Abstract: CuCr contact material has excellent mechanical and electrical properties and is widely used in vacuum switchgear.In this paper,the effects of Cr content on the breaking capacity,chopping current,high voltage withstanding and anti-weld property of CrCu contact material are reviewed.The function of other new alloy composition on its properties is also summarized.For the existing problems of CuCr contact material it is pointed out that strict control of the purity of raw materials and addition of new alloy are the main trend for development of high performance CuCr contact material.

Abstract: For increasing the efficiencies and standardize of casting process,the ways and technologies of casting process are researched.Integrating access database made by parameters of the casting process with graphic database of AutoCAD2000.A 2D casting graph library system was developed by making full use of the opening character of AutoCAD2000 and the powerful function of ObjectARX2000 supplied by Co.Autodesk,by the virtual of the developing tools(Virtual C++6.0) supplied by Co.MicroSoft.Combining the Access database made by the parameters of the Casting Process with the graphic database of AutoCAD2000 Combining with practical application of casting engineering.Casting graph library based on parameterized are developed using those technologies.Research and development show that the Parameterized graph library is a key technology in development of casting process CAD.

Abstract: The broken high strength bolt was studied on chemical composition analysis,mechanical properties,micrographic,etc.The results show that there are two factors to cause the failure: one is fatigue failure,the other is hydrogen embrittlement and stress corrosion failure,and hydrogen embrittlement mainly occurs at the initial stage of the crack.

Abstract: The development of Fe-B-C alloy was reviewed.Combining Fe-B binary phase diagram and isothermal Fe-B-C ternary phase,the solidification structures,mechanical properties,and wear properties were described in detail.The effect of modification on the toughness and wear resistance of Fe-B-C alloy was summarized.Some feasible suggestions were proposed to overcome the deficiency of the alloy for the sustainable development in wear resistant field.

Abstract: The hot compressive deformation test of Ti-22Al-25Nb alloy was performed on Gleeble-1500 hot simulator in the range of deformation temperature from 940℃ to 1000℃, strain rate from 10-2s-1 to 50s-1, maximum deformation degree 50%. The effect of hot-deformatim parameters on flow stress was analyzed. A constitutive relationship of this alloy described by Zener-Hollomon parameter was formulated.The result shows that the flow stress of the alloy decreases with the strain rate decreasing or the temperature increasing.The flow softening extensively is attributed to temperature rising and microstructurel changes of this alloy. Discontinuous yielding which occurred at higher strain rate(≥10s-1) is associated with the generation of new mobile dislocation from grain boundary sources, but independent of solute-pinning.

Abstract: The viscosity(μ) of Fe-xC(x = 2. 0-4. 30%) molten alloy was measured by oscillating crucible viscometer. The results show that the fluidity (1/μ) of the eutectic Fe-C alloy has linear relationship with temperature and free volume. At 1 350 and 1 450℃, the fluidity increases with increasing carbon content, which is related to the increase of superheat and the free volume of Fe-xC melt. AtΔT = 20℃, the fluidity of Fe-xC molten alloy decreases with increasing carbon content, which are mainly caused by the strengthening C-C bond in the melt.

Abstract: Effect of rare earth La on the strength,hardness,ductility and impact toughness of 45Cr2NiMoVSi hot die steel is studied.The mechanical properties of 45Cr2NiMoVSi steel with three different contents of La are compared with those of the 45Cr2NiMoVSi steel without La addition under the same heat treatment process.The results show that strength,hardness,ductility and impact toughness of 45Cr2NiMoVSi steel increase significantly if the content of La is proper.When the content of La is 0.20wt%,the 45Cr2NiMoVSi steel has the best combination of mechanical properties.

Abstract: Three passes of vertical-horizontal(V-H) rolling process with 3-D thermal and mechanic field was simulated by explicit dynamic FEM,updating geometric method and implicit static FEM. Based on simulation results,the variation of temperature was analyzed during the rolling process,the distribution of equivalent strain field and stress field along different directions were obtained. Using the results,the defects on slab during the rouing process can be analyzed,a new method for studying multipass rolling process and the deformation of slab with complex profile during cooling process is provided.

