to  break  a  V-notched  test  piece  using  a 
pendulum  impact  test  machine)  and  the  associated  expanded  uncertainty  (k = 2 
corresponding to a confidence level of about 95 %) calculated for the mean of a set of 
five test pieces, is: 

Steel Charpy V-notch test pieces 

Certified value 2) 
[J] 

Absorbed energy (KV) 1) 

78.1 

Uncertainty 3) 
[J]  

2.5 

1) The absorbed energy (KV) is an operationally defined measurand. KV is the impact energy required to 
break a V-notched test piece of standardised dimensions, as defined in ISO 148-1. The certified value is 
valid only for strikers with a 2 mm tip radius, and at temperatures of (20 ± 2) °C. 
2) The certified value of ERM®-FA015aa, and its uncertainty, are traceable to the International System 
of  Units  (SI),  via  the  master  batch  ERM®-FA015v  of  a  similar  nominal  absorbed  energy  by  testing 
samples of ERM®-FA015v and ERM®-FA015aa under repeatability conditions on an impact pendulum 
verified and calibrated with SI-traceably calibrated tools.  

3)  Estimated  expanded  uncertainty  of  the  mean  KV  of  the  5  specimens  (delivered  as  1  set),  with  a 
coverage factor k = 2, corresponding to a level of confidence of about 95 %, as defined in ISO/IEC Guide 
98-3,  Guide  to  the  expression  of  uncertainty  in  measurement  (GUM:1995).  The  number  of  degrees  of 
freedom of the certified uncertainty is n RM = 46. 

2 

 
 
 
 
 
 
 
 
Table of contents 

Summary ........................................................................................................... 2 

Table of contents .............................................................................................. 3 

Glossary ............................................................................................................ 4 

1 

Introduction ............................................................................................... 5 

2  Participants ................................................................................................ 7 

3  Processing ................................................................................................. 7 

4  Homogeneity ............................................................................................. 9 

5  Stability ...................................................................................................... 9 

6  Characterisation ...................................................................................... 10 

7  Value assignment .................................................................................... 12 

8  Metrological traceability ......................................................................... 13 

9  Commutability ......................................................................................... 13 

10  Summary of results ................................................................................. 14 

11 

Instructions for use ................................................................................. 15 

Acknowledgements ........................................................................................ 16 

References ...................................................................................................... 17 

Annex 1 ........................................................................................................... 18 

Annex 2 ........................................................................................................... 19 

3 

 
 
 
Glossary 
AISI 
ASTM 
BCR 
CRM 
EC 
IEC 
ERM® 
IMB 
ISO 
JRC 
k 
KV 

KVCRM 

KVMB 
LNE 
MB 
nMB 

nSB  
RSD 
s 
SB 
sh 

sMB  

sSB 

uCRM 
UCRM 
uchar 
uchar,rel 
uh 
ui 
uMB 
uMB,rel 
MBX  

SBX  

D h 

n RM 

n i 

American Iron and Steel Institute 
American Society for Testing and Materials 
Community Bureau of Reference 
Certified Reference Material 
European Commission 
International Electrotechnical Commission 
European Reference Material 
International Master Batch 
International Organization for Standardization 
Joint Research Centre 
Coverage factor 
Absorbed energy = energy required to break a V-notched test piece of 
defined shape and dimensions when tested with a pendulum impact 
testing machine 
Certified KV value of a set of 5 reference test pieces from the 
Secondary Batch 
Certified KV value of the Master Batch test pieces 
Laboratoire national de métrologie et d’essais 
Master Batch 
Number of samples of the Master Batch tested during certification of 
the Secondary Batch 
Number of samples of the Secondary Batch tested for certification  
Relative standard deviation 
Standard deviation 
Secondary Batch 
Standard deviation of the results of the samples tested to assess the 
homogeneity of the Secondary Batch  
Standard deviation of the nMB results of the samples of the Master 
Batch tested for the certification of the Secondary Batch  
Standard deviation of the nSB results of the samples tested for the 
characterisation of the Secondary Batch  
Combined standard uncertainty of KVCRM 
Expanded uncertainty (k = 2, confidence level of about 95 %) of KVCRM 
Standard uncertainty of the result of the characterisation tests 
Relative standard uncertainty of the result of the characterisation tests 
Contribution to uncertainty from homogeneity 
Value of uncertainty from contribution i 
Standard uncertainty of KVMB 
Relative standard uncertainty of KVMB 
Mean KV value of the nMB measurements on samples of the Master 
Batch tested when characterising the Secondary Batch  
Mean KV value of the nSB results of the samples tested for the 
characterisation of the Secondary Batch  
difference between the height of the centre of gravity of the pendulum 
prior to release and at the end of the half-swing during which the test 
sample is broken 
Effective number of degrees of freedom associated with the 
uncertainty of the certified value 
Degrees of freedom 

4 

 
 
BELAC 

Belgian Accreditation Body 

1 

Introduction 

1.1  The Charpy pendulum impact test 
The Charpy pendulum impact test is designed to assess the resistance of a material 
to  shock  loading.  The  test,  which  consists  of  breaking  a  notched  bar  of  the  test 
material  using  a  hammer  rotating  around  a  fixed  horizontal  axis,  is  schematically 
presented in Figure 1. 

