渗碳Cr-Ni高强硬度合金钢超高周疲劳寿命预测

为了给渗碳合金钢提供一种有效可行的超高周疲劳寿命预测方法,在应力比为0和0.3两种情况下,对渗碳Cr-Ni高强硬度合金钢展开疲劳试验研究.通过对试样断口的微观组织观测,发现渗碳层与基体材料中均有非金属夹杂的存在;通过对裂纹萌生位置和疲劳断口形貌的观察,将疲劳失效分为带有细晶粒区(Fine Granular Area,F...

Prediction of very-high-cycle fatigue life of carburized Cr-Ni high-hardness alloy steel

In order to provide an effective and feasible method for predicting the very-high-cycle fatigue life of carburized alloy steels, fatigue experiments were carried out on carburized Cr-Ni high-hardness alloy steels with stress ratios of 0 and 0.3. By observing the microstructure of the fracture of the sample, it was found that there were non-metallic inclusions in both carburizing layer and matrix material. The fatigue failure was divided into internal fatigue failure with fine granular area (FGA) and surface fatigue failure with surface smooth area (SSA) based on the observation of the crack initiation position and fatigue fracture morphology. The S-N curves of carburized Cr-Ni high-hardness alloy steel with stress ratios of 0 and 0.3 were constructed, and the internal fatigue failure mechanism of the alloy steel under very-high-cycle condition was explained. On the basis of the cumulative damage method and considering the stress ratio, FGA stress intensity factor, FGA size, and inclusion size, two fatigue life prediction models for carburized Cr-Ni high-hardness alloy steels with different stress ratios were established. Through comparative analysis, the two prediction models both had high prediction accuracy, which can be used as an effective method for predicting the very-high-cycle fatigue life of carburized Cr-Ni high-hardness alloy steels.