This standard specifies the type, size, technical conditions and marks of hexagon head bolts with fine pitch and full thread. This standard applies to threads with nominal diameter = 8 mm to 64 mm, fine thread, full thread, property class 5.6, 8.8, 10.9, A2-70, A4-70, A2-50, A4-50, CU2, CU3 and Hexagon head bolts of AL4 grade, product grades A and B. Class A is used for d = 8 mm~24 mm and Z≤10 d or Z≤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. Coarse thread bolts specified in GB/T 5783 are preferred.