最新刊期
卷 ， 期 4 ， 2008
- 摘要：The influence of pouring temperature on the solidified microstructure of Al-Cu alloy in semi-continuous casting has been simulated by a multi-scale simulation method.The modelings of temperature field and phase transformation in Al-Cu alloy in semi-continuous casting have been established based on coupling temperature field with microstructure evolution through solid fraction change.The calculated steady temperature field in the Al-Cu alloy was projected to a mesoscale area to determine the nucleation of cell in semi-continuous casting by calculating the average under-cooled rate of cell in liquid-solid phase transformation zone.The microstructures of the Al-Cu alloy with contents of 8% and 10% Cu have been simulated by the cellular atomaton poured at different temperature,including 50 K and 5 K higher than liquidus temperature as well as liquidus temperature with the casting velocity of 2 mm/s.The results indicate that the microstructure of Al-Cu alloy poured at near-liquidus temperature is superior to that of ones in conventional casting.The desirable microstructure with excellent grain size and distribution can be prepared with pouring at a larger range of near-liquidus temperature with the Cu content more than 8% or 10%.关键词：Semi-solid;Multi-scale Simulation;Near-liquidus Pouring;Liquid-solid Phase Transformation
- 2
- |
- 226
- |
- 3
发布时间：2023-12-18 - 摘要：Directional solidification experiments were performed on peritectic Nd13.5 Fe79.75 B6.75 alloy with temperature gradient of 180 K/cm and 250-360 K/cm obtained from total melting and zone melting,respectively,at pulling velocity ranging from 5 to 500μm/s to investigate the effects on microstructure and phase constituent in the alloy.The results indicate that the microstructure of the alloy is composed of primary α-Fe dendrites,peritectic Nd2Fe14B phase and minor Nd-rich phase.The volumetric fraction of ferromagnetic Nd2Fe14B phase is firstly increased and then decreased with rising the pulling velocity,and is improved with increasing temperature gradient.Grown at 50μm/s,the volumetric fraction of ferromagnetic Nd2Fe14 B phase reaches up to 90% in the zone melting specimens（given a temperature gradient at 300 K/cm）,which is about 30% higher than that in the total melting specimens（given a temperature gradient at 180 K/cm）.关键词：Peritectic Alloy;Directional Solidification;Temperature Gradient;Pulling Velocity
- 2
- |
- 154
- |
- 0
发布时间：2023-12-18 - 摘要：The solidification structures of AZ61 magnesium alloy under different electromagnetic fields were observed.It is found that the solidification structure of AZ61 magnesium alloy consists of basically equi-axed grain under static magnetic field or combination of static field with alternating current（AC）,while dendrite in the rapid solidification structure can be increased with a certain orientation under the combination of static magnetic field with direct current（DC）.The grain boundary in the solidification structure is composed of magnesium matrix and continuous net-like compound in static field,while it is composed of magnesium matrix and net-like as well as spot-like Mg-Al-Zn compound in combination of static magnetic field with alternating current.The absence of continuous net-like compound at grain boundary can be observed,and the discontinuous lamellar structure is dis-tributed in the magnesium matrix in combination of static magnetic field with direct current.关键词：Magnesium Alloy;Solidification;Static Magnetic Field;Current;Equaixed Grain;Dendrite
- 2
- |
- 187
- |
- 2
发布时间：2023-12-18 -
-
-
-
-
- 摘要：The 7075/6009 gradient aluminum alloy composites have been prepared by double-stream-pouring semi-continuous casting.The macro-structure and micro-structure and composition distribution in the internal,transitional and external layers of the ingot have been analyzed,and the Rockwell hardness in radial of the ingot has been measured also.The results indicate that the 7075/6009 aluminum alloy composites with gradient distribution in composition and hardness can be successfully prepared by optimizing processing parameters.The turbulent flows is dominant in internal and external alloy melt solidification process.The width of the transitional region is dependent on the pouring temperature of internal and external alloy melt,aperture of the throttle bore and the depth of the nozzle submerged in the mold.关键词：Continuous Casting;Composites;7075 Alloy;6009 Alloy
