Optimization of Properties in Ti-6Al-4V Alloy Castings and Weldments

The use of Ti-alloys in the as-cast condition leads to a considerable savings in the manufacturing costs. This study aimed at optimizing the properties of Ti-6Al-4V alloy castings and weldments. This goal is achieved through studying the effect of different pre-designed heat treatment cycles on the microstructure and properties of cast Ti-6Al- 4V alloy. The alloy was characterized after heat treatments using microstructural investigation, tensile, Charpy impact toughness, hardness and wear tests. The worn surfaces and the fracture surfaces of the broken impact samples were investigated using Scanning Electron Microscope. Finally, the relation between the heat treatment, microstructure and properties of the Ti-6Al-4V alloy was established and the optimum heat treatment cycle that optimized all the properties was selected. This selected heat treatment cycle was then applied to the gas-tungsten arc welding and electron beam welding joints of the alloy as a postweld heat treatment, and the characterization of the as-welded and heat treated joints was conducted to examine the effect of the optimum selected heat treatment cycle on the properties of the welding joints of Ti-6Al-4V alloy.