This SAE Recommended Practice covers six levels of high strength carbon and high-strength low-alloy steel plates, bars, and shapes for structural use. The six strength levels are 290, 345, 415, 450, 485, and 550 MPa or 42, 50, 60, 65, 70, and 80 ksi minimum yield point. Different chemical compositions are used to achieve the specified mechanical properties. In some cases there are significant differences in chemical composition for the same strength level, depending on the fabricating requirements. Because the chemical compositions may vary significantly among the producers, despite the required mechanical properties being the same, it is important that the fabricator consult with the producer to determine the relative effects of the producer's composition on the forming, welding, and field service requirements. The products within the scope of this document include the following:

1. a Plates—Flat hot-rolled steel (cut length only) greater than 200 mm (8 in) wide and greater than 5.8 mm (0.230 in) thick, and greater than 1220 mm (48 in) wide and greater than 4.6 mm (0.179 in) thick. For sheet and strip products (less than 5.8 mm (0.230 in) thickness), refer to SAE J1392.
2. b Bars—Rounds, squares, and hexagons of all sizes (cut length only, flats 5.2 mm (0.203 in) and greater in thickness but not greater than 150 mm (6 in) wide, and flats greater than 5.8 mm (0.229 in) thick and over 150 mm (6 in) to 204 mm (8 in) wide.
3. c Structural Shapes—Hot-rolled flanged sections having at least one dimension of the cross section 75 mm (3 in) or greater. (Size groupings for tensile property classification are listed in ASTM A 6/A 6M Table A.)
4. d Bar Size Shapes—Hot-rolled flanged sections having a maximum dimension of the cross section less than 75 mm (3 in).