最新刊期
卷 30 ， 期 5 ， 2010
- 摘要：The semi-solid ZL201A alloy slurry was prepared by the low superheating pouring at 678,663,648℃ and weak electromagnetic stirring method,and microstructure of the samples was observed by optical microscope.The results reveal that with decreasing in pouring temperature,primary α-Al grains in the semi-solid ZL201A aluminum alloy slurry are changed from rosette to spherical shape with refinement of grain size and more homogeneous distribution,meanwhile,that in the edge and bottom of the slurry are converted from coarse dendrite into rosettes.The appropriate temperature for preparation of semi-solid ZL201A aluminum alloy slurry is 663℃ under the given conditions.The refinement of primary α-Al grains is attributed to the weak electromagnetic stirring homogenizing the temperature field of liquid ZL201A alloy and widening the region of simultaneous solidification,meanwhile,the latent heat of the ZL201A aluminum alloy is released during a shorter period,which promotes the secondary arm roots of the rosette α-Al grains to be melted,accelerating the formation of spherical α-Al grains.关键词：Semi-solid;Pouring Temperature;Electromagnetic Stirring;ZL201A Aluminum Alloy;Microstructure
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发布时间：2023-12-18 - 摘要：The microstructure,wear resistance and hardness of the five brake discs which were produced by three kinds of composites at different processing conditions,such as different pouring temperatures,mould temperatures and rotating velocities of centrifugal machine,were comparatively analyzed in as-cast,T4 and T6 treatment composite in order to provide the most suitable materials and forming process for brake disc.The results indicate that Al-21Si-5Mg-1Cu-1Ni-0.2Ti-0.4Mn alloy which is poured at 757℃ into permanent mold with 100 ℃ and 400 r/min exhibits a better wear resistance and hardness of HRB89.6,showing a desirable material for brake disc.关键词：Particle Reinforced Composites;Centrifugal Casting;Brake Disc
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发布时间：2023-12-18 -
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- 摘要：The heat transfer model of air slip mold was established by the heat resistance theory,and effects of the contacted heat resistance between graphite ring and water cooling wall on the heat transfer and temperature distribution in the mold were analyzed,meanwhile,effects of different assembling ways on heat transfer and working temperature of graphite ring were approached.New method to structure design of mold for air slip continuous casting was presented.The results reveal that with increasing in heat resistance between graphite ring and mold,working temperature of graphite ring is increased,resulting in the deterioration of processing stability.In addition,the lubricating oil layer adhered on graphite ring in condition of a loose fit can result in the decrease of permeability of graphite,which is responsible for the absence of air film.The calculated results are in good agreement with the experimental ones.关键词：Air Slip;Continuous Casting;Heat Transfer;Heat Resistance
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发布时间：2023-12-18 - 摘要：Effects of different RE （rare earth） additions on the microstructure and mechanical properties of AZ61 alloys during hot deformation were investigated.With 1%～4% mischmetal addition,β-Mg17Al12 phase in as-cast microstructure of AZ61 magnesium alloy is greatly decreased,and grain size is obviously refined,and acicular,rod-like or irregular block Al4Ce phase or compound phase of Al4Ce and Al3Nd which is distributed into grain boundary or grain can be observed,meanwhile,irregular block α-Al8Mn5 phase can be observed in the experimental alloys too.During hot deformation process,Al4Ce phase or compound phase of Al4Ce and Al3Nd can refine microstructure of the alloy by inhibiting growth of grain or sub-grain,which slightly improves the mechanical properties of the alloy,however,compared with those of AZ61 matrix alloy,mechanical properties of the AZ61 alloy with RE addition are sharply deteriorated as a result of coarse RE phase dissevering grain boundary and binding force in grains.Fracture mechanism of as-cast AZ61+xRE alloy is characterized by brittle crack,and that of as-extruded AZ61 alloy is characterized by ductility-brittle crack,and that of as-extruded AZ61+xRE alloy is characterized by cleavage crack.关键词：Magnesium Alloy;Rare Earth;Hot Extrusion;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：Effects of various routes and passes of ECAP （equal channel angular pressing） on the hardness and mechanical properties of the Mg-1Zn-2Nd magnesium alloy at different strain rates and temperatures were investigated,and tensile fracture morphology of the ECAPed alloy was observed by SEM （scanning electron microscope）.The results show that the elongation and yield strength of the ECAPed Mg-2Zn-2Nd alloy at different temperatures are closely related to the pressing route and pass as well as the imposed strain rate.The ECAPed alloy exhibits typical ductile fracture morphology at different pressing routes and passes in condition of tensile loading.Elongation of the alloy with C route for four passes reaches maximum value of 381.8% at 300℃.关键词：Magnesium Alloy;ECAP;Elongation;Yield Strength
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发布时间：2023-12-18 -
