燃料元件包壳材料CN-1515不锈钢在可控氧铅铋环境下的腐蚀行为

国产CN-1515不锈钢因其良好的抗辐照肿胀能力和高温力学性能成为铅铋快堆燃料包壳的主要候选材料。在铅铋冷快堆中，由于液态铅铋合金对金属材料具有强烈的腐蚀性，会影响到反应堆的安全稳定运行，因此，铅铋冷快堆中结构材料应用还需充分考虑耐液态铅铋腐蚀性能。本文以国产CN-1515奥氏体不锈钢为研究对象，在自行研发的控氧静态铅铋腐蚀实验装置上，开展了高温铅铋腐蚀实验。实验温度分别为450、500、550、600 ℃，实验时间分别为1 000、3 000、6 000 h，液态铅铋合金中氧含量控制在10^-6%～10^-7%之间。实验结果表明，低温（T≤450 ℃）下，CN-1515不锈钢表面会生成一层保护性氧化膜，但随着腐蚀时间的增加，氧化膜会逐渐疏松而失去其保护作用；然而温度大于500 ℃时，不锈钢发生严重的Ni元素溶解腐蚀，腐蚀深度随温度的升高和时间的延长而增加。

Corrosion Behavior of Fuel Cladding Material CN-1515 Stainless Steel in Lead-bismuth Eutectic Alloy with Oxygen Control

Domestically-developed CN-1515 stainless steel is one of the candidates for fuel cladding in lead-bismuth-cooled fast reactor due to its favorable irradiation swelling resistance and mechanical properties at evaluated temperature. Because of its severe corrosive effect to metals, compatibility of materials in lead-bismuth eutectic (LBE) alloy should be noticed during reactor development to ensure reactor safety. In this article CN-1515 Austenitic stainless steel was tested at homemade lead-bismuth corrosion experiment device with controlled oxygen concentration between 10^-6% and 10^-7% at 450, 500, 550, 600 ℃ for up to 6 000 h. As a result, protective oxide layer was initially formed at samples tested at lower temperature (≤450 ℃) which loses its protection after extended corrosion period. At higher temperature (≥500 ℃), no oxide layer is formed even with increased oxygen content. Severe nickle dissolution is observed, and dissolution layer depth is positively correlated with experiment temperature and duration.