ASTM A890/A890M-18a

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Designation: A890/A890M − 18 A890/A890M − 18a
Standard Specification for
Castings, Iron-Chromium-Nickel-Molybdenum Corrosion-
Resistant, Duplex (Austenitic/Ferritic) for General
Application
This standard is issued under the fixed designation A890/A890M; 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 cast duplex stainless steels (austenitic/ferritic).
1.2 The duplex stainless steel alloys offer a combination of enhanced mechanical properties and corrosion resistance when
properly balanced in composition and properly heat treated. Ferrite levels are not specified, but these alloys will develop a range
of approximately 30 to 60 % ferrite with the balance austenite. It is the responsibility of the purchaser to determine which grade
shall be furnished depending on design and service conditions, mechanical properties, and corrosion-resistant characteristics.
NOTE 1—Because of the possibility of precipitation of embrittling phases, the grades included in this specification are not recommended for service
at temperatures above 600 °F [315 °C].
1.3 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.
1.3.1 Within the text, the SI units are shown in brackets.
1.4 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:
A781/A781M Specification for Castings, Steel and Alloy, Common Requirements, for General Industrial Use
A957/A957M Specification for Investment Castings, Steel and Alloy, Common Requirements, for General Industrial Use
E562 Test Method for Determining Volume Fraction by Systematic Manual Point Count
E1245 Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis
3. Ordering Information
3.1 Orders for material to this specification shall include the following, as required, to describe the material adequately:
3.1.1 Description of casting by pattern or drawing number (dimensional tolerance shall be included on the casting drawing),
3.1.2 Specification designation and grade, including year of issue,
3.1.3 Options in the specification (see 9.1), and
3.1.4 Supplementary requirements desired, including the standards of acceptance.
4. Process
4.1 The steel shall be made by the electric furnace process, with or without separate refining such as argon-oxygen-
decarburization (AOD).
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 May 1, 2018Sept. 1, 2018. Published May 2018October 2018. Originally approved in 1988. Last previous edition approved in 20132018 as
A890/A890M – 13.A890/A890M – 18. DOI: 10.1520/A0890_A0890M-18.10.1520/A0890_A0890M-18A.
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.
*A Summary of Changes section appears at the end of this standard
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A890/A890M − 18a
5. Heat Treatment
5.1 Castings shall be heat treated in accordance with the requirements in Table 1.
NOTE 2—Proper heat treatment of these alloys is usually necessary to enhance corrosion resistance and, in some cases, to meet mechanical properties.
Minimum heat-treat temperatures are specified; however, it is sometimes necessary to heat treat at higher temperatures, hold for some minimum time at
temperature, and then rapidly cool the castings in order to enhance the corrosion resistance and meet mechanical properties.
6. Chemical Composition
6.1 The steel shall conform to the requirements as to chemical composition prescribed in Table 2.
7. General Requirements
7.1 Material furnished to this specification shall conform to the requirements of Specification A781/A781M, including any
supplementary requirements that are indicated in the purchase order. Failure to comply with the general requirements of
Specification A781/A781M constitutes nonconformance with this specification. In case of conflict between the requirements of this
specification and Specification A781/A781M, this specification shall prevail.
7.2 Steel investment castings furnished to this specification shall conform to the requirements of Specification A957/A957M,
including any supplementary requirements that are indicated in the purchase order. Failure to comply with the general requirements
of Specification A957/A957M constitutes nonconformance with this specification. In case of conflict between the requirements of
this specification and Specification A957/A957M, Specification A957/A957M shall prevail.
8. Repair by Welding
8.1 The composition of the deposited weld metal may be similar to that of the casting, or may be suitably alloyed to achieve
the desired corrosion resistance and mechanical properties.
8.2 Weld repairs shall be subject to the same quality standards as are used to inspect the castings.
8.3 When post-weld heat treatment is believed necessary for adequate corrosion resistance or impact resistance, Supplementary
Requirement S33, Post-Weld Heat Treatment, shall be included in the purchase order.
9. Product Marking
9.1 Castings shall be marked for material identification with the specification designation and grade. In addition, the
manufacturer’s name or identification mark and the pattern number shall be cast or stamped using low-stress stamps on all castings.
TABLE 1 Heat Treatment Requirements
Grade Heat Treatment
1B, 1C Heat to 1900 °F [1040 °C] minimum, hold for sufficient time to
heat casting uniformly to temperature, quench in water or rapid
cool by other means.
2A Heat to 2050 °F [1120 °C] minimum, hold for sufficient time to
heat casting uniformly to temperature, quench in water or rapid
cool by other means.
3A Heat to 1950 °F [1070 °C] minimum, hold for sufficient time to
heat casting uniformly to temperature, quench in water or rapid
cool by other means.
4A Heat to 2050 °F [1120 °C] minimum, hold for sufficient time to
heat casting uniformly to temperature, and water quench, or the
casting may be furnace cooled to a temperature no lower than
1850 °F [1010 °C], hold for 15 min minimum and then water
quench. A rapid cool by other means may be employed in lieu of
water quench.
5A Heat to 2050 °F [1120 °C] minimum, hold for sufficient time to
heat casting to temperature, furnace cool to a temperature no
lower than 1910 °F [1045 °C], then quench in water or rapid cool
by other means.
6A Heat to 2010 °F [1100 °C] minimum, hold for sufficient time to
heat casting uniformly to temperature, quench in water or cool
rapidly by other means.
6A Heat to 2010 °F [1100 °C] minimum, hold for sufficient time to
heat casting uniformly to temperature, quench in water or rapid
cool by other means, or the casting may be furnace cooled to a
temperature no lower than 1925 °F [1050 °C], hold for 15 min
minimum and then quench in water or rapid cool by other
means.
7A Heat to 2065 °F [1130 °C] minimum, hold for sufficient time to
heat casting to temperature,
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