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. Heat analysis shall be used to determine the percentage of carbon, manganese, phosphorus, sulfur, silicon, and copper for the required chemical composition. A tension test shall be used to determine the required tensile properties such as tensile strength, yield strength, and elongation. Materials shall undergo: (1) an impact test for non-fracture critical and fracture critical members; and (2) a Brinell hardness test for Grades 100 and 100W. Atmospheric corrosion resistance shall also be determined.

1.1 This specification covers carbon and high-strength low-alloy steel structural shapes, plates, and bars, quenched and tempered alloy steel, and stainless steel for structural plates intended for use in bridges. Twelve grades are available in five yield strength levels as follows:

Grade U.S. [SI]

Yield Strength, ksi [MPa]

      36 [250]

 36 [250]    

      50 [345]

 50 [345]    

      50S [345S]

 50 [345]    

      QST 50 [QST 345]

 50 [345]    

      QST 50S [QST 345S]

 50 [345]    

      50W [345W]

 50 [345]    

      HPS 50W [HPS 345W]

 50 [345]    

      50CR [345CR]

 50 [345]    

      QST 65 [QST450]

 65 [450]    

      QST 70 [QST485]

 70 [485]    

      HPS 70W [HPS 485W]

 70 [485]    

      HPS 100W [HPS 690W]

100 [690]    

1.1.1 Grades 36 [250], 50 [345], 50S [345S], 50W [345W], 50CR [345CR], QST 50 [QST 345], QST 50S [QST 345S], QST 65 [QST 450], and QST 70 [QST 485] are also included in Specifications A36/A36M, A572/A572M, A992/A992M, A588/A588M, A1010/A1010M (UNS S41003), and A913/A913M respectively. When the requirements of Table 11 or Table 12 or the supplementary requirements of this specification are specified, they exceed the requirements of Specifications A36/A36M, A572/A572M, A992/A992M, A588/A588M, A1010/A1010M (UNS S41003), and A913/A913M. Product availability is shown in Table 1.

1.1.2 Grades 50W [345W], 50CR [345CR], HPS 50W [HPS 345W], HPS 70W [HPS 485W], and HPS 100W [HPS 690W] have enhanced atmospheric corrosion resistance (see 13.1.2). Product availability is shown in Table 1.

1.2 Grade HPS 70W [HPS 485W] or HPS 100W [HPS 690W] shall not be substituted for Grades 36 [250], 50 [345], 50S [345S], 50W [345W], or HPS 50W [HPS 345W]. Grade 50W [345W], or HPS 50W [HPS 345W] shall not be substituted for Grades 36 [250], 50 [345] or 50S [345S] without agreement between the purchaser and the supplier.

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 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.

1.5 Supplementary requirements are available but shall apply only if specified in the purchase order.

1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.7 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.

1.8 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.