Pub Date : 2025-12-21DOI: 10.1016/j.ijfatigue.2025.109453
Xiaoming Wang , Yitong Shi , Weijia Dong , Qing He , Boyang An , Bing Yang , Jun Huang , Ping Wang
Significant interactions exist among multiple surface cracks in railheads. This study investigates the competitive propagation behavior of rail surface cracks using the compact tension (CT) tests and a peridynamic (PD) model. Four sets of CT tests for multi-crack propagation were designed with U75V railhead material, and corresponding PD fatigue models were established. Significant shielding effects were observed among cracks during propagation, with the PD model accurately replicating crack propagation paths and fatigue lives from CT tests. A PD model was constructed to simulate the dynamic crack propagation on rail surfaces under rolling wheel loading, revealing significant promotion and suppression effects among cracks dominantly influenced by crack number and spacing. PD-predicted crack branching and coalescence align with field rail damage patterns.
{"title":"Competitive propagation of multiple surface fatigue cracks in railheads: compact tension tests and peridynamic simulations","authors":"Xiaoming Wang , Yitong Shi , Weijia Dong , Qing He , Boyang An , Bing Yang , Jun Huang , Ping Wang","doi":"10.1016/j.ijfatigue.2025.109453","DOIUrl":"10.1016/j.ijfatigue.2025.109453","url":null,"abstract":"<div><div>Significant interactions exist among multiple surface cracks in railheads. This study investigates the competitive propagation behavior of rail surface cracks using the compact tension (CT) tests and a peridynamic (PD) model. Four sets of CT tests for multi-crack propagation were designed with U75V railhead material, and corresponding PD fatigue models were established. Significant shielding effects were observed among cracks during propagation, with the PD model accurately replicating crack propagation paths and fatigue lives from CT tests. A PD model was constructed to simulate the dynamic crack propagation on rail surfaces under rolling wheel loading, revealing significant promotion and suppression effects among cracks dominantly influenced by crack number and spacing. PD-predicted crack branching and coalescence align with field rail damage patterns.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"206 ","pages":"Article 109453"},"PeriodicalIF":6.8,"publicationDate":"2025-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145813860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-21DOI: 10.1016/j.ijfatigue.2025.109452
Raffaele De Biasi , Lorenzo Romanelli , Ciro Santus , Matteo Perini , Filippo Berto , Matteo Benedetti
The industrial sector continues to explore innovative strategies to exploit the full potential of Additive Manufacturing (AM). Among its many advantages, AM enables the fabrication of lattice structures; these are lightweight metamaterials with tunable mechanical properties and excellent energy absorption capabilities. Despite their promise, the widespread industrial use of such structures is limited by the difficulty in accurately assessing their fatigue behavior. This study presents a methodology aimed at predicting the fatigue life of polymer-based lattice components, with a specific focus on PA12 manufactured using the Multi Jet Fusion (MJF) process. This is an industrially relevant technology offering large production volumes, high printing quality and low production costs. The approach begins with fatigue testing of bulk PA12 specimens to establish baseline material behavior. Based on these results, a predictive algorithm is developed to estimate the fatigue performance of lattice structures. The model adopts an energy-based framework inspired by the Average Strain Energy Density (ASED) method, previously used for metallic materials, and adapts it to the characteristics of polymer lattices. The proposed methodology contributes to the development of efficient fatigue assessment tools, supporting the broader adoption of lattice structures in cost-sensitive industrial applications where polymer-based materials are effective.