b
b

1
1

2
2

d
d

D h
D h

a
a

3
3

c
c

Figure 1: Schematic presentation of the Charpy pendulum impact test, showing a: the 
horizontal rotation axis of the pendulum, b: the stiff shaft on to which is fixed d: the 
hammer. The hammer is released from a well-defined height (position 1). When the 
hammer  has  reached  maximum  kinetic  energy  (shaft  in  vertical  position  2),  the 
hammer strikes c: the test sample, which is positioned on a support and against the 
pendulum anvils (not shown). The height reached by the hammer after having broken 
the sample (position 3) is recorded. The difference in height between position 1 and 3 
(D h)  corresponds  with  the  difference  in  potential  energy,  and  is  a  measure  of  the 
energy required to break the test sample. 

The energy absorbed by the test sample is very dependent on the impact pendulum 
construction  and  its  dynamic  behaviour.  Methods  to  verify  the  performance  of  an 
impact  pendulum  require  the  use  of  reference  test  pieces  as  described  in  ISO  and 
other international standards [1, 3]. The reference test pieces dealt with in this report 
comply with a V-notched test piece of well-defined geometry [1], schematically shown 
in Figure 2. 

anvil
anvil

anvil
anvil

sample
sample

location and direction of impact
location and direction of impact

Figure 2: Schematic drawing of a V-notched Charpy test piece (top-view), indicating 
the place and direction of impact. 

5 

 
 
 
 
 
 
 
 
1.2  The certification concept of Master Batch and Secondary Batch 

1.2.1  Master and Secondary Batches 
The  BCR  reports  by  Marchandise  et  al.  [4]  and  Varma  [5]  provide  details  of  the 
certification of BCR “Master Batches” (MB) of Charpy V-notch certified reference test 
pieces. The certified value of a Master Batch is obtained using an international inter-
laboratory comparison.  

This report describes the production of a “Secondary Batch” (SB) of Charpy V-notch 
certified  reference  test  pieces  at  the  Directorate  F  –  Health,  Consumers  and 
Reference  Materials  of  the  European  Commission's  (EC)  Joint  Research  Centre 
(JRC). The work was performed in accordance with procedures described in the BCR 
reports [4] and [5]. The certification of a SB is based on the comparison of a set of 
SB  test  pieces  with  a  set  of  test  pieces  from  the  corresponding  MB  under 
repeatability conditions on a single pendulum.  

The  BCR  reports  [4]  and  [5]  were  published  in  1991  and  1999,  respectively.  Since 
2000, the calculation of the certified value and the estimation of its uncertainty have 
been updated to an approach compliant with the ISO/IEC Guide to the Expression of 
Uncertainty  in  Measurement  [6].  This  revised  approach  was  developed  and 
presented by Ingelbrecht et al. [7, 8], and is summarised below.  

1.2.2  Certification of a Secondary Batch of Charpy V-notch test pieces 
The  certified  absorbed  energy  of  a  SB  of  Charpy  V-notch  reference  test  pieces 
(KVCRM) is calculated from the mean KV-value of a set of test pieces of the SB (
SBX ) 
tested on a single pendulum. This value 
SBX  has to be corrected for the bias of this 
particular pendulum. The bias of the pendulum at the moment of testing the samples 
of the SB, is estimated by comparing the mean KV-value of a number of samples of 
the  MB  ( MBX ),  tested  together  with  the  SB  samples  under  repeatability  conditions. 
The certified value of the MB is used then to calculate KVCRM as follows [8]: 

=

CRM





MB

MB





SB

Eq. 1 

For  this  approach to  be reliable,  the  pendulum  used for  the tests  on  MB  and  SB  in 

repeatability conditions must be well performing. In other words, the ratio 

MB

 must 

KV
X

MB

be close to 1. Procedures at the JRC allow a difference of 5 % (KVMB ≥ 40 J) or 2 J 
(KVMB < 40 J) between KVMB and  MBX , corresponding to the level of bias allowed for 
reference pendulums specified in  ISO 148-3 [9].  

Also,  the  interaction  of  the  pendulum  with  a  SB  sample  must  be  similar  to  the 
interaction with a MB sample. This is the reason why MB and SB samples are made 

from nominally the same steel. Moreover, it is checked that the ratio 

CRM

 is close 

KV
KV

MB

to 1. Procedures at the JRC allow a difference of 25 % (KVMB ≥  40 J) or 10 J (KVMB < 
40 J) between KVCRM and KVMB. 

