FATIGUE CHARACTERISTICS OF BIOMEDICAL TITANIUM ALLOYS

摘要

Fatigue strength of fairly new biomedical titanium alloys, fatigue strength of biomedical titanium alloys in simulated body environments, fretting fatigue strength of biomedical titanium alloys in air and simulated body environment, and crack propagation characteristics of biomedical titanium alloys in air and simulated body environment are described in the present paper. The fatigue strength of Ti-6Al-7Nb alloy can be controlled to be nearly equal to that of Ti-6Al-4V ELI by heat treatments. The fatigue strength of biomedical titanium alloys in simulated body environment is degraded under lower oxygen content depending on the stress conditions. The fretting fatigue strength of biomedical Ti-6Al-4V ELI in simulated body environments is degraded in the regions of lower and higher cycles to failure comparing with that in air. The fatigue crack propagation rate in T-L direction of rolled bars of Ti-6Al-4V is greater in higher Δ K region in 3 % NaCl solution because of texture. The fatigue crack propagation rate of biomedical Ti-5Al-2.5Fe in simulated body environment is greater than that in air at relatively higher nominal cyclic stress intensity factor range. The fatigue crack propagation rate of Ti-5Al-2.5Fe in simulated body environment is nearly the same as that in air when the fatigue crack propagation rate is plotted versus effective cyclic stress intensity factor range.