ASTM A957/A957M-21

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: A957/A957M − 20 A957/A957M − 21
Standard Specification for
Investment Castings, Steel and Alloy, Common
Requirements, for General Industrial Use
This standard is issued under the fixed designation A957/A957M; 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 This specification covers a group of requirements that are mandatory for castings produced by the investment casting process
to meet the metallurgical requirements of the following steel casting specifications issued by ASTM.
ASTM Designation Title of Specification
A27/A27M Steel Castings, Carbon, for General Ap-
plication
A128/A128M Steel Castings, Austenitic Manganese
A148/A148M Steel Castings, High-Strength, for Struc-
tural Purposes
A297/A297M Steel Castings, Iron-Chromium and Iron-
Chromium-Nickel, Heat-Resistant, for
General Application
A447/A447M Steel Castings, Chromium-Nickel-Iron Al-
loy (25-12 Class), for High-Temperature
Service
A494/A494M Castings, Nickel and Nickel Alloy
A560/A560M Castings, Chromium-Nickel Alloy
A732/A732M Castings, Investment, Carbon and Low-
Alloy Steel for General Application, and
Cobalt Alloy for High Strength at Elevated
Temperatures
A743/A743M Castings, Iron-Chromium, Iron-Chromium-
Nickel, Corrosion-Resistant, for General
Application
A744/A744M Castings, Iron-Chromium-Nickel, Corro-
sion Resistant, for Severe Service
A747/A747M Steel Castings, Stainless, Precipitation
Hardening
A890/A890M Castings, Iron-Chromium-Nickel-
Molybdenum Corrosion-Resistant, Duplex
(Austenitic/Ferritic) for General Applica-
tion
A915/A915M Steel Castings, Carbon and Alloy, Chemi-
cal Requirements Similar to Standard
Wrought Grades
A958/A958M Steel Castings, Carbon and Alloy, with
Tensile Requirements, Chemical Require-
ments Similar to Standard Wrought
Grades
A1002 Castings, Nickel-Aluminum Ordered Alloy
This specification is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.18
on Castings.
Current edition approved July 1, 2020May 1, 2021. Published August 2020May 2021. Originally approved in 1996. Last previous edition approved in 20182020 as
A957/A957M – 18a.A957/A957M – 20. DOI: 10.1520/A0957_A0957M-20.10.1520/A0957_A0957M-21.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A957/A957M − 21
1.2 This specification also covers a group of supplementary requirements that may be applied to the above specifications as
indicated therein. These are provided for use when additional testing or inspection is desired, and apply only when specified
individually by the purchaser in the order.
1.3 When investment castings are ordered, the requirements stated in this specification form an integral part of the material
specification. In cases of conflict, the requirements of this specification shall take precedence over the individual material
specification requirements.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in nonconformance with the standard.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
A27/A27M Specification for Steel Castings, Carbon, for General Application
A128/A128M Specification for Steel Castings, Austenitic Manganese
A148/A148M Specification for Steel Castings, High Strength, for Structural Purposes
A297/A297M Specification for Steel Castings, Iron-Chromium and Iron-Chromium-Nickel, Heat Resistant, for General
Application
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
A380/A380M Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems
A447/A447M Specification for Steel Castings, Chromium-Nickel-Iron Alloy (25-12 Class), for High-Temperature Service
A488/A488M Practice for Steel Castings, Welding, Qualifications of Procedures and Personnel
A494/A494M Specification for Castings, Nickel and Nickel Alloy
A560/A560M Specification for Castings, Chromium-Nickel Alloy
A609/A609M Practice for Castings, Carbon, Low-Alloy, and Martensitic Stainless Steel, Ultrasonic Examination Thereof
A732/A732M Specification for Castings, Investment, Carbon and Low-Alloy Steel for General Application, and Cobalt Alloy
for High Strength at Elevated Temperatures
A743/A743M Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application
A744/A744M Specification for Castings, Iron-Chromium-Nickel, Corrosion Resistant, for Severe Service
A747/A747M Specification for Steel Castings, Stainless, Precipitation Hardening
A751 Test Methods and Practices for Chemical Analysis of Steel Products
A800/A800M Practice for Estimating Ferrite Content of Stainless Steel Castings Containing Both Ferrite and Austenite
A890/A890M Specification for Castings, Iron-Chromium-Nickel-Molybdenum Corrosion-Resistant, Duplex (Austenitic/
Ferritic) for General Application
A903/A903M Specification for Steel Castings, Surface Acceptance Standards, Magnetic Particle and Liquid Penetrant
Inspection
A915/A915M Specification for Steel Castings, Carbon, and Alloy, Chemical Requirements Similar to Standard Wrought Grades
A941 Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys
A958/A958M Specification for Steel Castings, Carbon and Alloy, with Tensile Requirements, Chemical Requirements Similar
to Standard Wrought Grades
A967/A967M Specification for Chemical Passivation Treatments for Stainless Steel Parts
A991/A991M Test Method for Conducting Temperature Uniformity Surveys of Furnaces Used to Heat Treat Steel Products
A997 Practice for Investment Castings, Surface Acceptance Standards, Visual Examination
A1002 Specification for Castings, Nickel-Aluminum Ordered Alloy
A1058 Test Methods for Mechanical Testing of Steel Products—Metric
A1067/A1067M Specification for Test Coupons for Steel Castings
A1080/A1080M Practice for Hot Isostatic Pressing of Steel, Stainless Steel, and Related Alloy Castings
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 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 the ASTM website.