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- 摘要：Numerical simulation for dual squeezing casting aluminum alloy wheel for automobile was conducted by the FEM （finite element method） software to observe the distribution of temperature field and to predict potential shrinkage hole （porosity） location during filling and solidification process.The results reveal that shrinkage hole （porosity） easily occurs in the center of the aluminum alloy wheel hub,so feeding location is set in the center during dual squeezing casting.Empirical formula for feeding force was analyzed and derived by the yield criterion,and numerical simulation of dual squeezing casting aluminum alloy wheel was conducted to eventually determine the feeding force.关键词：Squeezing Casting;Feeding;Numerical Simulation
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发布时间：2023-12-18 - 摘要：Based on flow process before establishment of strip casting,a continuous casting technology of low superheat casting that molten steel is cooled through rotating cooling roller is forced to pour into mould has been put forward to reduce molten steel superheat,enhancing the efficiency of heat transfer and improving structure in billets.The filling process of low superheat casting and SEN casting was dynamically simulated by the fluid dynamic software to obtain velocity distribution diagrams and temperature distribution diagrams at different time.The results show that low superheat casting with double-roller cooling can effectively decrease superheat of molten steel and increase the solidification rate of molten steel during filling process.关键词：Double Roller Cooling;Low Superheat;Slab Continuous Casting;Temperature Field;Solidification
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发布时间：2023-12-18 - 摘要：Effects of self-inoculation method （SIM） and melt treated temperature on as-cast microstructure of ZL101 semi-solid slurry prepared by a novel self-inoculation rheoforming method were investigated.The results show that grain with 25～49 μm in size and 37 μm in average equivalent spherical diameters can be observed in self-inoculated ZL101 alloy slurry.The desirable refinement can be obtained in the alloy slurry with 5% self-inoculators addition at 710 ℃ by flowing on the deflector with 45°.Inoculator addition can promote the nucleation of primary α-Al,and shearing and chilling effects of deflector can generate new nuclei by broking dendrite,which results in the increase of grain size during alloy solidification,greatly refining grain size in the alloy slurry.关键词：ZL101 Aluminum Alloy;Self-inoculation;Semi-solid;Grain Refinement
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发布时间：2023-12-18 -
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- 摘要：Die casting process for Dmax oil pan was simulated by the Anycasting software.Filling process in different gating systems was visualized to predict potential defect position in the castings by observing liquid aluminum filling.Gating system with liquid aluminum filling from two-sides of castings was designed.The practical production verifies that the gating system has desirable effects.关键词：Aluminum Alloy;Die Casting;Gating System;Simulation
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发布时间：2023-12-18 - 摘要：Temperature field,thermal stress field and thermal fatigue distribution of the mould were visualized by the Procast software simulating forming process of aluminum alloy dome of coffee machine.Two typical processing feature regions in which thermal fatigue easily appeared were selected to simulate.The T-shape gating system and comb-shape gating system were analyzed comparatively.The results show that comb-shape gating system exhibits more desirable.The experimental results verify the feasibility of the optimized design for decreasing thermal fatigue and improving service life of the mould.关键词：Thermal Fatigue;Numerical Simulation;Die Casting Die;Stress Field;Temperature Field
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发布时间：2023-12-18 - 摘要：According to its characteristics,a die casting die for aluminum alloy magnifier frame was designed.Structure characteristics and working principle of the die were described.Some design was adopted in the die,such as one mould-two cavities and side-gating system with rectangular cross section for feeding,contracting core for core pulling and rotating core for thread demoulding.Core that forms loop groove of hole-wall of the castings is designed of 6 large sector segments and 6 small sector segment,which realizes the core-pulling of loop groove by relative motion of large and small sector segment making 12 sector segment move inside along radial direction.Meanwhile,with the help of open-mould force to transmit gear-rack mechanism,thread demoulding can be realized by rotating horizontal thread core.The die exhibits advantages of compact structure,reliable working performance,high efficiency and high product precision.关键词：Rotating Thread Demoulding;Die Casting Die;Gear-rack Mechanism;Thread Core;Core Segment;Contracting Core
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发布时间：2023-12-18 - 摘要：Aiming at practical production conditions at some plants,the common defects in EPC （expendable pattern casting） iron castings were analyzed,and countermeasures were presented.The practical production verifies that the analysis and countermeasures are available..关键词：Lost Foam Casting;Common Defects;Countermeasures
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发布时间：2023-12-18 - 摘要：The developing procedure of complicated investment casting based on the Pro/E software was described including 3D model design,rapid prototype manufacture,plaster mold manufacture and mould design.The result verifies that the Pro/E software can effective shorten the developing period and improve the designing and casting quality.
