CEMS、AES和XPS研究361钢中Mo在抗高温高压水应力腐蚀中的作用

用内转换电子穆斯堡尔谱(CEMS)、俄歇电子能谱(AES)和X-光电子能谱(XPS)研究比较了316和321两种奥氏体不锈钢在含Cl~-2000ppm,含O_28～9ppm高温水中应力腐蚀开裂前后的氧化膜结构及其元素分布,发现合金氧化膜层组成和结构与其抗应力腐蚀性间有一定的对应关系。合金元素Mo在一定条件下与介质作用形成Fe_2(MoO_4)_3相。Mo能控制铁的氧化物相,降低Cr的过钝化溶解速率以及抑制Cl-向膜穿透,起着延长应力腐蚀孕育期的作用。所得结果为阐明含Mo的316钢较不含Mo的321钢有较高的抗应力腐蚀性、以及两者有不同的SCC断口形貌提洪论据。文中还根据合金热力学的作用进一步作了讨论。

A STUDY OF THE ROLE OF MOLYBDENUM IN 316 STAINLESS STEEL ON SCC RASISTANCE IN HIGH TEMPERATURE AND HIGH PRESSURE WATER WITH THE AID OF CEMS,AES & XPS

The structure and chemical composition of the oxide film on 316 and 321 stainless steels corroded in high temperature and high pressure water, containing 2000 ppm Cl~- and 8 ppm dissolved oxygen, was studied by conversion electron Mossbauer spectroscopy(CEMS), AES and XPS before and after SCC. A correlation between the structure arid chemical composition of the oxide film and SCC resistance was established. Experimental results show that the alloying element Mo reacted with corrosive medium to form Fe_2(MoO_4)_3 phase. Mo in 316 alloy affected the composition and growth rate of iron oxides, decreased the dissolution rate of Cr at transpassive region and inhibited Cl~- in its penetration through the oxide film, playing therefore a role to prolong the incubation period of SCC. Results obtained showed that Mo-bearing 316 alloy has better SCC resistance than 321 alloy with different SCC fractographs. The role of Mo on SCC resistance was also discussed based oa alloy thermody namics.