Effects of Grain Size, Thickness and Tensile Direction on Yield Behavior of Pure Titanium Sheet

Yield phenomena during the tensile testing of pure titanium sheets 0.2 mm and 0.4 in thickness were investigated detail focusing on effects grain size (d), (t), t/d ratio direction. With decreasing size, yielding behavior changed from continuous to one accompanied with yield point drop. Upper lower stresses 0.2%-proof stress followed Hall–Petch relationship; however, coarse-grained specimens (d ≧ 20 µm) showed larger scatter than others. Consequently, coefficient (k) friction (σ0) derived are not accurate enough. The values k σ0 various directions range 250–600 MPa·µm0.5 30–180 MPa, respectively. Therefore, validity for was a concern, combination fine-grain ≦ excluding work-hardening coarse-grain > suggested obtain reliable σ0, resulting 370–460 65–140 Moreover, it revealed that decreased increased increasing angle direction rolling direction, regardless thickness. anisotropy is presumed be affected by boundary character rather Schmid factor, neither rigidity nor length Burgers vector responsible. Meanwhile, verified factors. Furthermore, clarified hardly affects upper (t/d 14) (1.5 14).