This document specifies qualities for high-yield-strength quenched and tempered structural steels. It applies to steel plates and wide flats rolled on a reversing mill which are used in the quenched and tempered condition and normally intended for welded or bolted structures.

This document covers 10 grades and 5 qualities. Grades°°S460Q, S500Q, S550Q, S620Q, S690Q, S890Q and S960Q are covered in Annex°°A. Grades°°SG460Q, SG500Q, and SG700Q 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 flat products with a minimum nominal thickness of 3°°mm and a maximum nominal thickness of 200°°mm for grades S460Q, S500Q, S550Q, S620Q and S690Q, a maximum nominal thickness of 125°°mm for grades S890Q and S960Q, a maximum nominal thickness of 100°°mm for grades SG460Q and SG500Q and a maximum nominal thickness of 150°°mm for grade SG700Q.

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.