Vertical wall surface forming of rectangular shell using multistage incremental forming with spherical and cylindrical rollers; A prediction of bursting failure in tube hydroforming processes based on ductile fracture...Vertical wall surface forming of rectangular shell using multistage incremental forming with spherical and cylindrical rollers; A prediction of bursting failure in tube hydroforming processes based on ductile fracture criterion;An approximation model of contact state between roll and strand - computation of three-dimensional deformation behavior of continuously cast steel strand in multiroll spans I;Analysis of hydraulic forming process for noncircular tube; Analysis of hydrostatic tube bulging with cylindrical die using static explicit FEM; CTR improves performance: management tool helps manufactures get their products into customer's hands展开更多
The present work numerically investigates two-dimensional （2-D） solidification transport phenomena （EM-STP） during continuous casting （CC） process in the absence and the presence of static magnetic fields （SMFs...The present work numerically investigates two-dimensional （2-D） solidification transport phenomena （EM-STP） during continuous casting （CC） process in the absence and the presence of static magnetic fields （SMFs）, based on a unified numerical model. For the purpose of controlling vortexes, the electromagnetic brake （EMBR） effects of various SMFs under the given depth of submerged entry nozzle （SEN） and the same casting velocity V0 are investigated. ANSYS software is used to analyze the SMFs that applied to the EMCC process, and then a data-conversion program based on the principle of linear interpolation proposed previously is used to deal with the issue of data-format-matching between FEM and FVM. The simulation results indicate that, an appropriate SMF can effectively suppress the bulk liquid flow in CC-process of steel plate, and with in- crease of the intensity of applied magnetic fields, the vortexes become weaker and the oscillating amplitude of impinging jet decreases. Based on the knowledge gained from the EMCC-STP analysis and by comparing the re- sults with the applied magnetic fields with those without magnetic fields, it is found that a SMF with 丨 Bmax 丨 = 5.5 × 10 -3 T can meet the need of braking, and consequently improve the quality of casting by reducing the penetration of non-metallic inclusions, as well as avoiding breakout, macro-segregation and crack ultimately.展开更多
The relationship between the microstructure and mechanical properties of the spark plasma sintered AA2024 Y composites subjected to cryo-rolling was investigated. Yttrium addition enhances the mechanical properties of...The relationship between the microstructure and mechanical properties of the spark plasma sintered AA2024 Y composites subjected to cryo-rolling was investigated. Yttrium addition enhances the mechanical properties of the composites by promoting grain refinement and precipitation. However, there is a clear trend of initial increase and later decrease in the properties. Also, it is observed that 0.3 wt.% of yttrium is the optimum amount of reinforcement content to obtain the highest mechanical properties. To further improve the tensile strength of the composites, cryo-rolling was performed on the composites under standard cryogenic conditions by several passes up to a reduction of 25%. The mechanical properties and the corresponding microstructures of composites after cryo-rolling were correlated. The SEM and TEM microstructures reveal that the samples exhibit dual size grains, i.e., nanograins are formed as sub-grains within the actual grain. Due to the grain size reduction and the increase in the dislocation density, the tensile properties are remarkably improved compared to those of the composites before cryo-rolling. The highest mechanical properties like hardness, YS and UTS are found to be 153 HV, 539 MPa and 572 MPa, respectively, with a reasonable ductility in the composite with 0.3 wt.% Y.展开更多
The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volu...The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.展开更多
Multi-wall carbon nanotubes reinforced Mg-14Li-1Al composite(MWCNTs/Mg-14Li-1Al) was prepared by the processes of electrophoretic deposition, friction stir processing, and cold rolling. The microstructure and mechanic...Multi-wall carbon nanotubes reinforced Mg-14Li-1Al composite(MWCNTs/Mg-14Li-1Al) was prepared by the processes of electrophoretic deposition, friction stir processing, and cold rolling. The microstructure and mechanical properties of the composite were investigated. The results show that, the microhardness of the composite is up to HV 84.4, which is 91.38% higher than that of the as-cast matrix alloy(HV 44.1). The yield strength and ultimate tensile strength of the composite are 259 and 313 MPa, which are 135.45% and 115.86% higher than those of the as-cast matrix alloy, respectively, and a high specific strength of 221.98 k N·m/kg is obtained. In the composite, the MWCNTs serve as nucleation particles during the friction stir processing and cold rolling, causing dynamic recrystallization and grain refinement. Furthermore, MWCNTs hinder the movement of dislocations and transfer the load from the matrix alloy, thus improving the strength.展开更多