6 

 
 
 
 
(cid:215)
  
 
 
 
 
 
 
1.2.3  Uncertainty of the certified value of a Secondary Batch of Charpy V-notch test 

pieces 

The uncertainty of the certified value of the SB is a combination of the uncertainties 
of  the  factors  in  Eq.  1.  The  MB-SB  approach  necessarily  results  in  a  larger 
uncertainty  of  the  certified  value  of  SB  in  comparison  with  the  MB.  The  additional 
uncertainty  contribution  depends  on  the  uncertainty  of  the  ratio 
SBX .  The 
measurement  uncertainty  of  the  values  MBX   and 
SBX   is  relatively  large.  However, 
(repeatability  conditions,  pendulum 
when  all  conditions  mentioned  above 
performance, and commutability between Secondary and Master Batch) are fulfilled, 
then  the  uncertainties  of  the  values 
SBX   have  several  contributions  in 
MBX   and 
common, in particular the uncertainty due to the bias of the pendulum. These shared 
SBX , 
uncertainty  components  do  not  contribute  to  the  uncertainty  of  the  ratio  MBX /
and only the standard deviations of the SB and MB results in the MB-SB comparison 
test  need  to  be  taken  into  account  (see  also  Section  6.3).  Thus,  the  MB-SB 
comparison  approach  can  produce  a  value  for  the  uncertainty  of  KVCRM  that  is 
sufficiently  small  to  meet  the  requirements  of  the  intended  use  of  the  certified 
reference material (CRM).  

MBX /

2  Participants 
The  processing  of  the  SB  (ERM®-FA015aa)  test  pieces  was  carried  out  by  the 
Laboratoire  national  de  métrologie  et  d’essais  (LNE),  using  AISI  4340  steel 
delivered  by  Aubert&Duval  (FR)  .  The  MB  samples  (ERM®-FA015v)  used  in  the 
characterisation of the SB were provided JRC, Directorate F (Health, Consumers and 
Reference  Materials),  Geel  (BE).  The  homogeneity  of  the  SB  was  evaluated  based 
on data obtained at LNE, within the scope of an ISO/IEC 17025 accreditation, using a 
pendulum  verified  according  to  the  criteria  imposed  by  ISO 148-2  [1].  The 
characterisation of the SB was carried out at the JRC also using a pendulum verified 
according to ISO 148-2 [1]. The tests performed were within the scope of an ISO/IEC 
17025 accreditation (BELAC 268-Test). 
Data  evaluation  was  performed  at  the  JRC.  The  certification  was  performed  within 
the scope of an ISO Guide 34 accreditation (BELAC 268-RM). 

3  Processing 
The  ERM®-FA015aa  test  pieces  were  prepared  from  bars  of  AISI  4340  steel 
delivered by Aubert&Duval (FR) . Production of the test pieces from these bars was 
performed under the supervision of LNE at FLEURY GF, France as described in [10]. 

3.1  Processing of hot-rolled bars 
The  base  material  consisted  of  AISI  4340  steel.  To  limit  the  amount  of  impurities 
potentially  affecting  the  homogeneity  of  the  fracture  resistance,  the  following 
compositional  tolerances  specified  in  Table  1  were  imposed  on  the  selected  steel 
batch. These tolerances are stricter than generally allowed for AISI 4340 steel. 

Table 1: Adapted composition tolerances of AISI 4340  

Composition (mass fraction) [g/kg] 

C 
1.1 – 1.3 
Mo 
15.5 – 17 

S 
< 0.03 
Cu 
< 2 

P 
<0.18 
Al 
< 0.1 

Si 
1.5 – 3 
V 
2.5 – 3 

Mn 
7.5 – 9 
W 
< 1 

Cr 
112.5 – 116.5 
N 
0.25 - 0.4 

Ni 
25.5 – 27.5 

7 

 
 
 
 
 
The  ingot  was  hot  rolled,  resulting  in  bars  that  were  6  m  long  and  with  a  squared 
cross-section of 12 mm x 12 mm. For the ERM®-FA015aa batch, steel was used from 
ingot number HS360303. 

3.2  Machining of Charpy test pieces 
The ingot was devided into 14 billets. All 14 bars from one billet 5 were cut into 1428 
Charpy specimens and  machined to the dimensional requirements of ISO 148-3 [9] 
and engraved to ensure identification. 

3.3  Heat treatment of hot-rolled bars 
The heat treatment of the 1428 specimens was performed at Aubert&Duval (FR) in a 
vacuum-furnace, according to the following procedure: 
Step 1: normalisation treatment at 950°C for 65 minutes in a furnace of 'class 10 °C' 
(the variation of the temperature in the furnace is smaller than 10 °C); 
Step 2: cool down in neutral gas; 
Step 3: austenisation treatment at 850 °C for 85 minutes in a furnace of 'class 10 °C' 
(the variation of the temperature in the furnace is smaller than 10 °C); 
Step 4: quenching in oil. 

3.4  Final machining of Charpy test pieces 
After heat treatment, the specimens were machined to the final dimensions specified 
in ISO 148-3 [9]. During this process the specimen numbers were engraved on both 
sides of the notch on one of the long faces of the sample. Finally the specimens were 
notched at LNE using an electro-erosion tool. 

3.5  Quality control 
When all samples from the batch were fully machined, a selection of 25 samples was 
made. The dimensions of the 25 samples were checked against the criteria specified 
in  ISO  148-3  [9]  (length 
 mm,  height  (10.00  ±  0.06)   mm,  width  (10.00  ± 
0.07) mm,  notch  angle  (45 ± 1)°,  height  remaining  at  notch  root  (8.00  ±  0.06) mm, 
radius at notch root (0.250 ± 0.025) mm, distance between the plane of symmetry of 
the  notch  and  the  longitudinal  axis  of  the  test  piece  (27.5  ±  0.2) mm.  None  of  the 
samples was outside the intervals specified in ISO 148-3 [9].  

