Influence of dual axial magnetic field and welding parameters on weld characteristics in GTAW process

Abstract

A methodology has been proposed that is capable of altering arc shape as per the requirement using an external magnetic field. Eight magnetic configurations were explored, out of which the N-S-S-N configuration yielded a wider bead width and lower penetration without any change in process parameters, which is more suitable for cladding and hard-facing applications. The central composite design technique has optimized the process parameters to achieve the maximum cladding width. Further, the effect of the selected configuration on the characteristics of claddings in terms of bonding strength, microhardness, and metallurgical properties have been investigated at optimal parameters. This investigation selected the SA 516 grade 70 as a substrate and SS 308 L as a cladding material. It was observed that bead width increases with increased excitation current and decreased travel speed. The maximum bead width (10.89 mm) was achieved at a 1.8 A excitation current and 1 mm/sec travel speed. The experiment has been conducted on the optimized value of process parameters to validate the developed model. A comparative study between magnetically controlled (MC-GTAW) and conventional GTAW processes. The result revealed that the MC-GTAW process has wider bead width (9.95 mm) and higher average hardness (391.45 HV), which is 67% and 15% more than that of the conventional GTAW process, respectively. The microstructure analysis has revealed that the MC-GTAW process yielded more granular bainite and refined grains. The claddings were subjected to a side bend test, which showed a good bonding strength between the substrate and the deposited metal.