With the experiment and finite element simulation, the influences of power ultrasonic on the solidification structure of 7050 aluminum alloy ingot in semi-continuous casting were researched, and the effects of casting...With the experiment and finite element simulation, the influences of power ultrasonic on the solidification structure of 7050 aluminum alloy ingot in semi-continuous casting were researched, and the effects of casting speed on solidification structure in ultrasonic field were also analyzed. The experiment and simulation results show that the solidification structure of the ingot is homogeneously distributed, and its grain size is obviously refined at ultrasonic power of 240 W. The average grain sizes, which can be seen from the Leica microscope, are less than 100 μm. When the casting speed is 45-50 mm/min, the best grain refinement is obtained.展开更多
In order to use the cast method to replace forge method in producing the load bearing wheel used in certain heavy duty vehicle, simplified and reduced size load bearing wheels were squeeze cast and studied using Al Cu...In order to use the cast method to replace forge method in producing the load bearing wheel used in certain heavy duty vehicle, simplified and reduced size load bearing wheels were squeeze cast and studied using Al Cu alloy. Tensile properties, hardness, microstructures and morphologies of the squeeze cast wheels were investigated. The results show that the finer microstructure, higher density, strength, toughness and hardness were achieved through the squeeze casting. Ultimate tensile strength of 428 MPa, yield strength of 360 MPa, elongation of 13.1% were achieved for T5 heat treated squeeze cast wheels. The Brinell hardness of squeeze cast wheels is from HB 120 to HB 137.展开更多
This study investigated the effect of pre-friction surfacing heat treatment of consumable rods and heat input during friction surfacing on the microstructure,mechanical properties,and wear resistance of hypereutectic ...This study investigated the effect of pre-friction surfacing heat treatment of consumable rods and heat input during friction surfacing on the microstructure,mechanical properties,and wear resistance of hypereutectic Al-Si alloy deposited on a commercially pure aluminum substrate.The results show that regardless of the consumable rod’s heat treatment conditions,the coating’s efficiency has increased with the increase in heat input,so the coating efficiency increases by 20%and 30%in the solid solution-treated rod and the artificially aged rod,respectively.By increasing the heat input,the average grain size in the coating fabricated by solid solution-treated rod and artificially aged rod increased from 0.1 to 0.9μm and from 0.2 to 1.3μm,respectively.At constant heat input,the average hardness and wear resistance of the coating created in the solid solution-treated rod are lower than those of the artificially aged rod.By decreasing heat input,the wear loss in the coating fabricated by solid solution-treated rod and artificially aged rod decreased by 10%and 20%,respectively,reaching 0.1 and 0.03μg/m.展开更多
The effect of T6I6 treatment on the dynamic mechanical and microstructure behaviour of Al-Si-Mg-Cu cast alloy was investigated using split Hopkinson pressure bar(SHPB), transmission electron microscopy(TEM), and highr...The effect of T6I6 treatment on the dynamic mechanical and microstructure behaviour of Al-Si-Mg-Cu cast alloy was investigated using split Hopkinson pressure bar(SHPB), transmission electron microscopy(TEM), and highresolution transmission electron microscopy(HRTEM). Besides, the impact resistances of T6I6 and T6 motor shells of new energy vehicles made of Al-Si-Mg-Cu cast alloy were compared using a trolley crash test. The results indicated that the main strengthening-phases of the T6 peak-aged and T6I6 peak-aged alloy were GP zone and β″ precipitates. T6I6treatment can increase the density and size of β″ precipitates in peak-aged alloy and enhance both its tensile strength(σb)and elongation(δ). The dynamic toughness values of T6I6 samples are 50.34 MJ/m^(3) at 2000 s^(-1) and 177.34 MJ/m^(3) at 5000 s^(-1) which are 20% and 12% higher than those of T6 samples, respectively. Compared with a T6 shell, the overall deformation of T6I6 shell is more uniform during the crash test. At an impact momentum of 3.5×10;kg·m/s, the T6I6shell breaks down at 0.38 s which is 0.10 s later than the T6 shell.展开更多
The rheological behavior of aluminum alloy and its influencing factors in physical simulation of continuous roll casting process were studied by using a Gleeble-1500 thermal-mechanical simulation tester with a set of ...The rheological behavior of aluminum alloy and its influencing factors in physical simulation of continuous roll casting process were studied by using a Gleeble-1500 thermal-mechanical simulation tester with a set of special clamp system. The relationships between the flow stress and the strain rate in the deformation process of simulating roll casting experiment were obtained. The results show that four different characteristic stages exist in the temperature range of the whole rheological process. The first occurs when the temperature is higher than 600 ℃, which belongs to the creep deformation stage; the second occurs when the temperature lies in the range of 500600 ℃, and it can be regarded as the high temperature and low stress level deformation stage; the third occurs when the temperature decreases to the range of 300500 ℃, it is considered to be the middle stress level deformation stage; the last occurs when the temperature is less than 300 ℃ and the strain rate is less than 1.00 s -1, it belongs to middle stress level deformation stage. But when the strain rate is larger than 1.00 s -1,it belongs to the high stress level deformation stage. And the relative constitutive models suitable for the four different stages of continuous roll casting process were established through multivariate linear regression analysis of the experimental data.展开更多
