ISO 16573-2:2022

Steel — Measurement method for the evaluation of hydrogen embrittlement resistance of high-strength steels — Part 2: Slow strain rate test

This document provides an evaluation method of the resistance of high-strength steels to hydrogen embrittlement (i.e. hydrogen delayed fracture) using slow strain rate test with hydrogen pre-charged specimens. The amount of hydrogen absorbed in the specimens is analysed quantitatively by thermal desorption analysis such as gas chromatography, mass spectrometry and so on. This document includes testing methods for either smooth or notched specimens. It is applicable to ferritic base steels.

Acier — Méthode de mesure pour l'évaluation de la résistance à la fragilisation par l'hydrogène des aciers à haute résistance — Partie 2: Essai à déformation lente

General Information

• Status: Published
• Publication Date: 27-Feb-2022
• ICS: 77.040.99 - Other methods of testing of metals
• Technical Committee: ISO/TC 17/SC 7 - Methods of testing (other than mechanical tests and chemical analysis)
• Drafting Committee: ISO/TC 17/SC 7/WG 3 - Slow strain rate test
• Current Stage: 6060 - International Standard published
• Start Date: 28-Feb-2022
• Completion Date: 28-Feb-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 16573-2
First edition
2022-02
Steel — Measurement method for the
evaluation of hydrogen embrittlement
resistance of high-strength steels —
Part 2:
Slow strain rate test
Acier — Méthode de mesure pour l'évaluation de la résistance à la
fragilisation par l'hydrogène des aciers à haute résistance —
Partie 2: Essai à déformation lente
Reference number
ISO 16573-2:2022(E)
© ISO 2022

---------------------- Page: 1 ----------------------
ISO 16573-2:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
  © ISO 2022 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 16573-2:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Specimen preparation . .2
5.1 General . 2
5.2 Cylindrical type specimen . . 2
5.3 Flat type specimen . 3
6 Hydrogen charging methods .4
6.1 General . 4
6.2 Cathodic charging . 4
6.2.1 Hydrogen charging solution . 4
6.2.2 Hydrogen charging conditions . 4
6.3 Hydrogen absorption in aqueous solution at free corrosion potential . 5
6.4 Hydrogen absorption in atmospheric corrosion environments . 5
6.5 Hydrogen absorption in high pressure hydrogen gas . 5
7 Preparation of electroplating solution and electroplating condition .5
7.1 General . 5
7.2 Electroplating solution . 5
7.3 Electroplating conditions . . . 6
8 Slow strain rate test. 6
8.1 General . 6
8.2 Procedure . 6
8.3 Presentation of the results . 7
9 Post-test specimen treatment . 9
10 Hydrogen thermal desorption.10
10.1 General . 10
10.2 Experimental apparatus (gas chromatograph) . 10
10.3 Experimental apparatus (mass spectrometry) . 11
11 Test report .11
Bibliography .12
iii
© ISO 2022 – All rights reserved

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ISO 16573-2:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 7, Methods of
testing (other than mechanical tests and chemical analysis).
A list of all parts in the ISO 16573 series shall be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
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ISO 16573-2:2022(E)
Introduction
The mechanical properties of high-strength steels, such as tensile strength, elongation and reduction
of area would be degraded by the effect of hydrogen, known as hydrogen embrittlement, and the
susceptibility of hydrogen embrittlement becomes greater by increasing the strength level of steels.
v
© ISO 2022 – All rights reserved

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INTERNATIONAL STANDARD ISO 16573-2:2022(E)
Steel — Measurement method for the evaluation of
hydrogen embrittlement resistance of high-strength
steels —
Part 2:
Slow strain rate test
1 Scope
This document provides an evaluation method of the resistance of high-strength steels to hydrogen
embrittlement (i.e. hydrogen delayed fracture) using slow strain rate test with hydrogen pre-charged
specimens. The amount of hydrogen absorbed in the specimens is analysed quantitatively by thermal
desorption analysis such as gas chromatography, mass spectrometry and so on. This document includes
testing methods for either smooth or notched specimens.
It is applicable to ferritic base steels.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 6892-2, Metallic materials — Tensile testing — Part 2: Method of test at elevated temperature
ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and verification of the force-measuring system
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
Figure 1 shows schematic sequences for the overall testing method including hydrogen pre-charging
(such as electrochemical method described in ISO 16573-1), mechanical testing and hydrogen analysis.
Mechanical properties such as, yield strength, tensile strength, fracture strength, elongation to fracture
and reduction of area are measured by applying tensile load at slow strain rate before and after hydrogen
charging. Hydrogen contents in the specimen shall be measured by thermal desorption analysis, and
the relationship between the diffusible hydrogen content and the degradation of mechanical properties
shall be obtained. Thermal desorption analysis of pre-charged but not deformed samples allows the
quantification of the initial diffusible hydrogen content. However, thermal desorption analysis of pre-
charged and deformed samples is only valid when the slow strain rate test is carried out using the
1
© ISO 2022 – All rights reserved

