Pub Date : 2024-07-20DOI: 10.1016/j.jmrt.2024.07.091
Lijie Zou, Jun-Chao Shao, Hai-Jun Jin
We report that the morphology of ligaments also governs the mechanical properties of dealloyed porous materials, in addition to the topology- and size-effects that have been extensively studied previously. Porous Fe–Cr with similar relative density but different Cr content were prepared by liquid metal dealloying. The mechanical efficiency of this material, which is quantified by relative elastic modulus, decreases dramatically with increasing Cr content, although the relative density and network connectivity do not vary significantly. This is linked to the more severe spheroidization of Fe–Cr ligaments at higher Cr, driven by the large excess energy of solid-liquid interfaces and interface energy anisotropy of Fe–Cr under dealloying environment. A shape parameter is introduced to quantitatively account for this ligament-morphology effect. Current study suggests that tailoring interfacial energy, which was largely overlooked in previous studies, is essential to improving the mechanical efficiency of porous or nanoporous materials self-organized in dealloying.
{"title":"Ligament morphology and elastic modulus of porous structure formed by liquid metal dealloying","authors":"Lijie Zou, Jun-Chao Shao, Hai-Jun Jin","doi":"10.1016/j.jmrt.2024.07.091","DOIUrl":"https://doi.org/10.1016/j.jmrt.2024.07.091","url":null,"abstract":"We report that the morphology of ligaments also governs the mechanical properties of dealloyed porous materials, in addition to the topology- and size-effects that have been extensively studied previously. Porous Fe–Cr with similar relative density but different Cr content were prepared by liquid metal dealloying. The mechanical efficiency of this material, which is quantified by relative elastic modulus, decreases dramatically with increasing Cr content, although the relative density and network connectivity do not vary significantly. This is linked to the more severe spheroidization of Fe–Cr ligaments at higher Cr, driven by the large excess energy of solid-liquid interfaces and interface energy anisotropy of Fe–Cr under dealloying environment. A shape parameter is introduced to quantitatively account for this ligament-morphology effect. Current study suggests that tailoring interfacial energy, which was largely overlooked in previous studies, is essential to improving the mechanical efficiency of porous or nanoporous materials self-organized in dealloying.","PeriodicalId":501120,"journal":{"name":"Journal of Materials Research and Technology","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Changes in structure and properties of resin matrix caused by water absorption is one of the key factors affecting the long-term durability of fiber reinforced polymer composites used in civil engineering. In the present study, the water diffusion and structural change in an epoxy resin were investigated experimentally through immersion in deionized water at 40, 60 and 80 °C for 135 days. Water absorption, thermal, mechanical and microstructure analysis tests were conducted to evaluate the long-term property evolution. It was found that the water absorption of epoxy resin followed a two-stage model, including an initial Fick's diffusion response and a subsequent relaxation response. Long-term hygrothermal exposure brought about the structural change of epoxy resin, which led to the significant degradation up to 8%–30% in the mechanical properties and 21% in glass transition temperature, respectively. The resin plasticization and hydrolysis was the key factors for the degradation of thermal and mechanical properties. It was proved that the plasticization effect was reversible with the remove of bonding water after the drying. Based on the Arrhenius equation, the long-term life of flexural strength in two service environments were predicted to provide the application guideline. The significant degradation of flexural strength was occurred at the initial exposure of 2000 days and then reached to the stable strength retention of 69.6%.
