Grain size dependence of flow stress in ECAPed Ti with constant texture
(1. Department of Materials Science and Engineering, Seoul National University of Science and Technology,
172 Kongneung-dong, Nowon-ku, Seoul 139-743, Korea;
2. Department of Automotive Engin)
172 Kongneung-dong, Nowon-ku, Seoul 139-743, Korea;
2. Department of Automotive Engin)
Abstract: The effect of grain size on the flow stress in an ECAPed Ti with a constant texture was investigated, assuming that 2, 4, 5 and 6 passes microstructures have a similar texture. The average size of recrystallized grains decreased to 0.5 μm, 0.4 μm, and 0.3 μm with respect to the ECAP pass number of 2, 4, and 6, respectively. The ultimate tensile strength (UTS) and yield strength (YS) increase with an increase in the number of pressing. The UTS and YS of the 6 passes ECAPed sample were found to be 740.2 MPa and 580.3 MPa, respectively. An equation for the flow stress of an ECAPed Ti with a constant texture as a function of the strain and grain size was derived for the ECAPed metal. The following equation was finally obtained: σ(ε)=103.9+1825ε?9.6ε1/2·d?1/2+8.3d?1/2.
Key words: Ti; mechanical properties; grain size; flow stress; equal channel angular pressing