Article
Metallurgy & Metallurgical Engineering
Osamu Umezawa, Weibo Li
Summary: The generation of subsurface fatigue cracks in a groove-rolled and cold-swaged Ti-Fe-O alloy was studied, and the effects of crystallographic texture on crack initiation and growth were discussed. Microcracks were found in beta grains, alpha grains, and at the alpha-beta interface. The presence of {10 (1) over bar0}(alpha) fiber texture hindered the growth of microcracks along the basal plane, but assisted their growth along the prismatic plane or at a {10 (1) over bar0}(alpha) twist boundary. The combination of shear stress and opening stress on {10 (1) over bar0}(alpha) resulted in Mode II or III microcracks and caused crack growth on the prismatic plane in neighboring grains.
ISIJ INTERNATIONAL
(2022)
Article
Nanoscience & Nanotechnology
Motoki Sakaguchi, Yoshinori Niwa, Wenxiang Gong, Keisuke Suzuki, Hirotsugu Inoue
Summary: The study found that at high temperatures, the fatigue crack growth resistance of the triplex microstructure is significantly increased, mainly due to the higher volume fraction of ductile p phase. Meanwhile, the fatigue crack growth threshold in different microstructures and temperatures is almost comparable and shows the same temperature dependency.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Zhihong Wu, Hongchao Kou, Jinshan Li, Nana Chen, Zhicheng Xi, Fan Sun, Frederic Prima
Summary: In this study, low-cycle fatigue tests were conducted on the dual phase titanium alloy Ti-5Al-7.5V at room temperature to investigate the deformation mechanisms and crack initiation. It was found that planar dislocation slip, localized at the basal and prismatic planes of the alpha phase, was the primary deformation mode. Multiple slips occurred simultaneously within a single grain. Microcracks were observed along the basal slip bands, but were confined within the primary alpha grains without propagating to the surrounding transformed beta matrix. The presence of silicides in contact with the microcracks and slip bands did not lead to crack initiation. It remains unclear whether the silicides can act as dislocation sources for planar slips and facilitate crack nucleation.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Nanoscience & Nanotechnology
B. H. Zhang, Z. B. Zhao, Q. J. Wang, J. R. Liu, R. Yang
Summary: The effect of deformation temperatures of 900℃ and 980℃ on the microstructure and crystallographic orientation evolution of Ti60 alloy has been studied. The characterizations of the microstructure and texture after annealing at 1020℃ were examined. The results showed that a fine homogenous bimodal microstructure was observed in the sample deformed at 900℃ after annealing, while a textured microstructure with macrozones was found in the sample deformed at 980℃. The formation of the main transformed α texture was related to the β fiber texture and variant selection influenced by primary α grains.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Engineering, Mechanical
Wencheng Liu, Jia Huang, Jianwen Liu, Xinhua Wu, Kai Zhang, Aijun Huang
Summary: This study investigates the fatigue crack initiation in MTRs using a crystal plasticity model, revealing that crack initiation is mainly attributed to high plastic strain and stress concentrations.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Engineering, Mechanical
C. Bean, J. C. Stinville, A. Nait-Ali, Z. Wu, F. Sun, F. Prima, S. Hemery
Summary: Twist grain boundaries (BTGB) are critical microstructures for fatigue crack initiation in titanium alloys. Different microstructures of Ti-Al-V based alloys were tested in low-cycle fatigue. Early cracking occurred at BTGB in all alloys and microstructures. The weak sensitivity to moderate differences in α and β stabilizers content and microstructural features was observed. Criteria for identifying crack initiation sites were defined. An automatic processing routine was applied to analyze the spatial distribution of BTGB susceptible to cracking. The low associated density implies that large microstructural regions must be considered to include microstructural configurations prone to crack nucleation, which may play a critical role in the high lifetime variability of Ti alloys.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Materials Science, Multidisciplinary
Conghui Liu, Rhys Thomas, Tianzhu Sun, Jack Donoghue, Xun Zhang, Tim L. Burnett, Joao Quinto da Fonseca, Michael Preuss
Summary: In this study, the relationship between plastic slip activity and fatigue crack initiation was investigated in a near-alpha titanium alloy. The findings showed that plasticity at low stress levels was dominated by basal slip and two types of cracking were observed parallel to basal slip traces. Detailed analysis revealed the mechanisms behind the crack initiation, such as out-of-plane Burgers vector activity and crystallographic facet formation. A new parameter was developed based on the geometric factors to predict transgranular surface crack initiation sites.
