High temperature tensile properties and microstructural characterization of gas tungsten constricted arc welded Ti–6Al–4V alloy

Abstract

Ti-6Al-4V alloy is extensively used in the low-pressure fan compressor blades in aero engine due to corrosion resistance was high and specific strength at room temperature and reasonably at elevated temperature. In case of autogeneous welding of thin to moderate sections of these alloys, high frequency Gas Tungsten Constricted Arc Welding (GTCAW) offers many metallurgical advantages than the conventional Gas Tungsten Arc Welding (GTAW) process such as fusion zone (FZ) grain refinement, minimized width of the heat affected zone (HAZ), fewer distortion, and residual stresses. Titanium alloys welded by GTAW process produce Widmanstätten structures and result in poor mechanical properties of the weld joints. Hence GTCAW was used to weld Ti-6Al-4V alloy to control the resultant fusion zone microstructure by constricting the arc using high frequency current. In this paper, the microstructural characterizations, hot tensile properties (RT, 150 °C, 250 °C, 300 °C) and fracture surface morphology of the GTCA welded Ti-6Al-4V alloy joints are presented. High frequency current pulsing of GTCAW process eliminated the formation of Widmanstätten structure in fusion zone and enhanced the tensile strength compared to the constant current GTAW process.