{"title":"Water absorption and property evolution of epoxy resin under hygrothermal environment","authors":"Guijun Xian, Yanzhao Niu, Xiao Qi, Jingwei Tian, Chenggao Li, Qingrui Yue, Rui Guo","doi":"10.1016/j.jmrt.2024.07.123","DOIUrl":"https://doi.org/10.1016/j.jmrt.2024.07.123","url":null,"abstract":"Changes in structure and properties of resin matrix caused by water absorption is one of the key factors affecting the long-term durability of fiber reinforced polymer composites used in civil engineering. In the present study, the water diffusion and structural change in an epoxy resin were investigated experimentally through immersion in deionized water at 40, 60 and 80 °C for 135 days. Water absorption, thermal, mechanical and microstructure analysis tests were conducted to evaluate the long-term property evolution. It was found that the water absorption of epoxy resin followed a two-stage model, including an initial Fick's diffusion response and a subsequent relaxation response. Long-term hygrothermal exposure brought about the structural change of epoxy resin, which led to the significant degradation up to 8%–30% in the mechanical properties and 21% in glass transition temperature, respectively. The resin plasticization and hydrolysis was the key factors for the degradation of thermal and mechanical properties. It was proved that the plasticization effect was reversible with the remove of bonding water after the drying. Based on the Arrhenius equation, the long-term life of flexural strength in two service environments were predicted to provide the application guideline. The significant degradation of flexural strength was occurred at the initial exposure of 2000 days and then reached to the stable strength retention of 69.6%.","PeriodicalId":501120,"journal":{"name":"Journal of Materials Research and Technology","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-19DOI: 10.1016/j.jmrt.2024.07.126
Tianhong Zhou, Li Zhu, Xiaonan Luo, Jiancheng Yu, Chuchu Ye, Xin Zhou, Xian Tong, Zhaoping Chen, Yuncang Li, Jixing Lin, Cuie Wen, Jianfeng Ma
Three mole percent yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) ceramics are exemplary materials for dental restoration due to their high mechanical strength, fracture toughness, chemical endurance, and biocompatibility. Nevertheless, 3Y-TZP ceramics are opaque and their CAD/CAM manufacturing process may cause micro-cracks in conventional clinical practice. In this study, 3Y-TZP ceramic samples were prepared using vat photopolymerization, pre-sintering, external staining, and final high-temperature sintering. The microstructures, mechanical properties, optical properties, and cytotoxicity of the 3Y-TZP ceramic samples were investigated. The results indicate that with increasing Fe concentration of staining solution from 0.1 mol/L to 0.3 mol/L and increasing staining time from 5 s to 30 min, the 3Y-TZP ceramic samples showed a tetragonal crystal structure of zirconia with densely packed grains and a slight increase in grain size. The flexural strength, Vickers hardness, and fracture toughness of 3Y-TZP ceramic samples stained in 0.1–0.3 mol/L Fe solution for 5 s to 3 min were all greater than 665 MPa, 11.9 GPa, and 5 MPa m, respectively, meeting the mechanical requirements for clinical application. Colorimetric analysis revealed a decrease in L* (black-white index) from 90.4 to 81.3, an increase in a* (green-red index) from −1.5 to 3.2, and an increase in b* (blue-yellow index) from 11.6 to 20.3, approximating the commercial VITA 3D-Master Shade Guide chromaticity. Furthermore, the 3Y-TZP ceramic samples exhibited a cell viability of 90% or higher toward L929 cells.
{"title":"Effects of external staining on mechanical, optical, and biocompatibility properties of additively manufactured 3Y-TZP ceramic for dental applications","authors":"Tianhong Zhou, Li Zhu, Xiaonan Luo, Jiancheng Yu, Chuchu Ye, Xin Zhou, Xian Tong, Zhaoping Chen, Yuncang Li, Jixing Lin, Cuie Wen, Jianfeng Ma","doi":"10.1016/j.jmrt.2024.07.126","DOIUrl":"https://doi.org/10.1016/j.jmrt.2024.07.126","url":null,"abstract":"Three mole percent yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) ceramics are exemplary materials for dental restoration due to their high mechanical strength, fracture toughness, chemical endurance, and biocompatibility. Nevertheless, 3Y-TZP ceramics are opaque and their CAD/CAM manufacturing process may cause micro-cracks in conventional clinical practice. In this study, 3Y-TZP ceramic samples were prepared using vat photopolymerization, pre-sintering, external staining, and final high-temperature sintering. The microstructures, mechanical properties, optical properties, and cytotoxicity of the 3Y-TZP ceramic samples were investigated. The results indicate that with increasing Fe concentration of staining solution from 0.1 mol/L to 0.3 mol/L and increasing staining time from 5 s to 30 min, the 3Y-TZP ceramic samples showed a tetragonal crystal structure of zirconia with densely packed grains and a slight increase in grain size. The flexural strength, Vickers hardness, and fracture toughness of 3Y-TZP ceramic samples stained in 0.1–0.3 mol/L Fe solution for 5 s to 3 min were all greater than 665 MPa, 11.9 GPa, and 5 MPa m, respectively, meeting the mechanical requirements for clinical application. Colorimetric analysis revealed a decrease in L* (black-white index) from 90.4 to 81.3, an increase in a* (green-red index) from −1.5 to 3.2, and an increase in b* (blue-yellow index) from 11.6 to 20.3, approximating the commercial VITA 3D-Master Shade Guide chromaticity. Furthermore, the 3Y-TZP ceramic samples exhibited a cell viability of 90% or higher toward L929 cells.","PeriodicalId":501120,"journal":{"name":"Journal of Materials Research and Technology","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-19DOI: 10.1016/j.jmrt.2024.07.116
