Article
Mechanics
Xing Ai, Lijian Shi, Fenghua Luo, Haiqing Pei, Zhixun Wen
Summary: In this study, a thermomechanical fatigue (TMF) test platform was constructed to investigate the TMF behavior of a second-generation nickel-based single-crystal superalloy (DD6) at temperatures ranging from 500 to 950 degrees C. The TMF tests were conducted in two phases (in-phase and out-of-phase) at various stress levels, and the TMF life of the single-crystal specimens was determined. The fracture and microstructures of the specimens were analyzed to elucidate the failure mechanism in different phases.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Mechanics
Haiqing Pei, Shuaishuai Wang, Xiaonan Gao, Zhixun Wen, Jundong Wang, Xing Ai, Zhufeng Yue
Summary: Thermomechanical fatigue (TMF) is a major cause of turbine blade failure. Test results show that the TMF life of the out-of-phase (OP) condition exceeds that of the in-phase (IP) condition, and increasing the stress ratio prolongs the TMF life. The TMF failure behavior involves fatigue, creep, and oxidation damage.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Mechanics
Bin Zhang, Rongqiao Wang, Haiyan Liu, Dianyin Hu, Kanghe Jiang, Fulei Jing, Dong Mi
Summary: Through stress-controlled low cycle fatigue (LCF) experiments, the influence of thickness debit effect on LCF performance of nickel-based single crystal superalloy DD6 with [001] orientation is studied. The formation mechanism of thickness debit effect and the damage mechanism under LCF loads are revealed through SEM observation. An improved slip-based damage model is developed based on the thickness debit effect, and the predicted LCF lifetimes and behaviors are in good agreement with experimental data, verifying the rationality and accuracy of the established thickness-sensitive LCF damage model.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Engineering, Mechanical
Cheng Luo, Huang Yuan
Summary: This study investigated the thermomechanical fatigue behavior of nickel-base single-crystal superalloy with different crystal orientations. The crack initiation modes and damage mechanisms were characterized using SEM and optical microscopy. In IP-TMF, creep damage originated from casting pores and propagated under mode I. The creep facets were influenced by activated slip systems, while fatigue damage depended on crystal orientation and developed by slipping along different crystallographic planes. In OP-TMF tests, oxidation-assisted cracking was non-crystallographic for all crystal orientations, with the crack growing within the oxidized material.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Materials Science, Multidisciplinary
Zhuangzhuang Mao, Yingbin Zhu, Yao Zhao, Huimin Xie, Yanhong Yang, Yizhou Zhou, Xianfu Huang, Zhanwei Liu
Summary: The high-cycle fatigue failure behavior of nickel-based single crystal alloys with different deviation angles was investigated. The fatigue life decreases as the deviation angle from the [001] orientation increases at 980°C/600 MPa. The fatigue mode is crystallographic fracture, and the dislocation motion is mainly Orowan deformation mechanism. At 980°C/640 MPa, the fatigue life is the longest when the deviation angle is 0° and the shortest when it is 10°. The fatigue failure mode is crystallographic fracture at 0° and 20°, and noncrystallographic fracture at 10°. The dislocation motion is mainly a single dislocation or paired dislocation shearing γ' phase deformation mechanism.