A957/A957M − 21
E94/E94M Guide for Radiographic Examination Using Industrial Radiographic Film
E125 Reference Photographs for Magnetic Particle Indications on Ferrous Castings
E165/E165M Practice for Liquid Penetrant Testing for General Industry
E186 Reference Radiographs for Heavy-Walled (2 to 4 ⁄2 in. (50.8 to 114 mm)) Steel Castings
E192 Reference Radiographs of Investment Steel Castings for Aerospace Applications
E280 Reference Radiographs for Heavy-Walled (4 ⁄2 to 12 in. (114 to 305 mm)) Steel Castings
E340 Practice for Macroetching Metals and Alloys
E353 Test Methods for Chemical Analysis of Stainless, Heat-Resisting, Maraging, and Other Similar Chromium-Nickel-Iron
Alloys
E354 Test Methods for Chemical Analysis of High-Temperature, Electrical, Magnetic, and Other Similar Iron, Nickel, and
Cobalt Alloys
E446 Reference Radiographs for Steel Castings Up to 2 in. (50.8 mm) in Thickness
E709 Guide for Magnetic Particle Testing
E2660 Digital Reference Images for Investment Steel Castings for Aerospace Applications
2.2 SAE Standards:
AMS 2750 Pyrometry
ARP 1341 Determining Decarburization and Carburization in Finished Parts of Carbon and Low-Alloy Steel
3. Terminology
3.1 Definitions:
3.1.1 The definitions in Test Methods and Definitions A370, Test Methods, Practices, and Terminology A751, Terminology A941,
and Test Methods A1058 are applicable to this specification and to those listed in 1.1.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 investment casting, n—a metal casting that is produced in a mold obtained by investing (surrounding) an expendable pattern
with a ceramic slurry that is allowed to solidify. The expendable pattern may consist of wax, plastic, or other material and is
removed prior to filling the mold with liquid metal.
3.2.2 master heat, n—a quantity of metal processed in a single furnace or refining vessel at one time in such a manner as to produce
the desired composition and properties.
3.2.3 sub-heat, n—a portion of a master heat remelted without additional processing for pouring into castings. Synonyms—melt,
production heat.
4. Materials and Manufacture
4.1 When the purchaser imposes the requirements of this specification, the manufacturer is responsible for compliance with the
specification requirements during the production and processing of the casting by themselves and any of their subcontractors.
4.2 Melting Process—Master heats shall be made by the electric furnace process, with or without separate refining such as
argon-oxygen-decarburization (AOD), vacuum-oxygen-degassing (VOD), vacuum-induction-melting (VIM), and so forth, unless
otherwise specified in the individual specification or agreed upon between the customer and producer. Master heats may be used
directly for producing castings or converted into ingot, bar, shot, or other suitable form, not including gates and risers from casting
production, for later remelting as a sub-heat.
4.3 Re-Melting Process—Sub-heats shall be produced from master heat metal in suitable batch sizes by electric induction furnace,
with or without atmosphere protection such as vacuum or inert gas, unless otherwise specified in the individual specification or
agreed upon between the customer and producer. Revert (gates, sprues, risers, and rejected castings) shall not be re-melted except
in master heats.
