Effect of electromagnetic arc constriction applied in GTAW-based wire arc additive manufacturing on walls' geometry and microstructure

Abstract

New technologies for the additive manufacturing process applied to metallic materials have created a great outlook for complex geometries, cycle time and waste reduction. However, advances in efficiency and productivity are still needed for this process to be consolidated as a reliable manufacturing process. Wire arc additive manufacturing (WAAM) uses metallic materials to deposit a series of layers through melting and solidification, and that have proved to be an attractive process for the manufacturing of medium to large size components due its high deposition rate and potentially unlimited building size. Among the available heat sources is the GTAW (Gas tungsten arc welding) process with feed wire, where the heat source comes from an electric arc. The electric arc cross section is bell shaped and forms a round shape when it touches the weld pool. This study presents a device to electromagnetically constrict the electric arc in the GTAW process, capable of changing the cross section from round to elliptical (elongated), and the result of its application in additive manufacturing. The results show that the application of this arc constriction in wire arc additive manufacturing increases the height of the deposited walls by 10%, produces more regular geometry walls, in addition to increasing the process efficiency and promoting a microstructural grain refining effect. The results were statistically supported by the t-student test with 95% reliability, enabling the applicability of this device to increase the height of the deposited walls.