Effect of dual axial magnetic field on metallurgical and corrosion properties of cladding in GTAW process

Abstract A novel methodology has been developed to tame the welding arc by incorporating the dual axial magnetic field in gas tungsten arc welding. This magnetic field was generated by using two electromagnets positioned on both sides of the workpiece. To investigate the effect of the dual axial magnetic field on bead geometry, metallurgical and corrosion properties of cladding, experiments were conducted on substrate SA 516 grade 70. A bed of SS 308L filler wire was deposited. The result revealed that dual axial magnetic field provided wider bead width (9.95 mm), which is 67% more than the conventional gas tungsten arc welding (C-GTAW). It was also observed that Magnetically controlled gas tungsten arc welding (MC-GTAW) required less number of passes to cover the entire substrate surface. The microstructural study has been carried out and revealed that the refined microstructure has been observed. The average grain size of the MC-GTAW and C-GTAW is 306.75 μm and 398.12 μm, respectively. Further, to investigate the corrosion behaviour of the cladding, degree of sensitization, cyclic potentiodynamic polarization, and potentiodynamic anodic polarization techniques were used. The result revealed that the MC-GTAW process yielded a lower degree of sensitization (2.29%) compared with the C-GTAW process. Samples produced using the MC-GTAW process demonstrated a higher pitting potential (213.7 mV) and a smaller pitting area (27558 μm 2 ) than those produced using the conventional GTAW process, which is desirable.