钢制拉伸器螺母开裂失效分析

Failure Analysis of the Steel Stretcher Nut Cracking

拉伸器在使用过程中螺母突然断裂。通过宏微观观察、扫描电子显微镜及能谱分析、金相观察及显微硬度检测。从材质、热处理工艺、应力状态和使用环境等方面综合分析了螺母的断裂情况、断裂性质和原因,并判定了断裂机理。结果表明:螺母断裂性质为韧性断裂,随后在交变应力下发生疲劳扩展,最终导致失效。夹杂物过多是造成失效的主要原因。

The nut of the stretcher broke suddenly during use.The fracture properties and causes were analyzed by macroscopic and microscopic observation,scanning electron microscope and energy spectrum analysis,metallographic observation and microhardness detection.The broken condition,fracture property and cause of the nut were analyzed comprehensively from the aspects of material,heat treatment technology,stress state and service environment,and the fracture mechanism is determined.The results show that the fracture property of the nut is ductile fracture,and then fatigue expansion occurs under alternating stress,finally leading to failure.Excessive inclusion is the main cause of failure.