Characterisation of weld bead and microhardness of SS316L weld overlays on S355J2+N steel using GTAW under E-type magnet

Abstract

Abstract In this study, a three-pole (E-type) electromagnet with magnetic configurations north-south-north (NSN) and south-north-south (SNS) was installed in the GTAW process to generate a combination of two symmetrically transverse external magnetic fields around the weld arc and the molten pool. The effects of magnetic fields obtained by these two types of magnetic configurations (NSN and SNS) on the weld bead characteristics and microhardness in GTAW were analysed. In these experiments, high-strength low alloy (HSLA) S355J2+N grade with a thickness of 10 mm was selected as the substrate material and S316L as the filler wire. Using magnetic fields during the welding process successfully enhanced the weld bead appearance and shape and improved the mechanical characteristics of weld overlays. It was also observed that for different values of excitation current, magnetic fields generated with both configurations ( i.e., NSN and SNS) provide greater bead width, a higher penetration shape factor, and higher microhardness values in comparison to specimens welded with conventional GTAW. The NSN and SNS configurations of the E-type magnet improve the penetration shape factor by 58% and 46%, respectively. These configurations were more suitable for weld overlays (cladding) and hardfacing. However, the observations indicated an enhancement in microhardness for all excitation current values by employing the NSN and SNS magnetic configurations.