| 摘要 |
<p>The invention relates to a hot-rolled steel sheet having a resistance higher than 800 MPa and an elongation at break higher than 10%, and having the following composition in weight: 0.050% <= C <= 0.090%, 1%< Mn <= 2%, 0.015% <= Al <= 0.050 %, 0.1 %<=Si <= 0.3%, 0.10% <= Mo <= 0.40%, S <= 0.010%, P<= 0.025%, 0.003%<=N<=0.009%, 0.12% <= V <= 0.22%, Ti<= 0.005%, Nb<= 0.020% and optionally Cr<= 0.45%, the balance consisting of iron and unavoidable impurities resulting from the production, wherein the microstructure of the sheet or the part includes, in surface fraction, at least 80 % of upper bainite, the optional balance consisting of lower bainite, martensite and residual austenite, the sum of the martensite and residual austensite contents being lower than 5 %.</p> |
