INVESTIGATION OF FRETTING FATIGUE BEHAVIOR OF TI811 ALLOY AT ELEVATED TEMPERATURE

Abstract

The fretting fatigue behavior of the Ti 811titanium alloy, as influenced by temperature, slip amplitude, and contact pressure, was investigated using a high-frequency fatigue machine and a home-made high-temperature apparatus. The fretting fatigue failure mechanisms were studied by observing the fretting surface morphology features. The results show that the sensitivity to fretting fatigue is high at both 350°C and 500°C. The higher the temperature is, the more sensitive the alloy is to fretting fatigue failure. Creep is an important factor that influences the fretting fatigue failure process at elevated temperature. The fretting fatigue life of the Ti 811 alloy does not change in a monotonic way as the slip amplitude and contact pressure increase. This is due to the fact that the slip amplitude affects the action of fatigue and wear in the fretting process, and the nominal contact pressure affects the distribution and concentration of the stress and the amplitude of fretting slip at the contact surface, and thus further influences the crack initiation probability and the driving force for propagation.