M50轴承钢温度时间相关高周疲劳损伤寿命模型的研究

Study on temperature time related high cycle fatigue damage life model of M50 bearing steel

通过QBWP-10000悬臂旋转弯曲疲劳试验机测得25、200、315℃的疲劳极限及S-N曲线,通过万能试验机测试了不同温度下慢速、稳定和快速裂纹扩展速率曲线。基于M50轴承钢疲劳裂纹主要源于钢中碳化物,结合弹性模量、泊松比等参数随温度变化规律与碳化物界面循环应力作用所引起硬化效应建立了与温度时间相关的局部损伤寿命模型。研究表明:M50轴承钢碳化物等疲劳缺陷应力强度因子是疲劳损伤量;温度升高缩短了裂纹萌生时间并加速裂纹扩展速率进而降低了M50轴承钢疲劳极限强度;主要影响萌生寿命的是循环次数、温度、疲劳缺陷及所施加循环应力引起的碳化物界面的局部硬化。

The fatigue limits and S-N curves at 25,200,and 315℃were measured by using the QBWP-10000 cantilever rotary bending fatigue testing machine.The slow,stable,and fast crack propagation rate curves at different temperatures were tested using a universal testing machine.Based on the fact that fatigue cracks in M50 bearing steel mainly originate from carbides in the steel,a local damage life model related to temperature and time was established by combining the temperature dependent variation of parameters such as elastic modulus and Poisson's ratio with the hardening effect caused by cyclic stress at the carbide interface.Research has found that the stress intensity factor of fatigue defects such as carbides in M50 bearing steel is the amount of fatigue damage;the increase in temperature shortened the crack initiation time and accelerated the crack propagation rate,thereby reducing the fatigue ultimate strength of M50 bearing steel;the main factors affecting the initiation life are the number of cycles,temperature,fatigue defects,and local hardening of carbide interfaces caused by applied cyclic stress.