Pub Date : 2023-09-28DOI: 10.1007/s41230-023-3042-1
Zhao-yang Yin, Qi-chi Le, Yan-chao Jiang, Da-zhi Zhao, Qi-yu Liao, Qi Zou
A transient 3D model was established to investigate the effect of spatial interaction of ultrasounds on the dual-frequency ultrasonic field in magnesium alloy melt. The effects of insertion depth and tip shape of the ultrasonic rods, input pressures and their ratio on the acoustic field distribution were discussed in detail. Additionally, the spacing, angle, and insertion depth of two ultrasonic rods significantly affect the interaction between distinct ultrasounds. As a result, various acoustic pressure distributions and cavitation regions are obtained. The spherical rods mitigate the longitudinal and transversal attenuation of acoustic pressure and expand the cavitation volume by 53.7% and 31.7%, respectively, compared to the plate and conical rods. Increasing the input pressure will enlarge the cavitation region but has no effect on the acoustic pressure distribution pattern. The acoustic pressure ratio significantly affects the pressure distribution and the cavitation region, and the best cavitation effect is obtained at the ratio of 2:1 (P15:P20).
{"title":"Understanding the spatial interaction of ultrasounds based on three-dimensional dual-frequency ultrasonic field numerical simulation","authors":"Zhao-yang Yin, Qi-chi Le, Yan-chao Jiang, Da-zhi Zhao, Qi-yu Liao, Qi Zou","doi":"10.1007/s41230-023-3042-1","DOIUrl":"https://doi.org/10.1007/s41230-023-3042-1","url":null,"abstract":"A transient 3D model was established to investigate the effect of spatial interaction of ultrasounds on the dual-frequency ultrasonic field in magnesium alloy melt. The effects of insertion depth and tip shape of the ultrasonic rods, input pressures and their ratio on the acoustic field distribution were discussed in detail. Additionally, the spacing, angle, and insertion depth of two ultrasonic rods significantly affect the interaction between distinct ultrasounds. As a result, various acoustic pressure distributions and cavitation regions are obtained. The spherical rods mitigate the longitudinal and transversal attenuation of acoustic pressure and expand the cavitation volume by 53.7% and 31.7%, respectively, compared to the plate and conical rods. Increasing the input pressure will enlarge the cavitation region but has no effect on the acoustic pressure distribution pattern. The acoustic pressure ratio significantly affects the pressure distribution and the cavitation region, and the best cavitation effect is obtained at the ratio of 2:1 (P15:P20).","PeriodicalId":55261,"journal":{"name":"China Foundry","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135344599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effect of slow shot speed on externally solidified crystal (ESC), porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy was investigated by optical microscopy (OM), scanning electron microscopy (SEM) and laboratory computed tomography (CT). Results showed that the newly developed AlSi9MnMoV alloy exhibited improved mechanical properties when compared to the AlSi10MnMg alloy. The AlSi9MnMoV alloy, which was designed with trace multicomponent additions, displays a notable grain refining effect in comparison to the AlSi10MnMg alloy. Refining elements Ti, Zr, V, Nb, B promote heterogeneous nucleation and reduce the grain size of primary α-Al. At a lower slow shot speed, the large ESCs are easier to form and gather, developing into the dendrite net and net-shrinkage. With an increase in slow shot speed, the size and number of ESCs and porosities significantly reduce. In addition, the distribution of ESCs is more dispersed and the net-shrinkage disappears. The tensile property is greatly improved by adopting a higher slow shot speed. The ultimate tensile strength is enhanced from 260.31 MPa to 290.31 MPa (increased by 11.52%), and the elongation is enhanced from 3.72% to 6.34% (increased by 70.52%).
