This specification covers iron-base, heat-resisting alloy castings, intended for structural elements, containers, and supports in electric furnaces, petroleum still tube supports, and for similar applications.

The alloys shall be electric-furnace processed and heat treated. The castings shall conform to the required chemical compositions of nickel, chromium, carbon, nitrogen, manganese, silicon, phosphorus, sulfur, and iron.

The specimens shall undergo tension test after aging and short-time high-temperature tension test and shall conform to the required values of tensile strength and elongation.

A stress-rupture test shall also be performed wherein the specimens shall conform to the required values of tensile stress.

The specimen shall also conform to the required values of magnetic permeability.

1.1 This specification covers iron-base, heat-resisting alloy castings of the 25 % chromium, 12 % nickel class, intended for structural elements, containers, and supports in electric furnaces, petroleum still tube supports, and for similar applications up to 2000 °F [1095 °C].

1.2 In the absence of significant proportions of elements other than those prescribed in Section 5, the two types of alloys covered by this specification may in general be distinguished as follows:

• 1.2.1 Type I—Alloys characterized by relatively low limiting creep stress at temperatures between 1500 and 2000 °F [815 and 1095 °C], and relatively high ductility at ordinary temperatures after aging for short periods at temperatures between 1300 and 1500 °F [705 and 815 °C].
• 1.2.2 Type II—Alloys having relatively high limiting creep stress but which may develop low ductility at ordinary temperatures when aged for short periods at temperatures between 1350 and 1500 °F [730 and 815 °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.