{"title":"Fatigue life prediction of multi jet fusion-manufactured polyamide12 lattice structures using the average strain energy density method","authors":"Raffaele De Biasi , Lorenzo Romanelli , Ciro Santus , Matteo Perini , Filippo Berto , Matteo Benedetti","doi":"10.1016/j.ijfatigue.2025.109452","DOIUrl":"10.1016/j.ijfatigue.2025.109452","url":null,"abstract":"<div><div>The industrial sector continues to explore innovative strategies to exploit the full potential of Additive Manufacturing (AM). Among its many advantages, AM enables the fabrication of lattice structures; these are lightweight metamaterials with tunable mechanical properties and excellent energy absorption capabilities. Despite their promise, the widespread industrial use of such structures is limited by the difficulty in accurately assessing their fatigue behavior. This study presents a methodology aimed at predicting the fatigue life of polymer-based lattice components, with a specific focus on PA12 manufactured using the Multi Jet Fusion (MJF) process. This is an industrially relevant technology offering large production volumes, high printing quality and low production costs. The approach begins with fatigue testing of bulk PA12 specimens to establish baseline material behavior. Based on these results, a predictive algorithm is developed to estimate the fatigue performance of lattice structures. The model adopts an energy-based framework inspired by the Average Strain Energy Density (ASED) method, previously used for metallic materials, and adapts it to the characteristics of polymer lattices. The proposed methodology contributes to the development of efficient fatigue assessment tools, supporting the broader adoption of lattice structures in cost-sensitive industrial applications where polymer-based materials are effective.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"206 ","pages":"Article 109452"},"PeriodicalIF":6.8,"publicationDate":"2025-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145813861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-21DOI: 10.1016/j.ijfatigue.2025.109448
Zhe Zhang, Bing Yang, Shiqi Zhou, Jinbang Liu, Long Yang, Shoune Xiao, Guangwu Yang, Tao Zhu
To address the fatigue aging of 6005A-T6 aluminum alloy—widely used in rail transit structures—under long-term service, this study investigates its crack growth behavior and remaining useful life (RUL) prediction under different fatigue aging conditions. The simulation covered 4 fatigue aging states, achieved by applying different numbers of pre-fatigue cycles. Compact-tension-shear specimens were tested under mixed-mode I + II fatigue crack growth at 4 loading angles (0°, 30°, 45°, and 60°). Digital image correlation was employed to capture crack tip strain fields for analyzing crack growth behavior. Experimental results show that fatigue aging significantly reduces the material’s resistance to crack growth. While increasing the loading angle suppresses crack growth rate, this suppressive effect is weakened under severe fatigue aging conditions. The antagonistic interplay between fatigue aging and increased loading angle in determining RUL is investigated for the first time. Fractographic analysis reveals that the reduction in fatigue striations and the increase in microcrack formation are the key microstructural mechanisms responsible for the fatigue aging-induced decline in crack resistance. Furthermore, an extended finite element model based on an energy release rate attenuation mechanism was developed. The simulation results show high agreement with experimental data, with a maximum standard deviation of 1.3887 and a maximum life prediction error within 7.5 %. These findings provide theoretical support and technical guidance for service life prediction and failure assessment of aluminum alloy structures.
{"title":"Investigation on fatigue crack growth behavior and remaining useful life prediction of 6005A-T6 aluminum alloy under fatigue aging","authors":"Zhe Zhang, Bing Yang, Shiqi Zhou, Jinbang Liu, Long Yang, Shoune Xiao, Guangwu Yang, Tao Zhu","doi":"10.1016/j.ijfatigue.2025.109448","DOIUrl":"10.1016/j.ijfatigue.2025.109448","url":null,"abstract":"<div><div>To address the fatigue aging of 6005A-T6 aluminum alloy—widely used in rail transit structures—under long-term service, this study investigates its crack growth behavior and remaining useful life (RUL) prediction under different fatigue aging conditions. The simulation covered 4 fatigue aging states, achieved by applying different numbers of pre-fatigue cycles. Compact-tension-shear specimens were tested under mixed-mode I + II fatigue crack growth at 4 loading angles (0°, 30°, 45°, and 60°). Digital image correlation was employed to capture crack tip strain fields for analyzing crack growth behavior. Experimental results show that fatigue aging significantly reduces the material’s resistance to crack growth. While increasing the loading angle suppresses crack growth rate, this suppressive effect is weakened under severe fatigue aging conditions. The antagonistic interplay between fatigue aging and increased loading angle in determining RUL is investigated for the first time. Fractographic analysis reveals that the reduction in fatigue striations and the increase in microcrack formation are the key microstructural mechanisms responsible for the fatigue aging-induced decline in crack resistance. Furthermore, an extended finite element model based on an energy release rate attenuation mechanism was developed. The simulation results show high agreement with experimental data, with a maximum standard deviation of 1.3887 and a maximum life prediction error within 7.5 %. These findings provide theoretical support and technical guidance for service life prediction and failure assessment of aluminum alloy structures.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"206 ","pages":"Article 109448"},"PeriodicalIF":6.8,"publicationDate":"2025-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145813862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-21DOI: 10.1016/j.ijfatigue.2025.109446
Lu Yubin , Wu Zhen
To ensure structural integrity, it is essential to establish an accurate fatigue life prediction model. Traditional regression models are constrained by predefined functional forms, which often neglect the effects of material properties. However, purely data-driven methods require large datasets and exhibit poor extrapolation ability. Therefore, this study develops a novel framework to accurately predict fatigue life using limited testing data. The framework consists of two main parts, namely feature selection and iterative generation-estimation process (IGEP). Based on Pearson correlation coefficient, Variance inflation factors and Shapley additive explanations, the stress level, strength, and stiffness are selected as critical features. The IGEP uniquely integrates two synergistic neural networks, namely a generative model L (mapping stress to life) and an estimated model D (mapping life to stress). Seven neural architectures are evaluated, and then Convolutional Neural Network (CNN) and a combined model including Convolutional Neural Network, Long Short-Term Memory, and Attention module (CNN-LSTM-Attention) are selected to construct L and D, respectively. Models L and D form a closed-loop system that iteratively refines life predictions under the constraint of the fundamental S-N relationship. Compared with experimental data, the predictive accuracy of the IGEP has been verified. Despite the paucity of available experimental data, IGEP can generate reliable fatigue life curves across a wide range of stress levels. Moreover, when applied to stress levels, laminate configurations and material systems beyond those represented in the training data, the IGEP demonstrates robust extrapolation capability. The proposed framework provides a practical and generalizable tool for fatigue life prediction in FRPs under data-limited conditions.