{"title":"Effect of slow shot speed on externally solidified crystal, porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy","authors":"Wen-ning Liu, Wei Zhang, Peng-yue Wang, Yi-xian Liu, Xiang-yi Jiao, Ao-xiang Wan, Cheng-gang Wang, Guo-dong Tong, Shou-mei Xiong","doi":"10.1007/s41230-023-3037-y","DOIUrl":"https://doi.org/10.1007/s41230-023-3037-y","url":null,"abstract":"The effect of slow shot speed on externally solidified crystal (ESC), porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy was investigated by optical microscopy (OM), scanning electron microscopy (SEM) and laboratory computed tomography (CT). Results showed that the newly developed AlSi9MnMoV alloy exhibited improved mechanical properties when compared to the AlSi10MnMg alloy. The AlSi9MnMoV alloy, which was designed with trace multicomponent additions, displays a notable grain refining effect in comparison to the AlSi10MnMg alloy. Refining elements Ti, Zr, V, Nb, B promote heterogeneous nucleation and reduce the grain size of primary α-Al. At a lower slow shot speed, the large ESCs are easier to form and gather, developing into the dendrite net and net-shrinkage. With an increase in slow shot speed, the size and number of ESCs and porosities significantly reduce. In addition, the distribution of ESCs is more dispersed and the net-shrinkage disappears. The tensile property is greatly improved by adopting a higher slow shot speed. The ultimate tensile strength is enhanced from 260.31 MPa to 290.31 MPa (increased by 11.52%), and the elongation is enhanced from 3.72% to 6.34% (increased by 70.52%).","PeriodicalId":55261,"journal":{"name":"China Foundry","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136107296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-09-01DOI: 10.1007/s41230-023-2185-4
Wei-long Wang, Kun Shi, Jun Zhao, Shi-bing Liu, Jiao-jiao Cheng, Wei-chen Qiu, Tian-yu Liu, Zhi-yong Zhang
The in situ (TiC+TiB)/TA15 composites with different volume percentages of reinforcement (10%, 15%, 20% and 25%) were prepared by water-cooled copper crucible vacuum suspension melting technology. The structures and compositions of the TA15 alloy and its composites were analyzed by XRD and EDS, and their electrochemical corrosion behavior in the 3.5% NaCl solution was studied. Corrosion wear testing was conducted using a reciprocating ball-on-disc wear tester under a 10 N load. Results show that the in situ fibrous TiB phase and the granular TiC phase are uniformly distributed on the composite matrix. The microhardness can reach up to 531 HV as 10vol.% TiC+TiB reinforcement is added. Compared with the TA15 alloy, the volume wear rate decreases from (2.21±0.07)×10−4 to (1.75±0.07)×10−4 mm3·N−1·m−1 by adding 15vol.% TiC+TiB reinforcement, and the wear mechanism is adhesive wear. When the volume percentage of the reinforcement phase reaches 25%, the volume wear rate increases from (1.75±0.07)×10−4 to (2.41±0.07)·10−4 mm3·N−1·m−1, and the wear mechanism changes into abrasive wear. The volume loss resulted by the interaction between corrosion and wear accounts for more than 27% of the total wear volume. The volume loss due to wear-induced corrosion changes from 1.94% to 4.06% with different addition of reinforcement. The volume loss caused by corrosion-induced wear initially increases from 24.08% to 26.90% as the reinforcement increases from 0 to 15% due to the increase of corrosion potential, and then decreases from 26.90% to 25.68% as the reinforcement increases from 15% to 25% due to the peeling of TiC phase.
