电子束钎焊接头组织分析

采用自主开发的电子束钎焊系统,对不锈钢毛细管板结构进行钎焊,通过电子探针显微分析仪研究了不同电子束钎焊规范下BNi-2钎料与管壁基体界面合金元素的分布,分析了钎料和界面区各相的化学组成.研究表明:在加速电压60kV,束流6.5 mA,加热时间37 s,扫描幅值O.5的电子束钎焊规范下,管板接头质量满足技术规范要求;随着电子束输入功率或功率密度增大,钎料和管壁的相互扩散作用增强,导致过渡层厚度增加,毛细管壁显著减薄;母材和钎料中合金元素的相互扩散导致过渡层的形成,过渡层主要由硼化铬、硼化镍和镍的固溶体组成.

Analysis of the microstructure of the electron beam brazed joint

The electron beam brazing system designed by our lab is used for the brazing of the capillary tubeto-sheet structure of stainless steel. The diffusion of alloy elements and the chemical composition of phases at the filler metal-base metal interface and alloy zones with different welding conditions are investigated using an electron probe microanalyser. The experimental results indicate that tube-to-sheet joints meet the technical standards when welding variables of accelerating voltage 60 kV, beam current 6. 5 mA, heating time 37 s and scanning amplitude 0. 5 are adopted. With the beam power or power density increasing, the interdiffusion effect of filler metal and tube wall is enhanced, which obviously causes the transition layer to thicken thicker and the tube wall to thin thinner obviously. The alloy elements interdiffusion of the base metal and the filler metal result in the formation of a transitional layer that consists of chromium boride, nickel boride and solid solution.