The deformation mechanism of TC4 alloy with different initial α sizes of 6μm,12μm,20μm respectively has been investigated by isothermal compression tests in a temperatures range 890~950℃ and strain rates range 0.1~10s-1.The results show that the effect of initial α size on flow stress is complicated and less significant compared to strain rate and temperature.Microstructure characterization and kinetic analysis show that the thermal activated deformation process of TC4 alloy is controlled by both phase transformation and grain growth.The calculated activation energy is much higher than the results reported.Small initial α size tends to aggregate and grow with a coarse grain size after deformation.With an initial α size of 12μm,phase transformation is improved and fine grain size is obtained after deformation.With initial α size increased to 20μm,slightly effect on grain size happened.
Key words
TC4 alloy /
flow stress /
α size /
phase transformation /
activation energy /
grain growth
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