Xiaoya Wang, Xuelin Wang, Zhenjia Xie, Chengjia Shang, Zhongzhu Liu
The effect of different welding heat inputs on the microstructure and mechanical properties of the simulated coarse grained heat affected zone (CGHAZ) of high-strength wind power steel with yield strength of 500 MPa has been investigated using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Charpy impact tests have demonstrated that there exists an optimum heat input of ∼20 kJ/cm that allows optimum impact toughness to be obtained for the CGHAZ. It was shown that this is related to the refined bainitic structure and the highest density of high-angle grain boundaries (HAGBs) with misorientation angle of more than 45°. In crystallographic visualization studies, it was shown that the weakest variant selection occurs for the bainite transformation in the optimal heat input, leading to the highest density of HAGBs with each Closed-packet group containing two or three Bain groups and showing a staggered arrangement structure. The contribution that can effectively deflect and prevent crack propagation during impact experiments has to come from the block boundary. However, it was also found that the center segregation induced by C and Mn reduces the low-temperature impact toughness of the core sample before and after simulated welding, and affects the fluctuations of impact toughness and fatigue performance of simulated CGHAZ. Mn segregation can have a genetic effect on the welding heat affected zone, inducing a lower temperature martensitic transformation, which in turn leads to a decrease in low-temperature toughness and fatigue crack arrest performance.
{"title":"Crystallographic study on microstructure evolution and mechanical properties of coarse grained heat affected zone of a 500 MPa grade wind power steel","authors":"Xiaoya Wang, Xuelin Wang, Zhenjia Xie, Chengjia Shang, Zhongzhu Liu","doi":"10.1016/j.jmrt.2024.07.116","DOIUrl":"https://doi.org/10.1016/j.jmrt.2024.07.116","url":null,"abstract":"The effect of different welding heat inputs on the microstructure and mechanical properties of the simulated coarse grained heat affected zone (CGHAZ) of high-strength wind power steel with yield strength of 500 MPa has been investigated using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Charpy impact tests have demonstrated that there exists an optimum heat input of ∼20 kJ/cm that allows optimum impact toughness to be obtained for the CGHAZ. It was shown that this is related to the refined bainitic structure and the highest density of high-angle grain boundaries (HAGBs) with misorientation angle of more than 45°. In crystallographic visualization studies, it was shown that the weakest variant selection occurs for the bainite transformation in the optimal heat input, leading to the highest density of HAGBs with each Closed-packet group containing two or three Bain groups and showing a staggered arrangement structure. The contribution that can effectively deflect and prevent crack propagation during impact experiments has to come from the block boundary. However, it was also found that the center segregation induced by C and Mn reduces the low-temperature impact toughness of the core sample before and after simulated welding, and affects the fluctuations of impact toughness and fatigue performance of simulated CGHAZ. Mn segregation can have a genetic effect on the welding heat affected zone, inducing a lower temperature martensitic transformation, which in turn leads to a decrease in low-temperature toughness and fatigue crack arrest performance.","PeriodicalId":501120,"journal":{"name":"Journal of Materials Research and Technology","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-19DOI: 10.1016/j.jmrt.2024.07.063
Junyi Gu, Xuan Su, Wenqin Li, Meiling Xin, Donghe Zhang, Yang Jin, Jie Xu, Bin Guo
Damage to the substrate hinders the application of laser paint stripping (LPS) on carbon fiber reinforced polymers (CFRP), but the damage mechanism is currently unknown. In this paper, the LPS characteristics of CFRP, such as paint stripping depth, surface morphology and dynamic behavior, are firstly obtained. Subsequently, the surface damage mechanism of CFRP is discussed in detail by theoretical analysis and finite element method, and the effect of substrate damage on adhesive properties is investigated. The results show that it is difficult for LPS to obtain a complete surface free of paint residue. The strong laser plasma impact and resin pyrolysis pressure cause the resin to crack and flake before the paint is fully ablated. The carbon fiber then breaks and are thrown outward by heat and forces, and the surface with slightly fracture of the fiber will facilitate bonding with the paint.
