Influence of Heat Treatment on Mechanical Properties of Sintered Ti-6Al-4V Alloy Using Metal Injection Molding Method

Abstract

Metal injection molding (MIM) has attracted attention as a method to produce implant bodies. The mechanical properties of titanium alloy materials produced using MIM are comparable to those of implant rods which are already being used for implantation. However, since the fracture of implant bodies has become a problem in recent years, further improvement is desired. Heat treatment is a method to improve the material properties of titanium, and it has been reported that the fatigue strength of titanium increases with heating at 450℃. In this study, we performed heat treatment of titanium alloy materials produced using MIM, and evaluated whether the mechanical strength of the heat-treated titanium alloy was improved.
The tensile strength after heat treatment was significantly greater than that before heat treatment. The proof stress (yield strength) was improved by heat treatment, being within the range of Japanese Industrial Standards (JIS). The elongation and hardness after heat treatment showed no significant differences in comparison with those before treatment. Metallographic structure observation confirmed voids, which developed accompanying sintering. However, no apparent differences in the structure were noted between before and after heat treatment.
It was suggested that the tensile strength of test specimens produced using MIM was improved after heat treatment at 450℃.