ISO 9328-6:2018 specifies the requirements for flat products for pressure equipment made of quenched and tempered weldable fine grain steels as specified in Tables A.1 and B.1. The requirements and definitions of ISO 9328‑1 also apply to this document. NOTE 1 Fine grain steels are understood to be steels with a ferritic grain size of 6 or finer when tested in accordance with ISO 643. NOTE 2 This document offers the possibility of specifying products in accordance with European design codes and ASME-type design codes.