- 2
- |
- 303
- |
- 1
发布时间：2023-12-18 - 摘要：The origination of wire breakage in traditional OCC（Ohno continuous casting） ultra-fine copper wire drawing was described.It is found that the deterioration of the ultra-fine wire drawing properties is resulted from the excessive content of oxygen,sulfur and hydrogen in the copper alloy.The horizontal vacuum melting directional solidification equipment with argon atmosphere which can remove hydrogen,oxygen and other undesirable element from molten copper is a-dopted to prepare the ultra-fine single crystal copper wire drawing.The chemical composition and properties of ultra-fine single crystal copper wire drawing prepared by the new technology were examined.The results reveal that the new technology obviously improves the properties of the copper wire drawing as a result of greatly decreasing the hydrogen,oxygen and other impurities content in the molten copper alloy.关键词：Heated Mold Continuous Casting;Single Crystal Copper;Ultra-fine Wire;Vacuum Melting;Wire Breakage
- 2
- |
- 399
- |
- 3
发布时间：2023-12-18 - 摘要：The induction cladding with adding protective coating on cold cladding alloy layer is a new technology.The frequency of induction power,heating specific power and processing parameters were expounded.The desirable cladding layer on Fe60 pre-coating can be generated with current frequency in rang of 40 kHz to 60 kHz and heating specific power of 5.5 kW/cm2 for 7-8s and moving velocity at 2.15-3.00 mm/s.关键词：Induction Cladding;Protective Coating;Frequency;Specific Power
- 2
- |
- 129
- |
- 1
发布时间：2023-12-18 - 摘要：Effects of four different pre-treatments including annealing,deformation,dual aging,RRA on Al-Zn-Mg-Cu alloy in ECAP have been described.The results show that the annealed alloy at room temperature can only be pressed two passes,while the other alloys are seriously cracked after pressing first pass in ECAP.In addition,the annealed alloy can be pressed many passes with annealing at 523 K,in which the grain size is obviously refined and gradually evolved into equaixed grain with increasing in ECAP passes,however,the refinement of grain size is greatly decreased after eight passes,and the equivalent true strain reaches up to 6.2 after 10 passes with the equaixed grain of about 0.8μm in size.The hardness of annealed alloy is increased with increasing passes,showing a quantitative relationship.关键词：Pre-treatment;Al-Zn-Mg-Cu Alloy;ECAP;Grain Refinement
- 2
- |
- 126
- |
- 3
发布时间：2023-12-18 - 摘要：The side-pouring and center-pouring system for the AM60B Mg alloy motorcycle wheel were simulated by the aid of numerical simulation software with some processing parameters,such as pouring at 680 ℃,injection at 0.5 m/s,and mold initial temperature of 250 ℃ and holding pressure of 80 MPa.The visual-ization of filling process was observed.It is found that the center-pouring system is more desirable.Furthermore,the solidification process of the optimized gating system was simulated with the analysis of defects.The simulated results reveal that the shrinkage porosity（hole） and entrapment gas in the motorcycle wheel can be greatly reduced,improving the quality of the wheel and optimizing the processing.关键词：Squeezing Casting;Magnesium Alloy;Motorcycle Wheel;Gating System;Numerical Simulation
- 2
- |
- 397
- |
- 9
发布时间：2023-12-18 - 摘要：A thermo-mechanical coupled model has been established by the thermo-elastic-plastic finite element method,in which the contact behavior between thin slab and mold was taken into account,to simulate the temperature field,stress field and longitudinal cracking index variations of carbon steel shell in funnel mold as well as effects of pulling velocity on stress and longitudinal cracking index.The results indicate that the temperature at the thin slab off-corner of wide face is higher than those of at the center of the wide face and narrow face,and the existence of two plateaus of temperature history can be observed at 280 mm and 840 mm below meniscus.The peak stress of solidification shell occurs in the funnel edge where the shell has high cracking susceptibility.The higher longitudinal cracking index occurs in the center,funnel edge and off-corner of thin slab wide face,showing easy occurrence of longitudinal crack.The longitudinal cracking index of initial solidified shell can be decreased to reduce the formation possibility of crack by proper increasing casting speed.关键词：Continuous Casting;Mold;Thin Slab;Solidification;Crack;Numerical Simulation
