Abstract: The microstructure transition process of Ni-5%Cu alloy is researched in therange of 2.6-130K/S cooling rate with zone melting unidirectional solidification technique. It is indicated that the solidified morphology transits from dendrite to superfine cell within the limitids of the crystal growth velocity 500~700μm/s. The temperature gradient has a great effect on the microstructure in hyporapid solidification. The crystal growth orientation is an important factor to the selection on the solidified microstructure.
Abstract: The evaporation dynamics of trace elements in nickel chrominium molybydenum steel during vacuum induction melting have been studied. The way to determine the transport coefficient of gas boundary layer has been developed. The formula to calculate the specific rate constant of element evaporating from the gas/metal surface has been deduced. The results of experiment and calculation show that Sn or As evaporation process during vacuum induction melting of steel is controlled by transport in both the metal boundary layer and the evaporation from the metal surface, in which K23 value is at the level of 10-3~10-2cm/s. The Sn or As loss reaction from the gas/metal surface includes probably the evaporations of itself and its oxide.
Abstract: The height and shape of the electromagnetically supported column of molten metal in electromagnetic caster was calculated by the coupled circuit method. The influence of melt shape on system stability was, discussed. Results were presented showing the effect of current and frepuency on the shape of meniscus and the effect of voltage and frequency on the current. With variation of voltage or frequency being within ±2.5% (other operating parameters held unchanged), the variation of current is within ±2%, and the process of electromagnetic casting is in stable condition.
Abstract: The contact condition of rail was simulated with twin-disk in laboratory. Effects of creepages and contact stresses on wear behaviours in pearlitic rail steel have been studied, based on the appearance observations and surveying below surface by SEM, the wear forms and their mutual effects in wear process have been approached. It is concluded that wear rates increase with both creepage level and contact pressure. The friction coefficients increase with creepages and when creepages rise to 4%, the limiting friction coefficient is reached. Mass loss is linear with sliding friction works and in proportion to sliding distances. Microstructures below surface show intense plastic deformation in dry wear and lamellarly distribute aling the direction of paralleled with surface. Adhesive wear and surface-fatigue wear are the two major wear forms in rail steel.
Abstract: Microstructure after long time aging have been observed by means of SEM in GH169 alloys. The results show that the microstructure almost no variation after long time aging up to 5×104h below 650℃, and reveals higher structure stability. However, microstructure is very sensitive to aging temperature beyond 650℃, and there existed complicated phase transformation. The experimental results also show that stress accelerates the complicated phase transformation by observing GH169 gas turbine disk with an engine service life of 2.8×104h
Abstract: Jn this work SHS-pressing process is studied. Concepts of compactable temperature minimum (Tp) and compactable time maximum (tp) are defined. A temperature-time-state diagram (TTSD) is presented. The upper limit of pressing time delay after combustion, τ, which is a control parameter of the SHS-pressing process, can be determined by tp-tc, where tc is combustion time. On the basis of the analysis, nearly full dense TiC-Ni-Mo alloy is synthesized.
Abstract: The integration of order, arranging daily plan and adjusting can be completed for the simultaneously control and dynamic adjustment of order, arranging and adjusting by using the model of multi-plan and adjustment integrated, and the above works can also be completed by expert system. Compared to the traditional methods, this method overcomes the disadvantages of separations among different stages.
Abstract: Through metallographical observation and pole figure analysis, the changes of recrystallization microstructure and texture have been studied in this paper in order to discover the influence mechanism of annealing process parameters on the properties of extra low-carbon and high strength bake-hardening sheet steel (ELC-BH sheet). Experimental results are shown as follows:① Recrystallization microstructure and texture weren't discovered at recovery stage; ② Forming nucleus and growth of {111} orientation grains were more precedent than that of other orientation grains at finished recrystallization stage because of its relatively high storage energy in cold-rolled deformation microstructure; ③ {111} textures were sharpened by annexing other orientation grains at grain growth stage; ④ The process of grain growth was prolonged with the increase of soaking temperature and soaking time so that deep drawability was improved.
Abstract: Puts forword combination of graphical rule language with the technology of forecast tree analysis on the basis of the construction of the forecast tree. By means of this method, knowledge base of expert system can be constructed conveniently and efficiently. An example in order to explain how to build up a knowledge base of the bearing failure diagnosis ES is given.
Abstract: The equi-precision fitting algorithm of dense modal parameter identification is presented, which defines the relationships between fitting precision and critical errors, and combines the precision of identification with the quantity of calculation directly. The examples of computation show that the results of the identification are satisfied.