{"title":"Investigation on laser paint stripping of CFRP: Morphological evolution, damage mechanism, and adhesive performance","authors":"Junyi Gu, Xuan Su, Wenqin Li, Meiling Xin, Donghe Zhang, Yang Jin, Jie Xu, Bin Guo","doi":"10.1016/j.jmrt.2024.07.063","DOIUrl":"https://doi.org/10.1016/j.jmrt.2024.07.063","url":null,"abstract":"Damage to the substrate hinders the application of laser paint stripping (LPS) on carbon fiber reinforced polymers (CFRP), but the damage mechanism is currently unknown. In this paper, the LPS characteristics of CFRP, such as paint stripping depth, surface morphology and dynamic behavior, are firstly obtained. Subsequently, the surface damage mechanism of CFRP is discussed in detail by theoretical analysis and finite element method, and the effect of substrate damage on adhesive properties is investigated. The results show that it is difficult for LPS to obtain a complete surface free of paint residue. The strong laser plasma impact and resin pyrolysis pressure cause the resin to crack and flake before the paint is fully ablated. The carbon fiber then breaks and are thrown outward by heat and forces, and the surface with slightly fracture of the fiber will facilitate bonding with the paint.","PeriodicalId":501120,"journal":{"name":"Journal of Materials Research and Technology","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This research explores the corrosion behavior of beryllium bronze over a period of 29 years in an industrial atmosphere, revealing an average corrosion rate of 0.557 μm·a. The skyward patina layer primarily consists of CuO, CuSO(OH) and CuSO, while the field-ward patina layer contains CuO, CuO, CuSO(OH) and CuSO. Density functional theory (DFT) calculations and XPS analysis show that Be oxidizes preferentially, providing early-stage corrosion protection. DFT and open circuit potential measurements suggest that the patina layer on the field-ward surface is more thermodynamically stable, but cracks serve as pathways for mass transport, accelerating corrosion.
{"title":"Insight into patina formed on beryllium-bronze after 29 years of exposure in an industrial environment and DFT research","authors":"Yuwei Liu, Chenzhi Xing, Guocai Yu, Chuan Wang, Gongwang Cao, Shuo Cao, Zhenyao Wang","doi":"10.1016/j.jmrt.2024.07.092","DOIUrl":"https://doi.org/10.1016/j.jmrt.2024.07.092","url":null,"abstract":"This research explores the corrosion behavior of beryllium bronze over a period of 29 years in an industrial atmosphere, revealing an average corrosion rate of 0.557 μm·a. The skyward patina layer primarily consists of CuO, CuSO(OH) and CuSO, while the field-ward patina layer contains CuO, CuO, CuSO(OH) and CuSO. Density functional theory (DFT) calculations and XPS analysis show that Be oxidizes preferentially, providing early-stage corrosion protection. DFT and open circuit potential measurements suggest that the patina layer on the field-ward surface is more thermodynamically stable, but cracks serve as pathways for mass transport, accelerating corrosion.","PeriodicalId":501120,"journal":{"name":"Journal of Materials Research and Technology","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-19DOI: 10.1016/j.jmrt.2024.07.088
Shijie Wang, Xingyu Lu, Jian Guan, Hongwei Liu, Chengshuai Lei, Chen Sun, Lina Zhou, Ming Liu, Ju Huang, Yanfei Cao, Qiang Wang, Dianzhong Li
Residual δ-ferrite is ubiquitous in M50NiL bearing steel and seriously deteriorates impact toughness. In the present work, the formation mechanism of δ-ferrite in M50NiL steel and the influence of element segregation on its formation process were investigated. The residual δ-ferrite was proved to form directly from the final liquid phase at the end of solidification due to serious segregation of Mo and V elements. Calculation results indicate that the segregation of Mo and V elements expanded the “L + δ" two-phase region and stabilized δ-ferrite. Due to the high concentration of Mo and V, large-sized V-rich MC and Mo-rich MC carbides would precipitate in δ-ferrite at 900–1200 °C if the cooling rate is slow. When kept at 1200 °C for no more than 30 min, Mo and V elements derived from the decomposition of large-sized carbides are preferentially diffused into δ-ferrite, enhancing the stability of δ-ferrite. To achieve the effective elimination of δ-ferrite in M50NiL steel, it is necessary to keep the ingot at 1200 °C for at least 20 h.
