This standard specifies the hexagon socket set screws with concave end of thread size M1.6 ~ M24, performance grades 45H, A1, A2, CU2, CU3 and AL4, and product grade A.
GB/T 80-2000 history
2007GB/T 80-2007 Hexagon socket set screws with cup point
2000GB/T 80-2000 Hexagon socket set screws with cup point