通过SEM、TEM、XRD、化学相分析等方法对比研究新型扭杆弹簧用40Si2Ni2CrMoV钢(代号N1)和现有45CrNiMoVA钢微观组织及其对力学性能的影响,并利用慢应变速率拉伸方法对比研究两种不同扭杆弹簧用钢的氢脆敏感性。结果发现,N1钢由于添加硅、钼等抗回火软化元素,使得N1钢在较高的300 ℃温度回火时还能保持一定的抗拉强度,N1钢有大量细小的ε-碳化物析出,使得屈服强度增加,屈强比在0.80以上,45CrNiMoVA钢经180 ℃低温回火后屈服强度在1 550 MPa左右,屈强比只有0.72;经相同条件充氢后,N1钢的慢拉伸强度下降幅度较小,其试样断口中也没有观察到沿晶断裂特征,N1钢的氢脆敏感性明显低于45CrNiMoVA钢。
Abstract
Microstructure and mechanical properties of newly developed 40Si2Ni2CrMoV steel (code name N1) and the existing 45CrNiMoVA steel were investigated by scamning electron microsope (SEM),transmission electron microscope (TEM),X-rany diffraction (XRD) and chemical phase analysis,and hydrogen embrittlement of these two steels was also investigated by slow strain rate tensile. The results show that N1 steel can keep high strength at higher temper temperature of 300 ℃ due to the addition with silicon and molybdenum element,which improve resistance to tempering softening. The fine ε-carbide in N1 steel can improve the yield strength,which keeps the yield ratio above 0.8,while the yield strength of 45CrNiMoVA steel is 1 550 MPa at the lower temper temperature of 180 ℃,and the yield ratio is only 0.72. The hydrogen embrittlement of N1 steel significantly lower than of 45CrNiMoVA steel,which is shown in the following aspects: the slow strain rate tensile strength of N1 steel decreases slightly compared with 45CrNiMoVA steel,and there is no intergranular fracture feature observed in tensile sample fracture.
关键词
氢脆敏感性,超高强度钢,扭杆弹簧,低温回火
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中图分类号:
TG142.1
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参考文献
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脚注
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基金
国家自然科学基金青年基金
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