4.4 Sampling:
4.4.1 If castings are poured directly from one or more master heats, then the samples for chemical and other required testing shall
also be poured directly from each of the master heats.
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, PA 15096, http://www.sae.org.
A957/A957M − 21
4.4.2 If castings are poured from a sub-heat, then the samples for chemical and other required testing shall also be poured from
a sub-heat of that same master heat, but not necessarily from the same sub-heat as the castings. The sub-heat used for the test
samples shall be produced using the same melting practices and additions as used to produce the castings.
4.4.3 Unless otherwise specified by the purchaser, test specimens may be taken from castings or from coupons cast integrally with
the castings, in the same molds as the castings, or in separate molds.
4.5 Heat Treatment:
4.5.1 Castings shall be heat treated in the working zone of a furnace that has been surveyed in accordance with Test Method
A991/A991M or AMS 2750.
4.5.2 When using furnaces surveyed in accordance with Test Method A991/A991M, the following requirements apply for heat
treatments above 2000 °F [1100 °C]. When castings are heat treated at temperatures above 2000 °F [1100 °C], then the working
zone shall have been established by a survey performed at not more than 25 °F [15 °C] below nor more than 200 °F [110 °C] above
the minimum heat treatment temperature specified for the grade. If a minimum heat treatment temperature is not specified for the
grade, then the survey temperature shall be not more than 50 °F [30 °C] below nor more than 175 °F [100 °C] above the furnace
set point used.
4.5.3 When using furnaces surveyed in accordance with AMS 2750, there are no additional requirements beyond those stated in
AMS 2750.
4.5.4 The maximum variation in measured temperature, as determined by the difference between the highest temperature and the
lowest temperature, shall be as agreed between the purchaser and producer, except that during production heat treatment no portion
of the furnace shall be below the minimum specified temperature nor above the maximum specified temperature for the grade being
processed.
5. Chemical Composition
5.1 Chemical Analysis—Chemical analysis of materials covered by this specification shall be in accordance with Test Methods,
Practices, and Terminology A751.
5.2 Heat Analysis—An analysis of samples obtained in accordance with 4.4 or Supplementary Requirement S20, as appropriate,
shall be made by the manufacturer to determine the percentages of the elements specified in the individual specification for the
grade being poured. When drillings are used, they shall be taken not less than ⁄16 in. [2 mm] beneath the surface. The chemical
composition thus determined shall conform to the requirements in the individual specification for the grade being poured.
5.3 Product Analysis—A product analysis may be made by the purchaser from material representing each master heat, sub-heat,
lot, or casting. The analysis shall be made on representative material. Samples for carbon analysis of carbon and alloy steel shall
be taken no closer than ⁄16 in. [2 mm] to a cast surface, except that castings too thin for this shall be analyzed on representative
material. The chemical composition thus determined shall meet the requirements specified in the applicable specification for the
grade involved, or shall be subject to rejection by the purchaser, except that the chemical composition determined for carbon and
low-alloy steel and stainless steel steel, stainless steel, and nickel and cobalt based castings may vary from the specified limits by
the amounts shown in Table 1 and , Table 2, and Table 3, respectively. The product analysis tolerances of Table 1Tables 1-3 are
not applicable as acceptance criteria for heat analysis by the casting manufacturer. When comparing product and heat analysis for
other than carbon and low-alloy steels, and stainless steels, the reproducibility data R2 in Test Methods E353 or E354, as
applicable, shall be taken into consideration.
5.4 Unspecified Elements—When chemical analysis for elements not specified for the grade ordered is desired, Supplementary
Requirement S13 may be specified.
NOTE 1—All commercial metals contain small amounts of various elements in addition to those that are specified. It is neither practical nor necessary
to specify limits for every unspecified element that might be present, despite the fact that the presence of many of these elements is often routinely
determined by the producer.