+
00.0
30.00.55

The  25  samples  selected  throughout  the  batch  and  checked  for  geometrical 
compliance  were  also  impact  tested  using  a  pendulum  type  Tinius  Olsen  model  74 
(nominal  energy  120  J),  verified  according  to  ISO  148-2  [1].  The  tests  were 
performed  on  17.02.2015.  The  results  are  reported  in  the  production  report  of 
01.02.2015 [10]. The average KV of the 25 samples was 78.5  J, which is within the 
desired energy interval ( 75 J - 85 J). The standard deviation of the test results (s = 
2.3 J,  RSD  =  2.9  %)  was  below  the  4  %  maximum  allowed  by  the  contract.  The 
variation  was  checked  again  during  the  characterisation  tests  at  the  JRC  (see 
Section 6). 

3.6  Packaging and storage 
Finally, the samples were cleaned and packed as sets of 5 randomised samples, in 
oil-filled  and  vacuum  sealed  plastic  bags.  These  oil-filled  bags,  were  packed  in  a 
second  sealed  plastic  bag,  and  shipped  to  the  JRC.  After  arrival  (26.02.2015)  the 

8 

 
 
 
 
 
-
 
 
1370  samples  (or  274  sets)  of  ERM®-FA015aa  were  registered  and  stored  at  room 
temperature. 

4  Homogeneity 
The test pieces are sampled from the SBs and analysed to estimate the homogeneity 
uncertainty contribution uh to the uncertainty of the certified value. uh is related to sh, 
the  standard  deviation  between 
the  SB  (sample-to-sample 
heterogeneity), but also depends on the number of samples over which the KV-value 
is  averaged.  ISO 148-2  [1]  specifies  that  the  pendulum  verification  must  be 
performed  using  5  test  pieces,  which  is  why  a  CRM-unit  consists  of  a  set  of  5  test 
pieces. The appropriate uncertainty contribution must be an estimate of the set-to-set 
heterogeneity,  which  in  the  case  of  a  set  of  5  test  pieces  can  be  calculated  as

the  samples 

in 

u =
h

s

h
5

. 

Here,  uh  is  estimated  from  sh,  the  standard  deviation  of  results  obtained  at  LNE  on 
s

17.02.2015 (sh = 2.3 J). This leads to 

= 1.03 J or (1.31 %).  

u =
h

h
5

As is required for a homogeneity test, the samples were randomly selected from the 
whole  batch.  The  number  of  samples  tested  (25)  is  sufficiently  large  to  reflect  the 
homogeneity of the full SB (1370 samples). It can be noted that uh is probably a slight 
overestimation,  since  it  contains  also  the  repeatability  of  the  instrument.  However, 
the latter cannot be separated or separately measured. 

5  Stability 
The stability of the absorbed energy of Charpy V-notch certified reference test pieces 
was first systematically investigated for samples of nominally 120 J by Pauwels et al. 
[11]. Additional evidence for the stability of the reference test pieces produced from 
AISI 4340  steel  of  lower  energy  levels  (nominally  15 J,  30 J  and  100 J)  has  been 
obtained during the International Master Batch (IMB) project [12]. In the IMB-project, 
the  stability  of  the  certified  test  pieces  was  judged  from  the  change  of the  mean  of 
means of the absorbed energy obtained on 7 reference pendulums over a three year 
period.  None  of  the  three  regression  slopes  for  the  tested  energy  levels  was 
statistically significant at the 5 % probability level. Given the large sample-to-sample 
heterogeneity and the limited number of samples (5) in a CRM unit, the uncertainty 
contribution from instability is considered to be insignificant in comparison to that of 
homogeneity.  A  dedicated  isochronous  study  (test  temperature  18  °C,  reference 
temperature  -20  °C)  on  batches  of  30,  80  and  120  J  from  the  same  steel  and 
showed,  as  expected,  no  change  of  the  measured  values.  Uncertainty  of  stabilities 
for  120  months  were  calculated  and  varied  between  0.7  -  2.8  J  (1.8  %  to  2.4  %). 
These  uncertainties  are  entirely  driven  by  the  measurement  precision  and  it  was 
concluded that no uncertainty contribution for potential change was needed [14]. 

treatment.  Annealing 

The main reason for the microstructural stability of the certified reference test pieces 
is  the  annealing  treatment  to  which  the  samples  were  subjected  after  the 
austenisation 
the 
equilibrium phases are the same as the (meta-)stable phases at ambient temperature 
(a -Fe  and  Fe3C).  The  only  driving  force  for  instability  stems  from  the  difference  in 
solubility  of  interstitial  elements  in  the  a -Fe  matrix,  between  annealing  and  ambient 
temperature.  Relaxation  of  residual  (micro-)stress  by  short-range  diffusion  or  the 

temperatures  where 

is  performed  at 

9 

 
 
 
 
additional  formation  or  growth  of  precipitates  during  the  shelf-life  of  the  certified 
reference test pieces is expected, but proceeds slowly .  

