This specification covers castings, iron-chromium-nickel-molybdenum corrosion-resistant, duplex(austenitic/ferritic) for general application. Castings shall be heat treated in accordance with the required procedure and heat-treat temperature. 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 the required mechanical properties. The steel shall conform to the required chemical composition for carbon, manganese, silicon, phosphorus, sulfur, chromium, nickel, molybdenum, copper, tungsten, and nitrogen. Castings shall be marked for material identification with the specification designation and grade.

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.

1.3 The values stated in either inch-pound units or metric (SI) units are to be regarded separately as standard. Within the text the metric (SI) units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.