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本文研究了超载对40CrMnsiMoVA 钢中准贝氏体组织和马氏体组织冲击疲劳裂纹起始寿命的影响。结果表明拉伸超载延长疲劳裂纹起始寿命 N_i,N_i 与试样缺口根部的残余应变ε_R 之间呈以下经验关系:N_i=N_i~0exp(mε_R);压缩超载缩短 N_i。准贝氏体组织的超载延寿效果明显地大于马氏体组织,认为这与准贝氏体组织具有良好的强韧性配合有关。还讨论了超高强度钢的超载延寿机制。
In this paper, the influence of overloading on the initial fatigue life of impact bainitic and martensite in 40CrMnsiMoVA steel was studied. The results show that the relationship between initial fatigue life N_i, N_i and residual strain ε_R at the root of notch is as follows: N_i = N_i ~ 0exp (mε_R); compression overload shortens N_i. The effect of quasi-bainite overloading life extension is obviously greater than that of martensite, which is considered to be related to the good toughness of quasi-bainite. It also discusses the mechanism of overload and prolongation of ultrahigh strength steel.