Abstract: The morphologies of carbides and variation in T91 Steel were analyzed by electroextraction, energy spectrum, XRD, and TEM. The results show that the carbide M23C6 ripens apparently after long-term high temperature and high pressure. The morphology of some carbides M23C6 changes into globular from short plate, but the large amount of carbides are still distributed in plate. Meanwhile, the chemical constitution of M23C6 is changed as well, Mo and Cr diffuse from matrix to carbides, the content of carbides in T91 Steel increases obviously. Subsequently, a novel viewpoint about ripening of M23 C6 is proposed and the concept of Ostwald ripening is further modified.

Abstract: Taking wrought magnesium alloy AZ31 as investigation objects,the process characteristics of CO2 laser beam welding was studied.The common defects in the welded joints were analyzed,and the main causes and significant preventive measures were discussed.The experimental results show that porosity and cracking are the main defects in AZ31 magnesium alloy joints.Sometimes there are other defects in the joints such as solid inclusion,incomplete fusion and penetration,undercut.However these defects can be avoided or minimized under the condition of appropriate process parameter and suitable treatment methods before and after welding.

Abstract: Twin-wire submerged arc welding was widely applied due to its high efficiency,saving energy and high quality.Its technical control was more complex,the fluencing factor on the bead appearance was much more than the single-wire welding.On the basic of the reference,aimed at high basicity agglomerated flux,the relation of the parameters including the current,voltage and welding speed,the position of the twin-wire and its space,the heat input and the form of groove was systemically analyzed by the overlaying on the plate and the butt joint test of V-groove.

Abstract: In order to improve the accuracy of the numerical simulation effectively,a continuous interfacial heat transfer coefficients(IHTC) model of the variable parameter with the change of temperature was proposed by the methods of actual-measurement and inverse computing.Following the experimental-scheme,using the specific electric thermo-couple,guaranteeing the accuracy of the measuring apparatus,the date of temperature field was gathered.The value of a function between the interfacial heat transfer and the temperature was figured out by manner of the measured data,the finite-element method(FEM)numerical simulation and the inverse computing of the interfacial heat transfer.Using the inverse module of ProCAST software to calculate the IHTC,the interface heat exchange value between a certain cast iron material and resin bonded sand casting material was determined.The results show that the predicted temperature is well agreed with the macrostructure of the cross section of the casting,the maximum deviation is by ±10℃ with respect to the measured temperatures,so the method of actual-measurement an inverse computing is feasible.

Abstract: The temperature field of 13-ton ingot and mould was simulated and studied by utilizing three-dimensional transient FEM and the change of solidified velocity in ingot and the regularity of temperature distribution in mould were discussed.The results show that longitudinal solidified velocity is accelerated by lateral ones at the place which is 60%～70% apart from the ingot bottom.Initially,the temperature rise velocity of the inner wall is far larger than that of the outer wall for the mould,the temperature difference between inner and outer walls is reduced as the solidification is proceeding.This conclusion may provide basis for the optimizing designation of mould and improvement of the ingot quality.

Abstract: 用Cu2O粉作氧化剂,采用简化的内氧化工艺,在900℃下使Cu-Al合金薄平板内氧化,获得Al2O3/Cu复合材料.然后采用热挤压法制取了Al2O3/Cu复合材料,对其显微组织和拉伸断口及界面进行观察与分析.结果表明:增强颗粒在基体中分布均匀,细化了晶粒,压制后组织进一步致密细化,且该材料具有良好的热稳定性;拉伸断口有韧窝断裂;能谱分析表明,板表面之间存在元素的扩散,热力学分析表明界面上有化学结合,界面结合状态较好.且复合层中Al2O3颗粒呈弥散状分布;复合层表面和内部的晶粒大小明显不同,表面晶粒较小.

