低温高锰钢的局部腐蚀行为研究

采用间浸腐蚀试验、极化曲线测试、扫描观察(SEM)和透射电镜观察(TEM)等方法研究了在3.5%NaCl溶液中添加氧化剂以及敏化处理对低温高锰钢局部腐蚀性能的影响。结果表明:经间浸腐蚀试验后,各试样均主要发生全面非均匀腐蚀,局部可见点腐蚀特征。试样在3.5%NaCl溶液中腐蚀产生的锈层疏松,在3.5%NaCl+0.25%Na₂S₂O₈溶液中腐蚀,试验初期自腐蚀电流密度提高两个数量级,在较短时间内产生致密的锈层,阻止了试验后期腐蚀向内层的快速扩展,试样平均腐蚀速率降低,点腐蚀深度减小。800 ℃×5 h敏化处理后,高锰钢的组织结构没有发生改变,晶界析出了断续分布的碳化物,其抗腐蚀性能与原始态相当,极化曲线印证了这一结果。

Research on Local Corrosion Behavior of High Manganese Austenitic Steel

The effects of adding oxidant to 3.5%NaCl solution and sensitization treatment on the local corrosion properties of high manganese steel are studied by using alternate immersion corrosion test, polarization curve test, scanning observation (SEM) and transmission electron microscope observation (TEM). The results show that after the alternate immersion corrosion test, all the samples show the morphologies of overall non-uniform corrosion and local pitting corrosion. The rust layer on the surface of the sample is loose after corrosion in 3.5% NaCl solution. The self-corrosion current density increases by two orders of magnitude in initial stage in 3.5%NaCl+0.25%Na₂S₂O₈ solution, which produces dense rust layer in a short time and prevents corrosion from spreading to the inner layer. The average corrosion rate and the depth of pitting corrosion are reduced. The microstructure of high manganese steel has not changed, carbides precipitated discontinues at the grain boundary after sensitization treatment at 800 ℃ for 5 hours, but the corrosion resistance of the sensitized state is equivalent to that of the original state. The polarization curve confirms the experimental results.