The casting-solid extrusion forging plus semi-solid partial remelting route is used to improve the properties of AZ31 magnesium alloy products.The effect of remelting temperature and holding time on the microstructure...The casting-solid extrusion forging plus semi-solid partial remelting route is used to improve the properties of AZ31 magnesium alloy products.The effect of remelting temperature and holding time on the microstructure of AZ31 magnesium alloy is studied.Furthermore,the properties of AZ31 magnesium alloy components produced by the casting-solid extru.sion forging plus partial remelting route are examined.The results show that the AZ31 components have very good smooth surface and are formed completely.The increases in holding time and remelting temperature result in the formation of spheroidal grains surrounded by liquid phases.The best combination of properties of thixoforged alloy is290 MPa of tensile strength,220 MPa of yield strength and 10%of percentage elongation.展开更多
The 2024/3003 aluminum gradient alloys are prepared by semi continuous casting. The influences of throttle bore diameter of embedded nozzle and temperature of internal melt on composition distribution, macrostructure,...The 2024/3003 aluminum gradient alloys are prepared by semi continuous casting. The influences of throttle bore diameter of embedded nozzle and temperature of internal melt on composition distribution, macrostructure, hardness are analyzed, and the stability of gradient distribution of composition, macrostructure and hardness along the axial direction of the ingot is also studied. The results show that diffe rent composition profiles can be achieved by adjusting the processing parameters; the volume fraction of inner alloy in the ingot can be increased by enlarging the throttle bore diameter and elevating the temperature of inner melt; quasi steady solidification can be realized within 20 s during cast processing, and consistent quality ingot is obtained by controlling the casting speed and liquid height of inner melt.展开更多
Cast Al alloys are widely employed for engine components,structural parts,gear box,chassis,etc.and subjected to mechanical cyclic load during operation.The accurate fatigue life prediction of these alloys is essential...Cast Al alloys are widely employed for engine components,structural parts,gear box,chassis,etc.and subjected to mechanical cyclic load during operation.The accurate fatigue life prediction of these alloys is essential for normal operation as fatigue cracks initiated during operation induce the lubrication oil leak and serious safety hazard.Microstructural heterogeneity,including shrinkage/gaspores and secondary phase particles,is the most detrimental factor that affects fatigue life of cast Al alloys.The approximate fatigue life cycles could be estimated based on the size distribution and locations of shrinkage pores/defects.The relationship between crack population and stress was reported by statistical distributions and the cumulative probability for cast Al alloys fail at a certain stress could be predicted by combination of Paris law and pore size distribution.Pore depth was found to dominate the stress field around the pore on the surface and the maximum stress increases sharply when the pore intercepted with the surface at its top.The microstructure of cast Al alloys usually is composed of primary Al dendrites,eutectic silicon,Fe-rich particles and other intermetallic particles are dependent upon alloy composition and heat treatment.The coalescence of microcracks initiated from the fractured secondary phases was clearly found and can accelerate the initiation and propagation of the fatigue cracks.A link between defect features and the fatigue strength needs to be established through a good understanding of the fatigue damage mechanisms associated with the microstructural features under specific loading conditions.This paper reviews the influences of shrinkage/gaspores and secondary phase particles,formed during casting process,on the fatigue life of Al-Si-Mg cast Al alloys.展开更多
Abstract： In order to improve the surface hardness and wear resistance of magnesium, Al-13%Si （mass fraction） alloy coating was deposited on pure magnesium by droplet spraying process. The microstructure was studie...Abstract： In order to improve the surface hardness and wear resistance of magnesium, Al-13%Si （mass fraction） alloy coating was deposited on pure magnesium by droplet spraying process. The microstructure was studied by electron probe microanalysis and X-ray diffraction. The micro-hardness and wear resistance of coating were investigated in comparison with those of the substrate. It is found that the coating layer is composed of a-Al cellular due to rapid solidification. Formation mechanism of the coating is due to the obstruction of diffusion by in-situ formed Mg2Si in interracial layer. The coating exhibits higher hardness compared to that of the Mg substrate. As result of its high hardness, the wear resistance of the coating layer is about ten times that of the substrate. The droplet spraying process demonstrates that the magnesium surface can be strengthened by using the existing Al-Si alloys.展开更多
基金Project(2010CB731700) supported by the National Basic Research Program of China
文摘With the experiment and finite element simulation, the influences of power ultrasonic on the solidification structure of 7050 aluminum alloy ingot in semi-continuous casting were researched, and the effects of casting speed on solidification structure in ultrasonic field were also analyzed. The experiment and simulation results show that the solidification structure of the ingot is homogeneously distributed, and its grain size is obviously refined at ultrasonic power of 240 W. The average grain sizes, which can be seen from the Leica microscope, are less than 100 μm. When the casting speed is 45-50 mm/min, the best grain refinement is obtained.