Abstract: The decarburization character of Si-Mn series and Cr-V series spring steels was investigated under the same heating condition by means of microstructure comparison technique.The effects of heating temperature and holding time on decarburization sensitivity were analysed,which offered the theoretical foundation to amend the heating system of high-strength and high-quality spring steels.The results show that,at the same holding time,as for Si-Mn series steels,the entire decarburization depth is the maximum at 900℃and the sensitive temperature of total decarburization depth is 1 100℃.But as for Cr-V series steels,above heating temperature 950℃,the entire decarburization depth rarely changes,and the entire decarburization depth reduces in some sort at 950～1 000℃,but increases rapidly above 1 000℃.Due to the function of elements,the decarburization sensitivity of Cr-V series spring steels is much lower than that of Si-Mn series spring steels at both isothermal and equitime heat treatment.

Abstract: The characteristics of crystal nucleation on a chilling solid surface with two different roughnesses under vibration were investigated using a transparent NH4Cl-70%wtH2O alloy.The results indicate that the average surface roughness has not affected the nucleation significantly;surface nucleation on the chilling solid surface has a distinctively localized behavior,and the sites which are easy to nucleate have good repeatability.The geometric micro-pattern of the chilling solid surface is examined with an atomic force microscope.It was found that there is an obvious difference in the areas with and without active nucleation sites.Some notches and pits with the size of 50～100 nm in the magnitude of the critical nucleation radius may serve as active nucleation sites while those small convex apices never act as active nucleation sites.

Abstract: The effect of rare earth on purifying molten metal and refining grain was studied by adding a little amount of rare earth(0.02%,0.04%,0.06%) into molten recycled copper,and the effect of rare earth on structure and properties,especially electric conductivity,of hot-rolled plate and cold-rolled strip of recycled copper were also studied.The results show that the molten metal can be decontaminated and the grains in the structure as-cast are refined by adding rare earth.The tensile strength,elongation and electric conductivity of 0.35mm strip,which is added 0.04% rare earth,are 213.8MPa,23% and 98.5IACS%,respectively.

Abstract: The effect of main alloying element Mg,Si and impurity element Fe,Zn on microstructure and property of Al-Mg-Si aluminum alloy was studied,and the reasonable proposal is given based on the mechanism of alloying element.The results show that the main alloying element Mg and Si have important affect on strength and corresion,their mass ratio should be less than normal value 1.73.These mpurity element Fe and Zn have some effect on the stability of microstructure,they usually induce variant point defect on the surface of product.

Abstract: The cold and warm extrusion technology of spring mandrel and its numerical simulation were introduced .The main parameter changes in this designing were studied including radius of die,the value of friction between workpiece and die,and temperature of warm extrusion.The influenceof these parameters on the quality and stress distribution of workpiece,and the temperature distribution of workpiece was analyzed. At last the best value of these parameters were chosen to improve the extrusion process.

Abstract: In order to study convection heat transfer between fluid and workpiece during gas quenching, the process of air-jet quenching with a flat probe was simulated using the computational fluid method (CFD). The heat transfer coefficient between fluid and the flat probe was obtained,which was changed with temperature and surface location of the flat. The result of the numerical simulation consists with the experimental data. The numerical simulation method may easily and exactly comprehend the heat transfer process during gas quenching and offer reference for gas quenching process. It should be an important method to study gas quenching process.

Abstract: Influences of different extruding parameters and equal channel angle pressing(ECAP) technology on the microstructure and properties of ZL102 aluminum alloy were studied.The results show that the critical value of extruding of the alloy is increased with temperature,being more than 50% at 310 ℃.The suitable temperature for deformation is within the range of 350 ℃～410 ℃.The microanalyses indicate that the refined degree of grains is enhanced with the amount of deformation.When the amount is in excess of 35%,the grain is refined remarkable.The hardness of the material is also raised with the amount of deformation.Using die of 120° angle and extruding with the route of A,the grains are refined more effectively and uniformly.

