ASTM A1084-15
(Test Method)Standard Test Method for Detecting Detrimental Phases in Lean Duplex Austenitic/Ferritic Stainless Steels
Standard Test Method for Detecting Detrimental Phases in Lean Duplex Austenitic/Ferritic Stainless Steels
SIGNIFICANCE AND USE
4.1 Test Method A shall only be used to supplement the results of Test Methods B and C. It shall not be used as a rejection criterion, nor shall it be used as an acceptance criterion. Test Methods B and C are intended to be the procedures giving the acceptance criteria for this standard.
4.2 Test Method A can reveal potentially detrimental phases in the metallographic structure. As the precipitated detrimental phases can be very small, this test demands high proficiency from the metallographer, especially for thinner material.
4.3 The presence of detrimental phases is readily detected by Test Methods B and C provided that a sample of appropriate location and orientation is selected.
4.4 The tests do not determine the precise nature of the detrimental phase but rather the presence or absence to the extent that the normally expected toughness and corrosion resistance of the material are significantly affected.
4.5 This standard covers testing of samples taken from coil, coil- and plate mill plate, sheet, tubing, piping, bar and deformed bar, though some of these products might not be suitable for testing according to Method B (see Test Method B for further details). Other product forms have thus far not been sufficiently tested and documented to be an integral part of this standard, though the standard does not prohibit testing of these product forms according to the three test methods. For these other product forms, this standard gives only limited and non-exhaustive guidance as to interpretation of result and associated acceptance criteria.
4.6 Testing on product forms outside the present scope of this standard shall be agreed between purchaser and supplier.
SCOPE
1.1 The purpose of this test method is to allow detection of the presence of detrimental chromium-containing phases in selected lean duplex stainless steels to the extent that toughness or corrosion resistance is affected significantly. Such phases can form during manufacture and fabrication of lean duplex products. This test method does not necessarily detect losses of toughness nor corrosion resistance attributable to other causes, nor will it identify the exact type of detrimental phases that caused any loss of toughness or corrosion resistance. The test result is a simple pass/fail statement.
1.2 Lean duplex (austenitic-ferritic) stainless steels are typically duplex stainless steels composed of 30 to 70 % ferrite content with a typical alloy composition having Cr > 17 % and Mo Table 1. Similar test methods for some higher alloyed duplex stainless steels are described in Test Methods A923, but the procedures described in this standard differ significantly for all three methods from the ones described in Test Methods A923.
1.3 Lean duplex stainless steels are susceptible to the formation of detrimental chromium-containing compounds such as nitrides and carbides and other undesirable phases. Typically this occurs during exposures in the temperature range from approximately 300 to 955°C (570 to 1750ºF) with a maximum susceptibility in the temperature range around 650 to 750°C (1200 to 1385ºF). The speed of these precipitation reactions is a function of composition and the thermal or thermo-mechanical history of each individual piece. The presence of an amount of these phases can be detrimental to toughness and corrosion resistance.
1.4 Because of the low molybdenum content, lean duplex stainless steels only exhibit a minor susceptibility to sigma or other types of molybdenum containing intermetallic phases. Heat treatment, that could lead to formation of small amounts of molybdenum containing intermetallics, would result in a large amount of precipitation of detrimental nitrides or carbides – long before any signs of sigma and similar phases would be observed.
1.5 Correct heat treatment of lean duplex stainless steels can eliminate or reduce the amount and alter the characteristics of these detrimental ...
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Designation: A1084 − 15
StandardTest Method for
Detecting Detrimental Phases in Lean Duplex Austenitic/
1
Ferritic Stainless Steels
This standard is issued under the fixed designation A1084; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope other types of molybdenum containing intermetallic phases.
Heat treatment, that could lead to formation of small amounts
1.1 The purpose of this test method is to allow detection of
of molybdenum containing intermetallics, would result in a
the presence of detrimental chromium-containing phases in
largeamountofprecipitationofdetrimentalnitridesorcarbides
selectedleanduplexstainlesssteelstotheextentthattoughness
– long before any signs of sigma and similar phases would be
or corrosion resistance is affected significantly. Such phases
observed.
can form during manufacture and fabrication of lean duplex
products.Thistestmethoddoesnotnecessarilydetectlossesof
1.5 Correctheattreatmentofleanduplexstainlesssteelscan
toughness nor corrosion resistance attributable to other causes,
eliminate or reduce the amount and alter the characteristics of
nor will it identify the exact type of detrimental phases that
these detrimental phases as well as minimizing Cr-depletion in
caused any loss of toughness or corrosion resistance. The test
the matrix phase in the immediate vicinity of these phases.
result is a simple pass/fail statement.
Adequately rapid cooling of the product from a suitable
annealing temperature provides the maximum resistance to
1.2 Leanduplex(austenitic-ferritic)stainlesssteelsaretypi-
formation of detrimental phases by subsequent thermal expo-
cally duplex stainless steels composed of 30 to 70% ferrite
sures. For details of the proper annealing temperature recom-
contentwithatypicalalloycompositionhavingCr>17%and
mendations for the alloy and product in question, the user is
Mo < 1% and with additions of Nickel, Manganese, Nitrogen
referredtotherelevantapplicableASTMproductspecification.
and controlled low carbon content as well as other alloying
elements. This standard test method applies only to those
1.6 Compliance with the chemical and mechanical require-
alloys listed in Table 1. Similar test methods for some higher
ments for the applicable product specification does not neces-
alloyed duplex stainless steels are described in Test Methods
sarilyindicatetheabsenceofdetrimentalphasesintheproduct.