残余δ-铁素体在 M50NiL 轴承钢中普遍存在，严重降低了冲击韧性。本文研究了 M50NiL 钢中 δ-铁素体的形成机理以及元素偏析对其形成过程的影响。研究证明，由于 Mo 和 V 元素的严重偏析，残余的 δ-铁素体是在凝固末期直接从最终液相中形成的。计算结果表明，Mo 和 V 元素的偏析扩大了 "L + δ "两相区，并稳定了 δ-铁素体。由于 Mo 和 V 的浓度较高，如果冷却速度较慢，900-1200 ℃ 时，δ-铁素体中会析出大尺寸的富 V MC 和富 Mo MC 碳化物。当在 1200 ℃ 下保持不超过 30 分钟时，大尺寸碳化物分解产生的 Mo 和 V 元素会优先扩散到 δ-铁氧体中，从而增强了 δ-铁氧体的稳定性。为了有效消除 M50NiL 钢中的δ-铁素体，必须将钢锭在 1200 °C 下保持至少 20 小时。
{"title":"The formation mechanism of δ-ferrite and its evolution behavior in M50NiL steel","authors":"Shijie Wang, Xingyu Lu, Jian Guan, Hongwei Liu, Chengshuai Lei, Chen Sun, Lina Zhou, Ming Liu, Ju Huang, Yanfei Cao, Qiang Wang, Dianzhong Li","doi":"10.1016/j.jmrt.2024.07.088","DOIUrl":"https://doi.org/10.1016/j.jmrt.2024.07.088","url":null,"abstract":"Residual δ-ferrite is ubiquitous in M50NiL bearing steel and seriously deteriorates impact toughness. In the present work, the formation mechanism of δ-ferrite in M50NiL steel and the influence of element segregation on its formation process were investigated. The residual δ-ferrite was proved to form directly from the final liquid phase at the end of solidification due to serious segregation of Mo and V elements. Calculation results indicate that the segregation of Mo and V elements expanded the “L + δ\" two-phase region and stabilized δ-ferrite. Due to the high concentration of Mo and V, large-sized V-rich MC and Mo-rich MC carbides would precipitate in δ-ferrite at 900–1200 °C if the cooling rate is slow. When kept at 1200 °C for no more than 30 min, Mo and V elements derived from the decomposition of large-sized carbides are preferentially diffused into δ-ferrite, enhancing the stability of δ-ferrite. To achieve the effective elimination of δ-ferrite in M50NiL steel, it is necessary to keep the ingot at 1200 °C for at least 20 h.","PeriodicalId":501120,"journal":{"name":"Journal of Materials Research and Technology","volume":"84 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-19DOI: 10.1016/j.jmrt.2024.07.085
Jie Ning, Linjie Zhang
The hairpin joints welding poses a significant challenge in flat wire motor manufacturing. Laser spot welding test under argon protection and laser galvanometer scanning welding test under air environment were carried out in the absence of ultrasound. The results show that the joints obtained when the welding time is about 5s are better shaped and have good repeatability during the laser spot welding under argon protection. The shape of the closed welding path gives better joint formation when laser galvanometer scanning welding is used. Compared with the argon protection environment, the repeatability of the joint appearance obtained in the air environment was reduced, and the porosity defects in the weld seam increased significantly. A novel non-contact ultrasonic-assisted laser welding method for copper hairpins was introduced to improve the weld formation quality. The influence laws and mechanisms of ultrasonic process parameters on weld formation were studied. After using ultrasonic-assisted laser welding, the repeatability of weld bead formation is significantly improved, the tendency of weld bead collapse is reduced, but the joint resistance increases. The main reason for the improvement of weld appearance in ultrasonic-assisted laser welding is the compressive effect of the ultrasonic field on the molten pool, which was confirmed by high-speed photographic images. The compression effect of standing-wave points closer to the emitting end on the molten pool is more pronounced. With the increase of ultrasonic power, the weld width and the tensile-shear load resistance of the joint decreased, while the joint resistance increased.