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发布时间：2023-12-18 - 摘要：A low-cost core for investment casting formed with hot-box process was investigated.The core consists of furan resin as binder at room temperature and liquid aluminum dihydrogen phosphate which plays the dual roles in curing agent and high-temperature binder,and it is assisted with low-temperature dipping enhancing processing.Taking pre-firing,post-firing and high temperature residual strength as bench marks for resin sand core,influential factors such as resin types,resin amounts,granularity of sand,amounts of aluminum dihydrogen phosphate,core dipping times,were optimized by orthogonal testing.The results reveal that proportion in which resin content accounts for 2%～3% sand weight and aluminum dihydrogen phosphate addition accounts for 2%～4% sand weight exhibits availability.And then the cores were manufactured with the optimized proportion for investment casting evaluation tests.The results show that the cores have the advantages such as separate firing being not needed,low cost and very low residual strength of 3.45～5.0MPa,meeting the requirements of investment casting cores with relatively simple shape.关键词：Investment Casting;Core;Aluminum Dihydrogen Phosphate;Hot Box;Furan Resin
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发布时间：2023-12-18 - 摘要：SiC particles reinforced aluminum matrix composites were fabricated by stirring casting,and effects of different stirring parameters on the particle distribution were analyzed.The distribution of particle in the matrix and phase constituent in the composites were investigated by SEM （scanning electron microscope） and XRD （X-ray diffraction）.The results reveal that the SiC particle is uniformly distributed into the prepared composites in the absence of gas hole at stirring velocity of 680 r/min with impeller diameters of 60 mm and blade angle of 30°.Obvious particle deposition in the prepared composites is absent in condition of slow cooling rate.The MgAl2O4,Mg2Si phase can be observed in the composites with the absence of Al4C3 phase.关键词：SiCp/Al Composites;Stirring Casting;Particle Distribution;SiC
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发布时间：2023-12-18 - 摘要：Ring WCp/Fe-C recycled composites castings were prepared by centrifugal casting,and distribution and morphology of reinforcement as well as microstructure of the alloy matrix were analyzed by optical microscope,JSM-5160LV scanning electron microscope （SEM） and EDAX electron spectrometer and XRD （X-ray diffraction）.The results show that WC particles are gathered in the outer layer along the radial direction of the sample under the experiments,leading to the formation of compound structural sample which consists of WCp/Fe-C composites working layer with 15 mm in thickness and Fe-C alloy matrix in core.It is found that the increase of rotating speed of centrifugal machine is beneficial to the gathering of WCp in the working layer.Microstructure of the as-cast sample exhibits as follows:in the working layer,a large amount of un-dissolved WCp with a little in-situ formed dendritic carbides are uniformly distributed into the bainite matrix;in the transition layer,the volume fraction of WCp is decreased sharply and a fine WCp layer is observed;in the core matrix layer,in-situ short-rod carbide and net-like carbide with little spheroidal graphite are created.关键词：Centrifugal Casting;Recycled Composites;Microstructure;Scrap Composites;Remelting
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发布时间：2023-12-18 - 摘要：Effects of cladding size changes on electric conductivity of copper-aluminum-copper cladding plate were examined by the FEM （finite element method） software.It is found that with a fixed loading,electric conductivity of copper-aluminum-copper cladding plate is increased with increasing in copper thickness.However,with copper thickness more than 0.5 mm,effects of copper thickness on impedance of cladding plate can be neglected.At a fixed cladding width,with increasing in cladding thickness,impedance of the cladding plate is greatly decreased,while effects on electric conductivity are slowly weakened.At a given copper thickness,with increasing in cladding thickness,impedance of the cladding plate is decreased,and with increasing in width of cladding plate,effects of thickness on impedance of the plate are greatly weakened.关键词：Copper-aluminum-copper Cladding Plate;Bus-bar;Cladding Plate Shape;Electric Conductivity
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发布时间：2023-12-18 - 摘要：3003/4004 aluminum alloy cladding materials were produced by double-stream-pouring semi-continuous casting using a self-developed semi-continuous casting device.The composition,microstructure and mechanical properties of the prepared composites were investigated.The results show that uniform distribution of different alloy composition in interface can be observed in produced 3003/4004 aluminum alloy cladding materials,and there exists observed corresponding relation among the hardness,mechanical properties and composition distribution,microstructure,showing a higher interfacial strength.It is feasible for preparing 3003/4004 aluminum alloy cladding materials by double-streaming-pouring semi-continuous casting.关键词：3003/4004 Aluminum Alloy;Cladding Materials;Semi-continuous Casting
