Application of electron beam welding technique for joining coarse-grained and ultrafine-grained plates from Al-Mg-Si alloy

In the present work, the attempt to weld coarse (CG) and ultrafine-grained (UFG) Al-Mg-Si alloy using an electron beam welding technique has been taken. Welding parameters were selected in a way to reduce the energy input, and thus the heat-affected zone (HAZ) and the evaporation of elements with high saturated vapor pressure. The UFG microstructure was beneficial in obtaining smaller grains in the fusion zone (FZ) and HAZ, resulting in higher mechanical strength than weldments from CG Al-Mg-Si alloy. The weld efficiency for CG alloy was 80 %, while for the UFG sample - 68 % (82 %, compared to CG base material). The reasons for a drop in mechanical properties in the FZ were a dissolution of strengthening precipitates and an increase in grain size. Also, the evaporation of Mg (alloying element) and Zn (impurity) occurred to a larger extent. The rupture in both welds occurred in the columnar dendritic area in the FZ, characterized by the elongated dendrites and cube texture that favoured the rupture.

Automated summary

In this study, an attempt was made to weld course and ultrafine-grained Al-Mg-Si alloy using electron beam welding. The welding parameters were selected to reduce energy input and minimize the evaporation of elements with high vapor pressure. The ultrafine-grained microstructure resulted in smaller grains in the fusion zone and heat-affected zone, leading to higher mechanical strength. The weld efficiency was 80% for coarse alloy and 68% for ultrafine-grained sample compared to the coarse-grained base material. The rupture in both welds occurred in the columnar dendritic area characterized by elongated dendrites and cube texture.