Gas Tungsten arc welding of Ti-6Al-4V sheet for pressure vessels used in aerospace application: A detailed characterization of weldment

Abstract

Titanium-Ti alloys are the most demanded material in manufacturing industries worldwide. Ti-6Al-4V alloys are the most commonly used material in the aerospace, chemical, and nuclear industries (pressure vessels) due to their excellent corrosion resistance and mechanical properties. In this present study, an autogenous Tungsten inert gas (TIG) welding process was successfully employed to fabricate the butt joint of the Ti-6Al-4V sheet of 1.6 mm thick. The mechanical properties and microstructural characterization of the welded joint were examined. Due to intense heat (TIG arc), a complex microstructure variation has occurred in the welded joint. The microscopic images of the welded joint indicated the existence of α and β phases. Electron backscatter diffraction (EBSD) analysis shows that the high angle grain boundary proportion to the Heat affected zone (HAZ) and Fusion zone (FZ) increases with the volume of applied heat input. The average hardness values for Parent metal (PM), HAZ, and FZ is 315.5 HV0.5, 352.5 HV0.5, and 395.52 HV0.5, respectively. Tensile strength of the welded joint reached 928.9 MPa and fracture location is noticed in the PM. Bend test results confirmed that it has better ductility under a bend of 90°. A good corroboration was noted in between mechanical behavior and microstructure appearance in the welded joint. In addition to that finite element analysis was performed using ABAQUS software to predict tensile strength (Smooth and V-notch tensile specimens). Their results are validated with experimental outcomes. Scanning electron microscopy (SEM) images reveals that fractured tensile samples were failed in ductile mode.