316L钢表面CrWMn铁基熔敷层在液态PbBi中耐腐蚀性分析

Analysis on corrosion resistance of CrWMn iron-based coatings on the surface of 316L steel in liquid lead bismuth eutectic

采用TIG焊在316L钢表面熔敷CrWMn铁基合金,研究了熔敷层在550℃动态(相对流速为1.70,2.31和2.98m/s)液态PbBi中的耐腐蚀性能。结果表明,受腐蚀试样表面均存在元素溶解现象,并生成了双氧化层,外层为疏松多孔的Fe3O4,内层为致密的FeCr_2O_4。相对流速超过2.31m/s时,加快Fe、O的扩散,内层已出现新相(Fe_(0.6)Cr_(0.4))_2O_3。短期内,流速越快,外层受腐蚀越严重,其厚度越薄;而内层厚度变化很小。尤其致密的内层很好地保护了熔敷层基体,从而保护316L钢表面,阻止了Ni等元素的溶解。

CrWMn iron-based alloy was clad on the surface of 316L by TIG and the corrosion resistance of coatings in dynamic（relative flowing velocity, 1.70, 2.31, 2.98 m/s） liquid lead bismuth eutectic at 550 ℃ was studied in this paper. The results show that dissolution of steel composition is observed and. a double layer oxide film is formed on the surface of coatings. The phase of outer layer is loose and porous Fe3 04, while the phase of inner layer is dense FeCr2O4. When the relative flowing velocity is over 2.31 m/s, diffusion of Fe, O elements is accelerated and new phase （Fe0.6 Cr0.4）2 03 has been created. In the short term, the faster the flowing velocity is, the more severely the outer layer is corroded, the thinner its thickness is, but the thickness of inner layer is almost unchanged. Especially the dense inner layer protects coatings well, also guards the surface of 316L and prevents the elementary dissolution of Ni, etc.