Article
Engineering, Mechanical
B. Fernandez Silva, J. Kawalko, K. Muszka, M. Jackson, K. Fox, B. P. Wynne
Summary: This paper investigates the formation and deformation mechanisms of quasi-cleavage facets in dwell fatigue in a bimodal titanium alloy. It identifies basal slip as the critical damage mode leading to dwell fatigue failure and presents a possible criterion for slip transfer.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
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
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
Crystallography
Haodong Rao, Dong Liu, Feng Jin, Nan Lv, Jungang Nan, Haiping Wang, Yanhui Yang, Jianguo Wang
Summary: This paper addresses the development of automated segmentation and quantitative characterization of micro textured regions (MTRs) from complex heterogeneous microstructures. It introduces the use of machine learning methods for segmentation and characterization and validates their accuracy and effectiveness.
Article
Materials Science, Multidisciplinary
Yukimi Tanaka, Koichiro Hattori, Yoshihisa Harada
Summary: The mechanism of cold-dwell fatigue of Ti-6242S and IMI 834 alloys was investigated, and the difference in strain-rate sensitivity between soft and hard grains was found to be related to the concentrations of solid elements and crystal orientation.
MATERIALS CHARACTERIZATION
(2022)
Article
Nanoscience & Nanotechnology
Christos Triantafyllou, Darren C. Pagan, Andrew McBride
Summary: This study used high-energy X-ray diffraction to investigate the evolution of elastic lattice strains in rolled Ti-6Al-4V specimens during cyclic loading. The effects of texture on the micromechanical response were explored by monitoring lattice planes in different orientations. The results showed that under cyclic loading conditions with a dwell period, the elastic strains in prismatic and basal lattice planes increased significantly when the specimen was loaded at 45 degrees from the rolling direction. In the absence of a dwell period, both RD and TD specimen orientations exhibited subtle cyclic hardening in all lattice plane families.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Engineering, Mechanical
Kai-Shang Li, Run-Zi Wang, Lv-Yi Cheng, Ti-Wen Lu, Xian-Cheng Zhang, Shan-Tung Tu, Guo-Dong Zhang, Zhi-Chao Fan
Summary: In this study, a dislocation-based crystal plasticity finite element (CPFE) framework was used to investigate the effects of loading conditions on dwell-fatigue crack initiation life. A life prediction approach based on accumulated energy dissipation at half-life cycle was proposed, and a new three-dimensional damage tolerance diagram was introduced to evaluate the residual dwell fatigue life.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Nanoscience & Nanotechnology
Yaoxin Huo, Zhengguan Lu, Min Cheng, Jinping Fan, Junwei Qiao, Lei Xu, Ruipeng Guo, Rui Yang, P. K. Liaw
Summary: This study presents the first investigation on the dwell-fatigue behavior and damage mechanism of as-HIPed Ti-6Al-4V powder compact. The results show that the peak stress and stress ratio have significant effects on dwell fatigue behavior. A crack-initiation and propagation model based on soft-hard grain pairs has been proposed to explain the dwell-fatigue mechanism.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Review
Materials Science, Multidisciplinary
Zhihong Wu, Hongchao Kou, Nana Chen, Zhicheng Xi, Jiangkun Fan, Bin Tang, Jinshan Li
Summary: This paper reviews the recent advances in dwell fatigue of titanium alloys, with the primary motivation being to understand the dwell fatigue damage mechanism related to microstructural configurations, dislocations, and local strain rate sensitivity.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Engineering, Mechanical
Chenwei Shao, Xinqiang Zhang, Shuo Zhao, Yankun Zhu, Huajie Yang, Yanzhong Tian, Zhenjun Zhang, Peng Zhang, Xianghai An, Zhefeng Zhang
Summary: This study proposes a crack growth model for LCF to enhance the LCF performance of engineering structural materials. By introducing strength gradient architecture and investigating the influences of strength/microstructure, it is found that TWIP steel with negative strength gradient exhibits excellent LCF properties.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Engineering, Mechanical
Yanju Wang, Zhenyu Zhu, Aixue Sha, Wenfeng Hao
Summary: This paper proposes a novel approach for estimating the low cycle fatigue (LCF) life of titanium alloy structural parts based on the continuous damage mechanics (CDM) model. The genetic algorithm-optimized back-propagation artificial neural network (GABP-ANN) accurately predicts the LCF life of titanium alloy structural parts.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Materials Science, Multidisciplinary
Zhichun Zhou, Binbin Jiang, Jianke Qiu, Linglei Zhang, Jiafeng Lei, Rui Yang, Kui Du
Summary: This study investigates the mechanism of crack formation in titanium alloys with lamellar microstructure under low-cycle dwell fatigue. The accumulation of residual dislocations and local tensile stress at the α/β interfaces are found to be the key factors leading to the formation of dwell fatigue cracks.
