Importance of shielding and mechanical characterization of GTAW on Ti-6AL-4V alloy sheet

Abstract

Welding and joining Titanium and its alloys are always challenging because getting a contamination-free joint is difficult with arc welding. For this concern, an attempt was made with and without shielding arrangements using the Gas Tungsten Arc Welding (GTAW) process on the Ti-6Al-4V alloy sheet. To study the presence of oxygen and other elements with respect to surface colourization at the weld zone, an Energy-dispersive X-ray spectroscopy (EDX) analysis is carried out. Based on the EDX analysis, post-flow and pre-flow shielding gases are also included in the operation window. Bead on Plate (BoP) trials are performed using the shielding arrangement setup and selected parameters on the thin sheets (2 mm) of Ti-6Al-4V. After examining the BoP trails, defect-free joins in a 2 mm sheet are fabricated using the optimal welding parameters. The microstructure of the joint is captured and compared with the simulation work. Compared to the base metal, coarse and enormous grains are identified at the weld zone. Due to the proper shielding, no cracks appeared in the joint subjected to the three-point bend test. The considerable heat input during the GTAW process resulted in the nucleation of (ά) in FZ, as spotted in the TEM images. The microhardness value at FZ for base metal is 373 HV and 332 HV, respectively. It is confirmed that the suggested shielding setup could prevent contamination in welds resulting in better mechanical properties.