Magnetic-enhanced keyhole TIG welding process

Improving of K-TIG welding process with a cusp magnetic field was experimentally tested. A cusp magnetic field setup was designed with water-cooled permanent magnetic poles. Stationary welding experiments were carried out to test the influence of magnetic field to the arc shape. Bead-on-plate welding processes were carried out to test the influence of magnetic field to the arc voltage and weld shape. Keyhole exit image sequence was captured with a vision system. It was found that, in the magnetic-enhanced K-TIG welding process, (1) the arc was constrained and changed into oval shape; (2) arc voltage was increased, front weld was narrowed and backside weld was widened; (3) keyhole exit shape also changed; (4) threshold current for fully penetrated keyhole was decreased and (5) the stainless steel weld microstructure experienced invisible change. The results show that the cusp magnetic field is feasible to improve the K-TIG arc behaviour and reduce the heat input.