| 摘要 |
The invention relates to a cold-rolled and annealed steel sheet having a strength greater than 1200 MPa, the composition of which comprises, the contents being expressed by weight: 0.10 % < C < 0.25 %, l % ≤ Mn< 3 %, Al > 0.010 %, Si < 2.990 %, S < 0.015 %, P < 0.1%, N < 0.008 %, it being understood that 1 % < Si + Al < 3 %, the composition optionally comprising: 0.05 % < V < 0.15 %, B < 0.005 %, Mo < 0.25 % Cr < 1.65 %, it being understood that Cr + 3 Mo > 0.3 %, Ti in an amount such that Ti/N ≥ 4 and Ti < 0.040 %, the balance of the composition consisting of iron and inevitable impurities resulting from the smelting, the microstructure of the steel comprising 15 to 90 % bainite, the remainder consisting of martensite and of residual austenite. |
