镀层金属对钒合金与不锈钢电子束焊接头组织与性能的影响

Effect of Electroplated Coatings on Microstructure and Mechanical Properties of Electron Beam Welding Joint of Vanadium Alloy to Stainless-steel

摘要:

采用高真空电子束阻隔熔化连接异种金属V-5Cr-5Ti钒合金和HR-2不锈钢，通过焊缝成型、微观组织和接头性能的对比分析，研究不同镀层金属（Au、Ag、Cr和Ni）的影响。结果表明：通过电子束流的偏移均可实现V-5Cr-5Ti/Au(Ag、Cr、Ni)/HR-2异种金属的连接，接头平滑过渡，焊缝正反面成型良好；V-5Cr-5Ti与熔化区的界面较为平直，在靠近钒合金一侧形成一个明显的镀层金属富集带；熔化区内部晶粒细小均匀，在靠近HR-2处形成取向明显的树枝晶。Au和Ag起到了很好的阻隔作用，V-5Cr-5Ti/HR-2接头的抗拉强度明显增加，达到400 MPa，X射线探伤未发现裂纹和气孔缺陷；镀层金属为Cr、Ni时，接头抗拉强度低于100 MPa

Abstract:

The high vacuum electron beam isolation welding (EBIW) was used to join vanadium alloy (V-5Cr-5Ti) to stainless-steel (HR-2) with different electroplated metal coatings. To investigate the effects of electroplated coating (Au, Ag, Cr and Ni) on the weldability, the weld appearance, the microstructure and the mechanical properties of the joints have been analyzed. The results show that the metallurgically bonded joints of V-5Cr-5Ti/Au(Ag, Cr, Ni)/HR-2 are achieved with EB off-set. The welds surface configuration are good and root reinforcement are full and smooth. The integration interface of V-5Cr-5Ti and fusion zone (FZ) is relatively flat, where an electroplated metal enrichment zone is found near V alloy side. The FZ consists of considerably smaller equiaxed dendritic structure in the center and columnar dendritic grained at the fusion line between FZ and HR-2. Au and Ag exhibit good isolation layer which helps increasing the weld quality. The maximal tensile strength of V-5Cr-5Ti/Au(Ag)/HR-2 of EBIW joint is over 400 MPa. There is no crack and detected porosity in the joints through X-ray inspection. In contrast, the tensile strength of V-5Cr-5Ti/Cr(Ni)/HR-2 of EBIW joints are lower than 100 MPa