This document specifies requirements for flat and long products of hot-rolled weldable fine-grain structural steels in the as-rolled (for SG grades only), normalized/normalized rolled and thermomechanical processed delivery conditions. It applies to steel plates rolled on a reversing mill, wide flats, hot-rolled sections and bars, which are intended for use in heavily loaded parts of welded or bolted structures.This document covers 13 grades and 6 qualities. Grades S275, S355, S390, S420, S460 and S500 are covered in Annex A. Grades SG245, SG290, SG325, SG345, SG365, SG415 and SG460 are covered in Annex B. Not all grades are available in all qualities, and some qualities have Charpy V-notch requirements.The steels specified in this document are applicable to hot-rolled plates, wide flats, sections and bars with a minimum nominal thickness of 3 mm and a maximum nominal thickness of 250 mm for grades S275N, S355N, S390N, S420N and S460N, a maximum nominal thickness of 150 mm for grades S275M, S355M, S390M, S420M, S460M, and S500M, a maximum nominal thickness of 200 mm for grades SG245, SG325 and SG415, a maximum nominal thickness of 100 mm for grades SG345, SG365 and SG460, and a maximum nominal thickness of 40 mm for grade SG290.This document does not include the following structural steels, some of which are covered by other International Standards:— Sheet and strip — refer to ISO TC 17/SC 12, Continuous mill flat rolled products;— Tubular products — refer to ISO TC 5/SC 1, Steel tubes.NOTE 1 Lists of standards covered by ISO/TC 17/SC 12 and ISO/TC 5/SC 1 are available on the ISO website.NOTE 2 In all parts of ISO 630, the term of "thickness" is considered as "nominal thickness", unless otherwise stated.