| 摘要 |
PROBLEM TO BE SOLVED: To improve mechanical properties such as strength, ductility and fatigue life by applying the hydrostatic treatment to a shape memory material after performing the heat treatment for the shape memory. SOLUTION: The pressure to be applied to the shape memory material during the hydrostatic treatment is preferably the value at which the mechanical properties of the material are improved to a maximum. Though the mechanical properties of the material are improved proportional to the magnitude of the pressure, the effect of the pressure becomes not remarkable at the prescribed pressure compared with the previous effect. Thus, the pressure can be specified, for example, up to the yield stress of the shape memory material. The temperature during the hydrostatic treatment is preferably <= the temperature range where the shape memory material shows the shape memory performance. Because the yield stress of the material becomes smaller as the temperature is lower in the above-mentioned temperature range, it is more favorable as the environmental temperature during the hydrostatic treatment is lower, but when the temperature is too low, the pressurizing medium is solidified or it becomes costly to drop the temperature, and the room temperature is preferable in a practical condition, and from the safety aspect. |
