含草酸的硝酸溶液对316L不锈钢的腐蚀行为

模拟金属材料在草酸钚沉淀母液蒸发浓缩工艺的服役条件，按GB/T 4334.3-2000要求，开展了含草酸的硝酸溶液对316L不锈钢板材和焊件的腐蚀行为研究。实验采用称重法获得了腐蚀速率数据，采用扫描电镜观察金属表面的腐蚀形貌，通过能谱分析腐蚀前后样品的表面元素分布，并测定了腐蚀溶液中金属离子的浓度。结果表明：模拟实验条件下316L不锈钢各腐蚀样品腐蚀速率较低，为均匀腐蚀。在103 ℃、8.0 mol/L硝酸条件下，316L不锈钢板材和焊缝的平均腐蚀速率分别为0.049 6 g/(m²·h)和0.068 6 g/(m²·h)。研究结果为草酸钚沉淀母液蒸发浓缩设备的材料选择提供了数据参考，优化焊缝工艺是316L不锈钢作为草酸母液蒸发浓缩设备材料使用重要的改进方向。

Corrosion Behavior of 316L Stainless Steel in Nitric Acid Solution Containing Oxalic Acid

In this work, the service environment of metal materials used in the evaporation and concentration process of the mother liquor after plutonium oxalate precipitation was simulated, and the corrosion behavior of 316L stainless steel plate and its welding samples in the mixed oxalic-nitric acid was studied according to the requirements of GB/T 4334.3-2000. The corrosion rates were obtained by weighting method, and the corrosion morphology of metal surface was observed by scanning electron microscope, and the distributions of surface elements before and after corrosion were analyzed by energy spectrum, and the concentrations of metal ions in the corrosion solutions were determined. The results show that the corrosion rates acquired by simulating corrosion tests are relatively low, and the corrosion is uniform. The average corrosion rates of 316L stainless steel plate in 8.0 mol/L nitric acid at 103 ℃ are 0.049 6 g/(m²·h) for plate and 0.068 6 g/(m²·h) for weld respectively. The research results provide data reference for the material selection of the equipment used in the evaporation and concentration process of the mother liquor after plutonium oxalate precipitation. The optimization of welding process is an important improvement direction for the use of 316L stainless steel as this equipment.