S30403不锈钢管道焊接接头点蚀原因分析  

Analysis on pitting corrosion of welded joint at S30403 stainless steel pipeline

作　　者：陈勋 彭泽军 雷宇 吕锋杰 CHEN Xun;PENG Zejun;LEI Yu;LYU Fengjie(Wuhan Boiler Pressure Vessel Inspection Institute,Wuhan 430024,China;Wuhan University of Science and Technology,Wuhan 430081,China)

机构地区：[1]武汉市锅炉压力容器检验研究所,湖北武汉430024 [2]武汉科技大学,湖北武汉430081

出　　处：《石油化工腐蚀与防护》2024年第6期50-54,共5页Corrosion & Protection In Petrochemical Industry

基　　金：湖北省重点研发计划项目(2023BAB059)。

摘　　要：通过宏观形貌分析、化学成分分析、显微组织分析、能谱分析和δ铁素体含量检测等方法,分析了S30403不锈钢管道焊接接头发生点蚀的原因。结果表明:焊接接头中的热影响区受奥氏体晶粒增大和残余应力的影响,使其表面Cr_(2)O_(3)钝化膜的保护作用减弱,导致点蚀发生;焊缝中δ铁素体质量分数约为13%,δ铁素体组织中Cr质量分数为24.58%,Ni质量分数为5.06%,而焊缝中奥氏体组织中Cr质量分数为17.98%,Ni质量分数为9.56%,两种组织化学成分相差较大,在含硫的腐蚀性介质中,焊缝发生了电偶腐蚀,使焊缝组织中的δ铁素体优先腐蚀。The causes of pitting corrosion in welded joints of S30403 stainless steel pipeline were analyzed through methods such as macroscopic morphology observation,chemical composition analysis,microstructure examination,energy spectrum evaluation,and δ-ferrite content detection.The results indicated that the heat affected zone in the welded joint was affected by the increase of austenite grains and residual stress,which weakened the protective effect of Cr_(2)O_(3) passivation film on its surface and led to pitting corrosion.The mass fraction of δ-ferrite in the weld was about 13%,and the mass fractions of Cr and Ni in the δ-ferrite structure were 24.58% and 5.06%,respectively.However,the mass fractions of Cr and Ni in the austenitic structure of the weld were 17.98% and 9.56%,respectively.The chemical compositions of the two structures were significantly different.Galvanic corrosion led to preferential corrosion of δ-ferrite in corrosive medium containing sulfur.

关 键 词：S30403不锈钢 焊接接头 点蚀 Δ铁素体 优先腐蚀 

分 类 号：TG407[金属学及工艺—焊接] TG172