ASTM A923-23

Standard Test Methods for Detecting Detrimental Intermetallic Phase in Duplex Austenitic/Ferritic Stainless Steels

ABSTRACT
These test methods cover the detection of detrimental intermetallic phase in duplex austenitic/ferritic stainless steel to the extent that toughness and corrosion resistance is affected significantly. These test methods will not necessarily detect losses of toughness or corrosion resistance attributable to other causes. Test method A-sodium hydroxide etch test, test method B-Charpy impact test, and test method C-ferric chloride corrosion test shall be made for classification of structures of duplex stainless steels.
SCOPE
1.1 The purpose of these test methods is to allow detection of the presence of intermetallic phases in certain duplex stainless steels as listed in Table 1, Table 2, and Table 3 to the extent that toughness or corrosion resistance is affected significantly. These test methods will not necessarily detect losses of toughness or corrosion resistance attributable to other causes. Similar test methods for other duplex stainless steels are described in Test Method A1084, but the procedures described in this standard differ significantly from Test Methods A, B, and C in A1084.  
1.2 Duplex (austenitic-ferritic) stainless steels are susceptible to the formation of intermetallic compounds during exposures in the temperature range from approximately 600 to 1750 °F (320 to 955 °C). The speed of these precipitation reactions is a function of composition and thermal or thermomechanical history of each individual piece. The presence of these phases is detrimental to toughness and corrosion resistance.  
1.3 Correct heat treatment of duplex stainless steels can eliminate these detrimental phases. Rapid cooling of the product provides the maximum resistance to formation of detrimental phases by subsequent thermal exposures.  
1.4 Compliance with the chemical and mechanical requirements for the applicable product specification does not necessarily indicate the absence of detrimental phases in the product.  
1.5 These test methods include the following:  
1.5.1 Test Method A—Sodium Hydroxide Etch Test for Classification of Etch Structures of Duplex Stainless Steels (Sections 3 – 7).  
1.5.2 Test Method B—Charpy Impact Test for Classification of Structures of Duplex Stainless Steels (Sections 8 – 13).  
1.5.3 Test Method C—Ferric Chloride Corrosion Test for Classification of Structures of Duplex Stainless Steels (Sections 14 – 20).  
1.6 The presence of detrimental intermetallic phases is readily detected in all three tests, provided that a sample of appropriate location and orientation is selected. Because the occurrence of intermetallic phases is a function of temperature and cooling rate, it is essential that the tests be applied to the region of the material experiencing the conditions most likely to promote the formation of an intermetallic phase. In the case of common heat treatment, this region will be that which cooled most slowly. Except for rapidly cooled material, it may be necessary to sample from a location determined to be the most slowly cooled for the material piece to be characterized.  
1.7 The tests do not determine the precise nature of the detrimental phase but rather the presence or absence of an intermetallic phase to the extent that it is detrimental to the toughness and corrosion resistance of the material.  
1.8 Examples of the correlation of thermal exposures, the occurrence of intermetallic phases, and the degradation of toughness and corrosion resistance are given in Appendix X1 and Appendix X2.  
1.9 The values stated in either inch-pound or SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.10 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.11 This internat...

General Information

• Status: Published
• Publication Date: 14-May-2023
• ICS: 77.040.99 - Other methods of testing of metals
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.14 - Methods of Corrosion Testing