Rather than neglecting the stability issue, it is decided to specify a limited shelf-life. A 
period of 10 years is chosen, counting from the date of the characterisation tests on 
the SB. Since batch ERM®-FA015aa was characterised in June 2015, the validity of 
the certificate reaches until June 2025.  

6  Characterisation 

6.1  Characterisation tests 
30 samples from ERM®-FA015aa (sets 1, 22, 65, 125, 199, 274) were tested under 
repeatability conditions together with 25 samples from MB ERM®-FA015v (sets 6, 52, 
110, 191, 239), using the JRC Instron Wolpert PW-30 machine (UK). The pendulum 
is annually verified according to procedures described in ISO 148-2 [1].  
Tests were performed on 1112 of June 2015 (laboratory temperature (20 ± 2) °C, in 
accordance  with  ISO 148-1  [2].  The  measurement  sequence  was:  SB-MB-SB-MB-
SB-MB-SB-MB-SB-MB-SB.  The  measured  absorbed  energy  values  were  corrected 
for friction and windage losses.  

The  accepted  data  obtained  on  individual  test  pieces  are  shown  in  Figure  3  and 
Annex 1.  The results of the measurements are summarised in Table 2.  

]
J
[

y
g
r
e
n
e
d
e
b
r
o
s
b
a

100

95

90

85

80

75

70

65

60

0

20

40
60
test sequence

80

100

Master batch
Secondary batch

Figure 3: Absorbed energy values of 25 test pieces of ERM®-FA015v, compared with 
30 test pieces of ERM®-FA015aa; data are displayed in the actual test sequence 

The sequence of the samples shows one high value for the master batch. This value 
was flagged as outlier using the Grubbs procedure. As the technical evaluation of the 
results  did  not  indicate  any  technical  flaw,  there  is  no  reason  to  exclude  this  value 
from  the  analysis  data  set.  Moreover,  the  respective  set  of  samples  met  the 
specification of ISO 148-3 for reference samples having standard deviation < 3 J. 

10 

 
 
 
 
 
 
 
 
 
 
 
Table 2: Characterisation measurements of Batch ERM®-FA015aa 

Number of 
test pieces  

Mean value  

Standard 
deviation   

Relative 
standard 
deviation  

nMB , nSB 

SBX  

MBX  , 
[J] 

ERM®-FA015v (MB) 

ERM®-FA015aa (SB) 

25 

30 

80.88 

77.67 

sMB , sSB 

RSDSB, RSDMB   

[J] 

2.29 

1.47  

[%] 

2.83 

1.89 

The  SB-results  meet  the  ISO  148-3  acceptance  criteria  for  a  batch  of  reference 
SBX , the  indicator 
materials  (RSDSB  <  5  %).  Also the  difference  between 
used  to  assess  the  similarity  of  master  batch  and  secondary  batch  behaviour,  is 
smaller than the allowed 25 % (see Section 1.2.2). 

MBX   and 

6.2  Data from Master Batch ERM®-FA015v  
To  calculate  KVCRM  for  ERM®-FA015aa  one  needs  KVMB  of  the  MB  used,  i.e. 
ERM®-FA015v.  Table  3  shows  the  main  MB-data,  taken  from  the  Certificate  of 
Analysis of ERM®-FA015v (Annex 2). 

Table 3: Data from the certification of Master Batch ERM®-FA015v 

Certified 
absorbed energy 
of Master Batch 

Standard 
uncertainty of 
KVMB 

Relative standard 
uncertainty of 
KVMB 

KVMB [J] 

ERM®-FA015v 

81.32 

uMB [J] 

0.51 

uMB,rel [%] 

0.63 

6.3  Calculation of KVCRM and of uchar 
From the data in Tables 2 and 3, and using Eq. 1, one readily obtains that KVCRM = 
78.09  J  (rounded  in  accordance  with  the  uncertainty;  see  Table  5). The  uncertainty 
associated  with  the  characterisation  of  the  SB,  uchar,  is  assessed  as  in  Eq.  2  [8], 
which sums the squares of the relative uncertainties of the three factors in Eq. 1: 

u

char

=

KV

CRM

u
KV

2
MB
2
MB

+

s

n
SB

2
SB
X

2
SB

+

s

n

MB

2
MB
X

2
MB

Eq. 2 

X

SB / X

SBX  and  MBX were obtained under repeatability conditions. Therefore, the uncertainty 
of the ratio 
 is not affected by the contributions from reproducibility and bias 
of  the  pendulum  used  to  compare  MB  and  SB.  Table  4  summarises  the  input 
quantities  of  the  uchar  uncertainty  budget,  their  respective  statistical  properties,  and 
shows  how  they  were  combined.  The  effective  number  of  degrees  of  freedom  (n eff) 

MB

11 

 
 
 
 
 
 
 
 
 
 
 
 
(cid:215)
(cid:215)
 
 
for  uchar  is  obtained  using  the  Welch-Satterthwaite  equation  from  the  combined 
uncertainty  (uc)  and  the  individual  uncertainty  contributions  (ui)  and  their  respective 
degrees of freedom (n i) (Eq. 3) [6]. 

