This specification covers low-alloy steel and martensitic stainless steels in the normalized and tempered, or quenched and tempered conditions, suitable for pressure-containing parts. All castings shall receive the specified heat treatment requirement: austenitizing temperature, medium, quenching cool, and tempering temperature. Preliminary heat treatment and multiple tempering are permitted. Recording-type pyrometers shall be used to control the furnace temperature. The steel shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, vanadium, boron, and copper. Residual elements include: copper, nickel, chromium, tungsten, molybdenum, and vanadium. Tensile properties of the steel shall conform to the requirements for tensile strength, yield strength, elongation, reduction of area, hardness, and maximum thickness. Product analysis tolerance is specified. Repair by welding may be done.

1.1 This specification2 covers low-alloy steels and martensitic stainless steels in the normalized and tempered, or quenched and tempered, condition suitable for pressure-containing parts. The weldability of the classes in this specification varies from readily weldable to weldable only with adequate precautions, and the weldability of each class should be considered prior to assembly by fusion welding.

1.2 Selection will depend on design, mechanical, and service conditions. Users should note that hardenability of some of the grades mentioned may restrict the maximum size at which the required mechanical properties are obtained.

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.