Effects of Ni element on the microstructure of hard alloy to steel joints after electron beam welding

摘要

In this paper, electron beam welding of hard alloy to steel was carried out with different parameters, and the microstructure and compounds of the joint were analysed. The direct electron beam weldability of hard alloy to steel was poor, with macroscopic cracks easily occurring at the hard alloy side. The microstructure of the weld was mainly a solid solution of Fe, while intermetallics and brittle (η)phase formed at the fusion line near the hard alloy. However, non-cracked joints could be obtained using appropriate parameters by means of a Ni interlayer. The microstructure of this weld was a solid solution of Fe and Ni which were dispersively distributed in the weld accompanied by less brittle compounds. The tensile strength of the joint reached 158 MPa, and fracture occurred at the fusion line of the hard alloy side. The hardness of the joint was significantly decreased.