Characterization of Electron Beam Weld Joints of Alpha-Beta Titanium Alloys for Cryogenic Applications

Titanium alloys play a major role in launch vehicle due to its high specific strength, good weldability, excellent corrosion resistance and retain toughness at cryogenic temperatures. In the present paper we discuss on the electron beam welding studies carried on alpha-beta titanium alloys for cryogenic applications in launch vehicle programme. The Ti6Al4V having extra low interstitial elements and Ti5.4Al3Mo1V alloys were joint individually through electron beam welding on 6.8mm thickness coupon. Carried microstructural observations of the weld by optical microscope and are reported. Further tensile properties evaluated in welded condition at ambient and cryogenic (20K) temperatures are compared with parent metal properties. Micro hardness plot was generated across the weld in the transverse direction for both the alloys. Showing highest hardness in the weld region and drops towards the parent metal, due to formation of very fine martensitic alpha with high dislocation densities within coarse beta grains of the weld and HAZ region. The failure location of all the weld specimens is in parent metal far away from the weld region.Keywords: Ti6Al4V-ELI, Ti5.4Al3Mo1V, electron beam welding, cryogenic, microstructure, micro hardness and tensile properties.