文摘In order to use the cast method to replace forge method in producing the load bearing wheel used in certain heavy duty vehicle, simplified and reduced size load bearing wheels were squeeze cast and studied using Al Cu alloy. Tensile properties, hardness, microstructures and morphologies of the squeeze cast wheels were investigated. The results show that the finer microstructure, higher density, strength, toughness and hardness were achieved through the squeeze casting. Ultimate tensile strength of 428 MPa, yield strength of 360 MPa, elongation of 13.1% were achieved for T5 heat treated squeeze cast wheels. The Brinell hardness of squeeze cast wheels is from HB 120 to HB 137.
文摘This study investigated the effect of pre-friction surfacing heat treatment of consumable rods and heat input during friction surfacing on the microstructure,mechanical properties,and wear resistance of hypereutectic Al-Si alloy deposited on a commercially pure aluminum substrate.The results show that regardless of the consumable rod’s heat treatment conditions,the coating’s efficiency has increased with the increase in heat input,so the coating efficiency increases by 20%and 30%in the solid solution-treated rod and the artificially aged rod,respectively.By increasing the heat input,the average grain size in the coating fabricated by solid solution-treated rod and artificially aged rod increased from 0.1 to 0.9μm and from 0.2 to 1.3μm,respectively.At constant heat input,the average hardness and wear resistance of the coating created in the solid solution-treated rod are lower than those of the artificially aged rod.By decreasing heat input,the wear loss in the coating fabricated by solid solution-treated rod and artificially aged rod decreased by 10%and 20%,respectively,reaching 0.1 and 0.03μg/m.
基金Projects(52075166, 51875197) supported by the National Natural Science Foundation of ChinaProjects(2019RS2064,2019GK5043) supported by the Science and Technology Planning Project of Hunan Province,China。
文摘The effect of T6I6 treatment on the dynamic mechanical and microstructure behaviour of Al-Si-Mg-Cu cast alloy was investigated using split Hopkinson pressure bar(SHPB), transmission electron microscopy(TEM), and highresolution transmission electron microscopy(HRTEM). Besides, the impact resistances of T6I6 and T6 motor shells of new energy vehicles made of Al-Si-Mg-Cu cast alloy were compared using a trolley crash test. The results indicated that the main strengthening-phases of the T6 peak-aged and T6I6 peak-aged alloy were GP zone and β″ precipitates. T6I6treatment can increase the density and size of β″ precipitates in peak-aged alloy and enhance both its tensile strength(σb)and elongation(δ). The dynamic toughness values of T6I6 samples are 50.34 MJ/m^(3) at 2000 s^(-1) and 177.34 MJ/m^(3) at 5000 s^(-1) which are 20% and 12% higher than those of T6 samples, respectively. Compared with a T6 shell, the overall deformation of T6I6 shell is more uniform during the crash test. At an impact momentum of 3.5×10;kg·m/s, the T6I6shell breaks down at 0.38 s which is 0.10 s later than the T6 shell.
文摘The rheological behavior of aluminum alloy and its influencing factors in physical simulation of continuous roll casting process were studied by using a Gleeble-1500 thermal-mechanical simulation tester with a set of special clamp system. The relationships between the flow stress and the strain rate in the deformation process of simulating roll casting experiment were obtained. The results show that four different characteristic stages exist in the temperature range of the whole rheological process. The first occurs when the temperature is higher than 600 ℃, which belongs to the creep deformation stage; the second occurs when the temperature lies in the range of 500600 ℃, and it can be regarded as the high temperature and low stress level deformation stage; the third occurs when the temperature decreases to the range of 300500 ℃, it is considered to be the middle stress level deformation stage; the last occurs when the temperature is less than 300 ℃ and the strain rate is less than 1.00 s -1, it belongs to middle stress level deformation stage. But when the strain rate is larger than 1.00 s -1,it belongs to the high stress level deformation stage. And the relative constitutive models suitable for the four different stages of continuous roll casting process were established through multivariate linear regression analysis of the experimental data.