=

eff

u
N

4
c
u
∑
= n

1

i

4
i

i

Eq. 3

Table 4: Uncertainty budget for uchar for ERM®-FA015aa 
source of 
uncertainty 

standard 
uncertainty 

probability 
distribution 

measured 
value  

relative 
uncertainty 

KVMB  Certification of 

81.32 

[J] 

[J] 

0.51 

normal 

[%] 

0.63 

SBX  

MBX

MB 

comparison of 
SB and MB 
under 
repeatability 
conditions 

77.67 

0.27 

normal 

0.35 

80.88 

0.46 

normal 

0.57 

relative standard uncertainty,  uchar,rel [%] 

standard uncertainty,  uchar [J] 

0.91 

0.71 

degrees 
of 
freedom 

13 

29 

24 

41 

7  Value assignment  

7.1  Certified value, combined and expanded uncertainty 
As shown in 6.3, the value of KVCRM = 78.09 (to be rounded in accordance with the 
expanded uncertainty. The uncertainty of the certified value is obtained by combining 
the  contributions  from  the  characterisation  study,  uchar,  and  from  the  homogeneity 
assessment, uh, as is summarised in the following uncertainty budget (Table 5).  

The relevant number of degrees of freedom calculated using the Welch-Satterthwaite 
equation [6], is sufficiently large (n RM =  46) to justify the use of a coverage factor k = 
2 to expand the confidence level to about 95 %. The obtained expanded uncertainty 
provides  justification  for  the  SB-MB  approach  followed:  UCRM  is  sufficiently  smaller 
(UCRM = 2.50 J) than the verification criterion of 10 % for industrial pendulums [1] or 
even 5 % for reference pendulums [9].  

12 

 
n
 
 
 
 
 
 
 
 
 
 
 
 
Table 5: Uncertainty budget of KVCRM for ERM®-FA015aa  

source of uncertainty 

relative value ui 
[%] 

uchar 

characterisation of SB 

uh 

homogeneity of SB 

0.91 

1.31 

Combined relative standard uncertainty, uCRM [%] 

1.60 

Combined standard uncertainty, uCRM [J] 

1.25 

Relative expanded Uncertainty, k = 2, UCRM [%] 

3.19 

Expanded Uncertainty, k = 2, UCRM [J] 

2.50 

degrees 
of 
freedom 

41 

24 

 46 

Because  of  inherent  imprecision  of  uncertainty  values,  the  value  of  the  UCRM  is 
rounded to 3 J. Correspondingly, the value of KVCRM is rounded to 78 J. 

8  Metrological traceability 
The  certified  property  is  defined  by  the  Charpy  pendulum  impact  test  procedure 
described in ISO 148-1 [2].  

The  certified  value  of  the  MB  ERM®-FA015v  is  traceable  to  the  SI,  since  it  was 
obtained using an interlaboratory comparison, involving a representative selection of 
the  standard 
qualified 
procedures and using instruments verified and calibrated with SI-traceably calibrated 
tools.  

laboratories  performing  the  tests 

in  accordance  with 

The certified value of ERM®-FA015aa is made traceable to the SI-traceable certified 
value of the MB by testing SB and MB samples under repeatability conditions on an 
impact pendulum verified and calibrated with SI-traceably calibrated tools. Therefore, 
the certified value of ERM®-FA015aa is traceable to the International System of Units 
(SI) via the corresponding Master Batch ERM®-FA015v of a similar nominal absorbed 
energy.  Absorbed  energy  KV  is  a  operationally-defined  value,  and  can  only  be 
obtained by following the procedures specified in ISO 148-1 [2].  

9  Commutability 
The  intended  use  of  the  certified  reference  test  pieces  is  the  verification  of  Charpy 
impact pendulums. During the certification of the MB, different pendulums were used, 
each  equipped  with  an  ISO-type  striker  of  2 mm  tip  radius.  Until  further  notice,  the 
certified values are not to be used when the test pieces are broken with striker of 8 
mm tip radius [10]. 

13 

 
 
 
 
 
 
 
 
10  Summary of results 
The certified value and associated uncertainty are summarized in Table 6. 

Table 6: Certified value and associated uncertainty for ERM®-FA015aa 

Steel Charpy V-notch test pieces 

Certified value 2) 
[J] 

Absorbed energy (KV) 1) 

78.1 

Uncertainty 3) 
[J]  

2.5 

1) The absorbed energy (KV) is an operationally defined  measurand. KV is the impact energy required to 
break a V-notched bar of standardised dimensions, as defined in ISO 148-1. The certified value is valid 
only for strikers with a 2 mm tip radius, and at temperatures of (20 ± 2) °C. 
2) The certified value of ERM®-FA015aa, and its uncertainty, are traceable to the International System 
of Units (SI), via the master batch ERM®-FA015v of similar nominal absorbed energy by testing samples 
of ERM®-FA015v  and ERM®-FA015aa under  repeatability  conditions on  an  impact  pendulum  verified 
and calibrated with SI-traceably calibrated tools.  

