Arc morphology and properties of plasma arc welding of Q235B steel via rotating tungsten electrode

A high-quality welding method, named plasma arc welding apparatus with rotating tungsten electrode (abbreviated as PAW-RT), was proposed in this paper. The rotation speed could be adjusted from 0 to 15 000 r/min. The rotary motion of the tungsten needle transferred circumferential momentum to the arc as well as the molten pool, thereby conferring the latter with rotating fluid flow characteristics. The influences of tungsten electrode rotation speed on PAW arc morphology, weld formation and interfacial microstructure of the final weld joints were discussed by the experimental procedures involving in-situ ablation, surfacing and butt welding. The experiments were conducted on Q235B steel. The results indicated that the increase of tungsten electrode rotation speed in PAW-RT contributed to improving arc eccentricity, leading to aesthetically improved welds with more uniformity. Additionally, the strength, hardness and toughness of the welded joint increased, while porosity was reduced.