NON QUENCHED AND TEMPERED STEEL FOR HOT FORGING WITH EXCELLENT IMPACT TOUGHNESS AND A METHOD FOR MANUFACTURING THE SAME AND THE CHASSIS PARTS FOR AUTOMOBILE USING THE SAME

摘要

Non-Heat-Treated Steel of a heat Forging type having superior impact toughness, a manufacturing method thereof, and a part of an automobile sash manufactured by using the same are provided to guarantee excellent balance of toughness and intensity and suppress carbon dioxide and soot under a thermal process. Non-Heat-Treated Steel of a heat Forging type having superior impact toughness comprises 0.29~0.33wt.% of carbon, 0.15~0.35wt.% of silicon, 1.30~1.60wt.% of manganese, 0.030wt.% and below of phosphorus, 0.015~0.030wt.% of sulfur, 0.05~0.20wt.% of nickel, 0.05~0.20wt.% of chromium, 0.04~0.08wt.% of vanadium, 0.010~0.030wt.% of aluminum, 0.0003~0.0020wt.% of boron, 0.010~0.020wt.% of titanium, 0.0050~0.013wt.% of nitrogen, residual Fe, and inevitable impurities.