A957/A957M − 21
TABLE 1 Product Analysis Tolerances – Carbon and Low-Alloy
Steels
B,C
Tolerances Over
A
Element Range, % Maximum or Under
Minimum Limit, %
C up to 0.65 0.03 × % C + 0.02
L
above 0.65 0.04
Mn up to 1 0.08 × % Mn + 0.01
L
above 1 0.09
Si up to 0.60 0.22 × % Si − 0.01
L
above 0.60 0.15
P all 0.13 × % P + 0.005
L
S all 0.36 × % S + 0.001
L
Ni up to 2 0.10 × % Ni + 0.03
L
above 2 0.25
Cr up to 2 0.07 × % Cr + 0.04
L
above 2 0.18
Mo up to 0.6 0.04 × % Mo + 0.03
L
above 0.6 0.06
V up to 0.25 0.23 × % V + 0.004
L
above 0.25 0.06
W up to 0.10 0.08 × % W + 0.02
L
above 0.10 0.02
Cu up to 0.15 0.18 × % Cu + 0.02
L
above 0.15 0.05
Al up to 0.10 0.08 × % Al + 0.02
L
above 0.10 0.03
A
The range denotes the composition limits up to which tolerances are computed
by the equation, and above which the tolerances are given by a constant.
B
The subscript for the elements in each equation indicates that the limits of the
L
element specified by the applicable specification are to be inserted into the
equation to calculate the tolerance for the upper limit and the lower limit (if
applicable), respectively. Examples of computing tolerances are presented in
footnote C.
C
To illustrate the computation of the tolerance, consider the manganese maximum
of 0.70 for an 0.30 carbon grade 65-35 in Specification A27/A27M. The maximum
permissible deviation is (0.08 × 0.70 + 0.01) = 0.066. Therefore, the highest
acceptable product analysis is 0.766. Similarly, for an 0.20 carbon grade 70-40 in
Specification A27/A27M, the maximum manganese content is 1.40; thus, the
highest acceptable product analysis is (1.40 + 0.09) = 1.49.
5.5 Grade Substitution—Grade substitution is not permitted. Grade substitution occurs when the material being supplied contains
one or more elements that are not specified for the supplied material such that the material conforms to the requirements of a
different grade.
6. Mechanical Test Requirements
6.1 The individual product specifications vary as to whether mechanical tests are required; for this reason, and to determine
specific test requirements, the individual product specification should be reviewed. If mechanical testing is required by the product
specification, sampling shall be in accordance with 4.4 or with Supplementary Requirement S21, as appropriate.
6.2 Unless otherwise specified by the purchaser, when mechanical properties are required by the product specification, test
coupons may be taken from castings, may be cast integrally with the castings, or may be cast in separate molds made of the same
material used for the production molds, cast in the same foundry and melted using the same foundry practices as those used for
the castings, in accordance with Specification A1067/A1067M, Fig. 1, Fig. 2, Fig. 3, or Fig. 4, except when Supplementary
Requirement S15 is specified. The test coupon in Specification A1067/A1067M, Fig. 4 shall be employed only for austenitic alloy
castings with cross sections less than 2 ⁄2 in. [65 mm].
NOTE 2—Test Coupons for Large and Heavy Steel Castings—The test coupons in Specification A1067/A1067M, Fig. 1, are to be used for large and heavy
steel castings. However, at the option of the foundry, the cross-sectional area and length of the standard coupon may be increased as desired.
NOTE 3—Bend Bar—If a bend bar is required, an alternate design (as shown by dotted lines in Specification A1067/A1067M, Fig. 1) is indicated.
Information on the relationship of mechanical properties determined on test coupons obtained as specified in 6.2 with those obtained from the casting may be found in
The Steel Casting Handbook, Fifth Edition, Steel Founders’ Society of America, 1980, pp. 15–35 through 15–43.
