最新刊期
卷 ， 期 6 ， 2004
- 摘要：One of key aspects of semi-solid rheoforming is to quickly produce semi-solid slurry related to the microstructure obtained by remelting process in thixoforming.The contribution to requirements for semisolid slurry and some new slurry-making processesing in criteria are presented to describe a certain microstructure suitable for rheoforming.A controlling pouring process with a low rotating duct was presented to efficiently produce top-quality semisolid slurry.The four criteria of slurry produced by the new rheoforming process were:solid fraction 20%～60%,shape factor 1.08～1.36,average grain diameter 40～100 μm and volume contiguity less than 0.22.Finally,formation mechanism of equiaxed non-dendrite were reviewed and some primary investigation results were presented.关键词：Rheoforming;Slurry-making Processes;Equiaxed Non-dendrite
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发布时间：2023-12-18 - 摘要：Effects of B and Sr and holding time on the thermal analysis cooling curves and solidification microstructure of Al-7Si alloy melt were investigated. A digital temperature measurement technique, the pattern recognition principle and the digital image analysis approach were used to measure the cooling curve shape and solidification microstructure respectively and compare between them. Based on a database established from a large amount of experimental results, the evaluation of melt features, such as the grain refinement and modification effects of the alloy was conducted. The results showed that the differences both in grain size and modification level converged to zero with zero limit of comprehensive deviation value expressing the shape analogy between two cooling curves . The whole shape of a thermal analysis cooling curve can characterise Al-Si alloy melt, including the grain refinement and modification effects.关键词：Refinement;Modification;Melt Feature Evaluation
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发布时间：2023-12-18 - 摘要：Microstructural evolution of the semi-solid Al-4Cu-Mg alloy prepared by SIMA at different deformation temperatures and deformation degree as well as strain rates during isothermal compression process was investigated. Microstructure of the semi-solid alloy under high temperature deformation condition was observed also. The results showed that the average grain size increased by 2%～9% with deformation temperature increase from 540 ℃ to 560 ℃ and increase by 3%～16% from 560 ℃ to 580 ℃ while decreased with deformation degree increase. The average grain size in large deformation area was smaller by 4%～15% than in small deformation area in same specimen. Average grain size increased and grain became round with strain rates reduction.关键词：Semi-solid Al Alloy;Compression Deformation;Microstructure;Grain Size
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发布时间：2023-12-18 - 摘要：Surface oxidized degree and oxidizing film morphology of Mg-Ca alloy with varying Ca contents were examined. Analysis of surface oxidizing film of the alloy by XRD, SEM, TEM and EPMA indicated that Ca addition can effectively reduce the oxidation of molten alloy surface. The surface quality can be improved due to the reduction of oxidation with Ca addition increase. The oxidizing film of the Ca containing molten Mg alloy is composed of MgO layer, CaO layer and MgO·CaO layer from outside to inside.The anti-ignition mechanism of Ca was approached based on the thermodynamics.关键词：Mg-Ca Alloy;Oxidizing Behavior;Thermodynamic Analysis
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发布时间：2023-12-18 - 摘要：Aimed at bomb-proof ceramics with high performance for modern armoured vehicle shield the nano-micron ceramics with Al 2O 3-ZrO 2 eutectic phase by SHS with coupled eutectic transformation in rapid single step has been perpared. Vickers indentation testing indicates that the ceramic is performed with higher fracture toughness and exhibits strong plastic behaviors. SEM observation shows that crack propogation of the ceramic is controlled by nano-submicron （Al 2O 3+ZrO 2） eutectic structures. The key factors influencing ceramic toughening behavior resulted from intra-crystalline structure with nano-phase of the unique enhanced toughness mechnism. It is forecast that the novel bomb-proof ceramic composite plate with high performance, low cost and high reliability for modern armoured shield can be prepared by SHS with controlling the composition of Al 2O 3/ZrO 2 ceramic composite and solidification behavior（such as centrifugal rapid cooling process condition）.关键词：Bomb-proof Ceramic Composite;SHS Metalurgical Process;Nano-micron Al 2O 3/ZrO 2 Ceramic Composite;Coupled Eutectic;Fracture Behaviors
