ASTM A1084-15a(2022)
(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 °C to 955 °C (570 °F to 1750 ºF) with a maximum susceptibility in the temperature range around 650 °C to 750 °C (1200 °F to 1385 ºF). 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 t...
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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: A1084 − 15a (Reapproved 2022)
Standard Test Method for
Detecting Detrimental Phases in Lean Duplex Austenitic/
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
large amount of precipitation of detrimental nitrides or
selectedleanduplexstainlesssteelstotheextentthattoughness
carbides, long before any signs of sigma and similar phases
or corrosion resistance is affected significantly. Such phases
would be 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.
fromapproximately300°Cto955°C(570°Fto1750ºF)with
1.7.3 Test Method C—Inhibited Ferric Chloride Corrosion
a maximum susceptibility in the temperature range around
TestfordeterminingthepresenceofdetrimentalphasesinLean
650°C to 750°C (1200°F to 1385ºF). The speed of these
Duplex Stainless Steels.
precipitation reactions is a function of composition and the
1.7.4 Examples of the correlation of thermal exposures, the
thermalorthermo-mechanicalhistoryofeachindividualpiece.
occurrence of detrimental phases, and the degradation of
The presence of an amount of these phases can be detrimental
toughness and corrosion resistance are given in Appendix X2,
to 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.
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 June 1, 2022. Published June 2022. Originally
conversions to other units that are provided for information
approved in 2013. Last previous edition approved in 2015 as A1084–15a. DOI:
10.1520/A1084–15AR22. only and are not considered standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A1084 − 15a (2022)
TABLE 1 List of Lean Duplex Grades Covered by This Standard
4.2 TestMethodAcanrevealpotentiallydetrimentalphases
Grades in the metallographic structure.As the precipitated detrimental
UNS S32101
phases can be very small, this test demands high proficiency
UNS S32304
from the metallographer, especially for thinner material.
UNS S32202
UNS S82011
4.3 The presence of detrimental phases is readily detected
byTestMethodsBandCprovidedthatasampleofappropriate
location and orientation is selected.
4.4 The tests do not determine the precise nature of the
1.10 This standard does not purport to address all of the
detrimental phase but rather the presence or absence to the
safety concerns, if any, associated with its use. It is the
extent that the normally expected toughness and corrosion
responsibility of the user of this standard to establish appro-
resistance of the material are significantly affected.
priate safety, health, and environmental practices and deter-
4.5 This standard covers testing of samples taken from coil,
mine the applicability of regulatory limitations prior to use.
coil- and plate mill plate, sheet, tubing, piping, bar and
1.11 This international standard was developed in accor-
deformed bar, though some of these products might not be
dance with internationally recognized principles on standard-
suitable for testing according to Method B (seeTest Method B
ization established in the Decision on Principles for the
for further details). Other product forms have thus far not been
Development of International Standards, Guides and Recom-
sufficientlytestedanddocumentedtobeanintegralpartofthis
mendations issued by the World Trade Organization Technical
standard, though the standard does not prohibit testing of these
Barriers to Trade (TBT) Committee.
product forms according to the three test methods. For these
other product forms, this standard gives only limited and
2. Referenced Documents
non-exhaustive guidance as to interpretation of result and
2.1 ASTM Standards:
associated acceptance criteria.
A370Test Methods and Definitions for Mechanical Testing
4.6 Testing on product forms outside the present scope of
of Steel Products
this standard shall be agreed between purchaser and supplier.
A923Test Methods for Detecting Detrimental Intermetallic
Phase in Duplex Austenitic/Ferritic Stainless Steels
5. Sampling, Test Specimens, and Test Units
A1084Test Method for Detecting Detrimental Phases in
Lean Duplex Austenitic/Ferritic Stainless Steels 5.1 Sampling:
E6Terminology Relating to Methods of MechanicalTesting
5.1.1 Because the occurrence of detrimental phases is a
E23Test Methods for Notched Bar Impact Testing of Me-
function of temperature and cooling rate, it is essential that the
tallic Materials
tests be applied to the region of the material experiencing the
G15TerminologyRelatingtoCorrosionandCorrosionTest-
conditions most likely to promote the formation of detrimental
ing (Withdrawn 2010)
phases. In the case of common heat treatment, this region can
G48Test Methods for Pitting and Crevice Corrosion Resis-
bethatwhichcooledmostslowlyorundergoesextremelyrapid
tance of Stainless Steels and Related Alloys by Use of
cooling.
Ferric Chloride Solution
5.1.2 For practical purposes, it is considered sufficient that
the sampling location for flat mill products be from a location
3. Terminology
that is at least twice the material thickness from the as-heated
edges.
3.1 Definitions:
5.1.3 Purchaser and supplier may agree on more detailed
3.1.1 The terminology used herein, if not specifically de-
rules regarding the sampling location.
fined otherwise, shall be in accordance with Terminology E6
5.1.4 The number of samples as well as frequency of
and G15. Definitions provided herein and not given in Termi-
samplingshallbeagreedbetweenpurchaserandsupplierofthe
nology E6 or in G15 are limited only to this standard.
material.
