Wire Arc Additive Manufacturing by Cold Metal Transferred (CMT) Arc Welding Process

Additive manufacturing (also known as 3D printing) is considered as a disruptive technology to produce limited number of high value components with topologically optimized complex geometries and functionalities that is not achievable by traditional manufacturing. Wire Arc Additive Manufacturing (WAAM) allows to produce metal components by depositing filler wire layer by layer with the help of welding arc. WAAM is a potential future process to manufacture complex parts without much of tooling required or with less material wastage. Cold Metal Transfer (CMT) arc welding technique offers high stable arc with less heat input and high welding speed which results in less distortion. The aim of this work is to optimize the critical welding parameters in CMT arc welding in order to achieve a stable arc to develop the component and to analyse the mechanical and micro structure properties fabricated using ER308L wire. In this experimental work, welding parameters in CMT process were optimized for the stainless steel component deposited using ER308L filler wire. From this investigation it was found that the weld speed, current, stick out and voltage were the most influencing parameters to achieve stable arc and for process feasibility. After the completion of fabrication, the component was tested non-destructively in order to confirm the soundness of the weld deposits and to ensure the component is free from porosity and lack of fusion between the layers. The component was sectioned and specimens were extracted from vertically at three sections (Top, middle and bottom). Mechanical properties were evaluated as per the ASTM standards. Microstructural analysis was done using optical microscopy and scanning electron microscopy. It is found that the mechanical properties and microstructural characteristics are uniform throughout the height of the component.