节能、长寿命的铜钢铸合瓦

就冶金电炉铜瓦的电耗，提出设计铜不锈钢铸合瓦，加大瓦的空腔储水量，选择非磁性材料（不锈钢），有效降低瓦温，以节约电能，延长使用寿命，降低维修费用。

铜钢铸合瓦在冶金电炉中的应用及节能

本文根据冶金电炉钢瓦的设计结构及运行中有关温度造成的电能损耗，提出设计铜－不锈钢铸合瓦，采取增大瓦的空腔储水量和选择非磁性材料（不锈钢）两种措施，有效地降低瓦的温升，并根据两种瓦实测温度进行理论推导计算，得出铜钢铸合瓦的结论：节约电能，延长使用寿命，减少维修等诸多优点。

转型期中国农民利益表达链条的断裂与铸合

农民在表达利益诉求时,因基层政府及其行政人员政绩观的错位、农民利益表达素养的低下、基层政府及其行政人员与农民对利益表达的认知偏差以及现有乡村治理模式既存缺陷导致本应同向、良性运行的链条出现断裂,影响着农民利益要求的传递,阻碍了农民利益的维护、实现与增进,也对农村的和谐与稳定、涉农政策的科学化与民主化产生重要影响。铸合断裂的利益表达链条应转变基层政府职能,提升行政人员公共服务精神,提高农民利益表达素养,构建新型乡村治理模式。

铸件内金属铸入物涂油防止呛火

在铸造生产中,经常会碰到需要将金属物与铸件铸合在一起。金属物放入铸型后,铸型或大气中的水蒸汽会冷凝吸附到众属物表面,时间越长吸附越多,到一定量时还可能形成水珠。这样在浇注时高温铁水与金属物表面的小水珠相遇,必然形成不同程度的呛火。

Effects of annulus gap on flow and temperature field in electromagnetic direct chill casting process

A comprehensive mathematical model of annulus-electromagnetic direct chill （A-EMDC） casting of A357 aluminum alloy was established with corresponding experimental verification. The model was based on a combination of the commercial finite element package ANSYS and the commercial finite volume package FLUENT. The effects of structural parameters on fluid flow, temperature field and solidification during A-EMDC process were investigated numerically. The results show that structural parameters such as annulus gap width, annulus gap position, and centre pipe length influence the flow and temperature fields. The smaller the annulus gap width is, the more uniform the temperature is, and the smaller the temperature gradient is. With increasing the centre pipe length, the circular flow would decrease due to the dislocation of centre pipe. Specially, when the annulus gap is located at periphery of the billet, the temperature gradient of the longitudinal direction in the solidification region falls evidently.

Analysis of phase in Cu-15%Cr-0.24%Zr alloy

The vacuum medium-frequency induction melting technology was employed to prepare the Cu-15%Cr-0.24%Zr alloy. The scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, transmission electron microscopy （TEM） and high-resolution transmission electron microscopy （HRTEM） were used to analyze the phase composition, morphology and structure of the alloy. The results reveal that the as-cast structure of the alloy consists of Cu matrix, Cr dendrite, eutectic Cr and Zr-rich phase. A large number of Cr-precipitated phases occur in the Cu matrix, and Cu5Zr particles can be found in the grain boundary of Cu matrix. The HRTEM images prove that there is a semi-coherent relationship between Cu5Zr and Cu matrix.

Influence of pouring temperature on solidification behavior, microstructure and mechanical properties of sand-cast Mg-10Gd-3Y-0.4Zr alloy

