最新刊期
卷 ， 期 4 ， 2006
- 摘要：A 3-D coupled model for turbulent fluid flow,heat transfer and solute transport has been established to analyze the effects of drawing velocity on turbulent fluid flow,temperature field and evolution of macrosegregation in continuous casting thin slab.The calculated results show that increasing in drawing velocity can dramatically improve the turbulent fluid flow of liquid steel and change the shape of the temperature field and distribution of solute concentration in the mould.Increase of the drawing velocity can accelerate the flow speed on the top surface of the liquid steel and result in the fluctuation on the meniscus,increasing the impacting energy of jet to narrow wall to thin the solidified skin,and decreasing macrosegregation of solute in the thin slab.关键词：Continuous Casting Thin Slab;Turbulent Fluid Flow;Solidification;Macrosegregation;Coupled Model;Drawing Velocity
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发布时间：2023-12-18 - 摘要：Effects of Cu and Ni on glass forming ability and thermal stability of Fe-（Al,Ga）-（P,C,Si,B） alloys were investigated by XRD and DSC.The Fe-based alloy can retain amorphous alloy morphology with less than 2% Cu addition （atom percentage）.Al/Cu ratio is a significant factor influencing glass forming ability of the alloy due to the complex action between Fe-Cu and Cu-Al compound.It is beneficial to improving the glass forming ability and thermal stability of the alloy with Ni addition of less than 4%（atom percentage）.
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发布时间：2023-12-18 - 摘要：Several kinds of grain refinement processes for Mg-Al series alloy were surveyed.Effects of C2Cl6 on the composition,density,microstructure and mechanical properties of the AM60 alloy were investigated by XRF spectrometer,optical microscope,Brinell hardness tester,electronic balance and MTS material testing machine etc.The results show that C2Cl6 has good effects on grain refinement,greatly improving the mechanical properties of the AM60 alloy castings.Compared with those of the alloy free C2Cl6,the grain size of as-cast AM60 alloy with the optimum addition of 1% C2Cl6 can be decreased from 250 μm to 70 μm,and tensile strength is 237 MPa and elongation is 18.9%, increased by 11.3% and 65.8%,respectively.Furthermore,the mechanisms of grain refinement and strengthening of Mg-Al series alloy with C2Cl6 were approached.关键词：Mg Alloy;Grain Refinement;C2Cl6;Microstructure;Mechanical Properties;Mechanism
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发布时间：2023-12-18 - 摘要：Micro-hardness and electric conductivities of Cu-0.43Cr-0.058Zr-0.031Y and Cu-0.20Cr-0.066Zr-0.060Y alloys treated by solid solution at 900～980 ℃ were measured,and microstructures of these solid solution alloys were observed.The results show that Cu-0.43Cr-0.058Zr-0.031Y alloy can be treated by solid solution at 960 ℃ while Cu-0.20Cr-0.066Zr- 0.060Y alloy only treated within 920 ℃.The comparison of electric conductivity and micro-hardness between the two solid solution treatment alloys after ageing at 400～520 ℃ reveals that the electric conductivity of Cu-0.43Cr-0.058Zr-0.031Y alloy is lower than that of Cu-0.20Cr-0.066Zr-0.060Y alloy after ageing at 400 ℃ while ageing at 480 ℃,Cr content can be ignored in effects on electric conductivity of two kinds of alloys.The hardness of Cu-0.43Cr-0.058Zr-0.031Y alloy is obviously lower than that of the Cu-0.20Cr-0.066Zr-0.060Y alloy regardless of ageing at 400 ℃ or 480 ℃.关键词：Cu Alloy;Micro-Hardness;Electric Conductivity;Solid Solution Temperature;Ageing
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发布时间：2023-12-18 - 摘要：The microstructure,hardness of rapidly solidified Zn-Al powder coating on surface of magnesium alloy by cold spray method as well as the bonding strength between the coating and the matrix were investigated,and only the bonding between the coating and the matrix were understood.The result shows that the coating with sound microstructure can be obtained,and only the mechanical bonding between the coating and the matrix can be observed.The hardness of the coating is greatly higher than that of the matrix alloy.关键词：Cold Spray;Magnesium Alloy;Rapidly Solidified Zn-Al Alloy Powder
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发布时间：2023-12-18 - 摘要：Physical simulation of melt flow in a mould in continuous casting steel slab was conducted by the digital particle image velocimetry （DPIV） system.Primary character of melt flow in the mould was described by analyzing the flow field.The effects of the submerged nozzle,immersion depth and drawing velocity on the flow field in the mould were investigated.The velocity vector,streamline and various equivalent cloud chart were calculated and analyzed by a commercial software TECPLOT to understand the flow change of liquid metal to control the flow and nozzle structure,improving the microstructure and properties of continuous casting steel slab.The results show that compared by nozzle with 15°,the tendency of flow-up of liquid metal at top of mould is more intense and impacting depth is lower for nozzle with 0°.With increase of submerging depth and decrease of flow velocity,inverse-flow range of up-moving of liquid metal is more broad,which results in the descending of eddy position.The liquid surface height should be controlled to be more than 100 mm.With the increase of drawing velocity,companying with increasing in flow velocity in the mould,surface-free becomes more and unstable,and impacting energy on narrow side is enhanced.关键词：Continuous Casting;Mould;DPIV;Physical Simulation
