Numerical simulation of electrical-thermal coupling field of electric field assisted welding process

Objective Electric field (pulse current) assisted welding, briefly SPS welding, is a multi-physical field coupling joining process that combines resistance heating, plasma activation, electric field assisted diffusion and hot pressure. It has promising wide applications owing to advantages of short time, low temperature, low deformation and good quality. The aim is to study influence of various factors such as conductivity of welding materials, high temperature performance, contact interface resistance, mold shape and loading sequence on welding heat production and current distribution. Methods In this paper, thermal/electrical coupled numerical model is established and finite element algorithm is presented based on MSC.MARC software. Temperature distribution, electric field of welding system, and thermal cycle of weldment are quantitatively and dynamically analyzed. Mechanisms of SPS welding process are elucidated. The numerical prediction results are compared with SPS welding process curve of 5A06 aluminum alloy, and validity and calculation precision of the model are verified. Furthermore, effect of electrical conductivity of material and welding assembly on electric field and temperature field of welding system are studied. Results The results show that current flows preferentially through conductive channels, and the greater contact resistance at the interface of weldment results in the smaller current flowing through it. There is a coupling effect between electric field and temperature field, and changes in the main heat generating location cause changes of temperature non-uniformity between weldment and mold. When electrical conductivity of welding materials varies greatly, electric field and temperature field no longer exhibit a symmetrical distribution relative to welding interface. Conclusion For SPS welding, assembly methods of weldment should be selected from two perspectives of electric field and temperature field. When the overall current density of the system is larger, temperature of welding interface is higher, and temperature of high melting point material is higher than that of low melting point material at the same time, which is preferred to recommend assembly method of weldment.