Influence of the pouring temperature ranging from 680 to 780 ℃ on the solidification behavior, the microstructure and mechanical properties of the sand-cast Mg-10Gd-3Y-0.4Zr alloy was investigated. It was found that the nucleation undercooling of the a-Mg phase increased from 2.3 to 6.3 ℃. The average a-Mg grain size increased from 44 to 71 μm, but then decreased to 46 μm. The morphology of the eutectic compound transformed from a continuous network into a discontinuous state and then subsequently into an island-like block. The volume fraction of β-Mg_24RE_5 phase increased and its morphology transformed from particle into rod-like. The increase in pouring temperature increased the solute concentration. YS increased from 138 to 151 MPa, and UTS increased from 186 to 197 MPa. The alloy poured at 750 ℃ had optimal combining strength and ductility. The fracture surface mode transformed from quasi-cleavage crack into transgranular fracture, all plus the dimple-like fracture, with the micro-porosity and the re-oxidation inclusion as major defects. The average a-Mg grain size played a main role in the YS of sand-cast Mg-10Gd-3Y-0.4Zr alloy, besides other factors, i.e. micro-porosity, morphology of eutectic compounds, re-oxidation inclusion and solute concentration.

Microstructure evolution of 3003/4004 clad ingots under diverse physical fields

In order to improve the quality of clad ingots, diverse physical fields including electromagnetic stirring, power ultrasonic and compound field of ultrasonic and electromagnetic stirring were attempted to prepare clad ingots of 3003/4004 alloys. The solidification structures near the interface in clad ingots were investigated. The experiment results indicate that the solidification structure of 4004 alloy changes from dendritic crystals to petal-like grains when the clad ingot is treated by electromagnetic stirring. With the effect of power ultrasonic, the solidified microstructure of 4004 alloy exhibits the refinement of both primary a（A1） and eutectic silicon. Under the compound field, the primary a（A1） is refined, the morphology of eutectic silicon has a transition from a coarse plate-like form without treatment or thin acicular-like form with power ultrasonic to fine coral-like form.

Influence of filling parameters on fatigue properties of A357 alloy produced by counter pressure plaster mold casting

The influence of filling parameters including pouring temperature, filling speed, boost pressure and synchronous pressure on the fatigue of A357 alloy produced by counter pressure plaster casting was studied. The Taguchi method was used to investigate the relationship between the fatigue performance and filling parameters. The results show that filling speed is the most significant factor among the four parameters. Synchronous pressures is less influential on the fatigue life when the value of synchronous pressure is from 400 kPa to 600 kPa.

Mechanical properties and microstructures of Al alloy tensile samples produced by serpentine channel pouring rheo-diecasting process

An innovative one-step semi-solid processing technique of A356 Al alloy,the serpentine channel pouring rheo-diecasting process （SCRC）,was explored.The mechanical properties and microstructures of the tensile samples made by the SCRC technique were tested in the as-cast and T6 heat treatment conditions.The experimental results show that the as-cast ultimate tensile strength can reach about 250MPa and the elongation is 8.6%？13.2%.The ultimate tensile strength can increase approximately 30% higher than that of the as-cast one but there is some slight sacrifice of the plasticity after T6 heat treatment.Under these experimental conditions,the semi-solid A356 Al alloy slurry with primary α1（Al） grains,which have the shape factor of 0.78？0.89 and the grain diameter of 35？45μm,can be prepared by the serpentine channel pouring process.The primary α2（Al） grains are very fine during the secondary solidification stage.Compared with the conventional HPDC process,the SCRC process can improve the microstructures and mechanical properties of the tensile test samples.The advantages of the SCRC process include easily incorporating with an existing HPDC machine,cancelling the preservation and transportation process of the semi-solid alloy slurry,and a higher cost performance.

Microstructures,corrosion and mechanical properties of as-cast Mg-Zn-Y-(Gd)alloys