{"title":"Corrosion and wear properties of in situ (TiB+TiC)/TA15 composites with a high volume percentage of reinforcement","authors":"Wei-long Wang, Kun Shi, Jun Zhao, Shi-bing Liu, Jiao-jiao Cheng, Wei-chen Qiu, Tian-yu Liu, Zhi-yong Zhang","doi":"10.1007/s41230-023-2185-4","DOIUrl":"https://doi.org/10.1007/s41230-023-2185-4","url":null,"abstract":"The in situ (TiC+TiB)/TA15 composites with different volume percentages of reinforcement (10%, 15%, 20% and 25%) were prepared by water-cooled copper crucible vacuum suspension melting technology. The structures and compositions of the TA15 alloy and its composites were analyzed by XRD and EDS, and their electrochemical corrosion behavior in the 3.5% NaCl solution was studied. Corrosion wear testing was conducted using a reciprocating ball-on-disc wear tester under a 10 N load. Results show that the in situ fibrous TiB phase and the granular TiC phase are uniformly distributed on the composite matrix. The microhardness can reach up to 531 HV as 10vol.% TiC+TiB reinforcement is added. Compared with the TA15 alloy, the volume wear rate decreases from (2.21±0.07)×10−4 to (1.75±0.07)×10−4 mm3·N−1·m−1 by adding 15vol.% TiC+TiB reinforcement, and the wear mechanism is adhesive wear. When the volume percentage of the reinforcement phase reaches 25%, the volume wear rate increases from (1.75±0.07)×10−4 to (2.41±0.07)·10−4 mm3·N−1·m−1, and the wear mechanism changes into abrasive wear. The volume loss resulted by the interaction between corrosion and wear accounts for more than 27% of the total wear volume. The volume loss due to wear-induced corrosion changes from 1.94% to 4.06% with different addition of reinforcement. The volume loss caused by corrosion-induced wear initially increases from 24.08% to 26.90% as the reinforcement increases from 0 to 15% due to the increase of corrosion potential, and then decreases from 26.90% to 25.68% as the reinforcement increases from 15% to 25% due to the peeling of TiC phase.","PeriodicalId":55261,"journal":{"name":"China Foundry","volume":"93 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135200600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Simulation of inclined dendrites under natural convection by KKS phase field model based on CUDA","authors":"Chang-sheng Zhu, Tian-yu Li, Bo-rui Zhao, Cang-long Wang, Zi-hao Gao","doi":"10.1007/s41230-023-2128-0","DOIUrl":"https://doi.org/10.1007/s41230-023-2128-0","url":null,"abstract":"","PeriodicalId":55261,"journal":{"name":"China Foundry","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135889245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-09-01DOI: 10.1007/s41230-023-2119-1
Da-shan Sui, Yu Shan, Dong-xin Wang, Jun-yi Li, Yao Xie, Yi-qun Yang, An-ping Dong, Bao-de Sun
K439B nickel-based superalloy is a new type of high-temperature material. There is insufficient research on its constitutive equations and numerical modeling of thermal stress. Isothermal tensile experiments of K439B superalloy at different temperatures (20 °C–1,000 °C) and strain rates (1.33×10−3 s−1–5.33×10−3 s−1) were performed by using a Gleeble-3800 simulator. The elastic moduli at different temperatures (20 °C–650 °C) were measured by resonance method. Subsequently, stress-strain curves were measured for K439B superalloy under different conditions. The elastic-viscoplastic constitutive equations were established and the correspongding parameters were solved by employing the Perzyna model. The verification results indicate that the calculated values of the constitutive equations are in good agreement with the experimental values. On this basis, the influence of process parameters on thermal stress was investigated by numerical simulation and orthogonal experimental design. The results of orthogonal experimental design reveal that the cooling mode of casting has a significant influence on the thermal stress, while pouring temperature and preheating temperature of shell mold have minimal impact. The distribution of physical fields under optimal process parameters, determined based on the orthogonal experimental design results, was simulated. The simulation results determine separately the specific positions with maximum values for effective stress, plastic strain, and displacement within the casting. The maximum stress is about 1,000.0 MPa, the plastic strain is about 0.135, and the displacement is about 1.47 mm. Moreover, the distribution states of thermal stress, strain, and displacement are closely related to the distribution of the temperature gradient and cooling rate in the casting. The research would provide a theoretical reference for exploring the stress-strain behavior and numerical modeling of the effective stress of the alloy during the casting process.