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ISO 16573-2:2022(E)
plated samples. This method provides at least a qualitative comparison of the resistance to hydrogen
embrittlement among several high-strength steels having different microstructures or compositions.
Figure 1 — Flow chart illustrating the test methods
5 Specimen preparation
5.1 General
Tension specimens (bar type and flat type specimens) shall be used for evaluation of hydrogen
[2][3]
embrittlement .
5.2 Cylindrical type specimen
The dimensions of the specimens shall be in accordance with Figure 2, and other configurations of the
test specimen may be applied. Unless otherwise specified, diameter of the specimen shall be 10 mm.
[4]
For samples with smaller diameter (i.e. D = 5 mm), ρ/D = 0,02 may be applied .
2
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ISO 16573-2:2022(E)
a) Notched specimen
b) Smooth specimen
Key
ρ radius of the notch bottom
d/D 0,6
ρ/D 0,01 or 0,02
L /D 7 7
c
G/D 5 5
NOTE Some types of specimen do not have thread.
Figure 2 — Dimension of cylindrical type specimens
5.3 Flat type specimen
Flat type specimens shall also be used. Dimensions are shown in Figure 3. It is recommended to
use specimens with 10 mm in grip width as a standard size. In case of a flat type specimen, refer to
ISO 6892-2:2018, Figure A.1 for grip with bolt.
a) Notched specimen
b) Smooth specimen
3
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ISO 16573-2:2022(E)
Key
W width of grip ends 1 C/W ≤ 0,6
C width of gauge 2 G/W ≥ 2,5
G length of gauge in smooth specimen 3 L /W ≥ 7
c
Ɵ notch angle (degree) 4 0,1 ≤ T/C ≤ 1
r radius of fillet (mm) 5 Ɵ= 60
1
T thickness:(mm) and should be larger than 1 mm 6 r = 10
1
T should be larger than 1 mm.
Figure 3 — Dimension of flat type specimens
6 Hydrogen charging methods
6.1 General
There are four hydrogen charging methods: cathodic charging, hydrogen absorption in aqueous solution
at free corrosion potential, hydrogen absorption in atmospheric corrosion environments and hydrogen
absorption in high pressure hydrogen gas. The examples of the condition of each method are as follows.
6.2 Cathodic charging
6.2.1 Hydrogen charging solution
To estimate the effect of hydrogen on the mechanical properties of steels, the hydrogen is forced to
diffuse into the specimens by the cathodic charging method. For hydrogen pre-charging, the charging
solution should be prepared in accordance with Table 1.
Two kinds of solutions may be used for hydrogen pre-charging. Solution 1 may be used for introducing
a relatively large amount of hydrogen to the specimens and Solution 2 may be used for introducing a
small amount of hydrogen.
Table 1 — Chemical composition of the solutions for hydrogen charging
Content
Charging solution Element Mark
g/l
NaCl 30
Solution 1 Large amount of Hydrogen
NH SCN 3
4
Solution 2 NaOH 4 Small amount of hydrogen
6.2.2 Hydrogen charging conditions
The electro-chemical cell for hydrogen pre-charging may be placed in a 200 ml to 1 000 ml beaker. It
is recommended that the anode of the electrochemical cell be made of platinum wire of spiral type
of 0,5 mm in diameter and 2 m in length (counter electrode), and the specimen works as the cathode
(working electrode). After the Pt wire and the specimen are placed in the cell, apply the constant
2 2
current of its current density in the range of 0 A/m to 20 A/m by using potentiometer/galvanostat for
48 h. A charging time of 48 h is recommended, but other charging times may be used as long as a total
time of 72 h is reached for hydrogen charging and the homogenization treatment by room temperature
exposure after cadmium (Cd) plating. For materials with low hydrogen diffusion coefficient, the
hydrogen charging time and the total time may be increased. The specimen’s surface area shall be
calculated for proper current supply. The pre-charged hydrogen amount may be changed by varying
the current density or pre-charging time. However, it is recommended to use fixed pre-charging time
and current density to
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 16573-2
ISO/TC 17/SC 7
Steel — Measurement method for the
Secretariat: AFNOR
evaluation of hydrogen embrittlement
Voting begins on:
2021-11-18 resistance of high-strength steels —
Voting terminates on:
Part 2:
2022-01-13
Slow stain rate test
Acier — Méthode de mesure pour l'évaluation de la résistance à la
fragilisation par l'hydrogène des aciers à haute résistance —
Partie 2: Essai de décoloration lente
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 16573-2:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO 2021

