This specification covers high-strength, low-alloy structural steel shapes, plates, and bars for welded, riveted, or bolted construction with atmospheric corrosion resistance. Heat analysis shall be performed wherein the low-alloy structural steel materials shall conform to the required chemical composition for carbon, manganese, phosphorous, sulfur, silicon, nickel, chromium, molybdenum, copper, vanadium, and columbium. Steel samples shall also undergo the tensile test and conform to required values of tensile strength, yield point, and elongation.

1.1 This specification covers high-strength low-alloy structural steel shapes, plates, and bars for welded, riveted, or bolted construction but intended primarily for use in welded bridges and buildings where savings in weight or added durability are important. The atmospheric corrosion resistance of this steel in most environments is substantially better than that of carbon structural steels with or without copper addition (see Note 1). When properly exposed to the atmosphere, this steel is suitable for many applications in the bare (unpainted) condition. This specification is limited to material up to 8 in. [200 mm] inclusive in thickness.

Note 1: For methods of estimating the atmospheric corrosion resistance of low-alloy steels, see Guide G101.

1.2 When the steel is to be welded, a welding procedure suitable for the grade of steel and intended use or service is to be utilized. See Appendix X3 of Specification A6/A6M for information on weldability.

1.3 Units—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. 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 are not exact equivalents; therefore, each system is to be used independently of the other. Combining values from the two systems may result in nonconformances with the standard.

1.4 The text of this specification contains notes, footnotes, or both, that provide explanatory material. Such notes and footnotes, excluding those in tables and figures, do not contain any mandatory requirements.

1.5 For structural products produced from coil and furnished without heat treatment or with stress relieving only, the additional requirements, including additional testing requirements and the reporting of additional test results, of Specification A6/A6M apply.

1.6 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.