{"title":"Elastic-viscoplastic constitutive equations of K439B superalloy and thermal stress simulation during casting process","authors":"Da-shan Sui, Yu Shan, Dong-xin Wang, Jun-yi Li, Yao Xie, Yi-qun Yang, An-ping Dong, Bao-de Sun","doi":"10.1007/s41230-023-2119-1","DOIUrl":"https://doi.org/10.1007/s41230-023-2119-1","url":null,"abstract":"K439B nickel-based superalloy is a new type of high-temperature material. There is insufficient research on its constitutive equations and numerical modeling of thermal stress. Isothermal tensile experiments of K439B superalloy at different temperatures (20 °C–1,000 °C) and strain rates (1.33×10−3 s−1–5.33×10−3 s−1) were performed by using a Gleeble-3800 simulator. The elastic moduli at different temperatures (20 °C–650 °C) were measured by resonance method. Subsequently, stress-strain curves were measured for K439B superalloy under different conditions. The elastic-viscoplastic constitutive equations were established and the correspongding parameters were solved by employing the Perzyna model. The verification results indicate that the calculated values of the constitutive equations are in good agreement with the experimental values. On this basis, the influence of process parameters on thermal stress was investigated by numerical simulation and orthogonal experimental design. The results of orthogonal experimental design reveal that the cooling mode of casting has a significant influence on the thermal stress, while pouring temperature and preheating temperature of shell mold have minimal impact. The distribution of physical fields under optimal process parameters, determined based on the orthogonal experimental design results, was simulated. The simulation results determine separately the specific positions with maximum values for effective stress, plastic strain, and displacement within the casting. The maximum stress is about 1,000.0 MPa, the plastic strain is about 0.135, and the displacement is about 1.47 mm. Moreover, the distribution states of thermal stress, strain, and displacement are closely related to the distribution of the temperature gradient and cooling rate in the casting. The research would provide a theoretical reference for exploring the stress-strain behavior and numerical modeling of the effective stress of the alloy during the casting process.","PeriodicalId":55261,"journal":{"name":"China Foundry","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135687466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-09-01DOI: 10.1007/s41230-023-2155-x
Li-dong Xing, Yan-ping Bao, Min Wang, Yi-hong Li
Mold electromagnetic stirring technology for optimizing the flow of molten steel is now widely used in the continuous casting production process of high-quality steels. However, studies on the case that the center of the electromagnetic stirrer is located outside the mold have not been reported. Herein, the effect of the electromagnetic stirrer centered outside the mold on the steel flow field was studied in detail by means of numerical simulations. A Gauss meter was used to measure the magnetic induction intensity at different positions, currents, and frequencies. The test results were compared with the simulation results of electromagnetic stirring to calibrate and verify the accuracy of the electromagnetic model. Then, electromagnetic force was introduced into the flow field model as a source term to study its effect on the flow field under anomalous conditions. The results show that when the center of the electromagnetic stirrer is located outside the mold, the magnetic field strength is about twice as strong as that located inside the mold. This also leads to an increase in the flow velocity near the electromagnetic stirrer. As a result, the optimal electromagnetic stirring parameters (200 A, 2.5 Hz) were specified when the center of the electromagnetic stirrer is located outside the mold.
