核反应堆用不锈钢管道焊缝附近的锈蚀

Rusting in Weld Region of Stainless Steel Tubes for Nuclear Reactor

为了探明反应堆用００Ｃｒ１９Ｎｉｌ０不锈钢焊缝区域产生锈蚀的本质，对该钢种管道焊接热影响区及焊缝附近生成锈蚀的部位进行了金相组织检查和耐晶间腐蚀、耐点蚀性能的电化学测定，并对锈层的形貌和结构进行了扫描电镜和俄歇能谱分析。结果表明，焊缝附近的锈蚀层具有层状结构，最外层是锈层，其下是贫铬的氧化物层，再下是富铬的氧化物到基体金属的过渡层。贫铬层耐点蚀性明显下降，锈蚀从该层生成。近海大气中的Ｃｌ~_在焊缝附近表面的吸附和浓集是产生锈蚀的诱因。

The optical microscopic examination of microstructure,and electro chemical determination of intergranular corrosion susceptibility and pitting resis tance of stainless steel tubes in rusted weld region were conducted,and then the morphology and structure of the rust were analysed by SEM and Auger analysis in order to get a good insight into the nature of the rusting in weld region of 00Cr19Ni10 stainless steel tubes used in reactor.The obtained result is as follows:(1)The rust in weld region consists of three layers; the external is thick rust,the medial is a chromium depleted oxide layer,the internal is a transition layer from ox ide to metal,which is rich in chromium.The pitting resistance of the chromium de pleted oxide layer is poor so that the rust forms there readily.(3) Cl￣-in off-shore atmosphere absorbed and consentrated on the surface of the weld region resulted in the formation of rust.