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发布时间：2023-12-18 - 摘要：Effects of pulsed peak value current on directional solidification structure in the pure aluminum were investigated by employing high intensity pulsed current during directional solidification process.It is found that with increasing in high intensity pulsed current,the directional solidification structure in the pure aluminum is evolved from regular columnar crystal to cellular crystal and then to developed dendrite and finally to columnar crystal.Taking into account of coupling effects of inductive magnetic field and pulsed current,based on electromagnetic hydromechanics,role mechanism of high intensity pulsed current on solidification structure was analyzed.The evolution of solidification structure is attributed to high-frequency oscillatory magnetic filed induced by high intensity pulsed current causing dynamic radial electromagnetic pressure which can affect distribution of the flow field and temperature gradient on the front face of liquid metal above solidification interface and scour the dendritic arm.关键词：Pulsed Current;Directional Solidification;Dendritic Arm Space;Induced Electromagnetic Pressure;Electromagnetic Hydromechanics
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发布时间：2023-12-18 - 摘要：Effects of different extruding temperature and cooling ways as well as heat treatment on properties of spraying deposited aluminum alloy components were investigated.It is found that properties of the alloy are closely related to them.Tensile strength and elongation of the alloy which is extruded with temperature increasing from 420℃ to 470℃ and cooled at air and then treated by solid solution plus ageing treatment are increased from 670MPa to 775MPa and from 3% to 8%,respectively.Tensile strength and elongation of the alloy which is extruded at 470℃ and cooled at water and then treated by solid solution plus ageing treatment reach 745MPa and 6%,respectively,while those of one which is extruded at 470℃ and cooled at water to ambient temperature and then treated by directly ageing treatment make 550 MPa and 5%,respectively.关键词：Spraying Deposition;Extrusion;Solid Solution and Ageing;Tensile Strength
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发布时间：2023-12-18 - 摘要：Heat resistant Mg-RE （Mg-11Y-5Gd-2Zn-0.5Zr） alloy engine piston was produced by gravity casting,and the processing parameters,such as pouring temperature,preheating temperature of the mould and heat treatment conditions,were optimized.Meanwhile,the microstructure of alloy piston was observed by optical microscope,SEM （scanning electron microscope）.The results reveal that there exist amounts of secondary phases distributed along grain boundary in as-cast microstructure,while amounts of lamellar phases are precipitated from grain boundary after solid solution and ageing treatment.The Vickers-hardness of aged alloy piston shirt reaches 131.4,and high temperature tensile strength of piston top exhibits excellent with 161.9MPa at 350℃.In addition,creep strain of piston top is only 0.428% at 250℃/80MPa for 100 hours.The density,specific heat capacity at 100℃,thermal conductivity at room temperature and linear expansion coefficient at 20～100℃ reach 1.995g/cm3,850J/（kg·K）,23W/（m·K） and 25.6×10-6/K,respectively.关键词：Mg-RE Magnesium Alloy;Piston;Mechanical Properties;Physical Properties
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发布时间：2023-12-18 - 摘要：Proper Sr and RE were added to A356 alloy during remelting to improve the microstructure of the alloy.Effects of complex addition of Sr and RE on primary phase size,eutectic Si morphology and mechanical properties of the alloy were investigated by optical microscope,XRD （X-ray diffraction） and tensile testing.The results reveal that during remelting,complex addition of Sr and RE can greatly refine grain size in the alloy and improve the modification effects of eutectic Si.Comprehensive mechanical properties of the alloy can be greatly improved by adding proper complex Sr and RE addition,where tensile strength is increased from 153MPa to 252MPa after modification,and elongation is increased from low than 5% to more than 13%.关键词：A356 Aluminum Alloy;Grain Refinement;Si Modification;Tensile Properties
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发布时间：2023-12-18 - 摘要：Low-density open-cell aluminum foam was prepared using soluble plaster mold by infiltrating casting,and its compressive behavior was analyzed.The soluble plaster mold was prepared by using polymeric reticular sponge as matrix plate,and effect of addition of MgSO4 and bauxite on solubility and compressive strength of the plaster mold were investigated.The low density open-cell aluminum foams were made by pressure infiltration casting,and the processing parameters of pressure infiltration casting were determined.In addition,compressive experiments for prepared aluminum foams were conducted to understand its compressive behavior.The results indicate that three deformed regions such as elastic zone,plastic collapsing zone and densification zone are observed in the compressive stress-strain curves of the open-cell aluminum foams,and the plastic plateau zone of the curves is characterized by distinct fluctuations in fluid stress.关键词：Open-cell Aluminum Foams;Polymeric Reticular Sponge;Soluble Plaster Mold;Quasi-static Compression
