Abstract
Pure titanium and titanium based alloy are commonly used as material of medical implant parts because of their biocompatibility. Mirror surface is necessary for these implant parts. However, since most of these parts have complicated shapes, it requires the excellent skills and much time to obtain mirror surfaces.
A new method for improving surface roughness, in which the large-area electron beam is irradiated in a very short time has been proposed. In this system, the high-energy density electron beam can be irradiated to the large area of about φ60mm at the same time. The surface roughness can be improved by the electron beam irradiation more efficiently than the conventional hand polishing. The effects of EB irradiation on the micro structure for pure titanium are experimentally investigated in this study.
The surface temperature of material went up to about 3273K by the EB irradiation. It was found that the crystal grains became small and plate after the EB irradiation. Moreover, it was confirmed that the structure of pure titanium which was originally the hcp(α-Ti), was partially transformed to the bcc(β-Ti) after the EB irradiation. However, it is possible to transform the bcc(β-Ti) to the hcp(α-Ti) by heat treatment.