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发布时间：2023-12-18 - 摘要：Carbon/Carbon fibers/Cu（C/CF/Cu） composites was prepared by squeezing casting. The effects of resin carbonated temperature, C/CF wire preform with copper plating and squeezing pressure on C/CF/Cu matrix composites were studied by tensile strength test and morphology observation of composite interface, constituent distribution and fracture appearance by SEM. The results showed that the tensile strength of C/CF wire preform decreased with carbonated temperature increase in vacuum condition. The C/CF wire preform exhibited a higher tensile strength （1 207 MPa）, better electric conductivity and copper plating at carbonated temperature of 600 ℃ in vacuum condition. The prepared C/CF reinforced Cu matrix composites with good sound interface and higher tensile strength may be obtained,preferably with C/CF wire preform in 40～60 μm copper plating thickness.With squeezing pressure increase, the tensile strength of the composites distinctly increased and reached up to 595 MPa , equivalent to more than three times of pure Cu with 28.5 MPa squeezing pressure.关键词：C/CF Reinforced Cu Matrix Composites;Interface;Squeezing Casting;Tensile Strength;Carbonation
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发布时间：2023-12-18 - 摘要：Semi-solid slurry of hypoeutectic high Cr cast iron was prepared by inclined cooling plate method. The condition and rule of semi-solid globular crystal formation of the cast iron were studied. The results showed that the spheroidal or near-spheroidal, non-dendrite primary austernite can be obtained sucessfully by regulating proper pouring temperature, melt chilling pre-treatment before mold filling and pertiment vibration of undercooled melt. Homogeneous solute and temperature fields resulting from impaction, flow and vibration of liquid metal during low pouring temperature,restricted the formation of developing primary austernite dendrite, which provided a basis to obtain spheroidal grain.关键词：Semi-solid Forming;High Cr Cast Iron;Non-dendrite;Inclined Cooling Plate
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发布时间：2023-12-18 - 摘要：Effects of ageing variables and deformation degree on the microstructures and properties of Cu-0.3Cr-0.048Zr alloy were investigated.It was found that the alloy solid solution treated at 920 ℃ for 1 h possesses a higher electric conductivity aged at 550 ℃ and a higher microhardness aged at 500 ℃.The precipitation of secondary phase at initial period can be accelerated with cold working before ageing, resulting in distinct increase in the properties of the alloy. The electric conductivity and microhardness of the 60% cold deformed alloy aged at 500 ℃ for 30 min can be up to 45.96 MS/m and 142.2 HV respectively while they are only 33.95 MS/m and 99.7 Hv with direct ageing following solid solution treatment.关键词：Cu-Cr-Zr Alloy;Ageing;Cold Deformation;Electric Conductivity;Micro-Hardness
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发布时间：2023-12-18 - 摘要：Pure aluminum was treated by pulse current with varying voltages using pulse power with 3 640 μF energy capacitor during solidification process. The results showed that pulse current can enlarge equiaxed crystal area, narrow columnar crystal area and refine crystal pure Al ingot. The increase of current density and pulse frequency can be helpful to refine and improve the solidification microstructure of the pure aluminum at a given pulse current range.关键词：Pulse Current;Solidification Microstructure;Fine Grain;Pure Aluminum
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发布时间：2023-12-18 - 摘要：Effects of Y and Nd on the as-cast and solid solution treated microstructure of Mg-6Al alloy were investigated. It was showed by OM, SEM, EMPA that both Y and Nd can promote the refinement of as-cast microstructure of Mg-6Al alloy. The grain size of 76.92 μm with 0.5% Y addition in modified Mg-6Al alloy was substituted for that of 102 μm in base alloy while it decreased to 65.79 μm with 1%Nd addition. Furthermore, the grain size with both Y and Nd addition reduced to 57.47 μm. The Y and Nd-RE can be combined with Al in base alloy to form block-like YAl 2 phase and rod-like NdAl 3 phase with high thermo-stability respectively. The Mg 17Al 12 phase was dissolved in α（Mg） matrix during solid solution treatment while the new phases were not dissolved in the α（Mg） matrix due to its high thermostability.关键词：Mg-6Al Alloy;Microstructure;Y;Nd
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发布时间：2023-12-18 - 摘要：The fracture toughness of the particulate reinforced Al matrix composites prepared by stirring-smelting method was measured. The factors influencing the fracture toughness of the materials were studied systematically. The results showed that the fracture toughness of SiC particulate reinforced Al matrix composites has more remarkable effect than that of the Al 2O 3 one at the same addition. The higher the volume fraction of reinforcing particulate,the lower the fracture toughness of the composites while the smaller the reinforcing particulate size, the higher the fracture toughness of the composite.The heat treatment has the significant effect on the fracture toughness of the composite.The composite has higher fracture toughness in artificial ageing than in natural ageing.关键词：Composite;Reinforcing Particulate;Fracture Toughness
