Optimizing the pulsed current GTAW parameters to attain maximum impact toughness

In this article, a procedure to select process parameters to obtain maximum impact toughness properties in the Pulsed Gas Tungsten Arc (PGTAW) welding of titanium alloy is presented. Titanium (Ti-6Al-4V) alloy has gathered wide acceptance in the fabrication of lightweight structures requiring a high strength-to-weight ratio, such as in road tankers and in space vehicles. The preferred welding process for titanium alloys is frequently Gas Tungsten Arc (GTA) welding due to its comparatively easier applicability and better economy. In the case of single pass gas tungsten arc welding of a thinner section of this alloy, the pulsed current has been found to be beneficial primarily due to its advantages over the conventional continuous current process. However, pulsed current welding is controlled by four important parameters, such as peak current, base current, pulse frequency, and pulse-on-time. To arrive at an optimum condition, one needs to carefully balance these four pulsed current parameters. The Design of Experiments concept has been used to optimize the experimental conditions. Regression analysis has been used to develop a mathematical model to predict impact toughness of titanium alloy joints incorporating pulsed current parameters. The model is optimized using the traditional Hooke and Jeeve's algorithm.