【摘要】 研究了不同热处理制度下得到的3种晶粒尺寸的42CrMoVNb细晶高强钢的疲劳性能.结果表明,它们的光滑疲劳试样S-N曲线在106-107周期范围内无平台出现,疲劳极限消失. SEM断口观察表明,光滑试样疲劳裂纹起源位置与寿命长短密切相关,测量了长寿命试样疲劳断裂源夹杂物的位置及尺寸.通过对实验数据的初步分析,给出了夹杂物及奥氏体晶粒尺寸应控制的水平.更多还原

【Abstract】 The fatigue properties of high strength steel 42CrMoVNb with three fine grain sizes produced by different heat treatment procedures were studied. The experimental results illustrate that at 106-107 cycles regime, there is no horizontal asymptote in fatigue S-N curves for smooth specimens, so the conventional fatigue limit disappears. SEM shows the fatigue crack initiation sites in smooth specimens are related closely to fatigue life, and most of the sites are at inclusions. From analyzing the experimental data, the critical size of inclusion and the most appropriate size of prior austenite, which should be controlled in practical production, are obtained.更多还原