---------------------- Page: 1 ----------------------
ISO/FDIS 16573-2:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
  © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/FDIS 16573-2:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
5 Specimen preparation . .2
5.1 General . 2
5.2 Cylindrical type specimen . . 2
5.3 Flat type specimen . 3
6 Hydrogen charging methods .4
6.1 General . 4
6.2 Cathodic charging . 4
6.2.1 Hydrogen charging solution . 4
6.2.2 Hydrogen charging conditions . 4
6.3 Hydrogen absorption in aqueous solution at free corrosion potential . 5
6.4 Hydrogen absorption in atmospheric corrosion environments . 5
6.5 Hydrogen absorption in high pressure hydrogen gas . 5
7 Preparation of electroplating solution and electroplating condition .5
7.1 General . 5
7.2 Electroplating solution . 5
7.3 Electroplating conditions . . . 6
8 Slow strain rate test. 6
8.1 General . 6
8.2 Procedure . 6
8.3 Presentation of the results . 7
9 Post-test specimen treatment . 9
10 Hydrogen thermal desorption.10
10.1 General . 10
10.2 Experimental apparatus (gas chromatograph) . 10
10.3 Experimental apparatus (mass spectrometry) . 11
11 Test Report .11
Bibliography .12
iii
© ISO 2021 – All rights reserved

---------------------- Page: 3 ----------------------
ISO/FDIS 16573-2:2021(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 7, Methods of
testing (other than mechanical tests and chemical analysis).
A list of all parts in the ISO 16573 series shall be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
  © ISO 2021 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/FDIS 16573-2:2021(E)
Introduction
The mechanical properties of high-strength steels, such as tensile strength, elongation and reduction
of area would be degraded by the effect of hydrogen, known as hydrogen embrittlement, and the
susceptibility of hydrogen embrittlement becomes greater by increasing the strength level of steels.
v
© ISO 2021 – All rights reserved

---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 16573-2:2021(E)
Steel — Measurement method for the evaluation of
hydrogen embrittlement resistance of high-strength
steels —
Part 2:
Slow stain rate test
1 Scope
This document provides an evaluation method of the resistance of high-strength steels to hydrogen
embrittlement (i.e. hydrogen delayed fracture) using slow strain rate test with hydrogen pre-charged
specimens. The amount of hydrogen absorbed in the specimens is analysed quantitatively by thermal
desorption analysis such as gas chromatography, mass spectrometry and so on. This document includes
testing methods for either smooth or notched specimens.
It is applicable to ferritic base steels.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 6892-2, Metallic materials — Tensile testing — Part 2: Method of test at elevated temperature
ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and verification of the force-measuring system
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
Figure 1 shows schematic sequences for the overall testing method including hydrogen pre-charging
(such as electrochemical method described in ISO 16573-1), mechanical testing and hydrogen analysis.
Mechanical properties such as, yield strength, tensile strength, fracture strength, elongation to fracture
and reduction of area are measured by applying tensile load at slow strain rate before and after hydrogen
charging. Hydrogen contents in the specimen shall be measured by thermal desorption analysis, and
the relationship between the diffusible hydrogen content and the degradation of mechanical properties
shall be obtained. Thermal desorption analysis of pre-charged but not deformed samples allows the
quantification of the initial diffusible hydrogen content. However, thermal desorption analysis of pre-
charged and deformed samples is only valid when the slow strain rate test is carried out using the
1
© ISO 2021 – All rights reserved

