Analysis of Microstructure Evolution and Mechanical Properties of Linear Friction Welded Titanium Alloys

Two titanium alloys, Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo were linear friction welded in similar and dissimilar combinations to analyze the effects of stress relieve annealing on the mechanical and microstructural properties and to compared the results with as-welded state. For the selected set of weld parameters, high-quality welds were obtained with minimal defects. Scanning electron and optical microscopes were used to study the microstructures at various weld zones. Mechanical properties were determined by micro-indentation hardness, tensile, and fatigue testing and compared. Formation of martensite at the weld zone was mainly the reason for high strength of the weld in the as-welded condition. The local mechanical properties were determined by the digital image correlation (DIC) technique showed the overall local strain concentration of the welds in the as-welded and stress relieved conditions. The fractographic analysis performed on both the tensile and fatigue samples using electron microscope showed the characteristic features of ductile fracture.