Pub Date : 2024-12-04DOI: 10.1016/j.ijfatigue.2024.108749
Jian Zhan, Alain Nussbaumer, Eugen Brühwiler
This paper investigates the high cycle tensile fatigue behavior of steel rebar reinforced − UHPFRC elements, at a fatigue load ratio, i.e., R-ratio of 0.3, representative for structural applications. Prior to testing, magnetoscopy is conducted on each specimen to determine the local fiber orientation and volume inside UHPFRC. During testing, global specimen deformation is recorded by displacement transducers; specimen surface is monitored by digital image correlation; and strain along rebars inside the specimen is measured by fiber-optic sensors. Based on the test results, an S-N diagram with a high regression coefficient is obtained. Hereby, the normalized fatigue force S is defined as the ratio between the maximum fatigue force and the estimated specimen ultimate tensile resistance. The fatigue endurance limit is identified as being about S = 0.40. It is found that fatigue deformation of the specimen mainly occurs in the zones with low fiber orientation coefficient μ0,y of UHPFRC (μ0,y decreases when average angle between fiber axis and principle tensile direction changes from 0° to 90°), where the strain along steel rebars also have their higher value and increase rates during fatigue testing. The lowest UHPFRC fiber orientation determines the locus of crack localization and of fatigue fracture of steel rebars, thus final fracture of the elements.
{"title":"High cycle tensile fatigue behavior of steel rebar reinforced - UHPFRC at high R-ratio","authors":"Jian Zhan, Alain Nussbaumer, Eugen Brühwiler","doi":"10.1016/j.ijfatigue.2024.108749","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2024.108749","url":null,"abstract":"This paper investigates the high cycle tensile fatigue behavior of steel rebar reinforced − UHPFRC elements, at a fatigue load ratio, i.e., R-ratio of 0.3, representative for structural applications. Prior to testing, magnetoscopy is conducted on each specimen to determine the local fiber orientation and volume inside UHPFRC. During testing, global specimen deformation is recorded by displacement transducers; specimen surface is monitored by digital image correlation; and strain along rebars inside the specimen is measured by fiber-optic sensors. Based on the test results, an S-N diagram with a high regression coefficient is obtained. Hereby, the normalized fatigue force S is defined as the ratio between the maximum fatigue force and the estimated specimen ultimate tensile resistance. The fatigue endurance limit is identified as being about S = 0.40. It is found that fatigue deformation of the specimen mainly occurs in the zones with low fiber orientation coefficient <mml:math altimg=\"si8.svg\"><mml:msub><mml:mi>μ</mml:mi><mml:mrow><mml:mn>0</mml:mn><mml:mo>,</mml:mo><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:math> of UHPFRC (<mml:math altimg=\"si8.svg\"><mml:msub><mml:mi>μ</mml:mi><mml:mrow><mml:mn>0</mml:mn><mml:mo>,</mml:mo><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:math> decreases when average angle between fiber axis and principle tensile direction changes from 0° to 90°), where the strain along steel rebars also have their higher value and increase rates during fatigue testing. The lowest UHPFRC fiber orientation determines the locus of crack localization and of fatigue fracture of steel rebars, thus final fracture of the elements.","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"28 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793439","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 : 2024-12-04DOI: 10.1016/j.ijfatigue.2024.108757
Xiaodong Liu, Kai Huang, Jindi Zhou, Xiaojian Han, Erqin Dong, Li Zhang, Licheng Guo
To investigate the temperature effect on the fatigue performance of plain-woven composites, a multi-information fusion method for damage identification under high-temperature conditions was established by integrating acoustic emission (AE), digital image correlation (DIC), infrared thermography (IRT) and scanning electron microscopy (SEM). Equipment for high-temperature AE and DIC acquisition was developed, and fatigue experiments were conducted at room temperature (25 °C), 100 °C, and 150 °C with in-situ observation. The AE data were classified into three clusters using the k-means++ method, corresponding to three damage modes with specific peak frequency ranges: matrix cracking (0 ∼ 200 kHz), fiber/matrix debonding (200 ∼ 400 kHz), and fiber breakage (400 ∼ 700 kHz), respectively. The AE results were cross-validated by analyzing surface temperature and strain fields during the fatigue process. The study revealed that higher temperatures accelerate damage accumulation during fatigue, relieve stress concentration and alter the damage proportion, but have little effect on the influence of fatigue stress levels.