- 2
- |
- 187
- |
- 4
发布时间：2023-12-18 - 摘要：There exists an obvious difference in solidification characteristics of the alloy melt between by weak electromagnetic stirring with low super-heating pouring and by conventional casting.It is important to understand deeply the microstructure evolution of the alloy by analyzing the grain nucleation and growth of the stirred alloy based on solidification theory.The solidification process of semi-solid Al-30Si alloy was described by analyzing effects of weak electromagnetic stirring with low super-heating pouring on the moving of melt and nucleation.The results reveal that the tangential velocity of liquid melt is dominant in stirring process,and the radial and axial velocity can be neglected.The low super-heating pouring can directly increase the nucleation rate in semi-solid alloy and the weak electromagnetic stirring can indirectly increase the nucleation rate.关键词：Electromagnetic Stirring;Low Super-heating Pouring;Solidification;Al-30Si Alloy;Semi-solid
- 2
- |
- 147
- |
- 3
发布时间：2023-12-18 - 摘要：The Al-10Mn and Al-10Cr alloy ingot were prepared by solid-liquid mixed casting.The effects of processing parameters on the microstructure and mechanical properties of the alloys were investigated.The alloys with homogeneous and fine microstructure were prepared under the optimized processing parameters including stirring rate at 500 r/min,temperature of die casting die of 500 ℃ and super-heating temperature of 20℃.The mechanical properties of two kinds of alloys suitable for wear resistant and corrosion resistant materials are increased with increasing in powder addition and decreasing in particle size.关键词：Solid-liquid Mixed Casting;Al-Mn Alloy;Al-Cr Alloy
- 4
- |
- 58
- |
- 0
发布时间：2023-12-18 - 摘要：Microstructure of semi-solid Al-20Sn-lCu bearing alloy was observed by OM（optical microscope） and SEM（scanning electron microscope）.The results indicate that the semi-solid Al-20Sn-lCu alloy possesses uniformly distributed fine microstructure,in which the absence of coarse dendrite Sn and Sn segregation can be observed.The phase constituent is composed of primary α-Al phase,sub-primary α-Al phase and eutectic Sn phase.The size of spheroidized primary α-Al phase is about 50 μm in equivalent diameters.The fine eutectic Sn phase is continuously uniformly distributed along the grain boundary,forming a network structure.However,the network structure in the alloy can be converted into fine Sn dispersoids after heat treatment at 623 K for 1 hour.关键词：Al-Sn Bearing Alloy;Semi-solid;Micro-structure
- 2
- |
- 149
- |
- 2
发布时间：2023-12-18 -
-
-
-
-
- 摘要：A vertical robotic manipulator of die casting machine for coating releasing agent was designed,and a series of manufacturing according to the existing die casting machine specification were conducted.The vertical robotic manipulator is composed of atomizer,spraying pipes,longitudinal back-forward mechanism,perpendicular rotating mechnism.etc,in which the perpendicular rotating mechanism driven by oil pressure was mainly composed of rack with moving plunger and gear mounted at the basis of longitudinal back-forward mechanism.
- 3
- |
- 239
- |
- 8
发布时间：2023-12-18 - 摘要：Design of die casting die for magnesium alloy DVD housing was described,focusing on the gating system,cooling and holding system as well as pushing mechanism.The key points in gating system design,such as injection angular,filling velocity and buffer packet,were expounded.The three design sketches on die casting processing and die casting dies were analyzed comparatively by CAD/CAE/CAM simulation.The results indicate that the desirable processing parameters as follows:injection pressure of 12.71 MPa,die preheating temperature at 250℃,diameter of spray nozzle of 16.2 mm,pouring at 89 m/s,flow volume at 9.18 L/s,plunger diameter of 80mm and plunger velocity of 1.83 m/s.
