Improvement in Hot Workability of Titanium Matrix Composite by Thermohydrogen Treatment

Ti-6Al-4V matrix composite (TMC) reinforced with TiB plus TiC was prepared and hydrogenated. Isothermal compression tests and high temperature tensile tests were carried out to study the effect of the hydrogen on hot deformation and superplastic deformation. The flow behaviour and microstructure evaluation of hot deformation was investigated. The results show hydrogen can reduce the flow stress and decrease the deformation temperature or increase the strain rate at the same flow stress level in hot deformation. Hydrogen increasing β phase and promoting dynamic recrystallizaiton (DRX) was considered as the main reasons for hydrogen-induced plasticity in hot deformation. The results of superplastic deformation indicate hydrogen can decrease the superplastic temperature 100°C or increase strain rate one order of magnitude at the same elongation level in superplastic deformation. Hydrogen promoting DRX were considered as the main reason for improvement of superplastic elongation.