{"title":"A framework for fatigue life prediction of fiber reinforced composites with limited testing data","authors":"Lu Yubin , Wu Zhen","doi":"10.1016/j.ijfatigue.2025.109446","DOIUrl":"10.1016/j.ijfatigue.2025.109446","url":null,"abstract":"<div><div>To ensure structural integrity, it is essential to establish an accurate fatigue life prediction model. Traditional regression models are constrained by predefined functional forms, which often neglect the effects of material properties. However, purely data-driven methods require large datasets and exhibit poor extrapolation ability. Therefore, this study develops a novel framework to accurately predict fatigue life using limited testing data. The framework consists of two main parts, namely feature selection and iterative generation-estimation process (IGEP). Based on Pearson correlation coefficient, Variance inflation factors and Shapley additive explanations, the stress level, strength, and stiffness are selected as critical features. The IGEP uniquely integrates two synergistic neural networks, namely a generative model <em>L</em> (mapping stress to life) and an estimated model <em>D</em> (mapping life to stress). Seven neural architectures are evaluated, and then Convolutional Neural Network (CNN) and a combined model including Convolutional Neural Network, Long Short-Term Memory, and Attention module (CNN-LSTM-Attention) are selected to construct <em>L</em> and <em>D</em>, respectively. Models <em>L</em> and <em>D</em> form a closed-loop system that iteratively refines life predictions under the constraint of the fundamental <em>S</em>-<em>N</em> relationship. Compared with experimental data, the predictive accuracy of the IGEP has been verified. Despite the paucity of available experimental data, IGEP can generate reliable fatigue life curves across a wide range of stress levels. Moreover, when applied to stress levels, laminate configurations and material systems beyond those represented in the training data, the IGEP demonstrates robust extrapolation capability. The proposed framework provides a practical and generalizable tool for fatigue life prediction in FRPs under data-limited conditions.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"206 ","pages":"Article 109446"},"PeriodicalIF":6.8,"publicationDate":"2025-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-20DOI: 10.1016/j.ijfatigue.2025.109444
Yuqi Qiao , Xiaohui Shi , Fengfeng Huo , Minhao Li , Junwei Qiao
In the present study, the fatigue crack growth characteristics of ER8 wheel steel were examined. Five billets with different microstructures were prepared by the hot working process. The correlation between fatigue crack growth rate (da/dN) and stress intensity factor range (ΔK) was derived based on stress-controlled fatigue experiments. Fatigue crack growth paths were analyzed with the assistance of electron backscatter diffraction (EBSD) technology. EBSD analysis revealed that cracks were deflected when encountering high-angle grain boundaries and tend to propagate along low-energy paths, with low-angle grain boundaries being such paths. Finally, based on the tensile property parameters of the materials, two prediction models were established to assess the effect of microstructural morphologies on the fatigue crack growth rate.
