Effect of deformation degree on microstructure and mechanical properties evolution of TiBw/Ti60 composites during isothermal forging
(School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201600, China)
Abstract: In order to investigate the influence of deformation degree on microstructure and mechanical properties during hot compression, TiB whiskers reinforced Ti60 composites were subjected to isothermal forging at 1030 ℃ and strain rate of 1×10-2 s-1 under 30%, 50%, and 70% deformation degrees. The results showed that with strain increasing, the fraction of high angle grain boundaries (HAGBs) significantly increased to 71.47% at 70% deformation degree, and the texture components of αs colonies gradually became dominant due to the enhanced recrystallization efficiency. TiB can promote nucleation of recrystallized grains and impede grain growth. After isothermal forging, the mechanical properties of composites at both RT and 600 ℃ were improved, and the specimen compressed at 50% deformation degree showed the best tensile strength and elongation. During tensile tests, the TiB whiskers can bear the load transmitted from surrounding matrix, showing strengthening effect on the material.
Key words: titanium matrix composites; isothermal forging; dynamic recrystallization; texture evolution; mechanical properties