TC17钛合金在3.5% NaCl溶液中的疲劳失效行为

Fatigue Failure Behavior of TC17 Titanium Alloy in 3.5% NaCl Solution

摘要:

为了研究海水环境中钛合金TC17疲劳失效行为，开展了不同介质环境中的TC17钛合金超声疲劳试验并分析了疲劳性能及失效特征。采用超声疲劳试验系统分别进行了空气及3.5% NaCl溶液环境的钛合金TC17疲劳试验，并对相同应力幅值条件下不同介质环境的疲劳寿命进行了比较分析，提出了高周疲劳阶段2种介质中疲劳寿命的转换模型，进一步分别根据Murakami模型及基于微观沟壑模型进行应力强度因子计算。使用SEM对疲劳试验试件断口特征进行观察，比较分析 3.5% NaCl溶液对疲劳失效特征的影响。结果表明：在3.5% NaCl溶液环境中，以表面微观沟壑为主要变量的应力强度因子计算结果与实际失效行为更加吻合，并且由于腐蚀环境的影响，断口出现了基体材料“堆积”、多个裂纹源等现象。

Abstract:

To study the fatigue failure behavior of TC17 titanium alloy in salty-water environment, ultrasonic fatigue tests of TC17 titanium alloy in different medias were conducted and the fatigue properties and failure characteristics were analyzed. The fatigue tests of TC17 titanium alloy in air and 3.5% NaCl solution were carried out using ultrasonic fatigue test system, and the fatigue lives in different medias under the same stress amplitude were compared and analyzed. The conversion model of fatigue life in two kinds of media in the "finite life" stage was put forward, and the stress intensity factors were calculated according to Murakami model and micro-gully model. The fracture characteristics of fatigue test specimens were observed by SEM, and the effects of 3.5% NaCl solution on fatigue failure characteristics were compared and analyzed. Results show that in 3.5% NaCl solution environment, the calculated results of stress intensity factor with surface micro-gully as the main variable are more consistent with the actual failure behavior, and due to the influence of corrosion environment, there are some phenomena such as "accumulation" of matrix materials and multiple crack sources on the fracture surface.