ISO/TS 4949:2016 specifies rules for the designation of internationally standardized steel grades by means of symbolic letters and numbers to express application and principal characteristics (e.g. mechanical, physical, chemical) so as to provide an abbreviated identification of steel grades.

NOTE 1 In order to avoid ambiguity, the principal symbols established according to this document can be supplemented by additional symbols identifying additional characteristics of the steel or steel product, e.g. suitability for use at high or low temperatures, surface condition, treatment condition, deoxidation.

NOTE 2 These rules can also be applied to nationally or regionally standardized steels.