409L和430铁素体不锈钢耐局部腐蚀性能

采用电化学测试技术与化学浸泡实验相结合,对比研究了409L和430铁素体不锈钢热轧板材耐点蚀和耐晶间腐蚀的能力.结果表明:409L不锈钢的击穿电位与保护电位的差小、钝化膜的修复能力较强,表现为小尺度的浅点蚀孔;430不锈钢的击穿电位较高,耐点蚀能力高于409L不锈钢,但430不锈钢热轧态的条带组织有明显的腐蚀微电池效应,表现为比较严重的全面腐蚀;409L不锈钢含Cr量低,且其热轧态未经过稳定化处理,使得409L不锈钢耐晶间腐蚀能力劣于430不锈钢.经微观分析:409L不锈钢为沿着基体等轴晶界的典型晶间腐蚀形貌特征,而430不锈钢在轧向碳化物(M₂₃C₆)与基体的相界面上呈现分层腐蚀痕迹.

Localized corrosion resistance of 409 L and 430 ferritic stainless steels

The pitting corrosion and intergranular corrosion resistance performances of 409 L and 430 hot-rolling plates were contrastively investigated by using electrochemical measurements and chemical immersion tests.The results show that the difference between breakdown potential and protection potential of 409 L stainless steel is little,and the restorability of the passive film is strong with small-scale shallow pits.The pitting corrosion resistance of 430 stainless steel is better than that of 409 L stainless steel because of a higher breakdown potential,but its banding microstructure has the apparent effect of a corrosion microcell,represented with a more serious general corrosion.The intergranular corrosion resistance of 409 L stainless steel performs worse than that of the 430 stainless steel because of the low content of Cr and the lack of stabilizing processes under the hot-rolled condition.Through microstructure analysis,409 L stainless steel presents a classic intergranular corrosion appearance along equiaxial grain boundaries,while 430 stainless steel exhibits a delamination corrosion trace at the phase interface between carbides(M₂₃C₆) and the matrix.