---------------------- Page: 6 ----------------------
ISO/FDIS 16573-2:2021(E)
plated samples. This method provides at least a qualitative comparison of the resistance to hydrogen
embrittlement among several high-strength steels having different microstructures or compositions.
Figure 1 — Flow chart illustrating the test methods
5 Specimen preparation
5.1 General
Tension specimens (bar type and flat type specimens) shall be used for evaluation of hydrogen
[3][5]
embrittlement .
5.2 Cylindrical type specimen
The dimensions of the specimens shall be in accordance with Figure 2, and other configurations of the
test specimen may be applied. Unless otherwise specified, diameter of the specimen shall be 10 mm.
[2]
For samples with smaller diameter (i.e. D = 5 mm), ρ/D = 0,02 may be applied .
2
  © ISO 2021 – All rights reserved

---------------------- Page: 7 ----------------------
ISO/FDIS 16573-2:2021(E)
a) Notched specimen
b) Smooth specimen
Key
ρ radius of the notch bottom
d/D 0,6
ρ/D 0,01 or 0,02
L /D 7 7
c
G/D 5 5
NOTE Some types of specimen do not have thread.
Figure 2 — Dimension of cylindrical type specimens
5.3 Flat type specimen
Flat type specimens shall also be used. Dimensions are shown in Figure 3. It is recommended to
use specimens with 10 mm in grip width as a standard size. In case of a flat type specimen, refer to
ISO 6892-2:2018, Figure A.1 for grip with bolt.
a) Notched specimen
b) Smooth specimen
3
© ISO 2021 – All rights reserved

---------------------- Page: 8 ----------------------
ISO/FDIS 16573-2:2021(E)
Key
W width of grip ends 1 C/W ≤ 0,6
C width of gauge 2 G/W ≥ 2,5
G length of gauge in smooth specimen 3 L /W ≥ 7
c
Ɵ notch angle (degree) 4 0,1 ≤ T/C ≤ 1
r radius of fillet (mm) 5 Ɵ= 60
1
T thickness:(mm) and should be larger than 1 mm 6 r = 10
1
T should be larger than 1 mm.
Figure 3 — Dimension of flat type specimens
6 Hydrogen charging methods
6.1 General
There are four hydrogen charging methods: cathodic charging, hydrogen absorption in aqueous solution
at free corrosion potential, hydrogen absorption in atmospheric corrosion environments and hydrogen
absorption in high pressure hydrogen gas. The examples of the condition of each method are as follows.
6.2 Cathodic charging
6.2.1 Hydrogen charging solution
To estimate the effect of hydrogen on the mechanical properties of steels, the hydrogen is forced to
diffuse into the specimens by the cathodic charging method. For hydrogen pre-charging, the charging
solution should be prepared in accordance with Table 1.
Two kinds of solutions may be used for hydrogen pre-charging. Solution 1 may be used for introducing
a relatively large amount of hydrogen to the specimens and Solution 2 may be used for introducing a
small amount of hydrogen.
Table 1 — Chemical composition of the solutions for hydrogen charging
Content
Charging solution Element Mark
g/l
NaCl 30
Solution 1 Large amount of Hydrogen
NH4SCN 3
Solution 2 NaOH 4 Small amount of hydrogen
6.2.2 Hydrogen charging conditions
The electro-chemical cell for hydrogen pre-charging may be placed in a 200 ml to 1 000 ml beaker. It
is recommended that the anode of the electrochemical cell be made of platinum wire of spiral type
of 0,5 mm in diameter and 2 m in length (counter electrode), and the specimen works as the cathode
(working electrode). After the Pt wire and the specimen are placed in the cell, apply the constant
current of its current density in the range of 0 A/m2 to 20 A/m2 by using potentiometer/galvanostat for
48 h. A charging time of 48 h is recommended, but other charging times may be used as long as a total
time of 72 h is reached for hydrogen charging and the homogenization treatment by room temperature
exposure after cadmium (Cd) plating. For materials with low hydrogen diffusion coefficient, the
hydrogen charging time and the total time may be increased. The specimen’s surface area shall be
calculated for proper
...