A Study to Enhance the Depth of Penetration in Grade P91 Steel Plate Using Alumina as Flux in FBTIG Welding

Abstract

Tungsten inert gas (TIG) welding has an inherent difficulty in achieving deep penetration. To improve the penetration in TIG welding process, many researchers are continuously working in this field. In this paper, weld penetration of bead on plate TIG welding was compared with flux-bounded TIG (FBTIG) welding which was carried out on 6-mm-thick P91 plates. In the present FBTIG welding, a ceramic flux consisting of alumina was used instead of silica. Sodium silicate was used instead of acetone in the experiments to bind the flux on to the plates. In this paper, bead on plate FBTIG welding was carried out to investigate whether weld penetration could be improved. It was observed that with FBTIG welding, using ceramic flux, the weld penetration increased 2–3 times the penetration obtained during TIG welding. The weld width in all the cases decreased compared with conventional TIG welding. The effect of flux gap on hardness and grain size at the heat-affected zone were also investigated. Compared with TIG welds, FBTIG-welded samples had larger grain size and lower hardness values in the welded and heat-affected zone.