A923, but the procedures described in this standard differ
1.7 These test methods include the following:
significantly for all three methods from the ones described in
1.7.1 Test Method A—Etch Method for detecting the pres-
Test Methods A923.
enceofpotentiallydetrimentalphasesinLeanDuplexStainless
1.3 Lean duplex stainless steels are susceptible to the
Steels
formation of detrimental chromium-containing compounds
1.7.2 Test Method B—Charpy V-notch Impact Test for
such as nitrides and carbides and other undesirable phases.
determiningthepresenceofdetrimentalphasesinLeanDuplex
Typicallythisoccursduringexposuresinthetemperaturerange
Stainless Steels.
from approximately 300 to 955°C (570 to 1750ºF) with a
1.7.3 Test Method C—Inhibited Ferric Chloride Corrosion
maximumsusceptibilityinthetemperaturerangearound650to
TestfordeterminingthepresenceofdetrimentalphasesinLean
750°C (1200 to 1385ºF). The speed of these precipitation
Duplex Stainless Steels.
reactions is a function of composition and the thermal or
1.7.4 Examples of the correlation of thermal exposures, the
thermo-mechanical history of each individual piece. The pres-
occurrence of detrimental phases, and the degradation of
ence of an amount of these phases can be detrimental to
toughness and corrosion resistance are given in Appendix X2,
toughness and corrosion resistance.
Appendix X3 and the References.
1.4 Because of the low molybdenum content, lean duplex
stainless steels only exhibit a minor susceptibility to sigma or
1.8 Guidelines for the required data needed for subcommit-
tee A01.14 to consider listing a lean duplex stainless steel in
this standard test method are given in Annex A1.
1
This test method is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and RelatedAlloys and is the direct responsibility of Subcommittee
1.9 The values stated in SI units are to be regarded as
A01.14 on Methods of Corrosion Testing.
standard. The values given in parentheses are mathematical
Current edition approved May 1, 2015. Published May 2015. Originally
conversions to other units that are provided for information
approved in 2013. Last previous edition approved in 2013 as A1084–13. DOI:
10.1520/A10
...
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: A1084 − 13 A1084 − 15
Standard Test Method for
Detecting Detrimental Phases in Lean Duplex Austenitic/
1
Ferritic Stainless Steels
This standard is issued under the fixed designation A1084; 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 this test method is to allow detection of the presence of detrimental chromium-containing phases in selected
lean duplex stainless steels to the extent that toughness or corrosion resistance is affected significantly. Such phases can form
during manufacture and fabrication of lean duplex products. This test method does not necessarily detect losses of toughness nor
corrosion resistance attributable to other causes, nor will it identify the exact type of detrimental phases that caused any loss of
toughness or corrosion resistance. The test result is a simple pass/fail statement.
1.2 Lean duplex (austenitic-ferritic) stainless steels are typically duplex stainless steels composed of 30-70 % 30 to 70 % ferrite
content with a typical alloy composition having Cr > 17 % and Mo < 1 % and with additions of Nickel, Manganese, Nitrogen and
controlled low carbon content as well as other alloying elements. This standard test method applies only to those alloys listed in
Table 1. Similar test methods for some higher alloyed duplex stainless steels are described in ASTM Test Methods A923, but the
procedures described in this standard differ significantly for all three methods from the ones described in Test Methods A923.
1.3 Lean duplex stainless steels are susceptible to the formation of detrimental chromium-containing compounds such as
nitrides and carbides and other undesirable phases. Typically this occurs during exposures in the temperature range from
approximately 300 to 955°C (570 to 1750ºF) with a maximum susceptibility in the temperature range around 650 to 750°C (1200
to 1385ºF). The speed of these precipitation reactions is a function of composition and the thermal or thermo-mechanical history
of each individual piece. The presence of an amount of these phases can be detrimental to toughness and corrosion resistance.
1.4 Because of the low molybdenum content, lean duplex stainless steels only exhibit a minor susceptibility to sigma or other
types of molybdenum containing intermetallic phases. Heat treatment, that could lead to formation of small amounts of
molybdenum containing intermetallics, would result in a large amount of precipitation of detrimental nitrides or carbides – long
before any signs of sigma and similar phases would be observed.
1.5 Correct heat treatment of lean duplex stainless steels can eliminate or reduce the amount and alter the characteristics of these
detrimental phases as well as minimizing Cr-depletion in the matrix phase in the immediate vicinity of these phases. Adequately
rapid cooling of the product from a suitable annealing temperature provides the maximum resistance to formation of detrimental
phases by subsequent thermal exposures. For details of the proper annealing temperature recommendations for the alloy and
product in question, the user is referred to the relevant applicable ASTM product specification.
1.6 Compliance with the chemical and mechanical requirements for the applicable product specification does not necessarily
indicate the absence of detrimental phases in the product.
1.7 These test methods include the following:
1.7.1 Test Method A—Etch Method for detecting the presence of potentially detrimental phases in Lean Duplex Stainless Steels
1.7.2 Test Method B—Charpy V-notch Impact Test for determining the presence of detrimental phases in Lean Duplex Stainless
Steels.
1.7.3 Test Method C—Inhibited Ferric Chloride Corrosion Test for determining the presence of detrimental phases in Lean
Duplex Stainless Steels.
1.7.4 Examples of the correlation of thermal exposures, the occurrence of detrimental phases, and the degradation of toughness
and corrosion resistance are given in Appendix X2, Appendix X3 and the References.
1.8 Guidelines for the required data needed for subcommittee A01.14A01.14 to consider listing a lean duplex stainless steel in
1
This test method is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.14
on Me
...
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