MATERIALS CHARACTERIZATION
(2023)
Article
Engineering, Mechanical
Zhicheng Ge, Guang Xie, Mikael Segersall, Viktor Norman, Zhe Chen, Johan Moverare, Langhong Lou, Jian Zhang
Summary: The deformation mechanisms of a single crystal nickel-base superalloy with and without Ru-doped have been investigated under out-of-phase thermomechanical fatigue. It was found that the Ru-doped alloy exhibits a longer thermomechanical fatigue life and different deformation mechanisms compared to the Ru-free alloy.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Engineering, Mechanical
Piao Li, Wen Jiang, Luca Susmel, Qi-nan Han
Summary: The fatigue limit of nickel-base single crystal (NBSX) at 980 degrees C was experimentally studied. The crack initiation position was found to be casting pores in the single crystal under scanning electron microscope (SEM), and a distinct fish-eye region was observed on the long cycle fatigue fracture surface. The failure mechanism was explored using focused ion beam (FIB) and electron backscatter diffraction (EBSD) techniques.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Mechanical
Dou Xuezheng, Liwu Jiang, Song Jinxia, Wang Dinggang
Summary: This paper studied the low cycle fatigue properties of the DD412 single crystal alloy at 760 degrees C in [001], [011], and [111] orientations. A correlation between low cycle fatigue properties and orientation was found, and the microstructure evolution and fatigue failure mechanism were investigated, providing a solid theoretical foundation for the engineering application of the DD412 single crystal alloy.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Mechanical
Bin Zhang, Rongqiao Wang, Haiyan Liu, Xiaosheng Chen, Dianyin Hu, Kanghe Jiang, Fulei Jing
Summary: The paper develops an anisotropic creep lifetime prediction model based on slip plane damage for nickel-based single crystal superalloys. The model accurately predicts the creep lifetimes of the alloys with different orientations. Additionally, the paper conducts creep experiment and failure analysis on thin-walled specimens, revealing differences in damage mechanisms between the surface and interior. A zone-based failure criteria considering thickness debit effect is proposed. By combining the anisotropic creep lifetime prediction model and the failure criteria, the creep lifetime of DD6 specimens with different thicknesses is predicted with good agreement to experimental results.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2023)
Article
Polymer Science
Hamid El Maanaoui, Jens Meier
Summary: This study extended a fracture mechanical model to incorporate thermal dependence for technical elastomers based on EPDM and NR, reinforced with 50 phr carbon black. The experimental data and calculations showed significant deviation at 23 degrees C, but were within confidence limits at 90 degrees C for both materials. The study also utilized computed tomography to analyze particle size distribution of the compounds.
Article
Engineering, Mechanical
H. Liu, X. M. Wang, Z. N. Zhao, H. T. Li, W. Z. Yang, L. Li
Summary: In this paper, the creep properties of nickel-based single crystal superalloys under the effect of Na2SO4 salt and mixed salts of Na2SO4 and NaCl are investigated. The failure mechanism influenced by the evolution of gamma/gamma' phase and element dissolution is fully discussed. The presence of NaCl and Na2SO4 results in different failure modes, mainly cleavage-like fracture for the specimen deposited with Na2SO4 and mixed mode of cleavage-like plane and tearing ridge for the specimen deposited with mixed salts.
ENGINEERING FAILURE ANALYSIS
(2023)
Article
Engineering, Mechanical
Tianyu Yuan, Min Dou, Lu Liu, Lei Li, Shouyi Sun, Chuanyun Hu
Summary: In this study, fretting fatigue (FF) tests were conducted on a nickel-based single crystal (NBSC) superalloy treated by shot peening (SP) at 600 degrees C. The results showed that the FF lives of the shot-peened specimens were improved by up to 4 times compared to the unpeened ones. This improvement was attributed to the increased dislocation density and hardness caused by shot peening, as well as the maximum compressive residual stresses (CRS) reaching -1016 MPa, which reduced the true stress acting on the fretting contact region and retarded crack initiation and propagation.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Mechanical
Fei Li, Zhixun Wen, Ziyan Wu, Zhenwei Li, Haiqing Pei, Qian Yin, Qianzhu Mao, Zhufeng Yue
Summary: This study investigates the fatigue life prediction of nickel-base single crystal superalloys with different drilling film cooling holes at high temperatures. The study quantifies surface integrity and uses fracture mechanics to analyze the crack initiation mechanism and propagation modes. A new equivalent stress intensity factor is proposed to describe the crack propagation driving force. The results provide valuable insights for predicting fatigue life and guiding engineering practices.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Mechanical
Wen Jiang, Weixing Yao, Piao Li, Peng Luo
Summary: In this study, nine porosity-related fatigue damage parameters were selected for evaluation using a crystal plastic finite element model, revealing that the geometric mean of stress-strain concentration factor was a satisfactory parameter for quantifying the impact of porosity defects on fatigue. Additionally, a method for predicting fatigue life and distinguishing fracture modes based on resolved stress-strain concentration factor was proposed, yielding improved results compared to traditional parameters.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2021)
Article
Engineering, Industrial
M. Long, N. Leriche, N. T. Niane, C. Labergere, H. Badreddine, D. Grange
Summary: A new methodology combining experimentation and modeling is proposed to predict the recrystallization of nickel-based single-crystal superalloy parts after heat treatment. By conducting thermal-mechanical tests and modeling, the occurrence and critical paths of recrystallization can be predicted. This methodology is of great importance for part design and process parameter optimization.
JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
(2022)