3)  Estimated  expanded  uncertainty  of  the  mean  KV  of  the  5  specimens  (delivered  as  1  set),  with  a 
coverage factor k = 2, corresponding to a level of confidence of about  95 %, as defined in ISO/IEC Guide 
98-3,  Guide  to  the  expression  of  uncertainty  in  measurement  (GUM:1995).  The  number  of  degrees  of 
freedom of the certified uncertainty is n RM =  46. 

14 

 
 
 
 
 
 
11  Instructions for use 

11.1  Intended use 
Samples  of  ERM®-FA015aa  correspond  to  the  ‘certified  reference  test  pieces’  as 
defined  in  ISO 148-3  [9].  Sets  of  five  of  these  certified  reference  test  pieces  are 
intended for the indirect verification of impact testing machines with a striker of 2 mm 
tip radius according to procedures described in detail in ISO 148-2 [1].  

The  indirect  verification  provides  an  assessment  of  the  bias  of  the  user’s  Charpy 
pendulum  impact  machine.  This  bias  assessment  can  be  used  in  the  calculation  of 
the  measurement  uncertainty  of  Charpy  tests  on  the  pendulum  after  indirect 
verification.  Such  uncertainty  calculation  requires  the  certified  value,  the  associated 
uncertainty,  and  in  some  cases  also  the  degrees  of  freedom  of  the  uncertainty,  all 
given on page 1 of the certificate. 

11.2  Sample preparation 
Special  attention  is  drawn  to  the  cleaning  of  the  specimens  prior  to  the  tests.  It  is 
mandatory  to  remove  the  oil  from  the  sample  surface  prior  to  testing,  without 
damaging the edges of the sample. Between the moment of removing the protective 
oil  layer  and  the  actual  test,  corrosion  can  occur.  This  must  be  avoided  by  limiting 
this period of time, while keeping the sample clean. 

The following procedure is considered a good practice. 

1. 

2.  

First  use  absorbent  cleaning-tissue  to  remove  the  excess  oil.  Pay  particular 
attention to the notch of the sample, but do not use hard (e.g. steel) brushes 
to remove the oil from the notch.  
Before  testing,  bring  the  specimens  to  the  test  temperature  (20  ±  2)  °C.  To 
assure  that  thermal  equilibrium  is  reached,  move  the  specimens  to  the  test 
laboratory at least 3 h before the tests. 

An optional cleaning step with organic solvents may be used between 1 and 2. Any 
residual  solvents  shall  be  removed  by  wiping  with  an  absorbent  tissue  before 
proceeding to step 2. 

11.3 Pendulum impact tests 
After  cleaning,  the  5  samples  constituting  a  CRM-unit  need  to  be  broken  with  a 
pendulum impact test machine in accordance with  ISO 148-2 [1]. Prior to the tests, 
the  anvils  must  be  cleaned.  It  must  be  noted  that  Charpy  test  pieces  sometimes 
leave debris on the Charpy pendulum anvils. Therefore, the anvils must be checked 
regularly and if debris is found, it must be removed. The uncertainty of the certified 
value applies to the mean of the 5 KV-values. 

15 

 
 
 
 
 
 
 
 
Acknowledgements 
The authors wish to thank to R. Jakopic, A. Held, R. Koeber and H. Emons (all from 
JRC) for reviewing of the certification report. 

16 

 
 
 
 
 
References 

1.  ISO 148-2: Metallic materials - Charpy pendulum impact test - Part 2: Verification 
of testing machines, International Organization for Standardization, Geneva (CH), 
2008 

2.  ISO  148-1:  Metallic  materials  -  Charpy  pendulum  impact  test  -  Part  1:  Test 

method, International Organization for Standardization, Geneva (CH), 2009 

3.  ASTM  E23  -  07ae1  Standard  Test  Methods  for  Notched  Bar  Impact  Testing  of 
Metallic Materials, ASTM International, West Conshohocken, PA (USA), 2007 
4.  Marchandise H., Perez-Sainz A., Colinet E., Certification of the impact toughness 
of V-notch Charpy specimens, in BCR information series, Community Bureau of 
Reference - BCR, Brussels (BE), 1991 

5.  Varma  R.K.,  The  certification  of  two  new  master  batches  of  V-notch  Charpy 
impact toughness specimens in accordance with EN 10045-2: 1992, CRM's 015 
and 415, EUR Report 18947 EN - European Communities, Luxembourg - 1999 - 
ISBN 92-828-2244-3 

6.  ISO/IEC  Guide  98-3:2008,  Uncertainty  of  measurement  -  Part  3:  Guide  to  the 
International 

in  measurement 

expression  of  uncertainty 
Organization for Standardization, Geneva (CH), 2008 

(GUM:1995), 

7.   Ingelbrecht, C. and Pauwels J., EC Reference Materials for Impact Toughness - 
Traceability  and  uncertainty.  Presentation  at  Eurachem  Eurolab  symposium  on 
Reference  Materials  for  Technologies  in  the  New  Millennium,  Berlin  (DE),  May 
22-23, 2000 

