【作者】 李久楷； 侯方； 刘永杰； 王清远；

【Author】 LI Jiukai;HOU Fang;LIU Yong-jie;WANG Qingyuan;College of Architecture and Environment,Sichuan University;

【机构】 四川大学建筑与环境学院；

【摘要】 为研究CrMoW转子钢在工作温度下的超高周疲劳性能,自主搭建了高温超声疲劳实验系统并完成了CrMoW转子钢在常温下与600℃下1×10¹⁰周次超高周疲劳实验。结果表明:600℃下及常温下转子钢S-N曲线均呈连续下降型,试件在10⁹后仍会发生断裂。断口分析也表明:常温实验条件下,疲劳寿命小于1×10⁷周次试件的裂纹多萌生于表面,而大于1×10⁷周次多以内部萌生为主。高温实验环境下,发现裂纹也会从内部夹杂处萌生,且裂纹萌生方式不对疲劳寿命起决定性作用。通过对鱼眼定量分析,得到了CrMoW转子钢在600℃下及常温下裂纹扩展的应力强度因子门槛值分别为3.2 MPa·m^1/2和1.0 MPa·m^1/2。更多还原

【Abstract】 A high temperature ultrasonic fatigue system had been set up and fatigue tests up to1×10¹⁰ cycles of CrMoW rotor steel at room temperature and 600℃ had been conducted successfully.Results reveal that the type of S-N curves at room temperature and 600℃ both present continuously descending.Fractograph of specimens show that there are two initiation mechanism of fatigue fracture at room temperature,Crack initiate mainly from the surface for the specimens that fatigue life is less than 1 × 10⁷ cycles.For specimens that fatigue life is greater than1×10⁷ cycles,crack initiate mostly from inclusions.It is found that crack can also initiate at inclusions and generate fisheye at high temperature,the mode of crack initiation do not play a decisive role in the fatigue life.Threshold values of fatigue crack growth obtained by measuring the size of fisheye are 3.2 MPa·m^1/2 and 1.0 MPa·m^1/2 at room temperature and 600℃respectively.更多还原