Microstructural evolution mechanism of hydrogenated Ti–6Al–4V in the friction stir welding and post-weld dehydrogenation process

The α + β titanium alloy, Ti–6Al–4V, was thermohydrogen processed and friction stir welded using a W–Re pin tool. Defect-free joints were obtained with proper welding parameters. Hydrogen was removed from the joints through a post-weld dehydrogenation process. The microstructures of the as-welded and dehydrogenated joints were examined, and the microstructural evolution mechanism was revealed in the friction stir welding and post-weld dehydrogenation process.