0Cr17Ni4Cu4Nb钢制螺钉断裂原因分析

Failure Analysis on 0Cr17Ni4Cu4Nb Screw

某故障螺钉所用材料为0Cr17Ni4Cu4Nb沉淀硬化型不锈钢。通过断口宏微观观察、金相检验、硬度检测和能谱分析等实验,确定螺钉的断裂性质及断裂原因。结果表明:螺钉的失效性质为疲劳断裂;故障螺钉与疲劳实验螺钉疲劳源区附近均为准解理与沿晶特征,故障螺钉的沿晶特征较明显,应与该材料特性有关,尤其是螺纹根部在预紧力、拉应力、弯曲应力等复杂的综合应力状态下,螺钉产生沿晶特征。

A precipitation-hardening stainless steel 0Crl7Ni4Cu4Nb screw was fractured. The feature and cause of the screw were analyzed by micro and macro observation on fracture surfaces, metallo- graphic examination, hardness testing and energy spectrum analysis. The results show that the fracture mode of the screw is fatigue failure. Failure and fatigue testing screw have the same feature of quasi-cleavage and intergranular in source zone, and the intergranular feature is more obvious in fail- ure screw. The main cause of the intergranular feature should be relevant to the material properties and the complex stresses such as pretighening force, tensile stress, bending stress of screw thread roots.