| 摘要 |
<p>The present invention relates to micro alloyed steel for a vehicle steering rack bar with high strength and high toughness comprising 0.35-0.45 wt% of C, 0.15-0.35 wt% of Si, 1.10-1.30 wt% of Mn, 0.001-0.020 wt% of P, 0.030-0.070 wt% of S, 0.001-0.20 wt% of Ni, 0.30-0.60 wt% of Cr, 1.50-1.70 wt% of Mn+Cr, 0.001-0.05 wt% of Mo, 0.10-0.15 wt% of V, 0.020-0.040 wt% of Nb, 0.010-0.030 wt% of Al, 0.0080-0.015 wt% of N, and the remainder consisting of Fe and inevitable impurities. According to the present invention, the steel has impact properties of 4 kgfm/cm^2 or more, and tensile strength of 1,000 MPa or more. Moreover, the present invention provides a method for manufacturing the micro alloyed steel for a vehicle steering rack bar with excellent physical properties, by optimizing the stress remove annealing temperature and the cross section reducing rate in cold drawing.</p> |
