| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method of manufacturing a Ti-added high strength hot rolled steel plate suitable, in particular, for automobile parts as well as for structural members such as building material and electrical equipment such as switchboard, capable of stably securing a strength of 490-780 MPa class, and insensitive to fluctuations in hot rolling conditions. SOLUTION: A steel, which has a composition containing, by weight, 0.01-0.10% C, 0.01-0.1% sol.Al, 0.001-0.008% N, 0.01-0.2% Ti, and 0.1-2.0% Mn, further containing Si, P, and S as impurities in amounts of <=0.05%, <=0.02%, and <=0.005%, respectively, and satisfying inequality 5<=(Mn/54.9)/(Ti*/47.9)<=15 [where Ti*=Ti-3.4N-1.5S is satisfied], is used. At the time of hot rolling this steel, finishing temperature FT is maintained at a value ranging from Ar3 to 930 deg.C and also coiling temperature CT is maintained at a value ranging from 500 to 650 deg.C.</p> |