{"title":"Temperature effects on fatigue properties of plain-woven composites by an acoustic-optical-thermal multi-information fusion method","authors":"Xiaodong Liu, Kai Huang, Jindi Zhou, Xiaojian Han, Erqin Dong, Li Zhang, Licheng Guo","doi":"10.1016/j.ijfatigue.2024.108757","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2024.108757","url":null,"abstract":"To investigate the temperature effect on the fatigue performance of plain-woven composites, a multi-information fusion method for damage identification under high-temperature conditions was established by integrating acoustic emission (AE), digital image correlation (DIC), infrared thermography (IRT) and scanning electron microscopy (SEM). Equipment for high-temperature AE and DIC acquisition was developed, and fatigue experiments were conducted at room temperature (25 °C), 100 °C, and 150 °C with <ce:italic>in-situ</ce:italic> observation. The AE data were classified into three clusters using the k-means++ method, corresponding to three damage modes with specific peak frequency ranges: matrix cracking (0 ∼ 200 kHz), fiber/matrix debonding (200 ∼ 400 kHz), and fiber breakage (400 ∼ 700 kHz), respectively. The AE results were cross-validated by analyzing surface temperature and strain fields during the fatigue process. The study revealed that higher temperatures accelerate damage accumulation during fatigue, relieve stress concentration and alter the damage proportion, but have little effect on the influence of fatigue stress levels.","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"30 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142825403","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 : 2024-12-04DOI: 10.1016/j.ijfatigue.2024.108750
Mehmet F. Yaren, Luca Susmel
This study presents a novel approach to predict the fatigue life of plain and notched polylactide (PLA) components 3D-printed with different in-fill levels. The proposed method models 3D-printed PLA with manufacturing voids as a continuous, homogeneous, linear-elastic, isotropic material weakened by equivalent cracks that scale with the size of the voids. This allows for accurate estimation of both plain material strength and notched component fatigue life, considering various in-fill levels.
{"title":"A novel critical distance-based homogenised material approach to estimate fatigue lifetime of plain/notched polylactide 3D-printed with different in-fill levels","authors":"Mehmet F. Yaren, Luca Susmel","doi":"10.1016/j.ijfatigue.2024.108750","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2024.108750","url":null,"abstract":"This study presents a novel approach to predict the fatigue life of plain and notched polylactide (PLA) components 3D-printed with different in-fill levels. The proposed method models 3D-printed PLA with manufacturing voids as a continuous, homogeneous, linear-elastic, isotropic material weakened by equivalent cracks that scale with the size of the voids. This allows for accurate estimation of both plain material strength and notched component fatigue life, considering various in-fill levels.","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"83 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793438","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 : 2024-12-03DOI: 10.1016/j.ijfatigue.2024.108729
Louis Hébrard, Thierry Palin-Luc, Nicolas Ranc, Arnaud Weck, Thierry Douillard, Nicholas Blanchard, Sylvain Dancette, Jean-Yves Buffiere
Ultrasonic fully reversed tension fatigue tests have been performed in the Very High Cycle Fatigue (VHCF) regime (NR>107−108cycles) on Ti-6Al4V specimens containing a controlled internal notch. Two sets of samples have been used. The first one contains a central chimney along the specimen longitudinal axis which brings air to the internal notch; in the second series the notches are not connected to the surface. The microstructure present below the fracture surface of the broken specimens has been studied by electron microscopy (EBSD, TKD and TEM). The formation of nanograins and nanovoids was observed below the surface of the cracks growing in a vacuum environment but not below the surface of cracks connected with ambient air. In the latter case extensive striations were observed. Below each striation the formation of tensile {101̄2} twins was observed.
