... :12-400mm length:6m or more for industry alloy steel round barstandard:Chinese GB,ASTM, DINMaterial:42CrMo,42CrMo4 ... gear, connecting rod, transmission gear, supercharger gear, engine cylinder, spring, 1200mm~2000mm rotary shouldered connections for petroleum industry ... , jar knocker, substitute of hardened and tempered steel with higher chromium composition, which demand higher strength ...