| 摘要 |
Disclosed herein is a precipitation hardening cold-rolled steel sheet and method for manufacturing the same, which can be used for structural components such as seat rails and the like of a vehicle body. The steel sheet comprises, by weight %, C: 0.07 ~ 0.1%, Mn: 1.4 ~ 1.7 %, P: 0.05 ~ 0.07 %, S: 0.005% or less, acid-soluble Al: 0.1 ~ 0.15 %, Nb: 0.06 ~ 0.09 %, B: 0.0008 ~ 0.0012 %, Sb: 0.02 ~ 0.06 %, and the balance of Fe and other unavoidable impurities. The steel sheet has a yield strength of 750 MPa or more and a yield ratio of 85 % or more, and is free from surface defects due to a very low degree of oxide enrichment on the surface thereof. |
