Steel plates, shapes, sheetpiling, and bars for structural uses—such as the load-carrying members in buildings, bridges, ships, and other structures—are usually ordered to the requirements of ASTM A6 and are referred to as structural-quality steels. (A6 does not indicate a specific steel.) This specification contains general requirements for delivery related to chemical analysis, permissible variations in dimensions and weight, permissible imperfections, conditioning, marking and tension and bend tests of a large group of structural steels. (Specific requirements for the chemical composition and tensile properties of these
steels are included in the specifications discussed in Art. 1.1.) All the steels included in Table 1.1 are structural-quality steels.
In addition to the usual die stamping or stenciling used for identification, plates and shapes of certain steels covered by A6 are marked in accordance with a color code, when specified by the purchaser, as indicated in Table 1.3.
Steel plates for pressure vessels are usually furnished to the general requirements of ASTM A20 and are referred to as pressure-vessel-quality steels. Generally, a greater number of mechanical-property tests and additional processing are required for pressure-vesselquality steel.