连接短节法兰开裂的失效分析

Failure Analysis of a Flange on Gasfier's Binding Site

通过断口、能谱、化学成分及ANSYS应力分析等,对某气化炉连接短节法兰进行了失效分析。分析结果表明:焊缝处组织恶化,晶粒粗大,在湿的H_2S环境下发生沿晶应力腐蚀,形成初始裂纹源。而超温导致较大的温差应力,引起焊缝处及螺钉连接处支撑板与法兰变形不协调,使失效部位应力急剧上升,是裂纹扩展的主要原因。

Based on the analysis of fracture, EDS, chemical composition and ANSYS stress simulation, etc, failure analysis of gasifier furnace joint flange was carried out. Results indicate that the structure of seam region deteriorates greatly where coarse grains are found. Under the circumstance of wet hydrogen sulfide, the SCC is easily caused along the grain boundaries and initial cracks are finally constituted. The main reason for cracking extension is the increasing stress in the failure component, when uncoordinated deformation in the seam region and the area between screw joint supporting plate and the flange is caused by the excessive thermal stress of the overheating operation.