Influence of Processes and Process Variables for WAAM – Geometry of Deposited Bead

Abstract

Wire Arc Additive Manufacturing (WAAM) is developing rapidly in recent years due to its advantages, such as higher productivity, lower cost, acceptable quality, and the availability of advanced welding processes. Cold Metal Transfer (CMT), as the most well-known Gas Metal Arc Welding (GMAW) process, is widely used in WAAM. The uniqueness of CMT lies in minimizing the heat input of the process. However, there is a drawback to the lower heat input, impacting the quality of the geometry of the welding bead, sharp transitions at the weld toe, inclusions, etc., particularly for higher alloyed steel, e.g., tool steel. In this study, two processes were employed: CMT and Pulse Multi Control (PMC). Two types of shielding gases were used, namely 2% CO2 + 98% Ar and 20% CO2 + 80% Ar. Two levels of wire feed speed were selected: high and low levels. A full-fraction factorial experimental matrix was created, and bead-on-plate samples were produced with different GMAW processes, i.e., CMT and PMC. The geometry of the bead-on-plate, including penetration, bead width and height, and toe angle, was evaluated and analyzed. A correlation between the process factors (shielding gas, type of process, and wire feed speed) and the geometry of the bead was analyzed and determined. A protocol is proposed based on the study results for the selection of WAAM processes.