Evaluation of thermal and geometric properties of martensitic stainless steel thin walls built by additive manufacturing cold metal transfer (CMT) processes

Additive manufacturing is often seen as a novel alternative compared to well-consolidated, subtractive, and formative manufacturing processes. Its presence in the industrial environment is rapidly increasing, and its performance and flexibility may be the answer for present-day fabrication challenges, combining solutions to minimize environmental impacts without losing competitiveness or product quality. Arc welding-based additive manufacturing (also known as wire arc additive manufacturing, WAAM) has been gaining prominence in the current Industry 4.0 scenario. For the advancement of this technology, multiple output analysis of the pertinent welding processes is essential, especially regarding studies applied to materials such as high-strength and high-cost steels. In this paper, a study was conducted with the AISI 420 alloy and CMT variants of the GMAW process applied to additive manufacturing of thin walls, comparing them with conventional GMAW process. The welding processes and deposited welds used were analyzed on electrical, thermal, morphological, and metallurgical aspects. In the end, CMT Advanced and CMT Pulse variants stood out as opposite extremes, whereby CMT Advanced presented the best performance in relation to wall height and heat input. CMT and conventional GMAW produced good and significantly similar results, highlighting the stability of CMT.