铬青铜与双相不锈钢电子束熔钎焊接头形成机制

Formation mechanism of electron beam melt-brazed joint of chromium-bronze and duplex phase stainless steel

采用光学金相、能谱分析及电子探针元素分析方法对QCr0.8／1Cr21Ni5Ti电子束熔钎焊接接头的组织结构进行了研究。研究结果表明,铬青铜与双相不锈钢电子束熔钎焊接头的焊缝组织为宏观均匀的Fe在Cu中的过饱和固溶体相,熔钎界面上部形成了与焊缝及钢侧母材连结良好的一薄的α+ε相熔合过渡层,下部为钎合面。给出了铜钢异种材料电子束熔钎接头形成的结构和热作用条件,并基于组织结构分析和电子束焊接的特点,建立了QCr0.8／1Cr21Ni5Ti电子束熔钎焊接接头形成的物理模型,探讨了其形成机制。分析认为,QCr0.8／1Cr21Ni5Ti电子束熔钎焊接头组织结构的形成是由匙孔形熔池形成阶段、熔合过渡层形成阶段、钎缝形成阶段及最终组织形成阶段组成。

The microstructure of electron beam (EB) melt-brazed joint of QCr0.8/1Cr21Ni5Ti was studied by means of optical microscopy, energy dispersive X-ray analysis and electron probe microanalysis. The results indicated that the microstructure of welding seam was macro-homogeneous supersaturated solid solution of iron in copper and thin transition layer consisting of α + Ε appeared in upper part of melt-brazed interface, which was joint to 1Cr21Ni5Ti soundly. The condition of structure and heat action to form electron beam melt-brazed joint was given. Based on microstructure and the characteristics of electron beam welding, the physical model that described formation process of EB melt-brazed joint of QCr0.8/lCr21Ni5Ti was proposed and formation mechanism of the joint was discussed. The analysis shows that the formation of EB melt-brazed joint is made up of four steps including formation of molten pool with keyhole, formation of fusion transition layer, formation of braze welding seam and formation of final microstructure.