Article
Mechanics
Marcos Bergant, Nicolas O. Larrosa, Alejandro Yawny, Mauro Madia
Summary: The role of defects in the fatigue strength of Wire Arc Additively Manufactured (WAAMed) Ti6Al-4V is analyzed using the IBESS model, a fracture mechanics short crack growth approach based on the cyclic R-curve. Pores and crack-like defects are examined, and estimations of the role of pore shape and size align well with published fatigue data. The model is also used to explain the impact of fabrication defects on the scatter of experimental data, highlighting the suitability of short crack growth models for assessing the fatigue of defective AM materials.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Engineering, Mechanical
Marcos Bergant, Tiago Werner, Mauro Madia, Alejandro Yawny, Uwe Zerbst
Summary: This study successfully assessed the fatigue strength of additively manufactured materials using short crack propagation models based on the cyclic R-curve, combined with root area parameter. The estimated S-N curves and Kitagawa-Takahashi diagrams fairly predicted the experimental data, especially the origin of failure from internal or surface defects. These findings suggest that methods based on the cyclic R-curve are appropriate tools for evaluating the fatigue behavior of AM materials.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Engineering, Mechanical
Luke Sheridan
Summary: In this paper, the El-Haddad model is enhanced to include finite life behavior and stress ratio effects. The improved model is validated against literature data and shown to accurately approximate crack growth rate behavior and represent in(finite) fatigue life of experimental components across multiple load ratios and defect sizes.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Mechanics
Wei Zhang, Lindong Chai, Luping Ren, Liang Cai
Summary: A unified model based on CTOD is proposed to calculate the growth rate of physically small crack (PSC) and long crack (LC). Experimental testing and theoretical derivation are used to establish a FCG model considering the small crack effect, and a theoretical equation for the transition crack length is provided. Several datasets of different materials are used for model validation.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Engineering, Mechanical
Sepehr Ghafari, Fereidoon Moghadas Nejad
Summary: J-Resistance curves are powerful tools for characterizing crack propagation trends in materials. The research found that reducing temperature increases crack blunting energy, while the incorporation of crumb rubber can enhance the blunting fraction of R-curves at different temperatures.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Engineering, Mechanical
Olusegun Fatoba, Robert Akid
Summary: The initiation and propagation behavior of cracks emanating from corrosion pits in a high strength low alloy steel were investigated. Fatigue cracks were found to initiate from the mouth of pits due likely to strain localization at this region. Crack initiation lifetime and fatigue endurance decreased with increasing pit depth.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Engineering, Mechanical
H. Y. Jin, G. Z. Wang, J. P. Tan, T. Jin, S. T. Tu
Summary: This study investigates and establishes unified constraint-dependent J-R curve equations considering both geometry and material constraints for accurate structural integrity assessment of dissimilar metal welded joints (DMWJ). The accuracy of the equations is verified through experimental validation, and methods for applying and constructing unified constraint-dependent J-R curves are discussed.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Engineering, Mechanical
Molin Su, Chao Feng, Chentao Peng, Lianyong Xu, Yongdian Han, Lei Zhao
Summary: This study investigated the crack growth behaviors of different materials at room temperature using a unified approach. By considering the influence of the metallic capability, the effect of material factor on crack growth rate was eliminated. The experimental results showed that the metallic crack growth rate was linearly related to the crack tip displacement.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Mechanical
A. Liu, Y. T. Zhang, X. S. Wang, W. Xu, Y. Zhang, Y. H. He
Summary: The influences of stress ratios, temperatures, and local microstructure on the propagation behavior of small fatigue crack in FGH96 superalloy were quantitatively investigated. Increased stress ratios and temperatures led to higher small fatigue crack growth rates. The effects of local microstructure on the restrained ability of small fatigue crack propagation were analyzed, and a critical stress range for small fatigue crack propagation in FGH96 superalloy at different stress ratios was proposed based on an amendatory three-dimensional Kitagawa-Takahashi diagram. These findings can contribute to the fatigue damage tolerance design of FGH96 superalloy components.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Mechanical
Jiacheng Qi, Caiyan Deng, Yong Liu, Baoming Gong, Dongpo Wang
Summary: In this study, the Chapetti cyclic resistance curve is modified using an R-dependence model based on the cyclic strain energy density to account for the effects of mean stress on crack propagation threshold and fatigue limit. As a result, a crack growth model for the modified NASGRO with mechanically short crack extension and Kitagawa-Takahashi diagram are derived with mean stress sensitivity. The modified approach shows good accuracy in predicting near-threshold crack propagation behavior and S-N curves for engineering aluminum alloys and titanium alloys in the high cycle regime.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Mechanics
Guangwei He, Lixun Cai, Chen Bao
Summary: This study presents a semi-analytical method to determine the J-R curves of round bars with elliptical cracks, by developing equations for load, displacement, and J-integral. The validation using finite element analysis shows good agreement between the predicted curves and simulation results. The study also obtains the average J-R curves for surface-cracked round bars using fracture toughness tests and measurements from finite element analysis.
