This standard specifies the type, size, technical conditions and marks of hexagon head bolts with full thread. This standard applies to thread specifications Ml.6~M64, full thread, performance grades 5.6, 8.8, 9.8, 10.9, A2-70, A4-70, A2-50, A4-50, CU2, CU3 and AL4 grades, Hexagon head bolts with product grades A and B. Class A is used for d = 1.6 mm~24 mm and l≤10 d or l≤150 mm (according to the smaller value); Class B is used for d>24 mm or l>10 d or l>150 mm (according to the smaller value value) bolts.