Relationship between various thermomechanical treatments and tensile properties of pure titanium

Pure titanium is a highly corrosion-resistant metal and is used in a wide range of fields. However, its tensile properties are greatly affected by processing history. For this reason, it is necessary to select an appropriate processing method according to the application. In the present study, the effects of various processing methods, such as tensile deformation, rolling, shot peening, and heat treatment, on the tensile properties of pure titanium were investigated. Pure titanium JIS2 sheets were pre-deformed by cold working. Then, heat treatment was performed at 673 to 873 K, a temperature range where recovery and recrystallization of the structure are likely to occur. The effects of different processing methods and heat treatment temperatures on the microstructure were investigated by microstructural observation. In all processing methods, there were conditions under which heat treatment at high temperatures reduced strength even with increasing pre-strain. Furthermore, when pre-strain was applied by tension, the elongation decreased monotonically as the pre-strain increased. On the other hand, when pre-strain was applied by rolling, the decrease in elongation gradually became more gradual as the pre-strain increased.