Yield point elongation in fine-grained titanium

Fine-grained (FG) titanium with average grain size of around 1 mu m was produced by annealing nano-grained (NG) Ti at 500 degrees C for different time. The tensile deformation behaviors of this FG Ti were investigated. The phenomenon of yield point elongation (YPE), namely, a plateau following yielding in the stress-strain curve, is observed in FG Ti. It is found that, with increase of the grain size, the YPE in FG Ti appeared and increased to a maximum value, then decreased and, finally disappeared. Microstructures of FG Ti samples before and after the YPE were investigated. The results show that this YPE phenomenon is attributed to the dislocation behaviors and characteristics of grain size in the FG Ti. (C) 2013 Elsevier B.V. All rights reserved.