hex head bolt DIN931 1.ISO9001:2008 CERTIFICATION 2.DIN931 DIN933 ISO4014 ... .M6-M30 1/4-2'' 4.304 316 321 hex head bolt DIN931 A2 A4 The main products: are stainless steel ... hex head bolts, hexagon socket setscrews, machine screws, expansion screws, ground screws ... .9 Q215 Q235 ML35 35CrMoA 25CrMoVA 35CMrMo 45# 1. Hex head bolt with carbon steel