ARCHIVE OF APPLIED MECHANICS
(2023)
Article
Mechanics
Merna Shaheen-Mualim, Guy Kovel, Fouad Atrash, Liron Ben-Bashat-Bergman, Anna Gleizer, Lingyue Ma, Dov Sherman
Summary: We presented a new fracture behavior and properties of brittle materials by combining macro and micro fracture. Macro-scale fracture cleavage experiments of dynamic cracks propagating in brittle single-crystal silicon specimens were conducted to investigate crack's energy-speed relationships and the fine details of the crack front. An atomistic model for bond-breaking mechanisms was developed at the micro-scale. The energy release rate (ERR) at crack initiation and its derivative, as well as the precrack length, played a major role in the novel behavior and properties.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Nanoscience & Nanotechnology
D. Firneis, S. Wurster, V Nikolic, R. Pippan, A. Hohenwarter
Summary: The fracture properties of pure tungsten sheets were tested at different thicknesses and temperatures. Thinner sheets exhibited refined microstructure and increased fracture toughness. The fracture behavior changed from transcrystalline fracture to mixed transcrystalline and delamination fracture as the thickness decreased. The fracture toughness increased significantly at room temperature, but only slightly at 200 degrees C.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Anna Wildeis, Hans-Juergen Christ, Robert Brandt
Summary: The crack initiation and short crack propagation in a martensitic spring steel were studied using in-situ fatigue testing. Slip bands formed early in the fatigue process and served as crack initiation sites. Most of the slip bands and short fatigue cracks were found to initiate at or near prior austenite grain boundaries. The density of the short cracks increased with the number of cycles and the applied stress amplitudes. The prior austenite grain boundaries acted as obstacles to short crack propagation. Compressive residual stresses enhanced the fatigue strength by delaying the transition from short crack propagation to long crack propagation and shifting the crack initiation site from the sample surface to the sample interior.
Article
Mechanics
K. Tanaka, Y. Akiniwa
Summary: A modified strip-yield model is used to simulate plasticity-induced crack closure in the wake of advancing cracks, with different lengths of precracks, under fully reversed loading. Two types of precracks, open and closed, are examined to understand their effects on fatigue thresholds. The results show that the crack opening stress and effective stress intensity range Delta Keff have significant influence on fatigue thresholds, and new master curve equations are proposed for the cyclic R-curve.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Nanoscience & Nanotechnology
Ahmad Mirzaei, Peter D. Hodgson, Xiang Ma, Vanessa K. Peterson, Ehsan Farabi, Gregory S. Rohrer, Hossein Beladi
Summary: This study investigated the influence of parent austenite grain refinement on the intervariant boundary network in a lath martensitic steel. It found that refining the parent austenite grain led to a decrease in the fraction of certain boundaries in the martensite and an increase in the connectivity of low energy boundaries, ultimately improving the impact toughness.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
N. L. Church, C. E. P. Talbot, L. D. Connor, S. Michalik, N. G. Jones
Summary: Metastable beta Ti alloys based on the Ti-Nb system have attracted attention due to their unique properties. However, the unstable cyclic behavior of these alloys has hindered their widespread industrial use. Recent studies have shown that internal stresses, including those from dislocations, may be responsible for this behavior. This study demonstrates that inter-cycle thermal treatments can mitigate the unstable cyclic behavior, providing a significant breakthrough in our understanding of Ti-Nb superelastic materials.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Di Zhao, Chenchen Zhao, Ziyang Xiu, Jiuchun Yan
Summary: This study proposes a novel strategy for achieving the bonding of SiC ceramic and Al alloy using ultrasound. The ultrasound promotes the dissolution of Al into the solder, activating the solder and triggering the interfacial reaction between SiC ceramic and solder. With increasing ultrasonic duration, the bonding between SiC and Al transitions from partial to full metallurgical bonding.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Kang Du, Yang Zhang, Guangda Zhao, Tao Huang, Liyuan Liu, Junpeng Li, Xiyu Wang, Zhongwu Zhang
Summary: This paper systematically investigated the evolution of microstructure in Fe-Ni-Co-Al polycrystalline alloys and its effects on mechanical properties. The results revealed that the migration of grain boundaries in different processes is driven by different factors, which impacts the grain orientation and precipitate formation. In the process of directional recrystallization, grains with specific orientations grow in the grain boundary region and form the dominant orientation, while grains with lower migration rate form the minor orientation. The alloy produced through directional recrystallization exhibited good recoverable strain and superelastic strain, while the alloy produced through solid solution treatment showed no evident superelastic behavior.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Edohamen Awannegbe, Liang Chen, Yue Zhao, Zhijun Qiu, Huijun Li
