Yield strength 800 MPa class high strength steel and method for producing the same

摘要

By weight percentage of the composition, C: 0.06-0.14%, Si: 0.10-0.30%, Mn: 0.80-1.60%, Cr: 0.20-0.70%, Mo: 0.10 to 0.40%, Ni: 0 to 0.30%, Nb: 0.010 to 0.030%, Ti: 0.010 to 0.030%, V: 0.010 to 0.0. 050%, B: 0.0005-0.0030%, Al: 0.02-0.06%, Ca: 0.001-0.004%, N: 0.002-0.005%, P ≦ 0 0.020%, S ≦ 0.010%, O ≦ 0.008%, the balance being Fe and inevitable impurities, and the above elements are 0.40% Ceq 0.50%, Ceq = C + Mn / 6 + (Cr + Mo + V) / 5 + (Ni + Cu) / 15, 0.7% ≦ Mo + 0.8Ni + 0.4Cr + 6V ≦ 1.1%, Yield strength 800MPa grade high strength steel and a manufacturing method thereof meet .7 ≦ Ti / N ≦ 7.0,1.0 ≦ Ca / S ≦ 3.0.