{"title":"Effect of electromagnetic stirrer centered outside the mold on steel flow field of bloom continuous casting","authors":"Li-dong Xing, Yan-ping Bao, Min Wang, Yi-hong Li","doi":"10.1007/s41230-023-2155-x","DOIUrl":"https://doi.org/10.1007/s41230-023-2155-x","url":null,"abstract":"Mold electromagnetic stirring technology for optimizing the flow of molten steel is now widely used in the continuous casting production process of high-quality steels. However, studies on the case that the center of the electromagnetic stirrer is located outside the mold have not been reported. Herein, the effect of the electromagnetic stirrer centered outside the mold on the steel flow field was studied in detail by means of numerical simulations. A Gauss meter was used to measure the magnetic induction intensity at different positions, currents, and frequencies. The test results were compared with the simulation results of electromagnetic stirring to calibrate and verify the accuracy of the electromagnetic model. Then, electromagnetic force was introduced into the flow field model as a source term to study its effect on the flow field under anomalous conditions. The results show that when the center of the electromagnetic stirrer is located outside the mold, the magnetic field strength is about twice as strong as that located inside the mold. This also leads to an increase in the flow velocity near the electromagnetic stirrer. As a result, the optimal electromagnetic stirring parameters (200 A, 2.5 Hz) were specified when the center of the electromagnetic stirrer is located outside the mold.","PeriodicalId":55261,"journal":{"name":"China Foundry","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135687589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ceramic cores are the key intermediate components of hollow blades for aero-engine. Conventional processes, such as hot-press molding and gel film casting, face difficulties in fabricating complex-structured ceramic cores due to the complexity of moulds and long process cycles. Stereolithography 3D printing provides a new idea for the fabrication of complex-structured ceramic cores. The effect of sintering temperature on open porosity, bulk density, weight loss rate, shrinkage rate, flexural strength and microstructure of the Al2O3-based ceramic core doped with 10vol.% polysilazane (PSZ) was studied. The sintering mechanism of PSZ-reinforced ceramic cores was analyzed. Results show that the optimum sintering temperature of PSZ-reinforced ceramic cores is 1,450 °C. At this temperature, the open porosity of the ceramic core is 36.60%, bulk density is 2.33 g·cm−3, weight loss rate is 22.11%, shrinkage rate along the X, Y, Z directions is 5.72%, 5.01%, 9.61%, respectively; the flexural strength is 28.794 MPa at 25 °C and 13.649 MPa at 1,500 °C. Properties of 3D printing PSZ-reinforced ceramic cores can meet the casting requirement of superalloy hollow blades, which is expected to promote the industrial application of 3D printing complex structure ceramic cores.
{"title":"Effect of sintering temperature on microstructure and properties of 3D printing polysilazane reinforced Al2O3 core","authors":"Wen-jun Dong, Qiao-lei Li, Tian-ci Chen, Ming-ke Zou, Jing-jing Liang, Li-rong Liu, Hui Mei, Jin-guo Li","doi":"10.1007/s41230-023-2122-6","DOIUrl":"https://doi.org/10.1007/s41230-023-2122-6","url":null,"abstract":"Ceramic cores are the key intermediate components of hollow blades for aero-engine. Conventional processes, such as hot-press molding and gel film casting, face difficulties in fabricating complex-structured ceramic cores due to the complexity of moulds and long process cycles. Stereolithography 3D printing provides a new idea for the fabrication of complex-structured ceramic cores. The effect of sintering temperature on open porosity, bulk density, weight loss rate, shrinkage rate, flexural strength and microstructure of the Al2O3-based ceramic core doped with 10vol.% polysilazane (PSZ) was studied. The sintering mechanism of PSZ-reinforced ceramic cores was analyzed. Results show that the optimum sintering temperature of PSZ-reinforced ceramic cores is 1,450 °C. At this temperature, the open porosity of the ceramic core is 36.60%, bulk density is 2.33 g·cm−3, weight loss rate is 22.11%, shrinkage rate along the X, Y, Z directions is 5.72%, 5.01%, 9.61%, respectively; the flexural strength is 28.794 MPa at 25 °C and 13.649 MPa at 1,500 °C. Properties of 3D printing PSZ-reinforced ceramic cores can meet the casting requirement of superalloy hollow blades, which is expected to promote the industrial application of 3D printing complex structure ceramic cores.","PeriodicalId":55261,"journal":{"name":"China Foundry","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135971832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-07-01DOI: 10.1007/s41230-023-3024-3
Le Chen, Ji-lin Li, Meng-jun Wang, Jie Zheng, Yao Zhu, Zhuo-lin Liu, Bing-gui Lü
NbC ceramic surface-reinforced steel matrix composites were prepared by an in-situ reaction method at different temperatures (1,050 °C, 1,100 °C and 1,150 °C) for different times (1 h, 2 h and 3 h). The phase constitution, microstructure and fracture morphology of NbC ceramic surface-reinforced steel matrix composites were analyzed by XRD, SEM and EDS, and the effects of the in-situ reaction temperature and time on the mechanical properties were systematically studied. The results indicate that the NbC reinforcement layer is formed through the reaction between Nb atoms and carbon atoms diffused from the steel matrix to the Nb plate. The thickness of this reinforcement layer increases as the reaction time prolongs. Additionally, an increase in reaction temperature results in a thicker reinforcement layer, although the rate of increase gradually decreases. The relationship among the thickness of the NbC reinforcement layer, the reaction time and temperature was established by data fitting. The optimal tensile performance is achieved at 1,100 °C for 1 h, with a tensile strength of 228 MPa. It is also found that the defects between the reinforcement layer and the steel matrix are related to reaction temperature. At 1,100 °C, these defects are minimal. Fracture mostly occurs in the NbC reinforced layer of the composites, and the fracture mode is characterized by typical intergranular brittle fracture.
