| Abstract |
| A study was made to investigate microstructural evolution and mechanical properties of ultra-fine grained (UFG) pure-Ti produced by equal channel angular (ECA) pressings. The deformed structures were analyzed by finite element method and transmission electron microscopy with the increment of straining. After 4 isothermal ECA pressings, initial coarse grains (30 μm) were significantly refined to ~0.3 μm with homogeneous distribution of microstructure which was resulted from 180˚ rotation of the sample between pressings. UFG pure-Ti exhibited the considerable improvement in yield strength while losing strain hardening capacity as compared to coarse grained microstructure at ambient temperature, which was mainly attributed to ultra-fine grain microstructure with non-equilibrium grain boundaries. Such high strength and unusual strain hardening behavior of UFG pure-Ti were discussed in relation with two dislocation models based on dislocation bow-out and dynamic recovery associated with trapped lattice dislocations. |
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| Key Words |
| Pure-Ti, Ultra-fine grain, Dislocation bow-out, Strain hardening, Dynamic recovery |
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