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发布时间：2023-12-18 - 摘要：A model of gas-solid bi-phase based on EURA-Lagilara method was developed to describe the filling process of foam particle shoot in lost foam casting.The numerical simulation of foam particle filling process at top and at sides was conducted by the commercial software.The calculated result is well in agreement with experimental ones.关键词：Gas-solid Two Phase Flow;Density;Filling Process;Simulation
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发布时间：2023-12-18 - 摘要：The volume shrinkage of semi-solid melt in a rheological forming process arises from a sum of such three parts as liquid,solid and solidification contract,which is controlled by the contract coefficient of every parts and solid fraction in semi-solid melt.The formation mechanism of shrinkage porosity in semi-solid melt is that contract can not be feed due to completely closing the liquid by solid phase to form discretely shrinkage porosity rather than centralized ones.The mechanism of feeding of the discrete porosity is solid rheological deformation,in which the feeding is carried out by wholly compression of the semi-solid alloy in directional pressing rheological forming process,while the feeding is carried out by the inflation of the alloy melt in an indirectional pressing forming process.In order to prevent the shrinkage porosity,three basic conditions are necessary and shown in mathematical equations: the first is that the pressure acted on the melt is larger than that by the deformation stress resistant,and the second is that holding time of the pressure is larger than that by the solidification,and the third is that pressing velocity is larger than the volume contraction velocity.关键词：Semi-solid Alloy;Contraction;Shrinkage Porosity;Rheological Feeding
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发布时间：2023-12-18 - 摘要：Effects of different holding temperatures on microstrucural evolution of AlSi7Mg alloy in permanent mold were observed.Morphology evolution of primary α phase in the alloy was observed by holding at 600～650 ℃ for 30 min.The results show that,while holding at 605～650 ℃,with decreasing in holding temperature,the primary α phase is gradually converted from developed dendrite into the rosette dendrite and then into particle crystal.Fine and uniform distributed particle phase in the alloy can be formed by holding at 605 ℃ for 30min.Furthermore,the primary α phase can be involved into rosette crystal.In addition,the primary α phase is converted from irregular dendrite to uniform equaixed particle crystal then to rosette structure at 605 ℃ with holding time from 10 min to 60 min.关键词：Semi-solid;Isothermal Treatment;AlSi7Mg Alloy
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发布时间：2023-12-18 - 摘要：Effects of extrusion ratio on microstructure and mechanical properties of AZ91D Mg alloy extruded tube at 430 ℃ were investigated.The results show that the maximum tensile strength of 306.9 MPa and maximum elongation of 10.1% can be observed with extrusion ratio of 7.125.With an extrusion ratio of 7.450,the yield strength can be reached 285.8 MPa while the tensile strength and elongation can be decreased.AZ91D Mg alloy extruded tube with excellent mechanical properties can be manufactured by adjusting the extrusion ratio to control recrystallization process in case of more than recrystallization temperature of 430 ℃.关键词：Mg Alloy;Extrusion Casting Tube;Extrusion Ratio;Microstructure and Properties
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发布时间：2023-12-18 - 摘要：The failure of M300 steel for nozzle body in zinc alloy die casting machine was investigated.The failure is contributed to amounts of inclusions and net-like carbon in M300 steel as well as tempered brittlity of M300 steel at high temperatures.Meanwhile,Fe-Zn corrosive compound formed by chemical action between zinc alloy melt with M300 steel during high velocity and pressure can erode crack on M300 steel nozzle to induce the propagation of the crack by impacting force of the zinc alloy melt,which can result in the failure of the M300 steel nozzle.The countermeasures of improving the service life of the nozzle body were proposed.关键词：Zinc Alloy Die Casting;M300 Steel;Nozzle Body;Failure
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发布时间：2023-12-18 - 摘要：The thermal deformation of the die casting die at high working temperatures can result in the block of the side drawing core and directing mechanism.The effects of thermal deformation on die casting die can be eliminated and service life of the die can be improved by adjusting the structure of slideway and directing mechanism.关键词：Die Casting Die;Thermal Deformation;Working Temperature
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发布时间：2023-12-18 - 摘要：The chemical composition,microstructure,properties of 1.4468 （German brand ）high strength stainless steel with two phases and its technological features were introduced.Effects of alloying elements in the stainless steel and heat treatment on microstructure and mechanical properties were analyzed.Larger riser should be set in investment casting to ensure the full feeding for the stainless steel.Deoxidation should be fully conducted during smelting process,and the pouring temperature should be strictly controlled to eliminate some defects including gas hole and inadequate filling as well as veining.关键词：Stainless Steel with Two Phases;Austenite;Ferrite;Investment Casting
