Analysis of Weld Joint of DX51D Steel with AlMg3 Alloy Made by CMT Welding Method

Abstract

The combination of steel and aluminum as a constructional material brings many benefits. Steel is characterized by strength and is suitable for components exposed to high stress. Aluminum is light and is suitable for less stressed parts. However, for technical and economic reasons, the arc welding of these materials has not been possible for a long time. The development of the technology that allows welding of steel with aluminum is linked to the requirements of the automotive industry. This is a process known as CMT -Cold Metal Transfer and refers to the low energy transition of the droplet during MIG/MAG welding. In this so-called "welding soldering", the base steel material is not melted, but merely wetted, whereas in the case of aluminum, a melt weld is formed. The advantage of this process is the lower heat input and consequently considerably less heat deformation. This paper deals with the analysis of the welded joint of the DX51D steel sheet with the Aluzinc layer and the AlMg3 alloy sheet made by CMT welding using the digitized inverter welding power from Fronius company. An AlSi5 welding wire of Ø 1.2 mm was chosen as an additive material. The used technology has led to the formation of a weld with a considerable porosity of the weld metal.