8.  Ingelbrecht,  C.,  Pauwels,  J.,  and  Gyppaz,  D.,  Charpy  specimens  from  BCR  for 
machine  verification  according  to  EN  10045-2.  Poster  presentation  at  Charpy 
Centenary Conference, October 2-5, Poitiers (FR), 2001 

9.  ISO 148-3: Metallic materials - Charpy pendulum impact test - Part 3: Preparation 
and  characterization  of  Charpy  V-notch  test  pieces  for  indirect  verification  of 
pendulum  impact  machines,  International  Organization  for  Standardization, 
Geneva (CH), 2008 

10. Characterisation  report:  Charpy  V-notch  reference  test  pieces  ERM-FA016bh, 

Laboratoire national de metrologie at d'essais (DE), December 2013 

11. Pauwels,  J.,  Gyppaz,  D.,  Varma,  R.,  Ingelbrecht,  C.,  European  certification  of 
Charpy  specimens:  reasoning  and  observations,  in  Pendulum  Impact  testing:  A 
Century  of  Progress.  Seattle,  Washington:  American  Society  for  Testing  and 
Materials, 1999  

12. McCowan,  C.N.,  Roebben,  G.,  Yamaguchi,  Y.,  Lefrançois,  S.,  Splett,  J.  D., 
Takagi,  S.,  Lamberty,  A.,  International  Comparison  of  Impact  Reference 
Materials, J. ASTM International, Vol. 3(2), 2004 

13. Schmieder, A. K., Purtscher P. T., Vigliotti, D. P., The role of strike marks on the 
reproducibility  of  Charpy  impact  test  results,  in  Pendulum  impact  machines: 
procedures  and  specimens  for  verification,  ASTM  STP  1248,  ed.  Siewert,  T.  A. 
and  Schmieder  A.  K.,  American  Society  for  Testing  and  Materials,  Philadelphia 
(USA), 1995 

14.  Lamberty, A, Roebben, G, Dean, A, Linsinger T, Study of the stability of Charpy 
V-notch  reference  test  pieces  for  tests  at  20  °C  (ERM®-FA013ba,  ERM®-
FA015v and ERM®-FA016ax) during long-term storage at 18°C, EUR 26348 EN, 
Luxembourg: Publications Office of the European Union, 2015 

17 

 
 
 
Annex 1 
Results  of  characterisation  measurements  of  ERM®-FA015aa  as  measured 
according to ISO 148-1 at JRC, 1112  June 2015. 

Master Batch ERM®-FA015v   Secondary Batch ERM®-FA015aa 

KV (J) 

KV (J) 

77.56 
78.62 
78.97 
75.27 
79.15 
75.97 
77.20 
77.38 
77.73 
78.80 
75.27 
77.03 
78.80 
78.97 
74.91 
79.94 
80.47 
79.58 
77.27 
77.45 
78.16 
76.39 
77.63 
77.80 
77.80 
77.63 
79.05 
74.46 
77.63 
77.27 

77.67 

1.47  

1.89 

1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 

Mean (J) 

Standard deviation 
(J) 
RSD (%) 

78.26 
77.20 
83.09 
82.01 
81.65 
79.86 
79.69 
80.04 
81.12 
82.55 
82.01 
87.07 
82.73 
80.65 
79.22 
80.29 
76.39 
81.90 
77.80 
81.72 
83.52 
81.19 
80.29 
78.87 
82.80 

80.88 

2.29 

2.83 

18 

 
 
 
 
 
 
 
 
 
 
 
 
 
Annex 2 

19 

 
 
 
 
 
 
 
 
 
 
20 

 
 
 
 
 
 
 
 
 
 
 
21 

 
 
 
 
 
 
 
 
 
 
European Commission 

EUR 28364 EN – Joint Research Centre – Directorate F – Health, Consumers and Reference Materials 
Title:   CERTIFICATION REPORT The certification of the absorbed energy (80 J nominal) of Charpy V-notch 

reference test pieces for tests at 20 °C: ERM®-FA015aa  

Author(s): Ts. Gerganova, G. Roebben, A. Dean, T. Linsinger 

Luxembourg: Publications Office of the European Union 
2017 – 22 pp. – 21.0 x 29.7 cm 
EUR – Scientific and Technical Research series – ISSN 1831-9424 
ISBN 978-92-79-64649-2 
doi: 10.2787/894362 

 
 
 
 
 
 
 
 
As the Commission's in-house science service, the Joint Research Centre's mission is to provide EU policies 
with independent, evidence-based scientific and technical support throughout the whole policy cycle. 

Working in close cooperation with policy Directorates-General, the JRC addresses key societal challenges 
while stimulating innovation through developing new methods, tools and standards, and sharing its know-
how with the Member States, the scientific community and international partners. 

Key policy areas include: environment and climate change; energy and transport; agriculture and food 
security; health and consumer protection; information society and digital agenda; safety and security, 
including nuclear; all supported through a cross-cutting and multi-disciplinary approach. 

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doi: 10.2787/894362 

ISBN: 978-92-79-64649-2