Quantitative Analysis aided by Image Processing on Creep-fatigue Mechanism of Heat-resisted Superally

本文通过SEM伺服原位观察，研究了镍基高温合金的高温疲劳裂纹扩展行为及其机理（扫描电镜与电液疲劳试验机的新型复合装置），试样为镍基多晶高温合金Hastelloy-X和镍基单晶高温合金CMSX-4。对镍基多晶高温合金Hastelloy-X进行了循环疲劳裂纹扩展试验和高周疲劳试验，并对微裂纹的萌生和扩展行为进行了原位观察。在此基础上，对裂纹扩展机理进行了研究.研究了循环载荷频率对疲劳寿命的影响。在此基础上，重点研究了微裂纹的萌生和扩展行为，并尝试构建了剩余寿命评估方法。利用扫描电镜伺服系统研究了具有初始各向异性的CMSX-4单晶在高温循环载荷作用下的损伤过程，并对裂纹扩展行为进行了研究。

In the present reserch, the high-temperature fatigue crack growth behavior of Ni-base super alloy and its mechanism were made clear through in-situ observation by SEM servo (the newcomplex apparatus of scanning electron microscope and electro-hydraulic fatigue testing machine).Besides, the specimens are the Ni-base polycrystalline superalloy Hastelloy-X and the Ni-base single crystal super alloy CMSX-4.High-temperature high-cycle fatiguecrack growth tests and high-cycle fatigue test are preformed in Ni-based polycrystalline super alloy Hastelloy-X.And in-situ observation on the behavior of the micro crack initiation and propagation. Then, the mechanism of the crack growth was investigated. And the dupendence of the cyclic load frequence on the fatigue life wasinvestigated. Furthermore, we focused on the behavior of the micro crack initiation and propagation, and tried to construct the residual life assessment. And the damage process of the singlecrystal CMSX-4 which has initial anisotropy was investigatedunder the condition of high-temperature and cyclic load by using SEM servo, and the behavior of the crack propagation was investigated.