{"title":"Deformation mechanisms at the tip of internal fatigue cracks in vacuum and in the presence of an air environment in a Ti alloy","authors":"Louis Hébrard, Thierry Palin-Luc, Nicolas Ranc, Arnaud Weck, Thierry Douillard, Nicholas Blanchard, Sylvain Dancette, Jean-Yves Buffiere","doi":"10.1016/j.ijfatigue.2024.108729","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2024.108729","url":null,"abstract":"Ultrasonic fully reversed tension fatigue tests have been performed in the Very High Cycle Fatigue (VHCF) regime (<mml:math altimg=\"si3.svg\" display=\"inline\"><mml:mrow><mml:msub><mml:mrow><mml:mi>N</mml:mi></mml:mrow><mml:mrow><mml:mi>R</mml:mi></mml:mrow></mml:msub><mml:mo linebreak=\"goodbreak\" linebreakstyle=\"after\">></mml:mo><mml:mn>1</mml:mn><mml:msup><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msup><mml:mo linebreak=\"goodbreak\" linebreakstyle=\"after\">−</mml:mo><mml:mn>1</mml:mn><mml:msup><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mn>8</mml:mn></mml:mrow></mml:msup><mml:mspace width=\"1em\"></mml:mspace><mml:mi>c</mml:mi><mml:mi>y</mml:mi><mml:mi>c</mml:mi><mml:mi>l</mml:mi><mml:mi>e</mml:mi><mml:mi>s</mml:mi></mml:mrow></mml:math>) on Ti-6Al4V specimens containing a controlled internal notch. Two sets of samples have been used. The first one contains a central chimney along the specimen longitudinal axis which brings air to the internal notch; in the second series the notches are not connected to the surface. The microstructure present below the fracture surface of the broken specimens has been studied by electron microscopy (EBSD, TKD and TEM). The formation of nanograins and nanovoids was observed below the surface of the cracks growing in a vacuum environment but not below the surface of cracks connected with ambient air. In the latter case extensive striations were observed. Below each striation the formation of tensile {10<mml:math altimg=\"si4.svg\" display=\"inline\"><mml:mover accent=\"true\"><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>̄</mml:mo></mml:mrow></mml:mover></mml:math>2} twins was observed.","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"28 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793440","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 : 2024-12-02DOI: 10.1016/j.ijfatigue.2024.108747
Jin-Yang Zhang, Jun Zhang
Uniaxial and biaxial multi-path cyclic loading experiments were carried out using the plate dumbbell-shaped specimens and the cruciform-shaped specimens prepared by silane-modified polyurethane adhesive, respectively. The uniaxial testing results showed that the stress–strain curve of the material was nonlinear, and its mechanical properties were viscoelastic. The adhesive exhibited cyclic softening and cyclic strain increase (cyclic creep and cyclic strain accumulation) under the tensile cyclic loading. The biaxial multi-path testing results showed that the non-proportional loading path caused additional ratcheting strain, which was related to different loading paths. According to the experimental observation, a uniaxial cyclic constitutive model was proposed. Furthermore, a biaxial cyclic constitutive model of the material was developed by introducing the loading path coefficient. By comparing the model prediction results with the experimental data, it was shown that the evolution of ratcheting strain and cyclic softening of the material under uniaxial cyclic loading was accurately described using the proposed model. Also, the biaxial cyclic constitutive model can well predict the mechanical behaviors of silane-modified polyurethane adhesive under biaxial multi-path cyclic loading.
{"title":"Investigation on the ratcheting strain and cyclic softening of viscoelastic soft adhesive under uniaxial and biaxial cyclic loadings","authors":"Jin-Yang Zhang, Jun Zhang","doi":"10.1016/j.ijfatigue.2024.108747","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2024.108747","url":null,"abstract":"Uniaxial and biaxial multi-path cyclic loading experiments were carried out using the plate dumbbell-shaped specimens and the cruciform-shaped specimens prepared by silane-modified polyurethane adhesive, respectively. The uniaxial testing results showed that the stress–strain curve of the material was nonlinear, and its mechanical properties were viscoelastic. The adhesive exhibited cyclic softening and cyclic strain increase (cyclic creep and cyclic strain accumulation) under the tensile cyclic loading. The biaxial multi-path testing results showed that the non-proportional loading path caused additional ratcheting strain, which was related to different loading paths. According to the experimental observation, a uniaxial cyclic constitutive model was proposed. Furthermore, a biaxial cyclic constitutive model of the material was developed by introducing the loading path coefficient. By comparing the model prediction results with the experimental data, it was shown that the evolution of ratcheting strain and cyclic softening of the material under uniaxial cyclic loading was accurately described using the proposed model. Also, the biaxial cyclic constitutive model can well predict the mechanical behaviors of silane-modified polyurethane adhesive under biaxial multi-path cyclic loading.","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"20 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793441","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 : 2024-12-02DOI: 10.1016/j.ijfatigue.2024.108748