{"title":"Non-contact ultrasonic-assisted laser welding of copper hairpins","authors":"Jie Ning, Linjie Zhang","doi":"10.1016/j.jmrt.2024.07.085","DOIUrl":"https://doi.org/10.1016/j.jmrt.2024.07.085","url":null,"abstract":"The hairpin joints welding poses a significant challenge in flat wire motor manufacturing. Laser spot welding test under argon protection and laser galvanometer scanning welding test under air environment were carried out in the absence of ultrasound. The results show that the joints obtained when the welding time is about 5s are better shaped and have good repeatability during the laser spot welding under argon protection. The shape of the closed welding path gives better joint formation when laser galvanometer scanning welding is used. Compared with the argon protection environment, the repeatability of the joint appearance obtained in the air environment was reduced, and the porosity defects in the weld seam increased significantly. A novel non-contact ultrasonic-assisted laser welding method for copper hairpins was introduced to improve the weld formation quality. The influence laws and mechanisms of ultrasonic process parameters on weld formation were studied. After using ultrasonic-assisted laser welding, the repeatability of weld bead formation is significantly improved, the tendency of weld bead collapse is reduced, but the joint resistance increases. The main reason for the improvement of weld appearance in ultrasonic-assisted laser welding is the compressive effect of the ultrasonic field on the molten pool, which was confirmed by high-speed photographic images. The compression effect of standing-wave points closer to the emitting end on the molten pool is more pronounced. With the increase of ultrasonic power, the weld width and the tensile-shear load resistance of the joint decreased, while the joint resistance increased.","PeriodicalId":501120,"journal":{"name":"Journal of Materials Research and Technology","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HT250 Gray cast iron (GCI) commonly utilized in diesel engine cylinders, is susceptible to fatigue failure under alternating stress conditions. To address this issue, the investigation involved the application of laser shock peening without coating (LSPwC) on HT250 GCI to assess its impact on the high cycle tension fatigue properties of the material. Both experimental and simulation methodologies were employed to analyze the effects of LSPwC on residual stress, microhardness, and microstructure in HT250 GCI. The LSPwC resulted in a substantial 29% enhancement in the high cycle tension fatigue limit of the HT250 GCI, which is attributed to a synergistic combination of factors induced by LSPwC, including high-amplitude compressive residual stresses, elevated microhardness, grain refinement, and carbon diffusion. This study contributes valuable insights into the reinforcement of complex cast components.
