ASTM A1084-15a(2022)

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 acceptance crite-
product piece or lot to be represented.
ria for Test Method B. These acceptance criteria have been
10.1.3 Provided purchaser and supplier have agreed upon a
showntoallowforthenaturalvariationofimpacttoughnessin
proper acceptance criterion, sub-size specimens may be used
soundmaterialtestedinthetransversedirectiononplateandin
for products with thickness less than that of full-size Charpy
the longitudinal direction on bar and deformed bar, while still
V-notch specimen. Required energy for sub-size specimens
being able to identify whether detrimental amounts of unde-
shall be established and agreed upon based on the specific
sirable phases are present.
product type and geometry in question.
8.4 AcceptancecriteriaforTestMethodBforotherproducts
10.2 Flat Products (Sheet, Coil, Plate):
including mill welded pipe, weldments and weld metal are not
10.2.1 The specimen shall be prepared in the transverse
presently covered by this standard, though purchaser and
direction. The notch shall be perpendicular to the major rolled
supplier may agree upon an acceptance criteria (see Note 1).
surface.
Note that the results of weldment testing will depend on the
filler metal or weld deposit chemistry. 10.3 Non-deformed bar products:
A1084 − 15a (2022)
10.3.1 The specimen shall be prepared in the longitudinal corrosive environments; in particular, it does not provide a
direction. basis for predicting resistance to forms of corrosion not
associated with the precipitation of detrimental phases (see
10.4 Deformed Bar Products:
Note 3).
10.4.1 The specimen shall be prepared in the longitudinal
direction. 13.2 The test method uses a ferric chloride solution inhib-
ited by addition of sodium nitrate, since a standard ferric
10.5 Other Products Including Mill Pipe:
chloride solution is too aggressive to give valuable results for
10.5.1 When this test is applied to a welded structure or to
lean duplex stainless steels.
any product having a less than uniform structure, particular
NOTE 3—Although this test method uses some equipment and proce-
attention shall be paid to the location of the V-notch. For
dures similar to those of Test Methods G48, this test method shall not be
example, in the heat-affected zone of a weld, the degree of
confusedwithTestMethodsG48.Thistestmethoddoesnotdeterminethe
detrimental phase formation can vary significantly over short
critical pitting temperature or test for the suitability for use in a particular
environment. This test method is designed solely for detection of the
distancesasafunctionofthelocalthermalcycle.Insuchcases,
precipitation of detrimental phases in lean duplex stainless steels. The
the placement of the V-notch can affect the measured result
inhibited solution might not give the same ranking as the uninhibited
significantly.
solution, when comparing a range of stainless steels, but it can reveal the
10.5.2 Following the guidelines of Test Methods A370, the
presence of deleterious phases in the lean duplex stainless steels listed in
specimen preparation method shall be agreed between pur- Table 1.
chaser and supplier.
14. Significance and Use (Test Method C)
11. Procedure 14.1 Theinhibitedferricchloridecorrosiontestmaybeused
to evaluate mill products as well as fabricated products,
11.1 Perform the test for a single specimen in accordance
providedthatitispossibletoobtainaspecimenfromarelevant
with the procedures described inTest Methods and Definitions
location and having the proper geometry.
A370.
14.2 Table 3 indicates the applicability and acceptance
11.2 The test temperature shall be as specified in Table 2 or
criteria for Test Method C.
lower (see also subsection 12.3) for the grade being evaluated.
14.3 Acceptance criteria for weldment and weld metal shall
12. Acceptance Values and Retests be agreed upon between purchaser and supplier of the product
in question prior to testing. Results obtained from testing of
12.1 Unless otherwise specified, the acceptance criteria
weldments also depend on the filler metal and weld deposit
shall be as given in Table 2.
chemistry.
12.2 If a test specimen shows a value below the specified
minimum, one retest of two specimens is permitted. For
15. Apparatus
acceptance, both retest specimens shall show a value at or
15.1 Glass Beakers, 1000 mL, tall-form, or Erlenmeyer
above the specified minimum value.
flasks, 1000 mL, wide neck, or 50mm (2-in.) diameter test
12.3 TestingatlowertemperaturesthanindicatedinTable2 tubes, or other suitable glass containers.
is permissible and if the obtained impact energy is higher than
15.2 Glass Cradles (Fig. 1)—The dimensions of the cradle
the acceptance criteria indicated in Table 2 then the sample is
shall be restricted to those that permit its passage through the
approved in accordance with Test Method B of this test
test container opening, a diameter of approximately 40 mm
method. Failure at a lower test temperature than indicated in
(1.6 in.) in the case of the Erlenmeyer flask.