文摘The casting-solid extrusion forging plus semi-solid partial remelting route is used to improve the properties of AZ31 magnesium alloy products.The effect of remelting temperature and holding time on the microstructure of AZ31 magnesium alloy is studied.Furthermore,the properties of AZ31 magnesium alloy components produced by the casting-solid extru.sion forging plus partial remelting route are examined.The results show that the AZ31 components have very good smooth surface and are formed completely.The increases in holding time and remelting temperature result in the formation of spheroidal grains surrounded by liquid phases.The best combination of properties of thixoforged alloy is290 MPa of tensile strength,220 MPa of yield strength and 10%of percentage elongation.
文摘The 2024/3003 aluminum gradient alloys are prepared by semi continuous casting. The influences of throttle bore diameter of embedded nozzle and temperature of internal melt on composition distribution, macrostructure, hardness are analyzed, and the stability of gradient distribution of composition, macrostructure and hardness along the axial direction of the ingot is also studied. The results show that diffe rent composition profiles can be achieved by adjusting the processing parameters; the volume fraction of inner alloy in the ingot can be increased by enlarging the throttle bore diameter and elevating the temperature of inner melt; quasi steady solidification can be realized within 20 s during cast processing, and consistent quality ingot is obtained by controlling the casting speed and liquid height of inner melt.
基金Projects(11790282,U1534204,11572267,51804202,51705344)supported by the National Natural Science Foundation of ChinaProject(E2019210292)supported by the Natural Science Foundation of Hebei Province,China+6 种基金Project(A2019210204)supported by the National Natural Science Foundation for Distinguished Young Scholars,ChinaProject(KQTD20170810160424889)supported by the Shenzhen Peacock Team Program,ChinaProject(2019DB013)supported by the Key Research Project of Southern Xinjiang,ChinaProject(C201821)supported by the High Level Talent Support Project in Hebei,ChinaProject supported by the Youth Top-notch Talents Supporting Plan of Hebei Province,ChinaProject(MCMS-E-0519G04)supported by the State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astronautics,ChinaProject(201919)supported by the Open Fund of State Key Laboratory of Metastable Materials Science and Technology,Yanshan University,China。
文摘Cast Al alloys are widely employed for engine components,structural parts,gear box,chassis,etc.and subjected to mechanical cyclic load during operation.The accurate fatigue life prediction of these alloys is essential for normal operation as fatigue cracks initiated during operation induce the lubrication oil leak and serious safety hazard.Microstructural heterogeneity,including shrinkage/gaspores and secondary phase particles,is the most detrimental factor that affects fatigue life of cast Al alloys.The approximate fatigue life cycles could be estimated based on the size distribution and locations of shrinkage pores/defects.The relationship between crack population and stress was reported by statistical distributions and the cumulative probability for cast Al alloys fail at a certain stress could be predicted by combination of Paris law and pore size distribution.Pore depth was found to dominate the stress field around the pore on the surface and the maximum stress increases sharply when the pore intercepted with the surface at its top.The microstructure of cast Al alloys usually is composed of primary Al dendrites,eutectic silicon,Fe-rich particles and other intermetallic particles are dependent upon alloy composition and heat treatment.The coalescence of microcracks initiated from the fractured secondary phases was clearly found and can accelerate the initiation and propagation of the fatigue cracks.A link between defect features and the fatigue strength needs to be established through a good understanding of the fatigue damage mechanisms associated with the microstructural features under specific loading conditions.This paper reviews the influences of shrinkage/gaspores and secondary phase particles,formed during casting process,on the fatigue life of Al-Si-Mg cast Al alloys.
基金Project(KZJ-48)supported by the Science and Technology Development Program of Qingdao,ChinaProject(51208288)supported by the National Natural Science Foundation of ChinaProject(BS2011CL032)supported by the Research Award Fund for Outstanding Youngand Middle-aged Scientists of Shandong Province,China
文摘Abstract： In order to improve the surface hardness and wear resistance of magnesium, Al-13%Si （mass fraction） alloy coating was deposited on pure magnesium by droplet spraying process. The microstructure was studied by electron probe microanalysis and X-ray diffraction. The micro-hardness and wear resistance of coating were investigated in comparison with those of the substrate. It is found that the coating layer is composed of a-Al cellular due to rapid solidification. Formation mechanism of the coating is due to the obstruction of diffusion by in-situ formed Mg2Si in interracial layer. The coating exhibits higher hardness compared to that of the Mg substrate. As result of its high hardness, the wear resistance of the coating layer is about ten times that of the substrate. The droplet spraying process demonstrates that the magnesium surface can be strengthened by using the existing Al-Si alloys.
