摘要:
采用化学浸泡腐蚀试验及微观组织和化学成分分析研究了5种铸造双相不锈钢在6%FeCl3溶液中的点腐蚀行为, 并与316L奥氏体不锈钢进行了对比。结果表明, 铸造双相不锈钢的抗点腐蚀性能均优于316L的, 腐蚀速率和点腐蚀深度均小于316L奥氏体不锈钢的;双相不锈钢主要耐点蚀能力合金元素在奥氏体和铁素体相内分布不均匀, 铬、钼更多地分配于铁素体相内, 而镍、氮则更多地分配于奥氏体相内, 铁素体相的耐点蚀指数PRE (Cr%+3.3Mo%+16N%) 大于奥氏体相;双相不锈钢的耐点腐蚀性能与化学成分有关, 随着PRE的增加, 双相不锈钢的耐点腐蚀性能提高, 铜元素在铁素体内析出的富铜相导致点蚀优先在铁素体内发生和发展。
Abstract:
Pitting corrosion behaviors of 5 kinds of cast duplex stainless steels in 6% FeCl3 solution were investigated by using chemical immersion corrosion test and microstructure and chemical composition analyses, and then were compared with that of 316 L austenite stainless steel. The results indicated that all the 5 kinds of cast duplex stainless steels exhibited better pitting corrosion resistance than 316 L austenite stainless steel. Compared with that of 316 L austenite stainless steel, both corrosion rates and pitting corrosion depth of cast duplex stainless steels were lower. Main pitting corrosion resistant alloying elements were non-homogeneously distributed in austenite phase and ferrite phase, with Cr and Mo more likely in ferrite phase and Ni and N in austenite phase, and the pitting resistance equivalent (PRE=Cr% + 3. 3Mo% + 16N%) of ferrite phase was higher than that of austenite phase. The pitting resistant properties of duplex stainless steels depended on their chemical compositions and increased with the increasing of PRE value. However, copper-rich phase precipitated from ferrite phase would lead pitting corrosion to preferentially occur and develop in ferrite phase, deteriorating the pitting corrosion resistance of the duplex stainless steel.
下载:
