Improvement of mechanical properties of cast pure titanium by repeated heat treatment

Pure titanium components fabricated by casting have a coarse grain microstructure. To improve the mechanical strength of pure titanium components by refining the grain size, the cast samples were repeatedly heat-treated. During the heat treatment, the titanium samples were repeatedly heated above the alpha-to-beta ( α– β) transition temperature and cooled to room temperature to undergo phase transformation. The heating cycle was performed 1, 3, 5, and 7 times. As the number of heating cycles increased, the grain size decreased. The tensile strength was 267.9 MPa in the as-cast sample and improved to 343.4 MPa after 7 heat-treatment cycles owing to the grain size refinement, while the elongation was maintained during the heat treatment. This paper is part of a thematic issue on Titanium.