GMAW-based twin wire arc additive manufacturing of NiTi shape memory alloy

Over the past decade, additive manufacturing has experienced substantial growth in popularity due to its near-net manufacturing capabilities, design flexibility, and accelerated production capabilities. The development of metal components with superior structural integrity, low material and equipment costs, and high deposition speeds is made possible by wire-based additive manufacturing techniques. The Twin-wire Arc Additive Manufacturing (T-WAAM) system was developed in the current study using two Gas Metal Arc Welding (GMAW) systems. This method was selected for its superior deposition rates, ease of welding, and lower cost compared to other wire-based methods. The two GMAW systems were physically integrated, and the torches were spaced 60 degrees apart to promote contact, melting, and alloy formation. Using the ideal parameters, a NiTi shape memory alloy sample was deposited and analysed for its microstructure, phases, phase transformation temperatures, and mechanical characteristics. The deposition using optimum parameters showed an excellent uniform bead. The higher concentration of the Ni3Ti phase, which increases hardness and fracture stress while decreasing ductility, was confirmed by Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) results. Diffraction Scanning Calorimetry (DSC) suggested that some austenite is retained along with the martensite phase at room temperature. The Electron Backscatter Diffraction (EBSD) results revealed that the grains are fully crystallised and equiaxed. The orientation map indicated that the obtained texture is random.

Rajendra Goud is a Mechanical Engineer, specialised in Manufacturing and Materials. With 7+ years of research experience, his current research focus is industry-oriented. With an emphasis on Additive Manufacturing, Advanced Materials, Shape Memory Alloys, and Surface Modification Engineering, he has filed three Indian patents and authored ten reputed publications, which have resulted in over 130 citations. Rajendra Goud is currently a PhD research scholar at the prestigious Indian Institute of Technology (IIT) Indore, India.