中国低活化马氏体钢TIG焊焊缝耐液态Pb-Bi腐蚀性能分析

Analysis on corrosion resistance of China low activation martensitic steel TIG welding seam in flowing Pb-Bi melt

文中研究了中国低活化马氏体(china low activation martensitic,CLAM)钢对接双层TIG焊焊缝在高速流液态Pb-Bi中的腐蚀行为.结果表明,腐蚀的主要特征是元素扩散迁移和表面形成双氧化层结构.焊后热处理改善了CLAM钢焊缝耐液态Pb-Bi腐蚀性能.研究发现试样经760℃保温0.5 h的回火热处理后,耐腐蚀性能最好.均匀细小的马氏体组织有效地提高了焊缝的耐蚀性能,马氏体组织的尺寸大小是焊缝耐蚀性能的决定性因素.试样焊缝区最先损坏,表现为内氧化层中出现裂纹导致氧化层脱落.因此,提高反应堆结构材料焊缝处的耐腐蚀性能可以有效延长结构材料的使用寿命.

In this paper,China low activation martensitic( CLAM) steel was welded by tungsten inert gas welding,and the corrosion properties of the welding seam in flowing liquid PbBi was investigated. The result indicated that the main characteristic of corrosion was element diffusion and migration,a double layer of oxide was formed on the surface of all samples. The post weld heat treatment significantly improved the corrosion resistance of welded joints,and the tempering of 760 ℃/30 min presented the best performance. The homogeneous fine martensite structure effectively improved the corrosion resistance of the welded joint,and the decisive factor of the corrosion resistance was the martensite size. The failure occured in the welded area,especially the welding seam firstly. The main mechanism was the cracks growing and propagation in the inner layer,which induced the oxide layer breaking away from the matrix. Therefore,improving the corrosion resistance of the welding seam can effectively extend the service life of the materials.