A957/A957M − 21
TABLE 2 Product Analysis Tolerances – Stainless Steels
Tolerance Over the Tolerance Over the
Limit or Maximum of Maximum Limit or Limit or Maximum of Maximum Limit or
Elements Elements
Specified Range, % Under the Minimum Specified Range, % Under the Minimum
Limit Limit
Tolerance Over the Tolerance Over the
Limit or Maximum of Maximum Limit or Limit or Maximum of Maximum Limit or
Element Element
Specified Range, % Under the Minimum Specified Range, % Under the Minimum
Limit Limit
Carbon to 0.010, incl 0.002 Titanium to 1.00, incl 0.05
over 0.010 to 0.030, incl 0.005 over 1.00 to 3.00, incl 0.07
over 0.030 to 0.20, incl 0.01
A
over 0.20 to 0.60, incl 0.02 Cobalt over 0.05 to 0.50, incl 0.01
over 0.60 to 1.20, incl 0.03 over 0.50 to 2.00, incl 0.02
over 2.00 to 5.00, incl 0.05
Manganese to 1.00, incl 0.03
over 1.00 to 3.00, incl 0.04 Columbium plus
over 3.00 to 6.00, incl 0.05 tantalum to 1.50, incl 0.05
over 6.00 to 10.00, incl 0.06 (niobium plus tantalum)
over 10.00 to 15.00, incl 0.10
over 15.00 to 20.00, incl 0.15 Tantalum to 0.10, incl 0.02
Phosphorus to 0.040, incl 0.005 Copper to 0.50, incl 0.03
over 0.040 to 0.20, incl 0.010 over 0.50 to 1.00, incl 0.05
over 1.00 to 3.00, incl 0.10
Sulfur to 0.040, incl 0.005 over 3.00 to 5.00, incl 0.15
over 0.040 to 0.20, incl 0.010 over 5.00 to 10.00, incl 0.20
over 0.20 to 0.50, incl 0.020
Aluminum to 0.15, incl –0.005, +0.01
Silicon to 1.00, incl 0.05 over 0.15 to 0.50, incl 0.05
over 1.00 to 3.00, incl 0.10 over 0.50 to 2.00, incl 0.10
over 3.00 to 6.00, incl 0.15
Nitrogen to 0.02, incl 0.005
Chromium over 4.00 to 10.00, incl 0.10 over 0.02 to 0.19, incl 0.01
over 10.00 to 15.00, incl 0.15 over 0.19 to 0.25, incl 0.02
over 15.00 to 20.00, incl 0.20 over 0.25 to 0.35, incl 0.03
over 20.00 to 30.00, incl 0.25 over 0.35 to 0.45, incl 0.04
over 0.45 to 0.55, incl 0.05
Nickle to 1.00, incl 0.03
Nickel to 1.00, incl 0.03
over 1.00 to 5.00, incl 0.07 Tungston to 1.00, incl 0.03
over 1.00 to 5.00, incl 0.07 Tungsten to 1.00, incl 0.03
over 5.00 to 10.00, incl 0.10 over 1.00 to 2.00, incl 0.05
over 10.00 to 20.00, incl 0.15
over 20.00 to 30.00, incl 0.20 Vanadium to 0.50, incl 0.03
over 0.50 to 1.50, incl 0.05
Molybdenum over 0.20 to 0.60, incl 0.03
over 0.60 to 2.00, incl 0.05 Selenium all 0.03
over 2.00 to 8.00, incl 0.10
A
Product analysis limits for cobalt under 0.05 % have not been established, and the manufacturer should be consulted for those limits.
NOTE 4—Specification A1067/A1067M, Fig 2—Pour through head; cover molten head with powdered charcoal, coke dust, and so forth, immediately after
pouring, in order to keep head fluid as long as possible.
NOTE 5—Specification A1067/A1067M, Fig 4—Coupons produced in this manner are suitable for austenitic alloys only. The mold may be preheated for
pouring to produce a sound coupon.
6.3 Choice of testing track from the options listed in Test Methods A1058 when material is ordered to an M-suffix (SI units)
product standard should be identified by the purchaser in the ordering information. If the choice of test track is not specified in
the order, then the default ASTM track shall be used as noted in Test Methods A1058.
6.4 The coupon from which the test specimen is taken shall be heat treated in production furnaces to the same procedure as the
castings it represents.
6.5 The specimens may be cast to shape or machined from coupons to dimensions in accordance with Test Methods and
Definitions A370 or the ICI-type bar shown in Specification A1067/A1067M, Fig. 3.
A957/A957M − 21
TABLE 3 Product Analysis Tolerances – Nickel and Cobalt Base Alloys
Limit or Maximum of Variation Under Min or Limit or Maximum of Variation Under Min or
Element Element
Specified Element, % Over Max Specified Element, % Over Max
Carbon up to 0.02, incl 0.005 Aluminum up to 0.10, incl 0.02
over 0.02 to 0.20, incl 0.01 over 0.10 to 0.50, incl 0.05
over 0.20 to 0.60 incl 0.02 over 0.50 to 2.00, incl 0.10
over 0.60 to 1.00, incl 0.03 over 2.00 to 5.00, incl 0.20
over 5.00 to 10.00, incl 0.25
Manganese up to 1.00, incl 0.03 over 10.00 to 15.00, incl 0.30
over 1.00 to 3.00, incl 0.04
over 3.00 to 6.00, incl 0.07 Boron up to 0.01, incl 0.002
over 6.00 to 10.00, incl 0.10 over 0.01
...