Fracture characteristics of dental precision castings of pure titanium and Ti-6AI-4V

摘要

Tensile tests static fracture toughness tests and dynamic fracture toughness tests were carried out on both unpolished and polished as-cast pure titanium and Ti-6Al-4V fabricated by dental precision casting process. The effect of the surface layer formed by the reaction with investment materials on fracture characteristics of pure titanium and Ti-6Al-4V castings was investigated based on the test results. The effects of heat treatment conditions on fracture behaviors of Ti-6Al-4V castings were then investigated. Polished pure titanium castings show a lower strength comparing with unpolished ones while Ti-6Al-4V castings show no difference in strength between unpolished and polished conditions. Static and dynamic fracture toughness of polished pure titanium castings is greater than that of unpolished ones. On the other hand, static and dynamic fracture toughness is nearly the same between unpolished and polished Ti-6Al-4V castings. The heat treatment of solutionizing at 1123 K for 1 h and aged at 813 K for 4h gives the greatest elongation for Ti-6Al-4V castings. The as-cast condition gives the greatest static fracture toughness for Ti-6Al-4V castings.