抄録
It is considered that work hardening can be present in titanium used for implants. In this study, to clarify the relationship between the heat treatment temperature and duration until fatigue failure, a constant strain was repetitively applied to titanium materials, the number of cycles to fatigue failure and hardness in areas near the fracture site were measured, and the fractograph and metallographic structures were observed. Furthermore, the bending strength, strain, and hardness of titanium materials before and after heat treatment were measured.
The bending strength and hardness of the specimens decreased after heat treatment. The crystal grains of specimens before heat treatment were fine, while those after heat treatment showed recrystallization with crystal growth. In the fractograph of the specimens after the fatigue failure test, striations and minute cracks were observed. The number of cycles to fatigue failure was greater in the specimens treated at 400℃ for 80 minutes, and at 450℃ for 40 minutes. It was considered that these heat treatments partially removed the work hardening.
