Abstract:The effect of processing parameters on deformation behavior and microstructures of TC4 titanium alloy were investigated by using simulated compression tests. Select the best hot-work parameters and ultra-fine grained TC4 sheets with high strength were manufactured by accumulative roll-bonding in this work. The results showed that the flow stress of TC4 alloys increased quickly to a peak and then decreased to a steady value with strain increasing. The steady and peak stress obviously decreased as deformation temperatures increased and strain rates decreased. The accumulative rolling were finally conducted at about 700℃ with rolling speed less than 0.5m/s to prepare sheets without cracking and interface oxidizing. As the accumulative layers increased to 16, the grain sizes were refined to 500nm and high-quality interfaces were obtained. The ultra-fine grain structure of TC4 alloy was fabricated by accumulative rolling bonding process, during which the hot deformation process and the ARB processed window were studied, and the effect of the ARB parameters and the heat treatment process on the interface bonding and the microstructure was investigated. The stress-strain curve takes on the dynamic recovery process, and the high temperature (≥700℃) and deformation rates (≤0.1s-1) can promote the fine grains and the sheet quality. Finally the excellent interface bonding and the sheet quality can be obtained at the temperature of 720℃ and the low rolling rate (≤0.5m/s) with the anti-oxidation treatment of the contact interface. The deformation during ARB process is composed with the cooperation deformation of α/β grains and the shear deformation, and the elongated band structure and the shear bands are observed in the ARB processed TC4 alloy. The band structure spacing decrease gradually with the increase of the ARB layers, and the bands spacing of 200nm~500nm can be obtained after the 16 layers ARB process. Simultinately the increasing heating temperature during the heat treatment can promote the solutes diffusion and the recrystallization process, which can be consisted with the matrix structure. Finally the ultra-fine grain with 300nm~600nm can be obtained with the heating temperature of 700℃ and the holding time of 60min for the ARB processed TC4 alloy.