EN ISO () MECHANICAL PROPERTIES OF BOLTS SCREWS AND STUDS (extract) 7 Mechanical and physical properties The bolts, screws and studs of the specified property . Mar 4,  · The strength class identification marking consists of two numerals: ± the first number corresponds to 1/ of the nominal tensile strength in N/mm2 (see table) ± the . This document specifies mechanical and physical properties of bolts, screws and studs made of carbon steel and alloy steel with coarse and fine pitch thread. It is