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发布时间：2023-12-18 - 摘要：The advantages of hot-forging die in precision casting were analyzed by comparing with ones in traditional machining method.The performant superiority of cast steel was evaluated.The application status of hot-forging die in precision casting was surveyed,showing wide prospect in die manufacturing.Some problems in application of hot-forging die in precision casting and countermeasures were approached.关键词：Hot-forging Die;Precision Casting;Cast Steel
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发布时间：2023-12-18 - 摘要：Dg75 valve case free machining in lost foam casting was introduced.The precision guarantee of important assemble dimension,control of castings surface cleanness,carbon defects in the castings and surface ripple were described also.The surface quality and dimension precision can meet requirements by the improving the mould structure and process,adjusting the parameters and pouring methods and applying ceramic gating system.The repairing rate resulting from slight defects in surface is decreased to low than 10% from 90%,and finished product rate reaches up to 99%.关键词：Lost Foam Casting;Ductile Iron Castings;Dg75 Throttle Valve;Ceramic Gating System;Carburization
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发布时间：2023-12-18 - 摘要：The formation of thin-walled in cast iron pipe in lost foam casting was analyzed.The positions of defects were formed mainly in the last solidification location,which results from the inadequate pouring of liquid metal and badly exhaustion of decomposition of the pattern.The thin-walled defects can be eliminated by improving the fire-resistance of refractory materials,choosing large size silicon sand and controlling the pouring velocity.The results show that the production rate is greatly increased,and the pipe grade is improved.关键词：Lost Foam Casting;Thin-walled Defects;Tube
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发布时间：2023-12-18 - 摘要：Bi is substituted for Pb in free-cutting brass Pb-free,meanwhile some Mn was added to improve the properties of the brass.Film-like or particle Bi exists in boundary of α phase and on phase interface of α and β phases by XRD and SEM observation.Partial Mn was solved into the matrix to strengthen the properties of the matrix alloy.Bi-containing free-cut brass can totally replace the Pb brass from the viewpoint of mechanical properties or environmental protection.关键词：Brass with Pb-Free;Bi;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：Thick-walled copper alloy castings can be ranked as conventional shape casting and abnormal shape casting from shape.Compared with the abnormal shape castings,the conventional shape castings possess high casting processing regulation.The casting technologies for typical conventional shape thick-walled castings were introduced,including axle sleeve,bearing bush,hopper,slider,wheel,valve and narrow plate,from practical experiences based on CAE.The proposed casting method can not only be fully feed but also be free cut for riser as well as taking simple assemble and operation and obtaining higher production volume rate through the analysis of regulation in the castings in the condition of ensuring casting product.关键词：Copper Alloy;Conventional Shape Thick-walled Casting;Casting Technology;Solidification Simulation
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发布时间：2023-12-18 - 摘要：Ti-48Al-2Cr-2Nb exhaust valves for CA4GE engine have been manufactured by centrifugally pouring the molten melt into preheated permanent mold in induction skull melting furnace.After HIP with 173 MPa at 1 270 ℃ for 4 hours,the microstructure is composed of double-phase structure,where γ phase with smaller size is uniformly distributed into near boundary.Tensile strength reaches 470 MPa at 815 ℃,increased by 100 MPa comparing with 370 MPa for as-cast structure,and elongation is increased by more than 10%.关键词：HIP;Exhausted Valve;Permanent Mold;TiAl Based Alloy
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发布时间：2023-12-18 - 摘要：The microstructure and mechanical properties of high strength 7A04 aluminum alloy were investigated by a compound strengthening method.The results show that not only comprehensive properties of the alloy are obviously improved by melts purification,grain refinement,strengthening homogenization,forging and progressive solid solution,but also holding time is greatly decreased.关键词：7A04 Aluminum Alloy;Compound Strengthening;Progressive Solid Solution;Properties
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发布时间：2023-12-18 - 摘要：In-situ β phase/Zr 56.2Ti 13.8Nb 5.0Cu 6.9Ni 5.6Be 12.5 BMG （bulk metallic glass composites ）composites were prepared by low pressure casting combining with water-cooling copper mould and by the melt water-quenching method,respectively.The microstructure and ambient compressive properties of the composites were investigated.It is revealed that the microstructure characteristics of the composites,including the volume fraction,morphology and size of β phase,sensitively depends on the processing conditions.Lower cooling rate can result in the formation of more and coarser β phase,in which different preparation methods,sample shapes and size can lead to different cooling rate.Ambient compressive properties of the composites are controlled by microstructural characteristics,where more and coarser β phase can significantly improve the macro-plasticity of the composites.关键词：Zr-based Bulk Metallic Glass Composites;Microstructure;Mechanical Properties
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发布时间：2023-12-18 -
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