Kangkai Song, Conghui Zhang, Wenguang Zhu, Tongguang Zhai, Xiangkang Zeng, Xuan Zhou, Zhuohang Xie, Jin Tian
Pressure tubes of Zr-2.5Nb alloy in Pressurized Heavy Water Reactors experience low cycle fatigue (LCF) due to cooling water flow and power fluctuations, which could be a factor destroying their structural integrity. Therefore, it is essential to systematically investigate their LCF properties and develop accurate life prediction models. Existing research primarily focuses on single-phase Zr alloys, leaving a gap in understanding the fatigue behavior and microstructural evolution of the dual-phase Zr-2.5Nb alloy. This study addressed these gaps by conducting LCF tests on the Zr-2.5Nb alloy under strain amplitudes ranging from ± 0.50 % to ± 1.5 % at room temperature. The results indicated that the cyclic response can be divided into three stages (Ⅰ, Ⅱ, Ⅲ) based on the relative number of cycles. Cyclic softening/hardening originated from microstructural changes such as dislocation sub-structure, grain rotation, and texture evolution. A novel fatigue life prediction model was proposed based on the plastic work of back stress. For non-Masing materials, this model overcame the limitations of traditional plastic strain energy models and demonstrated higher prediction accuracy. This work contributes to a more accurate prediction of fatigue life in Zr alloys and provides new insights into their fatigue behavior and microstructure evolution under LCF conditions.
{"title":"Low cycle fatigue properties and life prediction based on plastic work of back stress in a Zr-2.5Nb alloy","authors":"Kangkai Song, Conghui Zhang, Wenguang Zhu, Tongguang Zhai, Xiangkang Zeng, Xuan Zhou, Zhuohang Xie, Jin Tian","doi":"10.1016/j.ijfatigue.2024.108748","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2024.108748","url":null,"abstract":"Pressure tubes of Zr-2.5Nb alloy in Pressurized Heavy Water Reactors experience low cycle fatigue (LCF) due to cooling water flow and power fluctuations, which could be a factor destroying their structural integrity. Therefore, it is essential to systematically investigate their LCF properties and develop accurate life prediction models. Existing research primarily focuses on single-phase Zr alloys, leaving a gap in understanding the fatigue behavior and microstructural evolution of the dual-phase Zr-2.5Nb alloy. This study addressed these gaps by conducting LCF tests on the Zr-2.5Nb alloy under strain amplitudes ranging from ± 0.50 % to ± 1.5 % at room temperature. The results indicated that the cyclic response can be divided into three stages (Ⅰ, Ⅱ, Ⅲ) based on the relative number of cycles. Cyclic softening/hardening originated from microstructural changes such as dislocation sub-structure, grain rotation, and texture evolution. A novel fatigue life prediction model was proposed based on the plastic work of back stress. For non-Masing materials, this model overcame the limitations of traditional plastic strain energy models and demonstrated higher prediction accuracy. This work contributes to a more accurate prediction of fatigue life in Zr alloys and provides new insights into their fatigue behavior and microstructure evolution under LCF conditions.","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"20 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793724","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 : 2024-12-01DOI: 10.1016/j.ijfatigue.2024.108746
Cheng Zhong, Peng Liu, Xuechong Ren, Benli Luan, Alex A. Volinsky
Single-layer and double-layer Inconel 625 coatings were deposited on the Q235 steel using high-speed laser direct energy deposition (HL-DED). Steel grains in heat-affected zone (HAZ) coarsened due to the heat generated during the single-layer coating deposition. In contrast, double-layer coating specimens exhibited fine-grain regions in the HAZ due to repeated laser treatment reaching the solid-state phase transition temperature. Compared to bare Q235 steel, the yield and ultimate tensile strength of the single-layer coated specimens increased by 25% and 21%, respectively, while their elongation decreased by 32%. Tensile strength increased, while elongation decreased with the coating thickness. Although fatigue performance of bulk HL-DED Inconel 625 and as-deposited coating specimens was lower than bare Q235 steel, polished coated specimens exhibited better fatigue performance than bare Q235 steel. The coating thickness in the as-deposited condition had minimal impact on fatigue performance, but the fatigue performance of the polished coated specimens decreased with coating thickness. Corrosion fatigue life of the single-layer coated specimens in a 3.5% NaCl solution was three times better than bare Q235, and the fatigue life of double-layer coated specimens is not affected by the corrosive environment.
