Plasma arc welding: Process variants and its recent developments of sensing, controlling and modeling

Plasma arc welding process uses a highly constricted arc to produce a keyhole inside the weld pool, process efficiency is much increased compared to the traditional gas tungsten arc welding process. Keyhole stability is one of the critical factors to determine the process stability and the resultant weld quality. Deeper understanding of the keyhole, and appropriate process control methods are required to improve the welding process stability. This survey paper provides variants of the plasma arc welding process, recent advances in plasma arc keyhole process sensing, controlling and numerical modeling. It shows that recent research works, especially the employment of camera-based vision system to observe the keyhole behavior, deepen the understanding of the keyhole process, sound quality welds have been made in mid-thick stainless steels (9.5–12.5 mm) by new designed control systems; more accurate numerical models have established to explore the keyhole behavior evolution process.