Abstract: ProCAST is a famous software to simulate casting process, modeling and dividing grid are the important stages before simulation. the simulating process of the ProCAST software and its connecting with Pro/E are introduced, an example is given to describe the MeshCAST dividing grid process using Pro/E curved face modeling, and the stage before simulating cast process is explored. It is pointed out that curved face modeling is simpler than substance modeling in steps, and the lower error in the step of dividing grid is better than traditional substance modeling.

Abstract: A simple method is put forward to estimate the surface tension of binary liquid alloys. Through the medium of the activity coefficients and a certainly relationship between the bulk phase and the surface phase, that is ,the activity coefficient of the element in binary liquid alloys is related with the atomic number of complex. According to the thermodynamics datum filed, utilizing the Miedema model which can well calculate the enthalpies of formation of liquid alloy and the two mathematic softwares, the activity coefficients of every element in bulk phase are calculated. then the surface tension can be work out by the equation of Butler. In the paper, three kinds of binary alloys Fe-Cu、Fe-Ni、Cu-Ni,respectively,were used as examples to test the reliability of this method, the results show that there is a good agreement between the calculated values and the documents values.

Abstract: The structure evolution and the effect of structure on properties of 1Cr18Ni9Ti austenitic stainless steel were studied.The results show that cold deformation can largely raise the mechanical properties of the steel,especially the fatigue property.Compared with non-deformation steel,the fatigue stress of 1Cr18Ni9Ti austenitic stainless steel after 60% cold deformation is raised about 1.65 times.With the development of recrystallization,the strength of the steel decrease and the plasticity resume gradually.

Abstract: Nonionic and anionic dispersants were chosen on the basis of zeta value measurement of nano-sized iron powders prepared by high-vacuum DC Arc Plasma evaporation, The effect of oleic acid, polyvinylpirrolidone (PVP) and sodium dodecyl benzene sulfonate (SDBS) on dispersion capability of nano-sized iron powders was systematically studied. The results show that: the ultrasonic time, concentration of dispersant and pH has significant effect on dispersion property, with increase of ultrasonic time and surfactant concentration, the effect of dispersion firstly increases, then decreases; PVP and oleic acid have better effect on dispersing property of nano-sized iron powders, the dispersion effect is in the degrading order: PVPoleic acid SDBS. the optimal parameters are pH= 10, ultrasonic powder is 560 W, ultrasonic time is 15 min and the concentration of PVP is 4 wt% when absolute ethanol is used as solvents.

Abstract: Because of huge deformation of turbine blade in the process of forging,the defects,such as folds and cracks,appear in blade forgingsIn order to increase the production efficiency,the blade forgings are usually made by the hammer within one stroke using screw press So it is very important to use suitable shape of forging stocks to get the best forgings in the condition of the lowest loads There are many demerits in the traditional method to optimize the forging stock shape of blade in factory,but these demerits can be greatly overcome through the 3-D FEM simulation on computers

Abstract: Grain refinement is one of means of increasing strength and plastic of material,improving quality of casting,its success or not lie in manufacturing a high and long efficient and low price grain refiner.On the basis of study and application situation of Al-Ti-B grain refinement alloy and its classifications and production methods,refinement mechanism was detailed analyzed,and exiting problems and the development trends were pointed out.

Abstract: The thickness of solidified billet shell in secondary cooling region is determined by pin-shooting technique and sulfur print combined with the practical production situation of the continuous caster in Fujian.Mathematical model of the steady temperature filed with two-dimensional heat transfer is established as well.Heat transfer coefficient is modified in different secondary cooling region by pin-shooting result,thus the accuracy of the mathematical model is improved.By comparing the shell thickness determined by pin-shooting technique with that calculated by mathematical model,it shows that the modified mathematical model can simulate the heat transfer and solidification process of whole casting machine.

Abstract: The effect factors on the cutting quality in numerical control flames cutting contain the oxygen purity,the power of preheating flames and the preheating time,oxygen pressure,cutting velocity and the distance from cutting jet to workpiece.The various parameters in experiment and the real scene cutting were analyzed,and the conclusion of cutting quality parameter form was reached for reference only.