The thermal fatigue behavior of K465 superalloy was investigated at the peak temperature of 1050℃. By scanning electron microscopy （SEM） and optical microscopy, the main crack length was observed and measured. The ...The thermal fatigue behavior of K465 superalloy was investigated at the peak temperature of 1050℃. By scanning electron microscopy （SEM） and optical microscopy, the main crack length was observed and measured. The initiation sites of the tested alloys are different in as-cast （named as K465） and solution heat treatment （named as SK465） conditions. In K465 alloy, most thermal fatigue cracks nucleate at （Nb,W,Ti）C carbides. In SK465 alloy, thermal fatigue cracks initiate in interdendritic regions, MC-type carbides and some interfaces. Thermal fatigue cracks propagate in transdendritic mode, and M6C-type carbides could retard thermal fatigue crack growth for SK465 superalloy.展开更多
Damage accumulation and failure behaviors are crucial concerns during the design and service of a critical component, leading researchers and engineers to thoroughly identifying the crack evolution. Third-generation s...Damage accumulation and failure behaviors are crucial concerns during the design and service of a critical component, leading researchers and engineers to thoroughly identifying the crack evolution. Third-generation synchrotron radiation X-ray computed microtomo- graphy can be used to detect the inner damage evolution of a large-density material or component. This paper provides a brief review of studying the crack initiation and propagation inside lightweight materials with advanced synchrotron three-dimensional （3D） X-ray imaging, such as aluminum materials. Various damage modes under both static and dynamic loading are elucidated for pure aluminum, aluminum alloy matrix, aluminum alloy metal matrix composite, and aluminum alloy welded joint. For aluminum alloy matrix, metallurgical defects （porosity, void, inclusion, precipitate, etc.） or artificial defects （notch, scratch, pit, etc.） strongly affect the crack initiation and propagation. For aluminum alloy metal matrix composites, the fracture occurs either from the particle debonding or voids at the particle/matrix interface, and the void evolution is closely related with fatigued cycles. For the hybrid laser welded aluminum alloy, fatigue cracks usually initiate from gas pores located at the surface or sub-surface and gradually propagate to a quarter ellipse or a typical semi-ellipse profile.展开更多
文摘The thermal fatigue behavior of K465 superalloy was investigated at the peak temperature of 1050℃. By scanning electron microscopy （SEM） and optical microscopy, the main crack length was observed and measured. The initiation sites of the tested alloys are different in as-cast （named as K465） and solution heat treatment （named as SK465） conditions. In K465 alloy, most thermal fatigue cracks nucleate at （Nb,W,Ti）C carbides. In SK465 alloy, thermal fatigue cracks initiate in interdendritic regions, MC-type carbides and some interfaces. Thermal fatigue cracks propagate in transdendritic mode, and M6C-type carbides could retard thermal fatigue crack growth for SK465 superalloy.
基金Acknowledgements The authors thank the National Natural Science Foundation of China （Grant No. 11572267）, the Open Foundation of the State Key Laboratory for Strength and Vibration of Mechanical Structures of Xi＇an Jiaotong University （Grant No. SV2016-KF-21）, the Science and Technology Project of Sichuan Province （Grant No. 2017JY0216）, and the Self-Developed Research Project of the State Key Laboratory of Traction Power of Southwest Jiaotong University （Grant No. 2015TPL_T07）.
文摘Damage accumulation and failure behaviors are crucial concerns during the design and service of a critical component, leading researchers and engineers to thoroughly identifying the crack evolution. Third-generation synchrotron radiation X-ray computed microtomo- graphy can be used to detect the inner damage evolution of a large-density material or component. This paper provides a brief review of studying the crack initiation and propagation inside lightweight materials with advanced synchrotron three-dimensional （3D） X-ray imaging, such as aluminum materials. Various damage modes under both static and dynamic loading are elucidated for pure aluminum, aluminum alloy matrix, aluminum alloy metal matrix composite, and aluminum alloy welded joint. For aluminum alloy matrix, metallurgical defects （porosity, void, inclusion, precipitate, etc.） or artificial defects （notch, scratch, pit, etc.） strongly affect the crack initiation and propagation. For aluminum alloy metal matrix composites, the fracture occurs either from the particle debonding or voids at the particle/matrix interface, and the void evolution is closely related with fatigued cycles. For the hybrid laser welded aluminum alloy, fatigue cracks usually initiate from gas pores located at the surface or sub-surface and gradually propagate to a quarter ellipse or a typical semi-ellipse profile.