Article
Materials Science, Multidisciplinary
C. Lavogiez, C. Dureau, Y. Nadot, P. Villechaise, S. Hemery
Summary: The fatigue behavior of Ti-6Al-4V with a bi-modal microstructure was investigated using different waveforms, load ratios, and frequencies. It was found that cracks were initiated along (0001) twist grain boundaries, which is consistent with prior studies. The results also showed that the critical microstructural configurations were not sensitive to environmental factors, free surfaces, loading conditions, and microstructure and composition.
Article
Engineering, Mechanical
Fulin Liu, Haotian Peng, Yongjie Liu, Chong Wang, Qingyuan Wang, Yao Chen
Summary: The fatigue behavior of titanium alloy with different stress ratios was studied at 400 degrees C in the VHCF regime. The initiation of cracks depends on the formation of facets, which is related to the maximum shear stress. The formation of facets is induced by basal or prismatic slips with a high Schmid factor inside alpha(p) grains. The morphology of alpha(p) grains affects the initiation of cracks. High-density geometrically necessary dislocations (GNDs) accumulate along with the slips and form subgrain boundaries (sub-GBs) within alpha(p) grains. With cyclic loading, the created sub-GBs further form facets, initiating microcracks.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Engineering, Mechanical
S. Hemery, J. C. Stinville
Summary: This study monitored the microstructurally small crack growth in Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo with equiaxed and bimodal microstructures. The influence of microstructure on the lifetime variability observed in Ti alloys was evaluated, and primary alpha grains, basal plane cracking, and misalignment across boundaries were identified as key features for high crack growth rates. Dwell periods were found to induce significant small crack acceleration.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Chemistry, Multidisciplinary
B. Fernandez Silva, M. Jackson, K. Fox, B. P. Wynne
Summary: Microtexture heterogeneities, known as macrozones, are commonly found in titanium forgings due to thermomechanical processing, leading to reduced resistance to crack propagation. Efforts have been made to define and characterize macrozones, with the development of a computational tool using MATLAB for automatic macrozone identification based on a conservative approach. The tool allows for the detection of macrozones based on disorientation angle and density-fraction criteria, and has been successfully applied to various microstructures of titanium forgings.
JOURNAL OF APPLIED CRYSTALLOGRAPHY
(2023)
Article
Engineering, Mechanical
Anastasios G. Gavras, Anthony G. Spangenberger, Diana A. Lados
Summary: A study was conducted on the long and small fatigue crack growth mechanisms of various light structural aluminum and titanium alloys, leading to the development of a predictive model for microstructurally controlled small fatigue crack growth behavior, which agrees well with experimental data.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Chemistry, Physical
Jennie Palmer, Jonathan Jones, Mark Whittaker, Steve Williams
Summary: A bespoke TMF crack growth test set-up was developed and validated for this study, and the effects of phasing between mechanical loading and temperature were investigated. The study revealed that TMF cycles may exhibit increased crack growth rate behavior compared to isothermal fatigue. The phase angle of the applied TMF cycle also influenced crack growth behavior, with in-phase (IP) conditions showing faster crack growth rates than out-of-phase (OP) conditions. Propagating cracks interacted with the microstructure of the material, particularly the alpha/beta interfaces within the prior beta grains, and supporting fractography demonstrated subtle differences in fracture mechanisms due to phase angle.
Article
Nanoscience & Nanotechnology
Abdul Khadar Syed, Xiang Zhang, Alec E. Davis, Jacob R. Kennedy, Filomeno Martina, Jialuo Ding, Stewart Williams, Philip B. Prangnell
Summary: The influence of three different deposition strategies on the fatigue crack growth behavior of WAAM Ti-6Al-4V was studied. The oscillation build exhibited the lowest crack growth rates and behaved more similarly to an annealed microstructure compared to the other two deposition strategies.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Construction & Building Technology
Xiaowei Liao, Yuanqing Wang, Liuyang Feng, Huiyong Ban, Yong Chen
Summary: This study investigates the resistance to fatigue crack initiation of Q345qD steel and the effect of low temperatures on its fatigue life, demonstrating an increased resistance and excellent fatigue performance of Q345qD steel under low temperatures. The study proposes the use of plastic strain energy density and fatigue toughness concepts for predicting the fatigue life of Q345qD steel at room and low temperatures.
JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH
(2021)