Long period stacking ordered（LPSO） structure phases were prepared by conventional solidification method in Mg（94）Zn3YxGd（3-x）（x=3,2,1.5,1,mole fraction） alloys,the microstructures,corrosion and compressive mechanical properties of which were investigated,separately.The results reveal that the microstructures of the as-cast Mg（94）Zn3YxGd（3-x） alloys,with n（Zn）/n（Y＋Gd）=1：1,consist of α（Mg） phase,Mg3Zn3RE2（W） phase,Mg（12）ZnRE（14H-LPSO） phase and a few bright cube-shaped Mg-Y-Gd phases.The formation and the distribution of LPSO-phase in the alloys can be influenced by the content of Gd.The volume fraction of 14H-LPSO phase increases first and then decreases with the increase of the Gd content.For the electrochemical impedance spectroscopy（EIS） measurement,a R（Q（R（QR））） model was used to fit the test results in 3.5%（mass fraction） NaCl solution at room temperature.The corrosion current densities of all samples are about 10-（-5） A/cm-2.When x（Gd）≤1%,Mg-Zn-Y-（Gd）alloy shows good corrosion resistance,which is better than that of the commercial AZ91 D magnesium alloy.The corrosion rate increases when the Gd content is higher than 1.5%.At room temperature,the compressive properties of Mg-Zn-Y-（Gd） alloys increase remarkably with the increase of the volume fraction of LPSO phase.In addition,the pinning effect of W-phase and dispersive cube-shaped Mg-Y-Gd phase is beneficial to improving the mechanical properties of as-cast Mg（94）Zn3YxGd（3-x） alloy in deformation process.

Microstructure and mechanical properties of overcast aluminum joints

The aluminum joints were prepared by overcasting liquid aluminum A356 onto 6101 aluminum extrusion bars. The microstructure, element distribution, hardness and tensile strength of the joint interface area were investigated, the mechanism of interface formation and fracture behavior were analyzed. The results show that good metallurgical bonding was formed in the joints by electro-plating the solid 6101 aluminum alloy with a layer of zinc coating and carefully controlling the overcasting process. There is a transition zone between the two bonded aluminum alloys, and the fine equiaxed grained structure in the transition zone is due to the high undercooling during solidification. The tensile strength of the joint interface is higher than that of the as-cast A356 aluminum alloy(about 145 MPa) and the final fracture is always located in the as-cast A356 material.

Microstructure and properties at bonding interface of AA4045/AA3003 aluminum alloy cladding billet prepared by semi-continuous casting

AA4045/AA3003 cladding billet was prepared by direct chill semi-continuous casting process. The macrostructures, microstructures, temperature distribution, compositions distribution and the mechanical properties at the bonding interface were investigated in detail. The results show that the cladding billet with few defects could be obtained by semi-continuous casting process. At the interface, diffusion layer of about 10μm on average formed between the two alloys due to the diffusion of alloy elements in the temperature range from 596 to 632 °C. From the side of AA4045 to the side of AA3003, the Si content has a trend to decrease, while the Mn content has a trend to increase gradually. Tensile strength of the cladding billet reaches 103.7 MPa, the fractured position is located on the AA3003 side, and the shearing strength is 91.1 MPa, revealing that the two alloys were combined metallurgically by mutual diffusion of alloy elements.

GIGACYCLE FATIGUE BEHAVIOR OF CAST ALUMINUM IN TENSION AND TORSION LOADING

An improved understanding of fatigue behavior of a cast aluminum alloy（2-AS5U3G-Y35）in very high cycle regime is developed through the ultrasonic fatigue test in axial and torsion loading.The new developed torsion fatigue system is presented.The effects of loading condition and frequency on the very high cycle fatigue（VHCF）are investigated.The cyclic loading in axial and torsion at 35 Hz and 20 kHz with stress ratio R=-1 is used respectively to demonstrate the effect of loading condition.S-N curves show that the fatigue failure occurs in the range of 105—1010 cycles in axial or torsion loading and the asymptote of S-N curve is inclined,but no fatigue limit exists under the torsion and axial loading condition.The fatigue fracture surface shows that the fatigue crack initiates from the specimen surface subjected to the cyclic torsion loading.It is different from the fatigue fracture characteristic in axial loading in which fatigue crack initiates from subsurface defect in very high cycle regime.The fatigue initiation is on the maximum shear plane,the overall crack orientation is on a typical spiral 45° to the fracture plane and it is the maximum principle stress plane.The clear shear strip in the torsion fatigue fracture surface shows that the torsion fracture is the shear fracture.

Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy—double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr , Mo, Cu are induced into the TJ-6A1-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%. Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

Direct-chill semi-continuous casting process of three-layer composite ingot of 4045/3004/4045 aluminum alloys

Three-layer composite ingot of 4045/3004/4045 aluminum alloys was prepared by direct-chill semi-continuous casting process,the temperature field distribution near the composite interface,macro-morphology,microstructure and composition distribution of the composite interface were investigated.The results show that semi-solid layer with a certain thickness forms near the interface due to the effect of cooling plate,which ensures successful implementation of casting the composite ingot.Two different aluminum alloys are well bonded metallurgically.The mechanical properties of composite interface were measured,the tensile and shearing strengths of composite interface are 105 and 88 MPa,respectively,which proves that the composite interface is a kind of metallurgical bonding.

W, Mo, Co Co-diffusion on Steel with Different Carbon Content

Tungsten, molybdenum and cobalt were co-diffused into the surface of ingot, 20 steel, 45 steel and T8 steel by a double glow plasma surface alloying technique. Surface alloyed layers formed on ingot and 20 steel are composed of -Fe +(Fe,Co)7(W,Mo)6, which possess the same strong age-hardening ability as the metallurgical age-hardened high speed steel, the maximum hardness can reach 1100 HV0.o25 after ageing treatment. Surface alloyed layers formed on 45 steel and T8 steel are composed of M6C, hardness of which are over 1100-1400 HV0.o25- Alloyed layers formed on ingot and 20 steel possess good toughness. Alloyed layer of carbide type exhibits slightly brittleness.

As-cast structure and tensile properties of AZ80 magnesium alloy DC cast with low-voltage pulsed magnetic field

The effects of a low-voltage pulsed magnetic field on the solidified structure and mechanical properties of DC casting AZ80 magnesium alloy were investigated.The results showed that the solidified structure of the DC casting AZ80 magnesium alloy was refined obviously by the low-voltage pulsed magnetic field and significant grain refinement in the DC casting ingot of AZ80 magnesium alloy was achieved.Meanwhile,the morphology of the dentritic in the DC casting ingot was transformed from coarse dentritic to fine rosette with the application of low-voltage pulsed magnetic field.The ability of deformation of the ingot was enhanced and especially the plasticity of the ingot center after upsetting was improved greatly by more than 80%after deformation.

Effect of casting vacuum on thermodynamic and corrosion properties of Fe-based glassy alloy

The effect of casting vacuum on thermodynamic and corrosion properties of Fe61Co7Zr8Mo5W2B17 in shape of cylinder of 3 mm in diameter and ribbon of 20?40μm in thickness and 2?3 mm in width were investigated with X-ray diffraction (XRD), differential scanning calorimetry (DSC), dilatometer (DIL), scanning electron microscopy (SEM) and electrochemical station. It is found that high casting vacuum can improve the glass forming ability (GFA), the contraction degree during heating, and the pitting resistance of the glassy alloy, which can be ascribed to the fact that the dissolution of tungsten in the melt is improved under the high casting vacuum.

Effects of on-line solution and off-line heat treatment on microstructure and hardness of die-cast AZ91D alloy

The effects of on-line solution, off-line solution and aging heat treatment on the microstructure and hardness of the die-cast AZ91D alloys were investigated. Brinell hardness of die-cast AZ91D alloy increases through on-line solution and off-line aging treatment but decreases after off-line solution treatment. By X-ray diffractometry, optical microscopy, differential thermal analysis, scanning electron microscopy and X-ray energy dispersive spectroscopy, it is found that the microstructures of the die-cast AZ91D magnesium alloy before and after on-line solution and off-line aging are similar, consisting of α-Mg and β-Al12Mg17. The precipitation of Al element is prevented by on-line solution so that the effect of solid solution strengthening is enhanced. The β-Al12Mg17 phases precipitate from supersaturated Mg solid solution after off-line aging treatment, and lead to microstructure refinement of AZ91D alloy, so the effect of precipitation hardening is enhanced. The β-Al12Mg17 phases dissolve in the substructure after off-line solution treatment, which leads to that the grain boundary strengthening phase is reduced significantly and the hardness of die cast AZ91D is reduced.