Abstract
The weldability characteristics of an α 2+O+β titanium aluminide of nominal composition Ti–24Al–15.5Nb (at.-%) have been investigated. Conventional gas tungsten arc (GTA) and electron beam (EB) welds exhibited columnar fusion zone grains. Pulsed current and arc oscillated GTA welds exhibited predominantly equiaxed fusion zone grains. The microstructure of GTA welds and pulsed current GTA welds exhibited α 2+O phases, whereas arc oscillated GTA welds and EB welds contained α 2+O+β 0/β 2; however, β 0/β 2 is predominant in EB welds. The EB welds, which contained α 2+β 0/β 2 microstructure, exhibited high strength and ductility compared with GTA welds. The observed microstructural variations are explained on the basis of possible weld thermal cycles and convective currents in the weld pool.
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