Thermal efficiency analysis for laser-assisted plasma arc welding of AISI 304 stainless steel

Synergistic effects during hybrid laser-arc welding may cause increased process efficiencies. However, the basic interactions behind these effects are still being discussed, with some contradictory reports. In this study, particular welding parameters of interest were systematically varied to further the understanding of involved phenomena. The experimental trials are evaluated regarding their synergistic achievements in terms of process efficiency, melting efficiency and energy coupling efficiency using a factorial two-level Design-of-Experiment (DoE) approach. The results show that the growth in process efficiency can be attributed to a dramatic increase in melting efficiency whereas the energy coupling efficiency is only moderately increased. Thus, the synergistic effect is mainly caused by secondary mechanisms that change the energy usage inside the workpiece while direct interactions between the two heat sources can be excluded as a reasonable cause for increased process efficiencies. It is concluded that the different sizes of the heat sources change the heat and mass flow positively and consequently lead to a higher performance level.