MICROSTRUCTURAL CHARACTERIZATION OF EB-WELDED AM-SLM AlSi10Mg ALLOY

Aluminum alloys parts fabricated by a AM-SLM approach are widely used across many industrial sectors. The fine microstructure and improved mechanical properties of printed material are the end-result of pre-alloyed powder melting/solidification. Nevertheless, there are some difficulties in fabricating large AM-SLM aluminum modules and an attractive way to solve this problem is to fabricate the composite modules by joining AM-SLM components using a EBW technique. Generally, weld zones consist of a fusion zone, a partially melted zone and a heat affected zone. It was established that EB welded AM-SLM joints are characterized by a narrow heat affected zone (significantly narrower than those in arc welding-processes, such as GTAW) and fine-grained weld zone microstructure. These features result from a low heat input and high cooling rates of joint regions. The fusion zone consists primarily of fine columnar dendrites originating from the fusion line and equiaxed grains existing in the center of the fusion zone. The presence of porous and a grain growth in fusion zone are also detected. The effect of microstructural features on the welded region will be discussed.