- 2
- |
- 169
- |
- 2
发布时间：2023-12-18 - 摘要：Some measures on reducing product cost in investment casting were described.关键词：Investment Casting;Product Cost;Processing
- 2
- |
- 339
- |
- 2
发布时间：2023-12-18 - 摘要：The microstructure of AZ91D magnesium alloy in low pressure lost foam casting was observed by OM（optical microscope）,SEM（scanning electron microscope） and EPMA（electron probe micro-analysis）,which was compared with that of ones in other casting methods.The results reveal that the micro-structure of AZ91D magnesium alloy in low pressure lost foam casting is composed of primary AAAAAAAA-Mg phase and divorced eutectic β-Mg17Al12 phase with discontinuous skeleton shape distributed along grain boundary.A little amount of secondary precipitates β-Mg17 Al12 phase is precipitated from near eutectic α-Al-rich zone.Major Al is distributed along grain boundary to create the β-Mg17 Al12 phase,and minor Al is dissolved into the α-Mg matrix.Zn and Si elements were dispersively distributed in a-Mg and β-Mg17 Al12 phase and Mn elements are aggregated on the grain boundary.The microstructure of AZ91D magnesium alloy in low pressure lost foam casting is superior to that in sand casting and in gravity lost foam casting,and is equivalent to that in permanent mold.In addition,the improvement of elongation is attributed to better feeding effects in low pressure improving the compactness of microstructure.关键词：Magnesium Alloy;Microstructure;Low Pressure Lost Foam Casting
- 4
- |
- 117
- |
- 1
发布时间：2023-12-18 - 摘要：The conventional semi-continuous casting was optimized to improve the quality of Mg alloy billets,and the homogenization of magnesium alloy billets was described.The results reveal that the main alloy element and impurity Fe content meet the designed requirements without the introduction of new impurities after the processing optimization,purifying the magnesium alloy billets.The desirable homogenization parameters with holding at 400-430℃ for 10-15 h were obtained.The uniform microstructure in whole cross-section of AZ70 alloy billets with better mechanical properties and plasticity of 8.16% can be observed with homogenizing at 410℃ for 12 hours.关键词：Semi-continuous Casting;AZ70 Magnesium Alloy;Purification;Homogenization
- 2
- |
- 292
- |
- 2
发布时间：2023-12-18 - 摘要：The screwy sheath of double screw roller grinded-paste machine was produced by sand casting,centrifugal casting with permanent mold and resin sand mould coupled with centrifugal casting,respectively,and three casting technologies were analyzed.The results indicate that the screwy sheath produced by sand casting has coarse grain and rougher surface with misrun flaw and shrinkage porosity on the boot of the screw,while that produced by centrifugal casting with permanent mold has high surface quality with fine grain,however,there exists misrun at the thinner location of two ends of the screwy sheath due to high cooling rate,and that produced by resin sand-centrifugal casting has excellent surface quality without defect in the microstructure with fine grain,so it is the desirable technology.关键词：Screwy Sheath;Casting Technology;Centrifugal Casting
- 2
- |
- 97
- |
- 0
发布时间：2023-12-18 - 摘要：The effects of electromagnetic field on soli-dus-liquidus temperature of ZL104 alloy have been examined,and the solidus-liquidus temperature of aluminum alloy castings was comparatively measured.The results reveal that both silidus temperature and liqui-dus temperature can be obviously increased,and narrowed the crystal zone with increasing in electromagnetic field.关键词：Magnetic Field;ZL104 Alloy;Solidus-Ilq-uidus Temperature
- 2
- |
- 107
- |
- 1
发布时间：2023-12-18 - 摘要：The creep behavior of in-situ 15TiCp particu-late reinforced 2024 aluminum matrix composites was evaluated at various temperatures.The results indicate the in-situ 15TiCp/2024 Al composites exhibits excellent high temperature creep strength.The density change of the composite is increased with increasing in creep strain and creep time,and the change is higher at lower temperature than that at higher temperature.Creep rupture can be created as a result of creep damage resulting from the density change reaching to a certain extent.The creep strength of the composites can be improved,which is attributed to the interaction between the dislocation and the second phase particle.The morphology of creep fracture shows that the cavi-ties are usually created at the habitat of one particle or several particles,which continuously propagate with increasing in temperature to result in the ductility rupture,showing temperature distinctly controlling the creep process.关键词：Creep Behavior;TiCp/2024 Al Composites;Density Change
- 2
