Effect of Hydrogen Addition on the Diffusion Bonding Behavior of Titanium Alloys

Hydrogen as a temporary alloying element can be used as a powerful tool in optimizing microstructure and mechanical properties of titanium alloys. In this study, the effects of hydrogen addition on the diffusion bonding behaviors of Ti-55 titanium alloy and Ti2AlNb/TC4 titanium alloys were studied. The DSC/DTA results show hydrogen can escape from titanium alloys under the conditions of high temperature and vacuum. The diffusion bonding ratios and joint strength of Ti-55 titanium alloy are remarkably improved by hydrogenation at relatively low bonded temperature (700 °C). In addition, hydrogen addition can prominently increase the bonding interface strengths of Ti2AlNb/TC4 titanium alloys through rapid heating. The residual hydrogen content is a key factor for improving the diffusion bonding properties by hydrogenation. Both low-temperature bonding and rapid heating aim to hinder the hydrogen desorption during the diffusion bonding process.