文摘Vertical wall surface forming of rectangular shell using multistage incremental forming with spherical and cylindrical rollers; A prediction of bursting failure in tube hydroforming processes based on ductile fracture criterion;An approximation model of contact state between roll and strand - computation of three-dimensional deformation behavior of continuously cast steel strand in multiroll spans I;Analysis of hydraulic forming process for noncircular tube; Analysis of hydrostatic tube bulging with cylindrical die using static explicit FEM; CTR improves performance: management tool helps manufactures get their products into customer's hands
基金Sponsored by the National Natural Science Foundation of China (Grants No. 50801019,51071062)the State Key Lab of Advanced Metals Materials(Grant No.2009ZD-06)the National Basic Research Program of China (Grant No. 2011CB605504)
文摘The present work numerically investigates two-dimensional （2-D） solidification transport phenomena （EM-STP） during continuous casting （CC） process in the absence and the presence of static magnetic fields （SMFs）, based on a unified numerical model. For the purpose of controlling vortexes, the electromagnetic brake （EMBR） effects of various SMFs under the given depth of submerged entry nozzle （SEN） and the same casting velocity V0 are investigated. ANSYS software is used to analyze the SMFs that applied to the EMCC process, and then a data-conversion program based on the principle of linear interpolation proposed previously is used to deal with the issue of data-format-matching between FEM and FVM. The simulation results indicate that, an appropriate SMF can effectively suppress the bulk liquid flow in CC-process of steel plate, and with in- crease of the intensity of applied magnetic fields, the vortexes become weaker and the oscillating amplitude of impinging jet decreases. Based on the knowledge gained from the EMCC-STP analysis and by comparing the re- sults with the applied magnetic fields with those without magnetic fields, it is found that a SMF with 丨 Bmax 丨 = 5.5 × 10 -3 T can meet the need of braking, and consequently improve the quality of casting by reducing the penetration of non-metallic inclusions, as well as avoiding breakout, macro-segregation and crack ultimately.
基金the Indian Institute of Technology Roorkee and MHRD for providing financial support
文摘The relationship between the microstructure and mechanical properties of the spark plasma sintered AA2024 Y composites subjected to cryo-rolling was investigated. Yttrium addition enhances the mechanical properties of the composites by promoting grain refinement and precipitation. However, there is a clear trend of initial increase and later decrease in the properties. Also, it is observed that 0.3 wt.% of yttrium is the optimum amount of reinforcement content to obtain the highest mechanical properties. To further improve the tensile strength of the composites, cryo-rolling was performed on the composites under standard cryogenic conditions by several passes up to a reduction of 25%. The mechanical properties and the corresponding microstructures of composites after cryo-rolling were correlated. The SEM and TEM microstructures reveal that the samples exhibit dual size grains, i.e., nanograins are formed as sub-grains within the actual grain. Due to the grain size reduction and the increase in the dislocation density, the tensile properties are remarkably improved compared to those of the composites before cryo-rolling. The highest mechanical properties like hardness, YS and UTS are found to be 153 HV, 539 MPa and 572 MPa, respectively, with a reasonable ductility in the composite with 0.3 wt.% Y.
文摘The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.
基金supported by the National Natural Science Foundation of China (Nos. 51871068, 51971071, 52011530025, and U21A2049)the National Key Research and Development Program of China (No. 2021YFE0103200)+1 种基金the Zhejiang Province Key Research and Development Program, China (No. 2021C01086)the Fundamental Research Funds for the Central Universities, China (No. 3072021CFT1010)。
文摘Multi-wall carbon nanotubes reinforced Mg-14Li-1Al composite(MWCNTs/Mg-14Li-1Al) was prepared by the processes of electrophoretic deposition, friction stir processing, and cold rolling. The microstructure and mechanical properties of the composite were investigated. The results show that, the microhardness of the composite is up to HV 84.4, which is 91.38% higher than that of the as-cast matrix alloy(HV 44.1). The yield strength and ultimate tensile strength of the composite are 259 and 313 MPa, which are 135.45% and 115.86% higher than those of the as-cast matrix alloy, respectively, and a high specific strength of 221.98 k N·m/kg is obtained. In the composite, the MWCNTs serve as nucleation particles during the friction stir processing and cold rolling, causing dynamic recrystallization and grain refinement. Furthermore, MWCNTs hinder the movement of dislocations and transfer the load from the matrix alloy, thus improving the strength.
