| Microstructure evolution and the mechanical behavior of UFG commercially pure Ti (grade 2) produced by ECAP were investigated, using the procedure designated as route Bc. Repetitive pressings of the same sample were performed to 4 passes at 683K. After four pass, recrystallized gains were uniformly distributed throughout the specimen with an average size of 0.4 µm. The fatigue limit σe of the pure Ti increased by 29% from 183.1 to 236.1 MPa after 4 pass ECAP. This result indicates that a significant improvement in high-cycle fatigue life can be achieved by applying ECAP on pure Ti. The standard Hall-Petch relation for yield stress and fatigue limit exhibit in the ECAPed Ti. The grain size dependence of ky and ke in the present Ti are 7.5 MPa √mm and 2.5 MPa √mm, respectively. The present Ti exhibits higher σo compared to σoe. |
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