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发布时间：2023-12-18 - 摘要：Based on the theory of electromagnetic field, a physical and mathematical model for electromagnetic continuous casting has been established. The distribution of electromagnetic field in crystallyzer was obtained by measuring magnetic flux density under different powers with small coil method. The effect of processing variables on ingot surface quality was investigated. The forming experiment of Al alloy in electromagnetic continuous casting was conducted. The influence of inductor position and distance between inductor and crystallyzer on magnetic flux density and distribution in the system were simulated by finite element method. It was found that the maximum value of magnetic flux density was located in the center of the inductor and the magnetic flux density was reduced obviously with distance increase between inductor and crystallyzer. The distance of 5～10 mm was favorable to electromagnetic continuous process. It was showed that proper design of the electromagnetic continuous casting system would be favorable to realize well distributed magnetic field and to improve power efficiency. Determining appropriate technological parameters can ensure the electromagnetic continuous casting sucessfully and can be helpful to improve the quality of the ingot.关键词：Continuous Casting;Electromagnetic Continuous Casting;Magnetic Field
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发布时间：2023-12-18 - 摘要：The developed software for instable heat transfer calculation in crystallizer of continuous caster for square billet during solidification may be used to predict the temperature distribution in crystallizer and the thickness of billet shell.Due to the existence of longitudinal and transverse and corner air gap the ununiform heat transfer during solification has been considered in the model. Meanwhile, the equivalent specific heat method was introduced to deal with the latent heat on solification front.The temperature distribution in crystallizer and solidified shell thickness were obtained based on the square billet in the Capital iron-steel group company, and the effects of drawing speed on billet temperature and shell thickness were analyzed. The results showed that simulated billet temperature and solidified shell thickness were well in agreement with the pratical results.关键词：Continuous Casting;Crystallizer;Heat Transfer;Mathematical Model
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发布时间：2023-12-18 - 摘要：There are uncertainty and time-variation in the model of filling system in low-pressure die casting. Research results showed that the control system designed by Ziegler-Nichols oscillation method can insurely meet the requirements for specified performance while in turn, designed by constrained optimization, can better deal with model uncertainty and meet the requirements.关键词：Low Pressure Die Casting;Automatic Control;Computer-aided Control System Design
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发布时间：2023-12-18 -
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- 摘要：Based on the strctural characteristic of aluminum alloy reed valve, the technological analysis and selection of die casting machine were conducted. The die design was focused on parting surface and gating system. The designed die was produced in batch process.关键词：Reed Valve;Die Casting Die;Diecasting Machine;Parting Surface;Gating System
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发布时间：2023-12-18 - 摘要：The improved surface quality of belt whell parts resulted from the die made in vacuum die casting. The part has no deformation with double drawing core mechansim instead of single one in the mould. The key designing factors and running principle were expounded and the processing parameters and practical mould structure were given to improve the manufacturing technology of the mould based on the analysis of belt wheel part in die casting technology.关键词：Die Casting Die;Vacuum Die Casting;Drawing Core;Belt Wheel in Die Casting
