Vibration Fatigue Properties and Fracture Mechanism of DD6 Single Crystal Superalloy

• Main Authors: LIU Li-yu, GAO Xiang-yu, YANG Xian-feng, HE Yu-huai
• Format: Article
• Language: zho
• Published: Journal of Materials Engineering 2018-02-01
• Series: Journal of Materials Engineering
• Subjects: DD6 single crystal superalloy; vibration fatigue; fracture mechanism; quasi-cleavage plane
• Online Access: http://jme.biam.ac.cn/CN/Y2018/V46/I2/128
• ISSN: 1001-4381; 1001-4381

Room Temperature vibration fatigue <i>S-N</i> curves of single crystal superalloy DD6 with[001] orientation was investigated and room temperature vibration fatigue limit was obtained. The fracture mechanism was studied by OM, SEM and EBSD. The results show that based on <i>S-N</i> method, vibration fatigue limit of DD6 single crystal superalloy with[001] orientation is estimated to be around 337.5MPa. Vibration fatigue fracture presents single or several {111} octahedral slip planes. SEM observations show that fracture has two regions:fatigue source region and the fatigue crack propagation regions, the fatigue cracks initiate at the surface or internal defect of the cross-section with the maximum stress, and exhibits a single source feature, fatigue crack propagation region exhibits quasi-cleavage fracture, no typical fatigue striation feature. Crystal plane slip along {111} is the main deformation mechanism of RT vibration fatigue fracture of single crystal superalloy DD6, quasi-cleavage propagation plane in fracture and quasi-cleavage patterns in microstructure are the main features of RT vibration fatigue fracture of single crystal superalloy DD6.