SCIENCE CHINA-MATERIALS
(2023)
Article
Engineering, Mechanical
Zebang Zheng, Pandi Zhao, Mei Zhan, Songlin Shen, Yuyang Wang, M. W. Fu
Summary: Dwell fatigue failure of titanium alloys has been a long-standing threat to flight safety. Experimental tests in the lab have not fully captured the realistic loading conditions, leading to the neglect of the impact of the rise and fall time on fatigue life. This study uses crystal plasticity models to systematically investigate the effects of rise and fall time on the load shedding behaviors of titanium alloys, and reveals the correlations between load shedding and rise/fall time, as well as the underlying mechanisms.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Engineering, Mechanical
Litton Bhandari, Vidit Gaur
Summary: This study investigates the cyclic behavior and cold dwell sensitivity of additively manufactured Ti6Al4V alloy. Low cycle fatigue tests were conducted on specimens exposed to a dwell period, revealing a significant reduction in fatigue lives at lower strain amplitudes but similar lives at higher ones. Fractographic analysis identified multiple crack initiation regions, attributed to process-induced defects or facet formation in α laths. The study discusses the failure mechanism based on stress redistribution and relaxation.
ENGINEERING FAILURE ANALYSIS
(2023)
Article
Engineering, Mechanical
Yang Liu, Fionn P. E. Dunne
Summary: This study establishes a mechanistic link between macrozones and dwell fatigue damage, and outlines important criteria for the definition of macrozones in titanium alloy Ti-6Al-4V.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Nanoscience & Nanotechnology
Guohua Zhao, Xin Xu, David Dye, Pedro E. J. Rivera-Diaz-del-Castillo, Nik Petrinic
Summary: This study reported a method to deploy transformation-mediated strengthening in titanium alloys by supervised activation of TRIP and TWIP through mechanism-driven modelling, improving the mechanical properties of materials. By developing new alloys, notable resistance to strain localization was achieved, along with significant strain-hardening effects.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
Vassili A. Vorontsov, Thomas P. McAuliffe, Mark C. Hardy, David Dye, Ioannis Bantounas
Summary: The tensile creep performance of a polycrystalline Co/Ni-base superalloy with a multimodal gamma' distribution was studied at 800 degrees C and 300 MPa. The rupture life of the alloy was comparable to that of RR1000 tested under similar conditions. Microstructural examination revealed the presence of continuous gamma' precipitates and M23C6 carbides along the grain boundaries, as well as the coarsening of the secondary gamma' precipitates. Long planar deformation bands, identified as microtwins, were observed along with the depletion of gamma' stabilising elements. The mechanism for precipitate dissolution was suggested to be the Kolbe reordering mechanism.
Article
Engineering, Mechanical
Mengzhen Cao, Yang Liu, Fionn P. E. Dunne
Summary: A comparative study using crystal plasticity finite element modeling reveals that fatigue crack nucleation is highly sensitive to both lack of fusion and gas/keyhole pores in AlSi10Mg material. Lack of fusion pores, in particular, significantly reduces fatigue life at high stress levels.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Materials Science, Multidisciplinary
Kay Song, Hongbing Yu, Phani Karamched, Kenichiro Mizohata, David E. J. Armstrong, Felix Hofmann
Summary: Understanding the mechanisms of plasticity in structural steels is crucial for the operation of next-generation fusion reactors. This study focuses on the deformation behavior of FeCr and aims to differentiate the nucleation process of dislocations for initiating plasticity from their propagation through the material. The results show that the nucleation of dislocations is mainly derived from pre-existing sources and is not significantly affected by the presence of irradiation defects or Cr content.
JOURNAL OF MATERIALS RESEARCH
(2022)
Article
Engineering, Mechanical
Yilun Xu, Daniel S. Balint, Christian Greiner, Daniele Dini
Summary: Discrete dislocation plasticity calculations are used to investigate the response of a single crystal under sliding loading conditions with a rigid sinusoidal asperity contact. The study identifies lattice rotations and stored energy as the key factors causing microstructure change in the dislocation structure. Maps of surface slip initiation and substrate permanent deformation obtained from the calculations suggest ways to optimize the interface and microstructural material properties for different frictional loads.
Article
Materials Science, Multidisciplinary
Abdalrhaman Koko, Elsiddig Elmukashfi, Thorsten H. Becker, Phani S. Karamched, Angus J. Wilkinson, James Marrow
Summary: This study used high angular resolution electron backscatter diffraction to quantify the local elastic field in intragranular slip bands of age-hardened duplex stainless steel, revealing the changes in elastic fields around the tip of slip bands under different loading conditions.
Article
Materials Science, Multidisciplinary
Chris Hardie, Rhys Thomas, Yang Liu, Philipp Frankel, Fionn Dunne
Summary: A classical crystal plasticity formulation based on dislocation slip was extended to include dislocation channelling and strain softening observed in irradiated alloys. The model's performance was evaluated using experimental data on Zircaloy-4, showing good capture of the engineering stress-strain response but sensitivity in simulating characteristic strain heterogeneity.
