Stabilization of TIG Arc by CO₂ Laser

Study on High Speed Surface Treatment by Arc with laser (1st Report)

Abstract

In order to develop a fast surface treatment method or a fast welding method using an electric arc with a laser beam, stabilizing effects of a CO₂ laser on a TIG arc were investigated. A TIG arc makes discontinuous molten pools even when the travelling speed of a base metal is high and the distance between a base metal and a tungsten electrode is large. In such a case, the behavior of an arc usually becomes unstable and the arc voltage changes in the range of 5-8 V. Whereas, the arc behavior became stable by using a CO₂ laser beam simultaneously, and good continuous weld beads were made on conditions that the TIG arc current, the laser output, the distance between a SUS304 base metal and a tungsten electrode, and the travelling speed of a base metal were 100 A (DCEN), 2 kW, 15 mm and 200 mm/s, respectively.
It was found that the anode spot was fixed on the molten pool formed by the laser beam, and, the molten pool, the laser plume and the metallic vapor affected the stabilization of the path of a TIG arc and its voltage. Therefore, it is effective to controle a long arc by a laser that the beam irradiates near the tip of the arc where the arc stiffness becomes weak.