| 摘要 |
The subject of the invention is a part, the composition of which comprises, the contents being expressed as percentages by weight, 0.10 ≤ C ≤ 0.30, 1.6 ≤ Mn ≤ 2.1, 0.5 ≤ Cr ≤ 1.7, 0.5 ≤ Si ≤ 1.0, 0.065 ≤ Nb ≤ 0.15, 0.0010 ≤ B ≤ 0.0050, 0.0010 ≤ N ≤ 0.0130, 0 ≤ Al ≤ 0.060, 0 ≤ Mo ≤ 1.00, 0 ≤ Ni ≤ 1.0, 0.01 ≤ Ti ≤ 0.07, 0 ≤ V ≤ 0.3, 0 ≤ P ≤ 0.050, 0.01 ≤ S ≤ 0.1, 0 ≤ Cu ≤ 0.5, 0 ≤ Sn ≤ 0.1, the remainder of the composition consisting of iron and inevitable impurities resulting from the smelting, the microstructure consisting, in surface proportions, of 100% to 70% of bainite, of less than 30% of residual austenite and of less than 5% of ferrite, and process for the manufacture thereof. |