{"title":"Microstructure and mechanical properties of Fe/NbC composite layer prepared by in-situ reaction","authors":"Le Chen, Ji-lin Li, Meng-jun Wang, Jie Zheng, Yao Zhu, Zhuo-lin Liu, Bing-gui Lü","doi":"10.1007/s41230-023-3024-3","DOIUrl":"https://doi.org/10.1007/s41230-023-3024-3","url":null,"abstract":"NbC ceramic surface-reinforced steel matrix composites were prepared by an in-situ reaction method at different temperatures (1,050 °C, 1,100 °C and 1,150 °C) for different times (1 h, 2 h and 3 h). The phase constitution, microstructure and fracture morphology of NbC ceramic surface-reinforced steel matrix composites were analyzed by XRD, SEM and EDS, and the effects of the in-situ reaction temperature and time on the mechanical properties were systematically studied. The results indicate that the NbC reinforcement layer is formed through the reaction between Nb atoms and carbon atoms diffused from the steel matrix to the Nb plate. The thickness of this reinforcement layer increases as the reaction time prolongs. Additionally, an increase in reaction temperature results in a thicker reinforcement layer, although the rate of increase gradually decreases. The relationship among the thickness of the NbC reinforcement layer, the reaction time and temperature was established by data fitting. The optimal tensile performance is achieved at 1,100 °C for 1 h, with a tensile strength of 228 MPa. It is also found that the defects between the reinforcement layer and the steel matrix are related to reaction temperature. At 1,100 °C, these defects are minimal. Fracture mostly occurs in the NbC reinforced layer of the composites, and the fracture mode is characterized by typical intergranular brittle fracture.","PeriodicalId":55261,"journal":{"name":"China Foundry","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135711464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-07-01DOI: 10.1007/s41230-023-3041-2
Mohammad Taghi Asadi Khanouki
Nowadays, having an effective technique in preparing semi-solid slurries for rheocasting process seems to be an essential requirement. In this study, semi-solid slurry of A356 aluminum alloy was prepared by three-phase annular electromagnetic stirring (A-EMS) technique under different conditions. The effects of stirring current, pouring temperature and stirring time on microstructural evolution, mean particle size, shape factor and solid fraction were investigated. The rheocasting process was carried out by using a drop weight setup and to inject the prepared semi-solid slurry in optimal conditions into the step-die cavity. The filling behavior and mechanical properties of parts were studied. Microstructural evolution showed that the best semi-solid slurry which had fine spherical particles with the average size of ∼27 µm and a shape factor of ∼0.8 was achieved at the stirring current of 70 A, melt pouring temperature of 670 °C, and stirring time of 30 s. Under these conditions, the step-die cavity was completely filled at die preheating temperature of 470 °C. The hardness increases by decreasing step thickness as well as die preheating temperature. Moreover, the tensile properties are improved at lower die preheating temperatures. The fracture surface, which consists of a complex topography, indicates a typical ductile fracture.