Summary: This study employed laser metal deposition to additively manufacture Ti-15Mo wt% alloy, and subsequently subjected it to post-fabrication uniaxial thermomechanical processing. The results showed that different zones in the microstructure remained after processing, and deformation mechanisms mainly involved slip and martensite formation. The compressive mechanical properties were found to be dependent on strain rate, with higher flow stress and compressive strength observed at higher strain rates. Grain structure homogenisation was not achieved, leading to anisotropic tensile properties.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Reza Khatib Zadeh Davani, Enyinnaya George Ohaeri, Sandeep Yadav, Jerzy A. Szpunar, Jing Su, Michael Gaudet, Muhammad Rashid, Muhammad Arafin
Summary: This research aims to investigate the effect of roughing and finishing reductions on crystallographic texture. The results show significant heterogeneity in the centerline region, with higher intensity of certain textures. Drop Weight Tear Test indicates that steel specimens with lower and medium reductions exhibit superior low-temperature impact toughness compared to steel with higher reductions. The electrochemical hydrogen charging experiments confirm the presence of internal hydrogen cracks only in steel with lower and medium reductions.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Flavio De Barbieri, Denis Jorge-Badiola, Rodrigo Allende, Karem Tello, Alfredo Artigas, Franco Perazzo, Henry Jami, Juan Perez Ipina
Summary: This study examines the effect of Cr additions on the mechanical behavior of TWIP steel at temperatures ranging from 25°C to 350°C. The results indicate that different temperature-dependent strengthening mechanisms, including mechanical twinning, Dynamic Strain Aging, and slip bands, are at play. The stacking fault energy (SFE) influences the percentage of mechanical twinning, which in turn affects the strain hardening rate.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Hanlin Peng, Siming Huang, Ling Hu, Bingbing Luo, Liejun Li, Ian Baker
Summary: This study explores the weldability, microstructures, and mechanical properties of two L1(2)-nanoparticle-strengthened medium-entropy alloys after electron beam welding (EBW). The results show that strong yet ductile defect-free joints were produced, with larger grain sizes in the fusion zones compared to the heat-affected zones and base materials. Both EBWed MEAs exhibited high yield strengths, high ultimate tensile strengths, and good fracture strains at 77 K. The V-doping improved the cryogenic mechanical properties of the TMT MEA.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Yongxin Wang, Lei Chen, Lizi Shao, Shuo Hao, Motomichi Koyama, Xingzhou Cai, Xiaocong Ma, Miao Jin
Summary: This study investigated the tensile deformation behavior of an Mn-N bearing lean duplex stainless steel with metastable austenite. The results showed that the strain rate had significant influence on the work hardening, strain-induced martensitic transformation, and fracture mechanism.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Jong Woo Won, Seulbi Lee, Hye-Jeong Choe, Yong-Taek Hyun, Dong Won Lee, Jeong Hun Lee
Summary: Cold-rolled pure titanium showed improved sheet formability after undergoing cryogenic-deformation treatment. This treatment increased the thinning capability of the titanium and suppressed cracking during sheet forming. The formation of twins during deformation contributed to high thinning capability and increased strength through grain refinement and dislocation accumulation.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Handong Li, Lin Su, Lijuan Wang, Yanbin Jiang, Jiahui Long, Gaoyong Lin, Zhu Xiao, Yanlin Jia, Zhou Li
Summary: Homogenization heat treatment is a key procedure in controlling the second phase, enhancing composition uniformity, and workability of as-cast Cu-15Ni-8Sn alloy. This study found that electropulsing treatment (EPT) can significantly reduce treatment temperature and time, improve elongation and overall mechanical properties of the alloy.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Yuxuan Wang, Juntao Zou, Lixing Sun, Yunfei Bai, Zhe Zhang, Junsheng Cheng, Lin Shi, Dazhuo Song, Yihui Jiang, Zhiwei Zhang
Summary: A novel mechanical-heat-electricity synergistic method was proposed to enhance the mechanical properties of Cu-15Sn-0.3Ti alloy by forming annealing twins (ATs). The combination method of Rotary swaging (RS) and Electric pulse treatment (EPT) successfully induced recrystallization and refinement of the microstructure, leading to a significant increase in the strength of the alloy within a short time.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Zhiyi Ding, Jiangtao Xie, Tong Wang, Aiying Chen, Bin Gan, Jinchao Song
Summary: This study demonstrated the Ta-induced strengthening of CoCrNi-AlTi MEAs using nanoscale heterogeneous coherent precipitates. The addition of Ta and aging treatments significantly enhanced the mechanical properties of the alloy, including yield strength, ultimate tensile strength, and elongation.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Z. Y. You, Z. Y. Tang, B. Wang, H. W. Zhang, P. Li, L. Zhao, F. B. Chu, H. Ding
Summary: The mechanical properties and microstructural evolution of C-doped TRIP-assisted HEA under dynamic loading conditions were systematically investigated in this study. The results showed that dynamic tensile deformation led to an increase in yield strength and a decrease in ultimate tensile strength, with a trend towards increased total elongation. The primary deformation mechanisms shifted from TRIP and TWIP effects to deformation twinning and dislocations. The presence of carbides formed through C-doping hindered dislocation slip and promoted the activation of multiple twinning systems.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)
Article
Nanoscience & Nanotechnology
Feng Qin, Feihu Chen, Junhua Hou, Wenjun Lu, Shaohua Chen, Jianjun Li
Summary: Plastic instability in strong multilayered composites is completely suppressed by architecting nanoscale BCC Nb crystalline-amorphous CuNb interfaces.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2024)