This specification covers iron-chromium-nickel-copper corrosion resistance steel castings capable of being strengthened by precipitation hardening heat treatment. The steel shall be made by electric furnace process with or without separate refining such as argon-oxygen decarburization. The steel materials shall also undergo homogenization heat treatment, solution annealing heat treatment, precipitation hardening and shall conform to the required values of temperature and time and cooling treatment. The materials shall conform to the required chemical compositions of carbon, manganese, phosphorus, sulfur, silicon, chromium, nickel, copper, columbium, and nitrogen.

1.1 This specification covers iron-chromium-nickel-copper corrosion-resistant steel castings, capable of being strengthened by precipitation hardening heat treatment.

1.2 These castings may be used in services requiring corrosion resistance and high strengths at temperatures up to 600 °F [315 °C]. They may be machined in the solution heat-treated condition and subsequently precipitation hardened to the desired high-strength mechanical properties specified in Table S51.1 with little danger of cracking or distortion.

1.3 The material is not intended for use in the solution heat-treated condition.

Note 1: If the service environment in which the material is to be used is considered conducive to stress-corrosion cracking, precipitation hardening should be performed at a temperature that will minimize the susceptibility of the material to this type of attack.

1.4 Supplementary requirements of an optional nature are provided for use at the option of the purchaser. The supplementary requirements shall apply only when specified individually by the purchaser in the purchase order or contract.

1.5 This specification is expressed in both inch-pound units and in SI units; however, unless the purchase order or contract specifies the applicable M-specification designation (SI units), the inch-pound units shall apply.

1.6 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. Within the text, the SI units are shown in brackets.

1.7 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.