ASTM A923-01
(Test Method)Standard Test Methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels
Standard Test Methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels
SCOPE
1.1 The purpose of these test methods is to allow detection of the presence of intermetallic phases in mill products of duplex stainless steels 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.
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 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 in the mill product. Rapid cooling of the mill 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 mill 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 An example of the correlation of thermal exposures, the occurrence of intermetallic phases, and the degradation of toughness and corrosion resistance is given in .
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 and health practices and determine the applicability of regulatory limitations prior to use.
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An American National Standard
Designation: A 923 – 01
Standard Test Methods for
Detecting Detrimental Intermetallic Phase in Wrought
1
Duplex Austenitic/Ferritic Stainless Steels
This standard is issued under the fixed designation A 923; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope to promote the formation of an intermetallic phase. In the case
of common heat treatment, this region will be that which
1.1 The purpose of these test methods is to allow detection
cooled most slowly. Except for rapidly cooled material, it may
of the presence of intermetallic phases in mill products of
be necessary to sample from a location determined to be the
duplex stainless steels to the extent that toughness or corrosion
most slowly cooled for the material piece to be characterized.
resistance is affected significantly. These test methods will not
1.7 The tests do not determine the precise nature of the
necessarily detect losses of toughness or corrosion resistance
detrimental phase but rather the presence or absence of an
attributable to other causes.
intermetallic phase to the extent that it is detrimental to the
1.2 Duplex (austenitic-ferritic) stainless steels are suscep-
toughness and corrosion resistance of the material.
tible to the formation of intermetallic compounds during
1.8 An example of the correlation of thermal exposures, the
exposures in the temperature range from approximately 600 to
occurrence of intermetallic phases, and the degradation of
1750°F (320 to 955°C). The speed of these precipitation
toughness and corrosion resistance is given in Appendix X1.
reactions is a function of composition and thermomechanical
1.9 The values stated in either inch-pound or SI units are to
history of each individual piece. The presence of these phases
be regarded as the standard. The values given in parentheses
is detrimental to toughness and corrosion resistance.
are for information only.
1.3 Correct heat treatment of duplex stainless steels can
1.10 This standard does not purport to address all of the
eliminate these detrimental phases in the mill product. Rapid
safety concerns, if any, associated with its use. It is the
cooling of the mill product provides the maximum resistance to
responsibility of the user of this standard to establish appro-
formation of detrimental phases by subsequent thermal expo-
priate safety and health practices and determine the applica-
sures.
bility of regulatory limitations prior to use.
1.4 Compliance with the chemical and mechanical require-
ments for the applicable product specification does not neces-
2. Referenced Documents
sarily indicate the absence of detrimental phases in the mill
2.1 ASTM Standards:
product.
A 370 Test Methods and Definitions for Mechanical Testing
1.5 These test methods include the following:
2
of Steel Products
1.5.1 Test Method A—Sodium Hydroxide Etch Test for
G 48 Test Methods for Pitting and Crevice Corrosion Re-
Classification of Etch Structures of Duplex Stainless Steels
sistance of Stainless Steels and Related Alloys by Use of
(Sections 3-7).
3
Ferric Chloride Solution
1.5.2 Test Method B—Charpy Impact Test for Classification
of Structures of Duplex Stainless Steels (Sections 8-13).
TEST METHOD A—SODIUM HYDROXIDE ETCH
1.5.3 Test Method C—Ferric Chloride Corrosion Test for
TEST FOR CLASSIFICATION OF ETCH
Classification of Structures of Duplex Stainless Steels (Sec-
STRUCTURES OF DUPLEX STAINLESS STEELS
tions 14-20).
1.6 The presence of detrimental intermetallic phases is
3. Scope
readily detected in all three tests, provided that a sample of
3.1 The sodium hydroxide etch test may be used for the
appropriate location and orientation is selected. Because the
acceptance of material but not for rejection. This test method
occurrence of intermetallic phases is a function of temperature
may be used with other evaluation tests to provide a rapid
and cooling rate, it is essential that the tests be applied to the
method for identifying those specimens that are free of
region of the material experiencing the conditions most likely
detrimental intermetallic phases as measured in these other
tests.
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.
2
Current edition approved Sept. 10, 2001. Published October 2001. Originally Annual Book of ASTM Standards, Vol 01.03.
3
published as A 923–94. Last previous edition A 923–98. Annual Book of ASTM Standards, Vol 03.02.
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