Low Carbon Bainite Micro-alloyed Steels for Cold Heading Applications having High Strength and High Impact Toughness and Method for Manufacturing the Same

摘要

The present invention provides a low-carbon bainite non-alloy steel for cold rolling excellent in strength and impact toughness by using a microstructure as bainite by controlling cooling at a cooling rate of 10° C./s or higher after hot rolling the steel material, and a method for manufacturing the same. Preferably, the steel of the present invention is C: 0.04 to 0.10 wt%, Si: 0.05 to 0.30 wt%, Mn: 1.50 to 2.00 wt%, P: 0.030 wt% or less (not including 0), S: 0.030 wt% or less (0 not included), Cu: 0.20 to 0.40% by weight, Ni: 0.25% by weight or less (not including 0), Cr: 0.40 to 0.80% by weight, Mo: 0.10% by weight or less (not including 0), Nb: 0.010 to 0.050% by weight , B: 0.0005 to 0.0030% by weight, Al: 0.010 to 0.040% by weight, Ti: 0.010 to 0.050% by weight, and N: 0.0100% by weight or less (not including 0), and the balance is for cold pressure baths composed of Fe and unavoidable impurities. Low carbon bainite non-steel.