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发布时间：2023-12-18 - 摘要：Experiments of nodular iron in investment casting were conducted, focusing on smelting, pouring and cooling processes.The proper technological parameters were determined. The experimental results showed that the casting shrinkage ratio of wax pattern die can be selected in the range of 0.5%～1.2%. The silica sol-sodium silicate compound binder was used for shell mold. The chemical composition choice of nodular iron preferred higher C, Si contents and lower Mn, S, P contents. Some batches of production showed that microstructure of nodular iron in investment casting can reach to 2 grade nodularization, 6 grade nodule size and 10% pearlite. The mechanical properties can meet the performance requirements.关键词：Investment Casting;Nodular Iron in Investment Casting;Compound Technology
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发布时间：2023-12-18 - 摘要：A example of riser setted on feeding channel with sprue and ingate to build up a new gating system was introduced, focusing on the method of combination of riser with feeding channel, sprue and ingate.关键词：Investment Castings;Riser;Feeding Channel
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发布时间：2023-12-18 -
- 摘要：The effects of Ac on structures and properties of surface alloyed cast iron by casting-infiltration in EPC were investigated. It was found that the addition of Ac resulted in improving the distribution of carbide in surface alloyed layer,grain refinement and purification liquid Fe, reduction of inclusion amount and increasing the thickness and wear resistance increase in the alloyed layer.关键词：Ac;Surface Alloying;Expendable Pattern Casting（EPC）;Cast Iron
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发布时间：2023-12-18 - 摘要：The electrolytic low Ti aluminum alloys containing 0.1%～0.3% Ti can be produced by adding trace TiO 2 powder into Al 2O 3. The aluminum ingot with 130 μm equiaxed grain can be obtained by in-situ Ti alloying in Al base alloy and self-grain refinement. The grain of 6063 wraught Al alloy made of the alloy can be refined from 4 grade to 1～2 grade.关键词：Al Alloy;Electrolyte;Grain Refinement
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发布时间：2023-12-18 - 摘要：Changes in hydrogen content in liquid aluminum were measured under different relative humidity of compressed air in low pressure die casting. The results showed that although the vacuum smelting has strongly degassing capacity, the degassing effects is relevant to the relative humidity of compressed air in low pressure die casting. Fluctuation in hydrogen content results from wet air. The dry compressed air is helpful to highly qualified liquid Al.关键词：Low Pressure Casting;Hydrogen Content;Vacuum Degassing
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发布时间：2023-12-18 - 摘要：The gating system is the technological basis of Mg alloy in expendable pattern casting （EPC） under controllable pressure. The too large or small gating size can affect pattern,filling rate and casting quality.Filling rate is dominated by gate size lower than critical value while it is mainly controlled by evaporazation rate of the foam pattern and transmission velocity of thermal degradation products with gate size higher than critical value in conventional EPC. Based on four sets of samples, filling rate change of liquid Mg alloy with different gate area is studied. An approach to the relationship between critical gate area and pattern size under controllable pressure was conducted. The results showed that there exisits a larger critical gate area of Mg alloy with faster filling rate in EPC under controllable pressure of both compressed air and vacuum than under gravity pressure, increasing with casting modulus increase. The results will be helpful to the gating system design of Mg alloy under controllable pressure in EPC.关键词：Gating Area;Mg Alloy;Gating System;EPC Process under Controllable Pressure
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发布时间：2023-12-18 - 摘要：Effects of holding time on ZL102 liquid aluminum alloy quality in practical production were studied. Relation between holding time and modification effect and pin-porosity was approached. The results indicated that the optimum Sr modified effect occured for about 60 min. The loss of Sr during holding is about 0.002%/h with holding time increase, so the modification effect can extend to 6～7 h.The minimum pin-porosity and optimum liquid Al quality can be obtained for 30～90 min after modification.关键词：ZL102 Alloy;Holding Time;Modification;Fading;Pin-porosity
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发布时间：2023-12-18 - 摘要：Effects of RE on technological processing and product properties of oxygen free copper rod in up-drawing casting were studied. It was found that proper RE addition can improve not only stability of technological processing in up-drawing casting but also mechanical properties and electric conductivity of oxygen free copper rod.关键词：RE;Oxygen Free Copper Rod;Up-drawing Casting;Mechanical Properties;Electric Conductivity
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发布时间：2023-12-18 -
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