{"title":"Mechanical properties and microstructural evolution of rheocast A356 semi-solid slurry prepared by annular electromagnetic stirring","authors":"Mohammad Taghi Asadi Khanouki","doi":"10.1007/s41230-023-3041-2","DOIUrl":"https://doi.org/10.1007/s41230-023-3041-2","url":null,"abstract":"Nowadays, having an effective technique in preparing semi-solid slurries for rheocasting process seems to be an essential requirement. In this study, semi-solid slurry of A356 aluminum alloy was prepared by three-phase annular electromagnetic stirring (A-EMS) technique under different conditions. The effects of stirring current, pouring temperature and stirring time on microstructural evolution, mean particle size, shape factor and solid fraction were investigated. The rheocasting process was carried out by using a drop weight setup and to inject the prepared semi-solid slurry in optimal conditions into the step-die cavity. The filling behavior and mechanical properties of parts were studied. Microstructural evolution showed that the best semi-solid slurry which had fine spherical particles with the average size of ∼27 µm and a shape factor of ∼0.8 was achieved at the stirring current of 70 A, melt pouring temperature of 670 °C, and stirring time of 30 s. Under these conditions, the step-die cavity was completely filled at die preheating temperature of 470 °C. The hardness increases by decreasing step thickness as well as die preheating temperature. Moreover, the tensile properties are improved at lower die preheating temperatures. The fracture surface, which consists of a complex topography, indicates a typical ductile fracture.","PeriodicalId":55261,"journal":{"name":"China Foundry","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135711465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-07-01DOI: 10.1007/s41230-023-2015-8
Xiao-ping Zhu, Jun-qing Yao, Hai-long Wu, Xin-wang Liu, Hua Liu, Zi-tian Fan, Shu-lin Lü, Kai Wang, Zi-dong Wang
Microstructure, mechanical properties and phase transformation of a heat-resistant rare-earth (RE) Mg-16.1Gd-3.5Nd-0.38Zn-0.26Zr-0.15Y (wt.%) alloy were investigated. The as-cast alloy is composed of equiaxed α-Mg matrix, net-shaped Mg5RE and Zr-rich phases. According to aging hardening curves and tensile properties variation, the optimized condition of solution treatment at 520 °C for 8 h and subsequent aging at 204 °C for 12 h was selected. The continuous secondary Mg5RE phase predominantly formed at grain boundaries during solidification transforms to residual discontinuous β-Mg5RE phase and fine cuboid REH2 particles after heat treatment. The annealed alloy exhibits good comprehensive tensile property at 350 °C, with ultimate tensile strength of 153 MPa and elongation to fracture of 6.9%. Segregation of RE elements and eventually RE-rich precipitation at grain boundaries are responsible for the high strength at elevated temperature.
{"title":"Microstructure and mechanical properties of a cast heat-resistant rare-earth magnesium alloy","authors":"Xiao-ping Zhu, Jun-qing Yao, Hai-long Wu, Xin-wang Liu, Hua Liu, Zi-tian Fan, Shu-lin Lü, Kai Wang, Zi-dong Wang","doi":"10.1007/s41230-023-2015-8","DOIUrl":"https://doi.org/10.1007/s41230-023-2015-8","url":null,"abstract":"Microstructure, mechanical properties and phase transformation of a heat-resistant rare-earth (RE) Mg-16.1Gd-3.5Nd-0.38Zn-0.26Zr-0.15Y (wt.%) alloy were investigated. The as-cast alloy is composed of equiaxed α-Mg matrix, net-shaped Mg5RE and Zr-rich phases. According to aging hardening curves and tensile properties variation, the optimized condition of solution treatment at 520 °C for 8 h and subsequent aging at 204 °C for 12 h was selected. The continuous secondary Mg5RE phase predominantly formed at grain boundaries during solidification transforms to residual discontinuous β-Mg5RE phase and fine cuboid REH2 particles after heat treatment. The annealed alloy exhibits good comprehensive tensile property at 350 °C, with ultimate tensile strength of 153 MPa and elongation to fracture of 6.9%. Segregation of RE elements and eventually RE-rich precipitation at grain boundaries are responsible for the high strength at elevated temperature.","PeriodicalId":55261,"journal":{"name":"China Foundry","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135762285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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