Research On The Electron Beam Weldability And The Mechanical Properties Of The Joint For TiB₂ Reinforced Aluminum Composite

In situ TiB2/ZL101 composite prepared by mixed salts reaction is a kind of new structure-functional material with many advantages such as light weight, high specific strength and specific stiffness, small thermal expansion coefficient, high wear resistance, corrosion resistance and size stability etc.. Currently, metal matrix particle reinforced composite has great porosity, segregation and interface reaction tendency which seriously affect the performance of weld joints. In order to solve these problems and speed up the practical application of TiB2/ZL101, it is necessary to research the appropriate welding method. A kind of new scanning electron beam (EB) welding method was employed in this paper to research on the adaptability of welding process, melting pool behavior for second phase, the influence of process parameters on weld appearance, the relationship between microstructure and mechanical properties for weld seam. The research on EB welding of TiB2/ZL101 composite has important theoretical significance and could improve engineering application.The welding experiment results suggested that EB welding has a greater flexibility to TiB2/ZL101 composite, under the optimized process parameters the defect-free weld joint can be obtained which had high aspect ratio, fine grain and homogeneously distributed reinforcement.Due to the EB stirring effect and reaction force of metal vapor, the TiB2 reinforcement was crushed in the weld pool which presented as large cluster prior to welding. The grains were also be refined, it can be regarded into three reasons: the homogeneously distributed reinforcement TiB2, the crushing effect of stirring EB and fast solidification speed. Then the nucleation ratio increased greatly which lead to fine grains.Numerical simulation was employed in this paper. Comparing with ZL101, the calculated temperature field showed that weld pool of TiB2/ZL101 has higher peak temperature and temperature gradient, it meant that the typical"nail"weld seams can be obtained for TiB2/ZL101 by EB welding; at the same time, the viscosity increased for the composite because of TiB2, weld pool liquidity became difficult which would lead to porosity sensitivity. The porosity could be decreased by certain frequency EB scanning waveform.Finally, some mechanical tests were conducted, the fine defect-free weld seam of TiB2/ZL101 obtained by EB welding under proper processing parameters had higher tensile strength, wear resistance and hardness than base metal. The weld joint met the application requirements, and the research results provided technical support for practical application.