{"title":"Study on fatigue crack growth characteristics and microscopic damage evolution of ER8 wheel steel with different microstructures","authors":"Yuqi Qiao , Xiaohui Shi , Fengfeng Huo , Minhao Li , Junwei Qiao","doi":"10.1016/j.ijfatigue.2025.109444","DOIUrl":"10.1016/j.ijfatigue.2025.109444","url":null,"abstract":"<div><div>In the present study, the fatigue crack growth characteristics of ER8 wheel steel were examined. Five billets with different microstructures were prepared by the hot working process. The correlation between fatigue crack growth rate (d<em>a</em>/d<em>N</em>) and stress intensity factor range (Δ<em>K</em>) was derived based on stress-controlled fatigue experiments. Fatigue crack growth paths were analyzed with the assistance of electron backscatter diffraction (EBSD) technology. EBSD analysis revealed that cracks were deflected when encountering high-angle grain boundaries and tend to propagate along low-energy paths, with low-angle grain boundaries being such paths. Finally, based on the tensile property parameters of the materials, two prediction models were established to assess the effect of microstructural morphologies on the fatigue crack growth rate.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"206 ","pages":"Article 109444"},"PeriodicalIF":6.8,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-19DOI: 10.1016/j.ijfatigue.2025.109445
Peng Liu, Haoyuan Li, Hailong Tian, Lai Wei, Yunshenghao Qiu
Dynamic load spectra for electric-drive assemblies are difficult to estimate from road tests because the signals are non-stationary, non-Gaussian, and noisy. We propose a pseudo-damage-constrained data–model fusion framework that reconstructs torque/load histories while preserving rainflow counting and fatigue consistency. The approach combines trend extraction with nonlinear state estimation and an innovation-based adaptive step that enforces pseudo-damage equivalence to the raw signal within a controlled tolerance. Extreme-value fits are used only as tail diagnostics to verify that rare high-load behavior is preserved; they are not involved in cycle counting. On representative road data, the method achieved a Peak–Valley Preservation Rate ≈93% and the lowest weighted-MAPE (26.2%) among EKF, PF, KalmanNet, and LSTM baselines, with clear gains in fatigue-critical mid–high levels and no inflation of the spectrum tail. The results indicate that the proposed framework yields higher-fidelity spectra for durability analysis and test-bench replay while keeping established fatigue rules (four-point rainflow with Goodman correction) unchanged.
{"title":"A pseudo-damage-constrained data–model fusion method for dynamic load spectrum estimation in electric-drive assemblies","authors":"Peng Liu, Haoyuan Li, Hailong Tian, Lai Wei, Yunshenghao Qiu","doi":"10.1016/j.ijfatigue.2025.109445","DOIUrl":"10.1016/j.ijfatigue.2025.109445","url":null,"abstract":"<div><div>Dynamic load spectra for electric-drive assemblies are difficult to estimate from road tests because the signals are non-stationary, non-Gaussian, and noisy. We propose a pseudo-damage-constrained data–model fusion framework that reconstructs torque/load histories while preserving rainflow counting and fatigue consistency. The approach combines trend extraction with nonlinear state estimation and an innovation-based adaptive step that enforces pseudo-damage equivalence to the raw signal within a controlled tolerance. Extreme-value fits are used only as tail diagnostics to verify that rare high-load behavior is preserved; they are not involved in cycle counting. On representative road data, the method achieved a Peak–Valley Preservation Rate ≈93% and the lowest weighted-MAPE (26.2%) among EKF, PF, KalmanNet, and LSTM baselines, with clear gains in fatigue-critical mid–high levels and no inflation of the spectrum tail. The results indicate that the proposed framework yields higher-fidelity spectra for durability analysis and test-bench replay while keeping established fatigue rules (four-point rainflow with Goodman correction) unchanged.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"206 ","pages":"Article 109445"},"PeriodicalIF":6.8,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-18DOI: 10.1016/j.ijfatigue.2025.109451
Lu Zhang
The estimation of fatigue life is vital for ensuring structural durability and safety in engineering applications. To address the limitations of current nonlinear fatigue cumulative damage models, which often overlook the interplay between load sequence and material properties, a novel nonlinear fatigue damage accumulation model is developed in this work. By comprehensively reviewing and analyzing nonlinear action coefficients in prior enhanced models, a new function for the action coefficient is formulated, incorporating three key elements: adjacent stress ratio, material S-N curve slope, and equivalent fatigue damage. The key parameters of the model are determined based on two-level stress test data of multiple materials. Furthermore, using fatigue test data of various metal materials under two-level to five-level stress spectra, the prediction accuracy of the new model is compared and verified against 8 typical models. The results show that the new model exhibits better adaptability and prediction accuracy under different stress levels and load sequences, demonstrating good potential for engineering applications.