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发布时间：2023-12-18 - 摘要：Effects of Al-3B master alloy on grain refinement of Al-7Si alloy were analyzed by thermodynamics theory.It is found that the desirable refinement effects on Al-7Si alloy can be observed with 0.03% B addition.In addition,effects of Al-3B master alloy on grain refinement of hypoeutectic Al-Si alloy with varied Si content were approached.The results reveal that B exhibits the better refinement effects on grain size in hypoeutectic Al-Si alloy with high Si content.Refining mechanism of B on grain size in the hypoeutectic Al-Si alloy was described by Al-B eutectic theory.关键词：Al-3B Master Alloy;Al-Si Alloy;Grain Refinement;Thermal Analysis
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发布时间：2023-12-18 - 摘要：Porous Ti was prepared by powder metallurgy,and TiO2 films containing Ca and P on the surface of the porous Ti were fabricated by micro-arc oxidation.Effects of isostatic pressure on the density and elastic modulus of the porous Ti were analyzed,and morphology,phase constituent and bioactivity of the TiO2 films were described.The results show that with decreasing in forming pressure,density and elastic modulus of the porous Ti are effectively decreased.Titania films which are composed of anatase obtained by micro-arc oxidation at 300V exhibit porous structure,where it is difficult to induce the deposition of apatite on its surface by anatase.
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发布时间：2023-12-18 - 摘要：Effects of solid solution treatment and hot extrusion on microstructure and mechanical properties of Mg-6Y-7RE-0.4Zr alloys at room temperature and high temperature were investigated by optical microscope （OM）,SEM （scanning electron microscope）,EDS （energy dispersive spectroscopy）,XRD （X-ray diffraction） and tensile testing.The results reveal that as-cast microstructure of the alloy is composed of α-Mg matrix,Mg24Y5 and Mg12RE phases.After solid solution treatment at 500 ℃ for 5 hours,Mg-Y phase is mostly dissolved into the matrix,while part of Mg-RE phase still exists at the intergranular.Plasticity of as-extruded alloy at room temperature is greatly improved,and tensile strength is increased from 156MPa to 260MPa,and yield strength reach 220MPa,showing apparent yield plateau,and elongation is increased from 0.5% to 7%.In condition of high temperature,mechanical properties of extruded alloy are equivalent to those of one at room temperature below 250℃,while strength is slightly decreased with great increase of elongation at 300℃,where tensile strength,yield strength and elongation reach 215MPa,164 MPa and 20.5%,respectively.关键词：Mg-6Y-7RE-0.4Zr Magnesium Alloy;Solid Solution;Extrusion;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：Periodic oxidation behavior of high strength and high conductivity copper alloys at 400℃ and 500℃ in air was examined.The results indicate that oxidation resistance of the alloy is as follows in sequence:Cu-Zr-As,Cu-Zr-Cr,Cu-Zr-Te,Cu-Te,Cu-Te-La,Cu.XRD analysis shows that the oxidation film is mainly composed of Cu2O and CuO.The oxidation resistance of the Cu alloy is improved with Zr,Cr,As and Te based on different mechanism.关键词：High Strength and High Conductivity Copper Alloy;Oxidation Resistance;Oxidation Film
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发布时间：2023-12-18 - 摘要：Sn-Bi and Sn-Bi-Cu alloys were prepared by using pure Sn,Bi and Cu.Creep curves were mapped by indentation creep testing,and change of indentation creep with loading and temperature was described.Chemical composition of precipitated phase and microstructure before and after creep were analyzed by X-ray diffraction （XRD） and scanning electron microscope（SEM ） to understand effects of Cu on indentation creep behavior and microstructure of Sn-Bi alloy.The results reveal that creep resistance of Sn-Bi solder is improved with adding Cu.The precipitate in the Sn-Bi alloy is Bi while it is Cu6Sn5 and trace granular phase Bi in Sn-Bi-Cu alloy before creep.After creep,granular phase Bi is refined and dispersedly distributed in the matrix alloy,while block precipitates are converted into Cu6Sn5 particle with smooth edge and with the disappearance of Bi phase in Sn-Bi-Cu alloy as a result of occurrence of recrystallization,responsible for the improvement of creep resistance of the alloy.关键词：Lead-free Solder;Microstructure;Indentation Creep behavior;Cu;Sn-Bi Alloy
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发布时间：2023-12-18 -
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