This standard stipulates that the thread specification is M1.6~M24, the performance grade is 45H, A1-12H, A2-21H, A3-21H, A4-21H, A5-21H, CU2, CU3 and AL4, and the product grade is A grade. Hexagon socket set screws with flat point. If other technical requirements are required, they should be selected from current standards (such as GB/T 193, GB/T 3098.3, GB/T 3098.1 6, GB/T 9145 and GB/T 3103.1)