{"title":"Novel nonlinear fatigue damage model based on dynamic action coefficient with three factors","authors":"Lu Zhang","doi":"10.1016/j.ijfatigue.2025.109451","DOIUrl":"10.1016/j.ijfatigue.2025.109451","url":null,"abstract":"<div><div>The estimation of fatigue life is vital for ensuring structural durability and safety in engineering applications. To address the limitations of current nonlinear fatigue cumulative damage models, which often overlook the interplay between load sequence and material properties, a novel nonlinear fatigue damage accumulation model is developed in this work. By comprehensively reviewing and analyzing nonlinear action coefficients in prior enhanced models, a new function for the action coefficient is formulated, incorporating three key elements: adjacent stress ratio, material S-N curve slope, and equivalent fatigue damage. The key parameters of the model are determined based on two-level stress test data of multiple materials. Furthermore, using fatigue test data of various metal materials under two-level to five-level stress spectra, the prediction accuracy of the new model is compared and verified against 8 typical models. The results show that the new model exhibits better adaptability and prediction accuracy under different stress levels and load sequences, demonstrating good potential for engineering applications.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"206 ","pages":"Article 109451"},"PeriodicalIF":6.8,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-18DOI: 10.1016/j.ijfatigue.2025.109428
J. Arun, T.G. Ansalam Raj, K.E. Reby Roy, S. Suresh
{"title":"Corrigendum to “Fatigue life, distortion behavior of AA 8011–nano B4C composite using simulated acoustic emission technique – An experimental and statistical appraisal”. [Int. J. Fatigue 164 (2022) 107168]","authors":"J. Arun, T.G. Ansalam Raj, K.E. Reby Roy, S. Suresh","doi":"10.1016/j.ijfatigue.2025.109428","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2025.109428","url":null,"abstract":"","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"27 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-18DOI: 10.1016/j.ijfatigue.2025.109441
Rui Li , Zhiyuan Jia , Zhandong Wang , Peng Zhang , Guifang Sun , En-Hou Han
In this study, a modified GH4169 superalloy was designed via computational alloying and designated as GH4169-CoZr. Account is taken of the high-temperature fatigue behavior. Specimens of the GH4169-CoZr superalloy were produced via laser directed energy deposition (DED), and their properties were compared to those of the DED GH4169 specimens. Thermodynamic calculation, microstructural characterization, and high-temperature fatigue testing are used to assess the fatigue behavior of additively manufactured counterparts. The DED GH4169-CoZr alloy exhibited superior fatigue performance under various stresses below 845 MPa, which is attributed to its optimized microstructure. This includes: (1) striped γ′/γ′′ precipitates with an average length of 25 nm, a width of 7 nm, and a volume fraction of 30 %, which strengthen the γ matrix; (2) a reduced content of Laves phase, which minimizes brittle intermetallic sites; and (3) trace enrichment of Zr that improves grain boundary (GB) toughness. While both superalloys failed predominantly from the surface, the DED GH4169 exhibited distinct intergranular cracking characteristics. The strengthening mechanisms were further elucidated by multi-scale simulations: molecular dynamics (MD) revealed that the striped precipitates offer stronger resistance to dislocation movement than spherical ones, thereby reducing dislocation sliding and climbing. First-principles calculations indicated that Zr segregation at grain boundaries enhances their binding strength and thermodynamic stability. This advancement enhances crack resistance by coupling the effect of strength and toughness, broadening the scope of composition design and microstructure concepts for future superalloy development.
