This standard specifies the type, size, technical conditions and marks of Type 1 hex nuts. This standard applies to thread specifications Ml.6~M64, the performance grades are 6, 8 and 10, A2-50, A2-70, A4-50, A4-70, CU2, CU3 and AL4, and the product grade is A Type 1 hexagon nuts for grades and grades B. Grade A is used for nuts with D≤16 mm; Grade B is used for nuts with D>16 mm.