1. ASTM A709 is a standard specification for structural steel for steel bridges published by the American Society for Testing and Materials (ASTM). The latest version is ASTM A709/A709M-241. QST50 is a grade of steel covered by the standard.
2. Standard coverage
The ASTM A709/A709M-24 specification covers carbon steel and high-strength low-alloy steel structural shapes, plates and bars, quenched and tempered alloy steels, and stainless steel for bridge structural plates.
3. Yield strength
In the ASTM A709/A709M-24 standard, the yield strength of QST50 is 50 ksi (about 345 MPa).
4. Related products of the standards
This grade is related to products such as A36/A36M, A572/A572M, A992/A992M, A588/A588M, A1010/A1010M (UNS S41003) and A913/A913M. These related products are involved when supplementary requirements of this specification are specified in Table 11 or Table 12.
5. Related uses and restrictions
Welding requirements
When this steel is to be welded, it is assumed that a welding procedure suitable for the grade of steel and the intended use or service will be used. Information on weldability can be found in Appendix X3 A6/A6M of the quality standard.
Substitution Rules
Grades HPS 70W [HPS 485W] or HPS 100W [HPS 690W] may not be substituted for grades 36 [250], 50 [345], 50S [345S], 50W [345W], QST 50 [QST 345] or HPS 50W [HPS 345W]. Grades 50W [345W] or HPS 50W [HPS 345W] may not be substituted for grades 36 [250], 50 [345], 50S [345S] or QST 50 [QST 345] without the agreement of the buyer and supplier.