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: A923 − 23
Standard Test Methods for
Detecting Detrimental Intermetallic Phase in Duplex
1
Austenitic/Ferritic Stainless Steels
This standard is issued under the fixed designation A923; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.6 The presence of detrimental intermetallic phases is
readily detected in all three tests, provided that a sample of
1.1 The purpose of these test methods is to allow detection
appropriate location and orientation is selected. Because the
of the presence of intermetallic phases in certain duplex
occurrence of intermetallic phases is a function of temperature
stainless steels as listed in Table 1, Table 2, and Table 3 to the
and cooling rate, it is essential that the tests be applied to the
extent that toughness or corrosion resistance is affected signifi-
region of the material experiencing the conditions most likely
cantly. These test methods will not necessarily detect losses of
to promote the formation of an intermetallic phase. In the case
toughness or corrosion resistance attributable to other causes.
of common heat treatment, this region will be that which
Similar test methods for other duplex stainless steels are
cooled most slowly. Except for rapidly cooled material, it may
described in Test Method A1084, but the procedures described
be necessary to sample from a location determined to be the
in this standard differ significantly from Test Methods A, B,
most slowly cooled for the material piece to be characterized.
and C in A1084.
1.7 The tests do not determine the precise nature of the
1.2 Duplex (austenitic-ferritic) stainless steels are suscep-
detrimental phase but rather the presence or absence of an
tible to the formation of intermetallic compounds during
intermetallic phase to the extent that it is detrimental to the
exposures in the temperature range from approximately 600 to
toughness and corrosion resistance of the material.
1750 °F (320 to 955 °C). The speed of these precipitation
reactions is a function of composition and thermal or thermo- 1.8 Examples of the correlation of thermal exposures, the
mechanical history of each individual piece. The presence of occurrence of intermetallic phases, and the degradation of
these phases is detrimental to toughness and corrosion resis- toughness and corrosion resistance are given in Appendix X1
tance. and Appendix X2.
1.3 Correct heat treatment of duplex stainless steels can 1.9 The values stated in either inch-pound or SI units are to
eliminate these detrimental phases. Rapid cooling of the be regarded as the standard. The values given in parentheses
product provides the maximum resistance to formation of are for information only.
detrimental phases by subsequent thermal exposures.
1.10 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.4 Compliance with the chemical and mechanical require-
responsibility of the user of this standard to establish appro-
ments for the applicable product specification does not neces-
priate safety, health, and environmental practices and deter-
sarily indicate the absence of detrimental phases in the product.
mine the applicability of regulatory limitations prior to use.
1.5 These test methods include the following:
1.11 This international standard was developed in accor-
1.5.1 Test Method A—Sodium Hydroxide Etch Test for
dance with internationally recognized principles on standard-
Classification of Etch Structures of Duplex Stainless Steels
ization established in the Decision on Principles for the
(Sections 3 – 7).
Development of International Standards, Guides and Recom-
1.5.2 Test Method B—Charpy Impact Test for Classification
mendations issued by the World Trade Organization Technical
of Structures of Duplex Stainless Steels (Sections 8 – 13).
Barriers to Trade (TBT) Committee.
1.5.3 Test Method C—Ferric Chloride Corrosion Test for
Classification of Structures of Duplex Stainless Steels (Sec-
2. Referenced Documents
tions 14 – 20).
2
2.1 ASTM Standards:
1
These test methods are under the jurisdiction of ASTM Committee A01 on
Steel, Stainless Steel and Related Alloysand are the direct responsibility of
2
Subcommittee A01.14 on Methods of Corrosion Testing. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 15, 2023. Published June 2023. Originally contact ASTM Customer Service at service@a
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: A923 − 22 A923 − 23
Standard Test Methods for
Detecting Detrimental Intermetallic Phase in Duplex
1
Austenitic/Ferritic Stainless Steels
This standard is issued under the fixed designation A923; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 The purpose of these test methods is to allow detection of the presence of intermetallic phases in certain duplex stainless steels
as listed in Table 1, Table 2, and Table 3 to the extent that toughness or corrosion resistance is affected significantly. These test
methods will not necessarily detect losses of toughness or corrosion resistance attributable to other causes. Similar test methods
for other duplex stainless steels are described in Test Method A1084, but the procedures described in this standard differ
significantly from Test Methods A, B, and C in A1084.
1.2 Duplex (austenitic-ferritic) stainless steels are susceptible to the formation of intermetallic compounds during exposures in the
temperature range from approximately 600 to 1750 °F (320 to 955 °C). The speed of these precipitation reactions is a function of
composition and thermal or thermomechanical history of each individual piece. The presence of these phases is detrimental to
toughness and corrosion resistance.
1.3 Correct heat treatment of duplex stainless steels can eliminate these detrimental phases. Rapid cooling of the product provides
the maximum resistance to formation of detrimental phases by subsequent thermal exposures.
1.4 Compliance with the chemical and mechanical requirements for the applicable product specification does not necessarily
indicate the absence of detrimental phases in the product.
1.5 These test methods include the following:
1.5.1 Test Method A—Sodium Hydroxide Etch Test for Classification of Etch Structures of Duplex Stainless Steels (Sections 3 –
7).
1.5.2 Test Method B—Charpy Impact Test for Classification of Structures of Duplex Stainless Steels (Sections 8 – 13).
1.5.3 Test Method C—Ferric Chloride Corrosion Test for Classification of Structures of Duplex Stainless Steels (Sections 14 – 20).
1.6 The presence of detrimental intermetallic phases is readily detected in all three tests, provided that a sample of appropriate
location and orientation is selected. Because the occurrence of intermetallic phases is a function of temperature and cooling rate,
it is essential that the tests be applied to the region of the material experiencing the conditions most likely to promote the formation
1
These test methods are under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloysand are the direct responsibility of Subcommittee
A01.14 on Methods of Corrosion Testing.
Current edition approved June 1, 2022May 15, 2023. Published June 2022June 2023. Originally approved in 1994. Last previous edition approved in 20142022 as
A923 – 14.A923 – 22. DOI: 10.1520/A0923-22.10.1520/A0923-23.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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A923 − 23
of an intermetallic phase. In the case of common heat treatment, this region will be that which cooled most slowly. Except for
rapidly cooled material, it may be necessary to sample from a location determined to be the most slowly cooled for the material
piece to be characterized.
1.7 The tests do not determine the precise nature of the detrimental phase but rather the presence or absence of an intermetallic
phase to the extent that it is detrimental to the toughness and corrosion resistance of the material.
1.8 Examples of the correlation of thermal exposures, the occurrence of intermetallic phases, and the degradation of toughness and
corrosion resistance are given in Appendix X1 and Appendix X2.
1.9 The values stated in either inch-pound or SI units are to be regarded as the standard. The values given in parentheses are for
information only.
1.10 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limita
...