Microstructural analysis of pulse gas tungsten arc welding (GTAW) in Ti-6Al-4V alloy

Aerospace manufacturing industry needs high quality, skilled, accuracy work and reliability manufacturing operations. Tungsten Inert Gas (TIG) welding is one of the welding process methods where it is used effectively in aerospace manufacturing applications. Pulse TIG welding is a part of TIG welding and it is preferred to weld Ti-6AL-4V alloy in order to have sound welding. This work investigates the effects of pulse current TIG welding performance on Ti-6AL-4V. Effects of TIG welding parameters, such as pulse and amperage on material grain size (Gs), heat affected area (HAA) and micro hardness of heat affected zone Mh (HAZ) were analyzed throughout the experiment works. The experimental procedure was carried out according to the design of experiment (DOE) and the results were statistically evaluated by using analysis of variance (ANOVA). Response surface methodology (RMS) was used in evaluating the input factors performance with the responses or outputs and mathematical modeling of TIG welding input parameters for Gs, HAA and Mh (HAZ) were established. Gs is adversely affected by increasing amperage on Ti-6AL-4V alloy. On the other hand, Gs is directly proportional to pulsing. HAA is getting wider with increasing amperage on the contrary HAA is getting narrower when the pulsing increases. Mh HAZ shows a significant increase of hardness with the increasing of pulsing, but inversely reacting with the increasing in amperage.