Grain refinement mechanism of Ti-55 titanium alloy by hydrogenation and dehydrogenation treatment

The average grain size of Ti-55 titanium alloy is refined by hydrogenation and dehydrogenation treatment from 5.96 μm to 0.5 μm. The refinement mechanism is discussed through microstructural observations. The main refining effects may derive from recrystallization and phase transformation. The micro-strain field in the matrix by the formed hydride during the hydrogenation process results in serious distortion and many dislocations. The...