Study of the hot-wire TIG process with AISI-316L filler material, analysing the effect of magnetic arc blow on the dilution of the weld bead

Abstract

The TIG process with hot-wire addition is described as a highly productive process in comparison with conventional TIG process with cold-wire and achieves large deposition rates and low dilution percentages, characteristics that permit to the process to be an optimum alternative for cladding applications. There are many options of electrical circuit configurations to heat the addition wire in the TIG Hot-Wire process, highlighting the utilization of the continuous pulsed current and the alternating current. In the present paper were studied two configurations of the electrical circuit for heating the addition materials, which in theory provoke different behaviours in the welding arc, and therefore, in the geometrical properties of the welding bead too. A first analysis done on the welding arc, which demonstrates that to heat the wire with continuous constant current generates a permanent magnetic blow over the arc. According to trials made, the direction and intensity of the magnetic blow will depend on the polarity and on the current value to heat the wire. A macrographic analysis of the weld beads demonstrated that the best results were for the tests made with hot-wire, achieving dilutions up to 2% for a wire velocity of 7.5 m/min, 1 kW of power for to heat the wire and using a welding velocity of 30 cm/min.