This specification covers high-strength carbon-manganese steel shapes, plates, and bars of structural quality for use in riveted, bolted, or welded construction of buildings and for general structural purposes. Materials considered here are available in Grades 50 [345] and 55 [380]. Steel specimens shall be killed, and as such, be affirmed in the corresponding test report. Heat and product analysis shall be performed wherein steel materials shall conform to the required chemical compositions of carbon, manganese, phosphorus, sulfur, silicon, copper, columbium, chromium, nickel, molybdenum, and vanadium. Steel specimens shall also undergo tensile tests and shall conform to required values of tensile strength, yield strength, and elongation.

1.1 This specification covers carbon-manganese steel shapes, plates, and bars of structural quality for use in riveted, bolted, or welded construction of buildings and for general structural purposes.

1.2 Material under this specification is available in two grades:

Grade

Yield Strength,
ksi [MPa]

Thickness

50 [345]

50 [345]

Plates to 1 in. [25 mm] thick
to 15 in. [380 mm] wide

Bars to 3¹/₂ in. [90 mm]

Shapes with flange or leg thickness to
1¹/₂ in. [40 mm] inclusive

55 [380]

55 [380]

Plates to 1 in. [25 mm] thick
to 15 in. [380 mm] wide

Bars to 3 in. [75 mm]

Shapes with flange or leg thickness to
1¹/₂ in. [40 mm] inclusive

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

1.4 The values stated in either inch-pound units or SI units are to be regarded 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 must be used independently of the other.

1.5 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.