Critical assessment on the influence of process parameters in micro-plasma arc welding process: a review

The current review work critically examines the role of input process parameters in producing defect-free welds in the micro-plasma arc welding (M-PAW) of thin structures. With the reduction in thickness, commonly encountered problems like excessive heating (leading to burn-through), grain coarsening (resulting in larger heat-affected zones), diffusion-less phase transformation (high cooling rate), significant distortion, poor surface appearance and reduction of essential chemical elements become more sensitive to the process parameters. The existing studies suggest heat input (combination of welding current, voltage, and speed) as the most crucial variable that leads to a sound-quality weld. In this work, the input process parameters and their extent to control the weld joint characteristics are analysed, including the variants of M-PAW technique. Overall, the current study aims to identify the optimal heat input required to produce a mechanical and material defect-free weld for a thin structure fabrication.