alloy round bar standard:Chinese GB,ASTM, DIN Material:a42CrMo,42CrMo4,4040 diameter:12-400mm length: ... or more for industry alloy steel round barstandard:Chinese GB,ASTM, DINMaterial:42CrMo,42CrMo4,4040diameter:12-400mm length:6m or ... shouldered connections for petroleum industry, jar knocker, substitute of hardened and tempered steel with higher chromium composition, which demand higher strength ...