4. Significance and Use
5.2 Test Specimens and Test Units:
4.1 Test Method A shall only be used to supplement the 5.2.1 Details of test specimen and test unit requirements are
results of Test Methods B and C. It shall not be used as a listed together with each of the Test Methods A, B and C.
rejection criterion, nor shall it be used as an acceptance
TEST METHOD A—ETCH METHOD FOR
criterion. Test Methods B and C are intended to be the
EVALUATION OF THE PRESENCE OF
procedures giving the acceptance criteria for this standard.
POTENTIALLY DETRIMENTAL PHASES IN LEAN
DUPLEX STAINLESS STEELS
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6. Introduction
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
6.1 The etch test in this standard shall only be used for
the ASTM website.
exploratory purposes. The reason for this is the small size of
The last approved version of this historical standard is referenced on
www.astm.org. the detrimental phases typically occurring in lean duplex
A1084 − 15a (2022)
TABLE 2 Applicability and Acceptance Criteria for Test Method B
stainless steels and the difficulty in achieving a fully reproduc-
ible etch structure, which depends on factors such as specimen Sampling Test Minimum Impact
Grade
A
Location Temperature Energy
size and geometry, etching current and potential, composition
S32101 base metal Room 70 J (50 ft-lb)
of the lean duplex as well as the amount and type of
B
temperature
detrimental phases present. The test method contained in this
S32304 base metal Room 100 J (75 ft-lb)
B
temperature
standardis,however,thebestknownmetallographicprocedure
S32202 base metal Room 70 J (50 ft-lb)
toshowtheappearanceandapproximateamountofdetrimental
B
temperature
phases in a lean duplex stainless steel.
S82011 base metal Room 70 J (50 ft-lb)
B
temperature
6.2 Asthereisnoformaltestresultfromthemetallographic
A
Energy for a full-size specimen tested in transverse direction for flat rolled
etch method, the actual test method is attached to this standard
products and tested in the longitudinal direction for bar products. Required energy
as Appendix X1. for a sub-size specimen is discussed further in subsection 10.1.3 and Note 2.
B
In this standard, room temperature is defined as the temperature range 23 °C ±
5ºC(73°F±9ºF).
TEST METHOD B—CHARPY V-NOTCH IMPACT
TEST FOR DETERMINATION OF THE PRESENCE
OF DETRIMENTAL PHASES IN LEAN DUPLEX
STAINLESS STEELS
8.5 Acceptance criteria of sub-size specimens are not cov-
eredbythisstandard,thoughpurchaserandsuppliermayagree
7. Scope
upon a proper conversion factor of the given acceptance
criteria in Table 2. Conversion factors generally vary by
7.1 Thistestmethoddescribestheprocedureforconducting
product type and dimensions of product for which the sub-size
the Charpy V-notch impact test as a method of detecting the
specimen sampling is needed (see Note 2).
precipitation of detrimental phases in lean duplex stainless
NOTE 1—As no data has been presented to subcommittee A01.14 for
steels.The presence or absence of an indication of a detrimen-
welded mill products or other products, no recommendation can be given
tal phase in this test is not necessarily a measure of perfor-
as to the acceptance criteria for these products. Any acceptance criteria
mance of the material in service with regard to any property
and other details of the test should be supported with data from a
other than that measured directly. The Charpy V-notch proce-
pre-qualificationtestinlinewiththeminimumrequirementsof AnnexA1
in this standard.
dure as applied here is different from that commonly applied
NOTE 2—As stated in Test Methods and Definitions A370, Appendix
for the determination of toughness and shall not be used when
A5.3.3 and Test Methods E23, Appendix X1.3, there is no general
characterization of material toughness is the purpose of the
correlation between impact values obtained with specimens of different
testing.
size or shape. However, limited correlations may be established for
specification purposes on the basis of special studies of particular
materials and particular specimens. It is commonly seen that the conver-
8. Significance and Use (Test Method B)
sion factor is set directly proportional to the ratio between standard and
8.1 TheCharpyV-notchimpacttestmaybeusedtoevaluate sub-size specimen fracture surface area or a percentage thereof, though
whether this is an acceptable way forward to still be able to identify the
mill products, provided that it is possible to obtain a specimen
presence or absence of detrimental phases needs to be documented.
of the proper size from a relevant location.
9. Apparatus
8.2 Charpy V-notch impact toughness of a material is
affected by factors other than the presence and absence of
9.1 ThetestapparatusshallbeasdescribedinTestMethods
detrimental phases. These factors are known to include differ-
and Definitions A370.
ent compositions, even when the material is in fully annealed
condition; small and otherwise acceptable variations in 10. Test Specimens
austenite/ferrite balance; and the lamellar distance between
10.1 General Requirements (All Products):
phases.Testingtransverseandlongitudinaltestspecimensfrom
10.1.1 The test specimen shall be as described in Test
mill products can also give different absolute levels of impact
Methods and Definitions A370.
toughness.
10.1.2 Animpacttestforthepurposeofdetectingdetrimen-
tal phases shall consist of a single specimen taken from the
8.3 Table 2 indicates the applicability and accept
...
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