Electron Probe Micro Analyzer (EPMA) was used to study the grain boundary sensitization behaviour of high-nickel austenitic stainless steel 904L. After sensitization for different ageing times at 650 ℃, 904L was corroded in 1 M HCl for 7 days. There was an obvious 3 μm-wide corrosion-sensitized zone around the grain boundary. The EPMA results showed no significant segregation of elements around the grain boundaries. Transmission electron microscopy (TEM) results showed that the σ phase was detected along the grain boundary. The σ phase caused discontinuity in the passivation film near the grain boundary and the grain boundary sensitization of 904L.

中文翻译：

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敏化904L奥氏体不锈钢在Cl溶液中的腐蚀行为研究

电子探针显微分析仪（EPMA）用于研究高镍奥氏体不锈钢904L的晶界敏化行为。在650℃下经过不同的老化时间敏化后，904L在1 M HCl中腐蚀了7天。在晶界周围有一个明显的3μm宽的腐蚀敏感区。EPMA结果表明，晶界周围没有明显的元素偏析。透射电子显微镜（TEM）结果表明，沿晶界检测到σ相。σ相引起钝化膜在晶界附近的不连续和904L的晶界敏化。