{"title":"Effect of Inconel 625 coating via high-speed laser direct energy deposition on the fatigue characteristics of Q235 steel","authors":"Cheng Zhong, Peng Liu, Xuechong Ren, Benli Luan, Alex A. Volinsky","doi":"10.1016/j.ijfatigue.2024.108746","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2024.108746","url":null,"abstract":"Single-layer and double-layer Inconel 625 coatings were deposited on the Q235 steel using high-speed laser direct energy deposition (HL-DED). Steel grains in heat-affected zone (HAZ) coarsened due to the heat generated during the single-layer coating deposition. In contrast, double-layer coating specimens exhibited fine-grain regions in the HAZ due to repeated laser treatment reaching the solid-state phase transition temperature. Compared to bare Q235 steel, the yield and ultimate tensile strength of the single-layer coated specimens increased by 25% and 21%, respectively, while their elongation decreased by 32%. Tensile strength increased, while elongation decreased with the coating thickness. Although fatigue performance of bulk HL-DED Inconel 625 and as-deposited coating specimens was lower than bare Q235 steel, polished coated specimens exhibited better fatigue performance than bare Q235 steel. The coating thickness in the as-deposited condition had minimal impact on fatigue performance, but the fatigue performance of the polished coated specimens decreased with coating thickness. Corrosion fatigue life of the single-layer coated specimens in a 3.5% NaCl solution was three times better than bare Q235, and the fatigue life of double-layer coated specimens is not affected by the corrosive environment.","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"120 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142825404","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 : 2024-11-30DOI: 10.1016/j.ijfatigue.2024.108738
Shawkat I. Shakil, Wiktor Bednarczyk, Marta Gajewska, Zaynab Mahbooba, Ankit Saharan, Andrea Tridello, Davide S. Paolino, Meysam Haghshenas
This study investigates the fully reversed force-controlled fatigue response of a newly developed laser powder bed fused (LPBF) Al-Mg-Zr-Mn alloy (EOS Al5X1) in the post-aged condition. The fatigue behavior revealed a defect-driven response with a fatigue strength of approximately 140 MPa at 5 million cycles. Comprehensive microstructural analyses, including grain size, texture, and precipitate characterization, were performed using advanced microscopy techniques. Additionally, X-ray computed micro-tomography (XCT) was employed to assess defect size and distribution, yielding a relative density of 99.93 %. Fracture surfaces of all fatigue-failed specimens were examined using optical and scanning electron microscopy to determine the primary failure mechanisms, with a focus on distinguishing between defect-driven and microstructural causes. The results indicated that nearly all specimens, tested across seven stress levels, exhibited crack initiation from process-induced volumetric defects, such as pores and lack of fusion. At lower stress levels (up to 195 MPa), single crack initiation sites driven by defects were identified at either surface or subsurface locations. In contrast, at higher stress levels (234 to 351 MPa), multiple crack initiation sites were observed, also at the surface or subsurface.
