ISO 4991:2015 covers steel castings for pressure containing parts.
It includes materials which are used for the manufacture of components subject to pressure vessel codes and components not subject to codes.
This International Standard relates to castings manufactured from unalloyed and alloyed steel grades (characterized by their chemical composition, Table 1, and mechanical properties, Tables 2, 3, 4 and 5).
NOTE Annex D gives information on ISO grade designation and available UNS numbers which are similar to the ISO grade designation.