HDR超低碳双相不锈钢叉型接头开裂失效分析

Cracking Failure Analysis of HDR Ultra-Low Carbon Duplex Stainless Steel Forked Joint

HDR超低碳双相不锈钢叉型接头在线切割以及机加工的过程中开裂,导致叉型接头失效。通过对裂纹宏观形貌分析、冲击试验断口分析、基材化学成分分析、开裂部位力学性能检测、金相组织分析、断口微观形貌分析、微区能谱分析等项目的检测结果,综合分析引起HDR叉型接头开裂的原因。结果显示:HDR叉型接头开裂的原因为HDR材料在固溶热处理的过程,冷却速度不够,导致显微组织中晶界处析出大量σ相,σ相为脆性相,使HDR材料的塑韧性能急剧下降,随后在线切割及机加工的过程中开裂。

The HDR ultra-low carbon duplex stainless steel forked joint could crack and fail during wire cutting and machining.In this paper,the causes of the above-mentioned cracking were comprehensively analyzed by means of crack macroscopic morphology analysis,analysis on the fracture of impact test sample,chemical composition analysis of substrate,mechanical property testing of cracked area,metallographic structure analysis,fracture microscopic morphology analysis,micro-area energy spectrum analysis and other items.Results showed that the reason for the cracking of HDR forked joint was that the cooling speed of HDR material was too low in the process of solution heat treatment,so a large number of σ phases precipitated at the grain boundaries in the microstructure.The σ phases were brittle,which made the HDR material suffer a sharp decrease in plasticity and toughness,and then cracked in the process of wire cutting and machining.