{"title":"Synergistic effects of γ’/γ’’ precipitates and grain boundary engineering on high-temperature fatigue behavior in GH4169-CoZr superalloys: Multiscale mechanisms","authors":"Rui Li , Zhiyuan Jia , Zhandong Wang , Peng Zhang , Guifang Sun , En-Hou Han","doi":"10.1016/j.ijfatigue.2025.109441","DOIUrl":"10.1016/j.ijfatigue.2025.109441","url":null,"abstract":"<div><div>In this study, a modified GH4169 superalloy was designed via computational alloying and designated as GH4169-CoZr. Account is taken of the high-temperature fatigue behavior. Specimens of the GH4169-CoZr superalloy were produced via laser directed energy deposition (DED), and their properties were compared to those of the DED GH4169 specimens. Thermodynamic calculation, microstructural characterization, and high-temperature fatigue testing are used to assess the fatigue behavior of additively manufactured counterparts. The DED GH4169-CoZr alloy exhibited superior fatigue performance under various stresses below 845 MPa, which is attributed to its optimized microstructure. This includes: (1) striped γ′/γ′′ precipitates with an average length of 25 nm, a width of 7 nm, and a volume fraction of 30 %, which strengthen the γ matrix; (2) a reduced content of Laves phase, which minimizes brittle intermetallic sites; and (3) trace enrichment of Zr that improves grain boundary (GB) toughness. While both superalloys failed predominantly from the surface, the DED GH4169 exhibited distinct intergranular cracking characteristics. The strengthening mechanisms were further elucidated by multi-scale simulations: molecular dynamics (MD) revealed that the striped precipitates offer stronger resistance to dislocation movement than spherical ones, thereby reducing dislocation sliding and climbing. First-principles calculations indicated that Zr segregation at grain boundaries enhances their binding strength and thermodynamic stability. This advancement enhances crack resistance by coupling the effect of strength and toughness, broadening the scope of composition design and microstructure concepts for future superalloy development.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"206 ","pages":"Article 109441"},"PeriodicalIF":6.8,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-18DOI: 10.1016/j.ijfatigue.2025.109450
M. Niewczas , F.G. Basmaji , A. Kula
The stress-controlled fatigue of dissimilar friction stir welded AZ80/AZ61 and AZ80/AZ31 magnesium alloy joints was studied. Fatigue testing targeting the critical stir zone — base metal interface revealed endurance limits of 90 MPa for AZ80/AZ61 welds and 70 MPa for AZ80/AZ31 welds. Within the range 60–90 mm/min, welding speed did not affect the endurance limits, though lower speeds produced more homogeneous microstructures and reduced data scatter in AZ80/AZ61 joints. The superior fatigue resistance of AZ80/AZ61 welds is attributed to their stronger and more plastically uniform microstructure, which supports higher stress levels and sustains more cycles before crack nucleation. Cyclic stress–strain analysis shows that AZ80/AZ31 joints exhibit higher hardening rates under cyclic loading compared to AZ80/AZ61 joints, however, both joint types demonstrate significantly reduced hardening compared to monotonic tensile deformation. This behaviour is attributed to low plastic strains during cycling, texture effects inhibiting basal slip, and reversible twinning–detwinning mechanisms. Electron backscatter diffraction analysis revealed substantial texture evolution in the stir zone (SZ), thermomechanically affected (TMAZ) and heat-affected zones (HAZ), with mechanical twinning contributing to grain refinement and mechanical anisotropy. Transmission electron microscopy revealed a complex fatigue dislocation microstructure characterized by networks of basal and non-basal dislocations, with fine dislocation loops and debris present at all stress amplitudes. The density of these defects increased systematically with stress amplitude, providing insight into the cyclic deformation mechanisms governing fatigue life.
{"title":"Microstructure, texture and fatigue performance of friction stir welded dissimilar magnesium alloy joints","authors":"M. Niewczas , F.G. Basmaji , A. Kula","doi":"10.1016/j.ijfatigue.2025.109450","DOIUrl":"10.1016/j.ijfatigue.2025.109450","url":null,"abstract":"<div><div>The stress-controlled fatigue of dissimilar friction stir welded AZ80/AZ61 and AZ80/AZ31 magnesium alloy joints was studied. Fatigue testing targeting the critical stir zone — base metal interface revealed endurance limits of 90 MPa for AZ80/AZ61 welds and 70 MPa for AZ80/AZ31 welds. Within the range 60–90 mm/min, welding speed did not affect the endurance limits, though lower speeds produced more homogeneous microstructures and reduced data scatter in AZ80/AZ61 joints. The superior fatigue resistance of AZ80/AZ61 welds is attributed to their stronger and more plastically uniform microstructure, which supports higher stress levels and sustains more cycles before crack nucleation. Cyclic stress–strain analysis shows that AZ80/AZ31 joints exhibit higher hardening rates under cyclic loading compared to AZ80/AZ61 joints, however, both joint types demonstrate significantly reduced hardening compared to monotonic tensile deformation. This behaviour is attributed to low plastic strains during cycling, texture effects inhibiting basal slip, and reversible twinning–detwinning mechanisms. Electron backscatter diffraction analysis revealed substantial texture evolution in the stir zone (SZ), thermomechanically affected (TMAZ) and heat-affected zones (HAZ), with mechanical twinning contributing to grain refinement and mechanical anisotropy. Transmission electron microscopy revealed a complex fatigue dislocation microstructure characterized by networks of basal and non-basal dislocations, with fine dislocation loops and debris present at all stress amplitudes. The density of these defects increased systematically with stress amplitude, providing insight into the cyclic deformation mechanisms governing fatigue life.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"207 ","pages":"Article 109450"},"PeriodicalIF":6.8,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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