Low-temperature superplastic gas bulging of Ti-55 alloy by hydrogen addition

The effects of hydrogen addition on superplastic forming behavior of Ti-55 alloy were investigated through gas-bulging experiment. It was found that reasonable hydrogen content can significantly improve the superplastic forming properties. The maximum ratio of height to radius reaches 1.58 for hydrogenated specimen (with 0.3 wt%H) at 825 °C, a drop by about 100 °C when compared to as-received alloy. This is due to the increased volume fraction of extremely deformable β phase, with α/β phase ratio close to 1:1, as well as microstructural refinement and dynamic recrystallization in hydrogenated alloy.