This standard stipulates that the thread specifications are M1.6~M64, the performance grades are 5.6, 8.8, 9.8, 10.9, A2-70, A4-70, A2-50, A4-50, CU2, CU3 and AL4 grades, and the product grades are Hex head bolts of grades A and B. Grade A is used for d=1.6~24mm and l≤10d or l≤150mm (according to the smaller value); B grade is used for bolts with d>24mm or l>10d or l>150mm (according to the smaller value). If other technical requirements are required, they should be selected from current standards (such as GB/T 196, GB/T 3106, GB/T 3098.1, GB/T 3098.6 and GB/T 3103.1).