- |
- 141
- |
- 2
发布时间：2023-12-18 - 摘要：Recrystallizatton dynamics of Al-10Sn and TiB2/Al-10Sn composites was evaluated based on the sensitivities in hardness of the cold rolled aluminum alloy during recrystallization process.The recrystalli-zation activation energy of the two materials were calculated by hardness via time soften curves,and the re-crystallization structure in the two materials was observed.It is found that TiB2 particle can improve the thermal stability of the composites as a result of increasing recystallization temperature of composites by about 60℃.In addition,the recrystallization activation energy of Al-10Sn and TiB2/Al-10Sn composites is 83.16 kJ/mol and 92.98 kJ/mol,respectively.关键词：Al-Sn Alloy;Recrystallization;Composites
- 3
- |
- 162
- |
- 2
发布时间：2023-12-18 - 摘要：The microstructure of Al-Ti-B master alloy was improved by a new method with modified flux.The results indicate that the fine TiB2 particle with 0.35-2μm in average size is uniformly dispersively distributed in the α-Al matrix.Bulk TiAl3 phase with 25-95 μm in average size is uniformly distributed in the α-Al matrix also.The absence of segregation of compound/phase can be observed in the master alloy.关键词：Al-Ti-B Alloy;Master Alloy;Microstruc
- 2
- |
- 203
- |
- 6
发布时间：2023-12-18 - 摘要：The effects of Cu,Mg,Mn elements on tensile strength of Al-24Si piston alloy at high temperature have been examined based on orthogonal regression design,and the parabola equation between tensilestrength at 300℃ and three elements have been established.The results indicate that the change of tensile strength of Al-24Si piston alloy with P,MM（mistch-metal） and Sr compound modification can be neglected with changing Cu and Mg elements in a given range.The Mn content,such as in range of 0.2% to 0.31% or of 0.51 % to 0.6 %,can be emphatically determined and the calculated minimum tensile strength of Al-24Si alloy at 300 ℃ is about 127.39 MPa by the fitting e-quation.which can ensure tensile strength at 300 ℃ to meet the service requirements.关键词：Piston Al Alloy;Orthogonal Regression Design;Tensile Strength at High Temperature
- 2
- |
- 81
- |
- 2
发布时间：2023-12-18 - 摘要：Effects of different RE La additions on as-cast microstructure,mechanical properties,aging behavior and aging sequence of 6063 aluminum alloy have been investigated by hardness tester,DSC（differential scanning calorimetry）,XRD（X-ray diffraction） and SEM（scanning electron microscope）.It is found that the dendrite in alloy can be evidently refined and mechanical properties can be improved with proper La addition,meanwhile,the aging precipitation sequence can not be changed.However,mechanical properties of alloy can be obviously deteriorated with the increase of La addition,which is attributed to the creation of coarse AlFeSiLa compound restricting the precipitation of the β" and β’ phase and reduced Mg2Si phase.关键词：La;6063 Aluminum Alloy;Aging;DSC
- 2
- |
- 267
- |
- 4
发布时间：2023-12-18 - 摘要：The relationship between segregation degree of Si in A356.2 aluminum alloy ingot during solidification and melting time,electromagnetic stirring was examined.The results show that the segregation degree of Si can be decreased with extending melting time.In addition,electromagnetic stirring is helpful to decreasing segregation degree of Si element.关键词：Aluminum Alloy;Melting;Electromagnetic Stirring;Segregation
- 2
- |
- 248
- |
- 2
发布时间：2023-12-18 -
- 摘要：An environmental friendly Bi-brass with cutting-free and excellent properties was developed to substitute for Pb-brass.A proper amount of Al and Ce was added into the Bi-brass to improve its mechanical properties.The microstructure of Bi-brass containing Al and Ce was observed by OM（optical microscope）,SEM（scanning electron microscope） and XRD（X-ray diffractionmeter）.The observation results reveal that the alloy has fine microstructure with uniformly distributed Bi in the matrix.The machinability of the Bi-brass is greatly superior to that of conventional Pb-brass.The tensile strength and elongation of the alloy are more than 450 MPa and 35%,respectively,which is attributed to Al and Ce changing the distribution of Bi in the alloy by influencing the wettablity of Bi.关键词：Bi-brass;Pb-brass;Mechanical Properties
- 2
- |
- 191
- |
- 4
发布时间：2023-12-18 - 摘要：The application of recycled copper castings was limited due to the easy-existence of gas hole,inclusion and crisp-crack which is resulted from the nonqualification of recycled copper scrap.The origination and prevention of the defects in recycled copper were expounded.关键词：Recycled Copper;Melting Quality;Origination
- 2
- |
- 111
- |
- 2
发布时间：2023-12-18 -
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0