Article
Engineering, Mechanical
Bjorn Kunzelmann, Pawel Rycerz, Yilun Xu, Nagaraj K. Arakere, Amir Kadiric
Summary: This paper investigates the application of linear elastic fracture mechanics (LEFM) principles in predicting the crack propagation of rolling contact fatigue (RCF) in machine elements such as rolling bearings and gears. Experimental tests are conducted on AISI 52100 bearing steel roller specimens to measure crack propagation rates and establish crack geometry. A numerical finite element model based on LEFM methods is developed to predict stress intensity factors (SIFs) during over-rolling, considering factors such as Hertzian contact stresses, contact friction, and crack face friction. The results show that LEFM can accurately predict the growth of RCF cracks and provide insights into the dominant propagation mode and the effects of crack face friction. The findings contribute to the development of tools for predicting the remaining useful life of machine components, enhancing the reliability of mechanical systems.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Review
Materials Science, Multidisciplinary
T. W. J. Kwok, D. Dye
Summary: Medium Mn steels are emerging third-generation advanced high-strength steels with high strengths, large ductilities, and lower costs compared to their predecessor high Mn TWIP steels. They exhibit TWIP and/or TRIP effects, which contribute to a high strain hardening rate. The current review focuses on the alloy design, processing, microstructure, and property relationships of medium Mn steels, complementing the review by Sun et al. [Physical metallurgy of medium-Mn advanced high-strength steels, Int Mater Rev. 2023.], which primarily discusses phase interfaces and thermodynamics.
INTERNATIONAL MATERIALS REVIEWS
(2023)
Article
Engineering, Mechanical
Xiaoxian Zhang, Fionn P. E. Dunne
Summary: Short crack propagation near a coherent twin boundary in polycrystal nickel alloy is investigated using 3D crystal plasticity extended finite element modelling (CP-XFEM), with experimentally characterised microstructures and crack path observations. The results show that short 3D cracks at coherent twin boundaries grow on parallel (111) slip planes at a very high rate, serving as an intrinsic part of the nucleation process. This is mainly due to the stress states established by twin/parent constraint driven by local elastic anisotropy. Elastic isotropy modelling leads to non-planar and inclined crack growth towards the twin boundary, and the twist angle between the twin and parent phase influences the local stress state, crack morphology, and growth rate deviation from 60 degrees.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Mechanical
S. Lucarini, F. P. E. Dunne, E. Martinez-Paneda
Summary: A novel FFT-based phase-field fracture framework is proposed for modeling fatigue crack initiation and propagation at the microscale. The damage driving force is defined based on stored energy and dislocation density, linking phase-field fracture to microstructural fatigue damage. The formulation is numerically implemented using FFT methods allowing for modeling of large 3D microstructural regions. The simulation predicts crack paths, growth rates, and sensitivity to microstructural features.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Mechanical
Daniel J. Long, Yang Liu, Weifeng Wan
Summary: Short fatigue crack growth in engineering alloys is a significant challenge due to its microstructural sensitivity. A novel mechanistic analytical model using a stored energy density fracture criterion is presented, which achieves full-field implementation in polycrystalline materials. The model demonstrates strong agreement with experimental rates and crack paths in a range of Zircaloy-4 microstructures, capturing growth rate fluctuations and texture sensitivity. This work highlights the benefits of mechanistic analytical modelling for accurate material performance predictions, offering a reduction in computer processing time compared to numerical methods.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Engineering, Mechanical
Chaitanya Paramatmuni, Fionn P. E. Dunne
Summary: This study presents the influence of stress state on the drivers of non-classical twin nucleation in three-point bending of Magnesium alloy AZ31. Deformed microstructures and textures at the tensile and shear regions are investigated in detail. Experimental observations coupled with strain-gradient crystal plasticity analyses reveal that shear nucleates more twins compared to tensile and compressive stress states at near yield-point.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Materials Science, Multidisciplinary
Duncan W. MacLachlan, Vasilis Karamitros, Fionn P. E. Dunne
Summary: This paper proposes an engineering approach to the problem of fatigue crack initiation at the microstructural scale. The initiation of fatigue cracks is broken down into separate processes, and a fundamental approach to modelling these processes has been developed. The method successfully correlates with fatigue data for a specific material.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2023)
Article
Materials Science, Multidisciplinary
Yilun Xu, Felicity F. Worsnop, David Dye, Fionn P. E. Dunne
Summary: The slip intermittency and stress oscillations observed in titanium alloy Ti-7Al-O are investigated using a discrete dislocation plasticity model. The results show that these phenomena are caused by dislocation escape during stress holds, governed by a thermal activation constitutive law. The stress drops due to basal slip are larger than those along prism due to their differing rate sensitivities, which has been previously observed in micropillar testing. It is suggested that interstitial oxygen suppresses stress oscillations by inhibiting the thermal activation process. Understanding these mechanisms is important for the design and safety assessment of jet engine titanium alloys subjected to dwell fatigue.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2023)