扇形轴疲劳失效断裂原因分析

某扇形轴在疲劳试验时出现断裂现象,见图1。拆卸后发现在57×104圈时断裂。通过对扇形轴进行宏观检验、金相检验、硬度测试、化学成分分析、扫描电镜分析和能谱分析,对该扇形轴失效原因进行分析和探讨。结果表明:扇形轴裂纹从晶粒间的内氧化开始,沿晶界向内延伸。说明晶粒间的内氧化促成了扇形轴的疲劳失效。受到其他因素的影响,如装配、尺寸偏差、工作负载等等,也可能使扇形轴因疲劳失效而断裂。

the sector shaft cracked during the fatigue test, see fig. 1. It＇ s discovered after dismantling that the sector shaft cracked at in the 57 ×104 round. Failure cause of the sector shaft is analyzed via macroscopic inspection, metallographic inspection, hardness test, chemical composition analysis, scanning electron microscope analysis and energy spectrum analysis. The analysis result shows that： the crack starts from the intergranular internal oxidation, and extends entad. It explains that the intergranular internal oxidation caused the fatigue failure of sector shaft. Other factor such as assembly, dimension deviation and working load may also cause the fatigue failure.