| 摘要 |
<p>A cold rolled steel sheet capable of enhancing yield strength and lowering in-plane anisotropy by AlN precipitates in bake-hardening type interstitial free steel and a method for manufacturing the same are provided. A bake-hardening type cold rolled steel sheet with high yield ratio comprises, by weight percent, 0.001 to 0.01% of C, 0.08% or less of S, 0.1% or less of Al, 0.004 to 0.02% of N, 0.2% or less of P, 0.0001 to 0.002% of B and 0.005 to 0.15% of Ti with the balance being Fe and other inevitable impurities, wherein the Al, N, Ti, C and S, by weight percent, satisfy (Al/27)/(N^*/14)=1 to 10, and Cs(solid carbon) satisfies 5 to 30, wherein N^*=N-0.8Î(Ti-0.8Î(48/32)ÎS)Î(14/48), Cs=(C-(12/48)ÎTi^*)Î10000, Ti^*=Ti-0.8Î((48/14)ÎN+(48/32)ÎS), and Ti^*=0 provided that Ti^*<0, and wherein AlN precipitates have an average size of 0.2 mum or less.</p> |
