Electron beam welding of a Ti–45Al–2Nb–2Mn+0.8 vol.% TiB2 XD alloy

The feasibility of using conventional electron beam welding to join a Ti–45Al–2Nb–2Mn+0.8% TiB2 XD alloy was assessed. The alloy showed no evidence of hot cracking. However, a susceptibility to solid-state cracking was observed when weldments cooled at high cooling rates. The microstructural features of weldments were found to be a function of welding speed, heat input, preheating temperature, and thus cooling rate. Effects of cooling rates on microstructural evolution was evaluated with thermal simulation in a Gleeble 1500 system and it was found that cracking occurred when high cooling rates resulted in suppression of the α→γ phase transformation. It was observed that sound welds could be made when welding conditions were chosen so that the cooling rate at the fusion zone boundary was 250 K s−1 or less.