不同氧含量高温水中低合金钢/不锈钢堆焊层的氧化膜特性

摘要

研究了在含氧和除氧高温水中合金钢(A508Ⅲ)/不锈钢堆焊层(309L/308I)表面氧化膜的特性.结果表明:在含氧高温水中A508Ⅲ钢表面腐蚀产物主要是γ-Fe2O3,在除氧高温水中其表面腐蚀产物主要为Fe3O4;除氧高温水中309L/308L堆焊层表面尖晶石型氧化物的颗粒比含氧高温水中的大且密集,降低高温水中氧含量有利于形成尖晶石型氧化物,且309L比308L表面氧化物颗粒更多且更大;在含氧高温水中或除氧高温水中浸泡后,309L表面均出现点蚀,而308L表面均未发现明显的点蚀,309L表面夹杂物在高温水中的优先溶解是形成点蚀的重要原因.%The characteristics of oxide films formed on low alloy steel/stainless steel weld in oxygen-containing and deaerated simulated pressurized primary water at 290 ℃ were investigated.The results showed that the main corrosion product formed on the surface of A508 Ⅲ low alloy steel in oxygen-containing high temperature water was γ-Fe2O3,while the surface film was mainly composed of Fe3O4 in deaerated high temperature water.The spinel oxide particles on 309L/308L cladding surface in deaerated high temperature water were larger and more extensive than those in oxygen-containing water.Reducing the oxygen content in high temperature water favored the formation of spinel oxide particles that were more extensive and larger on 309L surface than those on 308L surface.In oxygencontaining or deaerated water,pitting appeared on the surface of 309L,while the surface of 308L had no significant pitting.The preferential dissolution of inclusions of 309L in high temperature water was thought to be the main cause of pitting.