Investigation on GTA weld repairs for Gas turbine blades

This research presents an automatic arc voltage control of Gas Tungsten Arc Welding (GTAW) for turbine blade build up repair which can restore performance, reduce costs and extend the lifetime of machinery. Blade repair is complicated by weld cracking problem inherent to blade alloy and by dimension changes. Welding on thin section of blade tip for dimensional restoration is a real challenge. In this experiment, weld repairs for the turbine blade thickness less than 3 mm can be achieved with an automatic arc voltage control (AVC) and appropriate scheduling of parameters such as travel speed, filler-wire feed rate and arc current. From the practical investigation, the AVC method by keeping the voltage constant during the process is able to control the quality of weld bead on turbine blade tips with good weld accuracy. Moreover, images data monitoring from high speed camera must be established, this is necessary in case of the defeat occurrence during welding process to analyze what happens at those instances.