Abstract: Test 700 MPa low carbon bainitic steel is melted by a 30 kg vacuum induction furnace, cast to 100 mm x 50 mm flat ingot and rolled to 12 mm plate. Based on CCT curves and analysis on structure of steel at cooling rate 3 ~30 Y/s, the effect of two group microalloying： 0. 06Ti-0. 05Nb and 0. 01Ti-0. 03Nb on structure and mechanical properties of low carbon bainitic steel- % : 0. 059 ~0. 066C, 1. 41 ~ 1. 67Mn, 0. 30 ~0. 36Si, 0. 37 ~0. 48Cu, 0. 21 ~0. 24Ni, 0. 18 ~ 0. 22Mo, 0.000 8 ~0. 002 2Bs, 0. 002 6N has been studied. Results show that the strength of steel with 0. 06Ti-0. 05Nb is higher than that of steel with 0. 01Ti-0. 03Nb, but the impact energy at -40 °C of the former, of which the Ti content is higher, is lower than that of the later. The available microalloying Ti-Nb content in 700 MPa low carbon bainitic steel is 0.015% -0. 025%Ti-0. 04% ~0. 05% Nb.

Key words: Low Carbon Bainitic Steel, Ti-Nb Microalloying, Structure, Mechanical Properties

摘要： 试验的700 MPa级低碳贝氏体钢由30 kg真空感应炉熔炼铸成断面100 mm×50 mm扁锭-轧成12mm板。通过CCT曲线和3～30℃/s冷却速度下组织的分析,研究0.01Ti-0.03Nb和0.06Ti-0.05Nb两种微合金化对(%)0.059～0.066C、1.41～1.67Mn、0.30～0.36Si、0.37～0.48Cu、0.21～0.24Ni、0.18～0.22Mo、0.000 8～0.002 2Bs、0.002 6N低碳贝氏体组织和力学性能的影响。结果表明,0.06Ti-0.05Nb钢的强度高于0.01Ti-0.03Nb钢,但前者Ti含量高,-40℃冲击功较后者低。700 MPa级低碳贝氏体钢合适的微合金化Ti-Nb成分为0.04%～0.05%Nb-0.015%～0.025%Ti。

关键词: 低碳贝氏体钢, Ti-Nb微合金化, 组织, 力学性能