( Corrosion and Protection Research Laboratory,
Northwestern Polytechnical University, Xi'an 710072, China)
摘 要: 利用高頻疲勞實(shí)驗(yàn)機(jī)和自制高溫微動疲勞裝置，研究了溫度、 位移幅度、 接觸壓力等因素在對Ti811鈦合金高溫微動疲勞（FF）行為的影響， 并通過形態(tài)特征分析， 研究了微動疲勞的失效機(jī)理。結(jié)果表明： 350 °C和500 °C的高溫下， Ti811合金微動疲勞敏感性較高， 且隨著溫度的升高，微動疲勞的敏感性增強(qiáng)， 蠕變是高溫下Ti811合金FF失效的重要影響因素； FF的壽命隨著接觸壓力和位移幅度的變化均呈現(xiàn)出非單調(diào)的變化規(guī)律，原因是名義接觸壓力的變化改變了接觸區(qū)應(yīng)力分布、 應(yīng)力集中狀況和微動位移幅度大小， 進(jìn)而影響FF裂紋萌生幾率和擴(kuò)展驅(qū)動力； 位移幅度變化影響了疲勞應(yīng)力因素和磨損在FF過程中所起作用和機(jī)制。
關(guān)鍵字: 微動疲勞；高溫； 鈦合金； 磨損； 蠕變
（ Corrosion and Protection Research Laboratory,
Northwestern Polytechnical University, Xi'an 710072, China）
Abstract: The fretting fatigue (FF) behaviors of Ti811 alloy influenced by temperature, slip amplitude and contact pressure were investigated using high frequency fatigue machine and self-made high temperature apparatus. The FF mechanisms were discussed by observing fretting surface morphology features. The results show that FF sensitivity is high at both 350 °C and 500 °C. The higher the temperature is, the more sensitive the FF failure of the alloy. Creep is the important factor which influences FF failure process of Ti811 alloy at elevated temperature. The FF life of the alloy doesn't change in a monotone way with the increasing slip amplitude and contact pressure. This is due to the fact that slip amplitude affects the action of fatigue and wear in fretting process, the nominal contact pressure affects the distribution and concentration of stress and fretting slip amplitude value at contact surface, further influences crack initiation probability and propagation driving force.
Key words: fretting fatigue; elevated temperature; titanium alloy; wear; creep
