HIGH STRENGTH NON-HEAT TREATED STEEL FOR FORGING SEPARATE CONNECTING ROD AND METHOD OF MANUFACTURING THE NON-HEAT TREATED STEEL

摘要

PURPOSE: High-strength non-normalized steel for a connecting rod and a manufacturing method thereof are provided to enhance fracture by ensuring a low reduction rate in sectional area of fractured surface and low permanent strain and enhance tensile strength by omitting thermal treating processes. CONSTITUTION: A manufacturing method of high-strength non-normalized steel for a connecting rod comprises next steps. Molten metal is formed and cast. Cast steel is re-heated and pilot-rolled. The rolled steel is normalized at high temperature. The molten metal comprises one or more of C of 0.30~0.50 weight%, Si of 0.50~0.80 weight%, Mn of 1.30~1.60 weight%, P of 0.030 weight% or less, S of 0.014~0.08 weight%, Cu of 0.02~0.30 weight%, Cr of 0.10~0.50 weight%, V of 0.050~0.095 weight%, Nb of 0.02~0.05 weight%. The molten metal further comprises Fe and other inevitable impurities.