This guide covers standard specification for hot-finished and cold-finished martensitic chromium steel bars for high-temperature service. The mechanical properties shall be developed by suitable heat treatment, as indicated for each alloy. The steel shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, chromium, nickel, molybdenum, vanadium, tungsten, nitrogen, aluminum, columbium, and copper. The microstructure shall not contain more than 5% delta-ferrite after full heat treatment. The material shall conform to the required mechanical properties such as tensile strength, yield strength, elongation, impact strength, and Brinell hardness. The material shall also undergo stress rupture testing using a combination test bar.

1.1 This specification covers hot-finished and cold-finished martensitic chromium steel bars for high-temperature service. The mechanical properties are developed by suitable heat treatment, as indicated for each alloy.

1.2 Where strength at temperature is a factor, these steels are generally limited to a maximum service temperature of 1200°F [650°C]. For oxidation (scaling) resistance and at low stresses, these steels are useful to 1450°F [790°C].

1.3 This specification is expressed in both inch-pound units and SI units; however, unless the purchase order or contract specifies the applicable M specification designation (SI units), the inch-pound units shall apply. The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. 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 specification.