Abstract: Test low carbon boron steel ( % ：0. 13 〜0. 21C, 0. 000 5 〜0. 003 7B) and low carbon Nb-V microalloying boron steel ( % ：0. 18 〜0. 24C, 0-0. 033Nb, 0 〜0. 050V, 0. 000 5 〜0. 002 2B) were melted respectively by laboratory 50 kg vacuum induction furnace and carbon tube furnace, and the tensile specimen and notched delayed fracture specimen were turned from φ13 mm rolled-forged rod. The delayed fracture resistance of test steels water-quenched at 950 T and tempered at 200℃ is presented by delayed fracture strength ratio R =σ_n( delayed fracture strength) / σ_c( tensile strength). Results showed that the tensile strength of 0. 000 5% B steel microalloying with 0. 028% Nb and 0. 032% V was 1 480 MPa and its R value was 0. 665 which was higher than that of 40Cr steel and 35CrMo steel queched at 880 ℃ , oil cold + tempered at 400 ℃ (both σ_c were respectively 1 460 MPa and 1 530 MPa, R value 0. 583 and 0. 556).

摘要： 试验用低碳硼钢(%:0.13～0.21C、0.000 5～0.003 7B)和低碳Nb-V微合金化硼钢(%:0.18～0.24C、0～0.033Nb、0～0.050V、0.000 5～0.002 2B)分别由实验室50 kg真空感应炉和碳管炉冶炼,轧-锻成φ13 mm圆棒,然后加工成拉伸和带缺口的延迟断裂试样。经950℃水淬+200℃回火处理后钢的延迟断裂性由延迟断裂强度比R=σ_n(延迟断裂强度)/σ_c (拉伸强度)表示。结果表明,0.028%Nb-0.032%V微合金化0.000 5%B钢的σe为1 480 MPa,R值为0.665,均高于880℃油淬+400℃回火40Cr钢和35CrMo钢的σ_c和R值(σ_c分别为1 460 MPa和1 530 MPa,R值0.583和0.556)。

关键词: 低碳微合金化, 高强度硼钢, 延迟断裂