Table 2 does not imply that the sample has failed Test Method
15.3 Constant Temperature Device—Water or Oil bath or
B,butonlythatthetestshallnotbecountedasapropertestand
other device that ensures constant temperature of solution and
a new test shall be performed at the temperature specified in
specimen.
Table 2.
12.4 A product that has failed the Charpy V-notch impact
16. Inhibited Ferric Chloride Test Solution
testmaybegivenafullannealandretestedattheoptionofthe
16.1 Dissolve 55.1 g of reagent-grade ferric chloride,
supplier.
FeCl ·6H O, and 6.6 g of reagent-grade sodium nitrate,
3 2
TEST METHOD C—INHIBITED FERRIC CHLORIDE
CORROSION TEST FOR DETERMINATION OF THE
TABLE 3 Applicability and Acceptance Criteria for Test Method C
PRESENCE OF DETRIMENTAL PHASES IN LEAN
Maximum
DUPLEX STAINLESS STEELS Acceptable
Test
Grade Sample Location Corrosion Rate
Temperature
Calculated from
13. Scope
Weight Loss
A
S32101 base metal 25°C (77°F) 10 mdd
13.1 This test method describes the procedure for conduct-
A
S32304 base metal 25°C (77°F) 10 mdd
ing an inhibited ferric chloride corrosion test for detecting the
A
S32202 base metal 25°C (77°F) 10 mdd
A
presence of detrimental phases in lean duplex stainless steels.
S82011 base metal 25°C (77°F) 10 mdd
The presence or absence of corrosion attack in this test is not A
For a definition of “mdd”, see Note 4.
necessarily a measure of performance of the material in other
A1084 − 15a (2022)
FIG. 1 Examples of Glass Cradles That Can Be Used to Support Specimen
NaNO ,in600mLofdistilledwater(approximately5%FeCl sion of the specimen shall be cut so that one-half to two-thirds
3 3
and 1% NaNO by weight). Filter the solution through glass of the product thickness is tested resulting in approximate
wool or filter paper to remove insoluble particles. specimen dimensions of 6mm by 25 mm ( ⁄4in. by 1 in.) by
one-half to two-thirds product thickness.
17. Test Specimen
17.2.2 All surfaces shall be polished to a uniform finish.
17.1 General Requirements (All Products):
17.3 Non-Deformed Bar Products:
17.1.1 Various shapes and sizes of test specimens may be
17.3.1 All surfaces of the specimen shall be polished to a
used.
uniform finish.
17.1.2 After the specimens are cut, any material that might
have been affected by high temperature or deformation asso-
17.4 Mill Tube and Pipe Products:
ciated with the cutting shall be removed by machining or
17.4.1 The ID side shall be left as is, whereas cut and OD
polishing prior to testing. This procedure shall include round-
surfaces shall be polished to a uniform finish.
ing of sharp edges with care taken to remove all burrs.
17.5 Mill deformed bar products:
17.1.3 For all polishing procedures, wet polishing is pre-
17.5.1 For practical reasons, the default specimen prepara-
ferred. If used, dry polishing shall be performed slowly to
tion shall be to let the deformed surface be as is, whereas cut
prevent overheating.
surfaces shall be polished to a uniform finish.
17.1.4 All polishing shall be done to a 120-grit finish or
finer. 17.5.2 If agreed between purchaser and seller, the deformed
surface may be machined and polished to a 120-grit finish, or
17.1.5 For other than mill products, testing of a specimen
with the surface in the as-fabricated condition can be relevant. finer.
However,ifoxidescalesfromheattreatmentorweldmentsare
17.6 Other Product Forms:
visibly present, then they shall be removed by polishing prior
17.6.1 Test specimens shall be cut into test specimens
to testing as the oxide scale is likely give rise to a weight loss
convenient for testing, provided that the specimen exposes
higherthan10mdddespitethefactthatnoactualattackonthe
surfaces representative of the full thickness of the product.
metallic part of the specimen is occurring.
17.6.2 All surfaces of the specimen shall be polished to a
17.2 Flat Products (Coil, Plate, Sheet):
uniform finish.
17.2.1 The test specimen shall be approximately 25mm by
17.7 Test Specimen Preparation—After cutting and polish-
50mm (1in. by 2 in.) by thickness. The full thickness of the
ing:
product shall be included if practical. In the case of thicker
sections, the specimen shall be taken in a perpendicular 17.7.1 Subsequent to polishing of the required surfaces, the
orientation so that the thickness of the product becomes the surfaces of the
...