Impact of the beam shape and process parameters on bead geometry in WLAM

Wire laser additive manufacturing (WLAM) is an emerging process to build rapidly metal parts of low complexity. In this paper, single beads of low alloy carbon steel, ER120, were welded with a filler on a S355J2 substrate to reproduce the conditions met in WLAM. The impact of the process parameters (power, wire feedrate, travel speed, spot size) on the stability and geometry of the beads were investigated. A configuration with a dual spot was also studied and found to give analogous results to a single, larger spot of the same area. For each bead dimension (height, width, area, depth) a power law relationship with the process parameters is fitted. Descriptors based on volume energy density and enthalpy were proposed to describe the transition from a conduction mode welding to a keyhole stage, which can lead to the creation of pores in the part.