摘要
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 present paper the effects of overload on the fatigue crack initiation life ofmeta-bainite and martensite in steel 40CrMnSiMoV have been investigated.The results showthat compressive overload decreases the fatigue crack initiation life(N_i),while tensile overloadincreases N_i,which is correlated with the residual strain(ε_R)at the notch tip of the specimen bythe following empirical relation:N_i= N_i^0exp(mεR).The increasing extent of the fatigue life ofmeta-bainite is much greater than that of martensite due to the good combination of strengthand toughness of meta-bainite.The mechanisms of overload effects on ultra-high strengthsteels have also been discussed in this paper.