{"title":"Improving tension fatigue performance of gray cast iron by LSPwC-induced gradient structure and carbon diffusion","authors":"Shaopeng Meng, Yanqing Yu, Lingfeng Wang, Liucheng Zhou, Zichuan Yu, Xinlie Pan, Rongping Wang, Cenchao Xie","doi":"10.1016/j.jmrt.2024.07.086","DOIUrl":"https://doi.org/10.1016/j.jmrt.2024.07.086","url":null,"abstract":"HT250 Gray cast iron (GCI) commonly utilized in diesel engine cylinders, is susceptible to fatigue failure under alternating stress conditions. To address this issue, the investigation involved the application of laser shock peening without coating (LSPwC) on HT250 GCI to assess its impact on the high cycle tension fatigue properties of the material. Both experimental and simulation methodologies were employed to analyze the effects of LSPwC on residual stress, microhardness, and microstructure in HT250 GCI. The LSPwC resulted in a substantial 29% enhancement in the high cycle tension fatigue limit of the HT250 GCI, which is attributed to a synergistic combination of factors induced by LSPwC, including high-amplitude compressive residual stresses, elevated microhardness, grain refinement, and carbon diffusion. This study contributes valuable insights into the reinforcement of complex cast components.","PeriodicalId":501120,"journal":{"name":"Journal of Materials Research and Technology","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-19DOI: 10.1016/j.jmrt.2024.07.094
Yihui Zhu, Yang Song, Wei Wu, Weilong Niu, Zhuangqing Fan, Yaoke Wen, Cheng Xu, Min Xia
Amid escalating localized conflicts worldwide, the elucidation of the mechanisms and quantification blunt trauma the emergency services and military personnel confronted becomes imperatively. However, the understanding of bullet-induced bulge formation on the laminate's back face, impact wave propagation, and consequent trauma assessment methods remains incomplete. This study applies 3-dimension digital image correlation (3D-DIC) method to reveals these phenomena by utilizing a lead-core bullet traveling at 334.93 m/s to impact an ultra-high molecular weight polyethylene (UHMWPE) laminate. The results show that the initial transverse propagation velocity of bulge profile is 24.79% smaller than the theoretical calculation, which indicates the reduction caused by cohesive matrix. The transverse wave demonstrates a double exponential attenuation pattern, which could be decomposed into two single exponential attenuation curves. The bulge profile shows hyperbolic pattern, which reveals the stability of the bulge shape and the temporal evolution pattern. Increasing the laminate-body gap leads to a decline in Blunt Criterion (BC) and the Abbreviated Injury Scale (AIS) values reduce from 2 to 0 correspondingly. The numerical model confirms the compression wave velocity as 1447.77 ± 123.10 m/s in the thickness direction and 9542.86 ± 3087.75 m/s in the fiber direction. These findings reveals and quantified the propagation patterns of back bulge and compressive wave, and thus could provide data-driven insights to improve body armor performance and blunt trauma assessment for individual soldiers.
{"title":"Ballistic impact wave and bulge profile propagation characteristics and blunt injury assessment of UHMWPE laminate composite","authors":"Yihui Zhu, Yang Song, Wei Wu, Weilong Niu, Zhuangqing Fan, Yaoke Wen, Cheng Xu, Min Xia","doi":"10.1016/j.jmrt.2024.07.094","DOIUrl":"https://doi.org/10.1016/j.jmrt.2024.07.094","url":null,"abstract":"Amid escalating localized conflicts worldwide, the elucidation of the mechanisms and quantification blunt trauma the emergency services and military personnel confronted becomes imperatively. However, the understanding of bullet-induced bulge formation on the laminate's back face, impact wave propagation, and consequent trauma assessment methods remains incomplete. This study applies 3-dimension digital image correlation (3D-DIC) method to reveals these phenomena by utilizing a lead-core bullet traveling at 334.93 m/s to impact an ultra-high molecular weight polyethylene (UHMWPE) laminate. The results show that the initial transverse propagation velocity of bulge profile is 24.79% smaller than the theoretical calculation, which indicates the reduction caused by cohesive matrix. The transverse wave demonstrates a double exponential attenuation pattern, which could be decomposed into two single exponential attenuation curves. The bulge profile shows hyperbolic pattern, which reveals the stability of the bulge shape and the temporal evolution pattern. Increasing the laminate-body gap leads to a decline in Blunt Criterion (BC) and the Abbreviated Injury Scale (AIS) values reduce from 2 to 0 correspondingly. The numerical model confirms the compression wave velocity as 1447.77 ± 123.10 m/s in the thickness direction and 9542.86 ± 3087.75 m/s in the fiber direction. These findings reveals and quantified the propagation patterns of back bulge and compressive wave, and thus could provide data-driven insights to improve body armor performance and blunt trauma assessment for individual soldiers.","PeriodicalId":501120,"journal":{"name":"Journal of Materials Research and Technology","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141783620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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