{"title":"Fatigue characteristics of a newly developed laser powder bed fused scandium-free Al-Mg-Zr-Mn alloy","authors":"Shawkat I. Shakil, Wiktor Bednarczyk, Marta Gajewska, Zaynab Mahbooba, Ankit Saharan, Andrea Tridello, Davide S. Paolino, Meysam Haghshenas","doi":"10.1016/j.ijfatigue.2024.108738","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2024.108738","url":null,"abstract":"This study investigates the fully reversed force-controlled fatigue response of a newly developed laser powder bed fused (LPBF) Al-Mg-Zr-Mn alloy (EOS Al5X1) in the post-aged condition. The fatigue behavior revealed a defect-driven response with a fatigue strength of approximately 140 MPa at 5 million cycles. Comprehensive microstructural analyses, including grain size, texture, and precipitate characterization, were performed using advanced microscopy techniques. Additionally, X-ray computed micro-tomography (XCT) was employed to assess defect size and distribution, yielding a relative density of 99.93 %. Fracture surfaces of all fatigue-failed specimens were examined using optical and scanning electron microscopy to determine the primary failure mechanisms, with a focus on distinguishing between defect-driven and microstructural causes. The results indicated that nearly all specimens, tested across seven stress levels, exhibited crack initiation from process-induced volumetric defects, such as pores and lack of fusion. At lower stress levels (up to 195 MPa), single crack initiation sites driven by defects were identified at either surface or subsurface locations. In contrast, at higher stress levels (234 to 351 MPa), multiple crack initiation sites were observed, also at the surface or subsurface.","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"9 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793442","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}
In order to expand the application scope of the quenching-partitioning-tempering (Q-P-T) steel in the industrial field, ultrasonic rolling treatment (USRP) is carried out, and the influence of USRP on the fatigue properties of the Q-P-T steel is elucidated. Compared with the Q-P-T specimen (580 MPa), the fatigue limit of the USRP3 specimen increases to 620 MPa, and the crack initiation location is transferred from the surface to the core. The primary reasons for this fatigue strength incensement are as follows: a higher surface hardness effectively inhibits surface fatigue crack initiation; residual compressive stress reduces the driving force at crack tips and impedes crack propagation. Moreover, there is a continuous increase in hardness for the USRP3 specimen during cyclic loading due to dominant phase transformation strengthening effect caused by transformation from austenite to martensite. On the other hand, the USRP6 specimen possesses a gradient grain size structure with higher hardness and deeper range, which can decelerate crack propagation rate. However, surface damage caused by excessive ultrasonic rolling as well as the cyclic softening effect of the surface during fatigue ultimately counterbalance the positive influence of surface strengthening on fatigue properties.
{"title":"Influence of ultrasonic surface rolling on fatigue performance of high carbon low alloy quenching-partitioning-tempering steel","authors":"Shengwei Qin, Guangrui Wang, Qihui Tian, Zhihua Liu, Minghao Zhao","doi":"10.1016/j.ijfatigue.2024.108734","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2024.108734","url":null,"abstract":"In order to expand the application scope of the quenching-partitioning-tempering (Q-P-T) steel in the industrial field, ultrasonic rolling treatment (USRP) is carried out, and the influence of USRP on the fatigue properties of the Q-P-T steel is elucidated. Compared with the Q-P-T specimen (580 MPa), the fatigue limit of the USRP3 specimen increases to 620 MPa, and the crack initiation location is transferred from the surface to the core. The primary reasons for this fatigue strength incensement are as follows: a higher surface hardness effectively inhibits surface fatigue crack initiation; residual compressive stress reduces the driving force at crack tips and impedes crack propagation. Moreover, there is a continuous increase in hardness for the USRP3 specimen during cyclic loading due to dominant phase transformation strengthening effect caused by transformation from austenite to martensite. On the other hand, the USRP6 specimen possesses a gradient grain size structure with higher hardness and deeper range, which can decelerate crack propagation rate. However, surface damage caused by excessive ultrasonic rolling as well as the cyclic softening effect of the surface during fatigue ultimately counterbalance the positive influence of surface strengthening on fatigue properties.","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"92 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793445","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 : 2024-11-28DOI: 10.1016/j.ijfatigue.2024.108733
Zheng Qiu-yang, Shi Hao-han, Li Yu, Jiang Zhi-guo, Zhou Zhen-yu, Ye Sen-bin, Piao Zhong-yu
Casting aluminum alloy faces challenges during service, such as micro defects, low surface hardness, and inadequate fretting fatigue performance. This study employs acousto-electropulsing-stress synergistic strengthening to construct a strengthened layer structure on the surface of casting aluminum alloy, characterized by “micro-defect healing + surface gradient nanostructure.” The results demonstrate that, compared to surface burnishing processing, electro-ultrasonic surface burnishing processing (EUSBP) increases the thickness of the fine-grained layer by 75 % and enhances the amplitude of surface residual compressive stress by 39.3 % while simultaneously achieving micro-defect healing in the surface layer. Through fretting fatigue tests, it is discovered that the fretting fatigue life of EUSBP specimens is significantly higher than that of burnished and original specimens. Fracture surface analysis and damage zone characterization indicate that EUSBP specimens exhibit the best crack propagation resistance and fretting damage resistance. Molecular dynamics simulations reveal that EUSBP specimens enhance their resistance to fretting fatigue damage by utilizing the nano-gradient grain structure to inhibit dislocation motion and reduce the influence range of plastic deformation during the fretting fatigue process, resulting in a reduction of damage depth in the fretting fatigue damage zone by more than 25 %.
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