ASTM A923-01e1
(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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Designation: A 923 – 01
Standard Test Methods for
Detecting Detrimental Intermetallic Phase in Wrought
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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.
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e NOTE—Table 3 was editorially updated in May 2003.
1. Scope occurrence of intermetallic phases is a function of temperature
and cooling rate, it is essential that the tests be applied to the
1.1 The purpose of these test methods is to allow detection
region of the material experiencing the conditions most likely
of the presence of intermetallic phases in mill products of
to promote the formation of an intermetallic phase. In the case
duplex stainless steels to the extent that toughness or corrosion
of common heat treatment, this region will be that which
resistance is affected significantly. These test methods will not
cooled most slowly. Except for rapidly cooled material, it may
necessarily detect losses of toughness or corrosion resistance
be necessary to sample from a location determined to be the
attributable to other causes.
most slowly cooled for the material piece to be characterized.
1.2 Duplex (austenitic-ferritic) stainless steels are suscep-
1.7 The tests do not determine the precise nature of the
tible to the formation of intermetallic compounds during
detrimental phase but rather the presence or absence of an
exposures in the temperature range from approximately 600 to
intermetallic phase to the extent that it is detrimental to the
1750°F (320 to 955°C). The speed of these precipitation
toughness and corrosion resistance of the material.
reactions is a function of composition and thermomechanical
1.8 An example of the correlation of thermal exposures, the
history of each individual piece. The presence of these phases
occurrence of intermetallic phases, and the degradation of
is detrimental to toughness and corrosion resistance.
toughness and corrosion resistance is given in Appendix X1.
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 in the mill product. Rapid
be regarded as the standard. The values given in parentheses
cooling of the mill product provides the maximum resistance to
are for information only.
formation of detrimental phases by subsequent thermal expo-
1.10 This standard does not purport to address all of the
sures.
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 and health practices and determine the applica-
sarily indicate the absence of detrimental phases in the mill
bility of regulatory limitations prior to use.
product.
1.5 These test methods include the following:
2. Referenced Documents
1.5.1 Test Method A—Sodium Hydroxide Etch Test for
2.1 ASTM Standards:
Classification of Etch Structures of Duplex Stainless Steels
A 370 Test Methods and Definitions for Mechanical Testing
(Sections 3-7).
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of Steel Products
1.5.2 Test Method B—Charpy Impact Test for Classification
G 48 Test Methods for Pitting and Crevice Corrosion Re-
of Structures of Duplex Stainless Steels (Sections 8-13).
sistance of Stainless Steels and Related Alloys by Use of
1.5.3 Test Method C—Ferric Chloride Corrosion Test for
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Ferric Chloride Solution
Classification of Structures of Duplex Stainless Steels (Sec-
tions 14-20).
TEST METHOD A—SODIUM HYDROXIDE ETCH
1.6 The presence of detrimental intermetallic phases is
TEST FOR CLASSIFICATION OF ETCH
readily detected in all three tests, provided that a sample of
STRUCTURES OF DUPLEX STAINLESS STEELS
appropriate location and orientation is selected. Because the
3. Scope
3.1 The sodium hydroxide etch test may be used for the
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acceptance of material but not for rejection. This test method
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.
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Current edition approved Sept. 10, 2001. Published October 2001. Originally Annual Book of ASTM Standards, Vol 01.03.
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published as A 923–94. Last previous edition A 923–98. Annual Book of ASTM Standards, Vol 03.02.
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