Thermal Modeling of Multipass Narrow Gap Pulse Current GMA Welding by Single Seam per Layer Deposition Technique

A thermal model has been developed for production of multipass single seam per layer narrow gap pulse current gas metal arc (GMA) weld joint of thick plates free from lack of groove wall fusion under no angle of attack to groove wall. The model considers the fusion of groove wall as well as a part of earlier deposited weld based on the geometrical aspects and temperature of weld pool, which primarily arises out of initial arc heating and heating by droplets of superheated filler metal transferred to the weld pool. The geometrical aspects of weld pool are considered as its width and height appeared under narrow weld groove. For prduction of a sound weld joint, the favorable role of pulse current gas metal arc welding (P-GMAW) has been amply justified. But the selection of pulse parameter is quite complex due to involvement of relatively large number of pulse parameters simultaneously interactive in nature, which has been solved by considering a summarized influence of pulse parameters defined by a dimensionless hypothetical factor [image omitted]. The model is able to help in proper selection of pulse parameters prior to carrying out welding with appropriate groove wall fusion. The model is experimentally verified by preparing weld joints of high strength low alloy high-strength low-alloy (HSLA) steel using different combinations of pulse parameters.