Abstract: Using modelling method of large scale system, and bounding up with the technological requirements in CC-CR, the mathematical models of logistics system in CC-DR and CC-DHCR are builded, which include the models in steelmaking-casting, casting-rolling and steelmaking-casting-rolling. Based on them, two-stage optimization method for production plan is discussed.
Abstract: This paper combines the robot position/force hybrid control algorithm proposed by Raibert and Craig and the robot dynamic hybrid control algorithm proposed by Yoshikawa. Taking account of the difficulty to identify the environment, especially the effect of mechanical disturbance, and the vibrations of mechanism, a PI learning hybrid control algorithm for using robot to do assembly task was presented. This algorithm was realized in a peg insertion by a three DOF robot. The experiment results showed that this algorithm could effectly realize the peg-and-hole task, and restrain and weaken the vibrations of mechanism.
Abstract: For ball bearing, cone bearing and cylinder bearing failures which are real failures acpuired on real running condition in a bearing test machine, this paper discusses the diagnostic method for bearings besed on neural networks. The application indicates this method is very good.
Abstract: Effects of different reducers as well as various reaction conditions on reducing of hexavalent chromium were investigated. The reaction process was discussed and the optimum reaction conditions were determined. The reaction product can serve as chromium source of nontoxic chromium plating and coating thicker than 100μm was obtained.
Abstract: ByX-ray powder diffraction technique and oxygen content analysis, a solid solution Sm1+xBa2-xCu3Oy was determined with the solid solution region in 0 ≤ x ≤ 0.4. When x<0.25, the Sm1+xBa2-xCu3Oy presents orthorhombic symmetry, and the orthorhombic-tetragonal transition occurs at x=0. 25. With the increase of x, Tc decreases and finally breaks off. The correlation between oxygen content and phase structure at different quench temperature related to SmBa2Cu3Oy, was investigated as well.
Abstract: On the basis of the theory of elastic thin plates in small deflections and the theory of Bessel functions, the frequency equation and the mode functions of usual circular saw blades are derived with the effects of the centrifugal force neglected. The relations between the frequency equation and the mode functions, and the specific dimensions of the saw blades are removed by nondimensionalizing the frequency equation and the mode functions so as to make them more generalized.
Abstract: The intercalation of lithium into benzene carbon black was investigated in nonaqueous solution by cycling voltammetric methods. The results showed that the exist of several irreversible reactions during the first cathodic scanning was due to the decompositions and intercalations of the solvents in the electrolyte. By increasing the content of graphitization region in the benzene carbon black, the intercalation and deintercalation of lithium could occur at about 0.1 V vs lithium and make it possible to change the lithium in the lithium secondary batteries with this kind of carbon.
Abstract: Porous alumina ceramics were obtained by preparing the specimens with various amounts of carbon powder used as pore-forming material. Samples of from 20% to 55% porosity were sintered. Effect of porosity and degree of specimen sintered on strength were investigated. It is show that the strength (σ) of specimens with changing porosity (ρ) can be represented by the empirical equation σ=σ0(1-ρ)m at low degree of specimens sintered or σ=σ0exp(-bρ)at high degree of specimens sintered. The empirical constants m,σ0 and b is dependent on the degree of specimens sintered. With increasing of the degree of specimens sintered, the value of m, σ0 and b decrease. The only method to obtain the specimens with high porosity and strength was by addition of pore-forming material not by decreasing degree of specimens sintered.
Abstract: This paper compared "CC"-pellets(pellet with organic material as binder), using roll scale as raw material and low cost coal as reductant. The results showed that "CC" and bentonite may reduce growth speed of green pellets and increase strengths of green and dry pellets, but "CC" addition rates were only one-tenth of that of bentonite producing the same quality pellets. DRI (Direct Reduction Iron)produced with "CC"-pellets were superior to that of bentonite pellets.
Abstract: Laboratory EMF measurements were conducted in Fe+C(sat)+Si system using ZrO2 (MgO) solid electrolyte equipped with a new auxiliary electrode SiO2+CaF2. The results showed that the measured EMFs reaches stable value within 5 seconds after immersion of the developed silicon probe into the above melt; the relation between measured EMFs and silicon activity corresponds with the theoretical calculation; the measured EMFs were nearly independent of measured temperature from 1 694 to 1 749K. Due to the rapid response and accuracy of the silicon probe developed in this study, it is expected to be used in situ.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
