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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%Fe Cl3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。
The corrosion behavior of five kinds of foundry duplex stainless steel in 6% FeCl3 solution was investigated by chemical immersion corrosion test, microstructure and chemical composition analysis, and compared with 316L austenitic stainless steel. The results show that the corrosion resistance of cast duplex stainless steel is better than that of 316L, and the corrosion rate and the depth of pitting corrosion are both less than that of 316L austenitic stainless steel. The main pitting corrosion resistance of duplex stainless steel is that austenite and ferrite The distribution of chromium and molybdenum is more in the ferrite phase, while nickel and nitrogen are more distributed in the austenite phase. The pitting resistance index of the ferrite phase PRE (Cr% + 3.3Mo% + 16N%) is larger than the austenite phase. The ductile corrosion resistance of duplex stainless steel is related to the chemical composition. With the increase of PRE, the ductile corrosion resistance of duplex stainless steel increases, and the precipitation of copper in ferrite The copper-rich phase causes pitting to occur preferentially in ferrite.