This specification covers carbon and high-strength low-alloy steel structural shapes, plates, and bars and quenched and tempered alloy steel for structural plates intended for use in bridges. Nine grades are available in four yield strength levels as follows:
Grades 36 , 50 , 50S [345S], 50W [345W], 100 , and 100W [690W] are also included in Specifications A 36/A 36M, A 572/A 572M, A 992/A 992M, A 588/A 588M, and A 514/A 514M, respectively. When the supplementary requirements of this specification are specified, they exceed the requirements of Specifications A 36/A 36M, A 572/A 572M, A 992/A 992M, A 588/A 588M, and A 514/A 514M.
Grades 50W [345W], HPS 50W [HPS 345W], HPS 70W [HPS 485W], 100W [690W], and HPS 100W [HPS 690W] have enhanced atmospheric corrosion resistance (see 14.1.2). Product availability is shown in Table 1.
Grade HPS 70W [HPS 485W], 100 , 100W [690W], or HPS 100W [HPS 690W] shall not be substituted for Grades 36 , 50 , 50S [345S], 50W [345W], or HPS 50W [HPS 345W]. Grade 50W [345W], or HPS 50W [HPS 345W] shall not be substituted for Grades 36 , 50  or 50S [345S] without agreement between the purchaser and the supplier.
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 A 6/A 6M for information on weldability.
For structural products to be used as tension components requiring notch toughness testing, standardized requirements are provided in this standard, and they are based upon American Association of State Highway and Transportation Officials (AASHTO) requirements for both fracture critical and non-fracture critical members.
Supplementary requirements are available but shall apply only if specified in the purchase order.
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, without combining values in any way.
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 A 6/A 6M apply.
Footnote * - A Summary of Changes section appears at the end of this standard.