奥氏体不锈钢三通裂纹分析

对与脱甲烷塔相连的奥氏体不锈钢管道三通上发现的裂纹性质与成因进行了试验分析。指出管件破裂基本上属氢脆引起的穿晶型解理开裂，即阴极型应力腐蚀破坏。三通冷加工成形后未经高温固溶处理，致使18—8型亚稳定钢中30％以上的奥氏体组织转变成马氏体组织；介质为未经脱硫的甲烷，含较多H2S；较高的加工残余应力、组织应力和应力集中；材料存在缺陷，是导致上述问题的主要原因。改进三通加工成形工艺，及时进行固溶处理，提高奥氏体不锈钢的稳定性，是避免裂纹的关键技术手段。此外，尚需严控介质中Cl^-离子和H2S含量，降低残余应力水平。

Cracking Analysis of Austnite Stainless Steel Tee Joint

Character and cause of the cracking accident of austnite stainless steel pipe tee joint connected with demethanizing column was studied. The results showed that the rupture is transcrystalline cleavage cracking by hydrogen embrittlement basically, i.e. cathodic stress corrosion cracking. It is caused by following factors mainly ： solution heat treatment at high temperature was not performed after forming, so that above 30% austnite structure of 18 -8 type metastable austnite stainless steel were transformed into martensite structure. There was more hydrogen sulfide in mathane medium; larger forming stress and phase transformed stress and stress concentration. Prevention measures include improve forming technology, carry out solution heat treatment in time , raise stability of austnite stainless steel , control strictly Cl^- and H2S content in medium; reduce residual stress .