查看更多>>摘要：To avoid the nonuniform phenomena of heat and mass transfer of metallurgical powdery materials caused by conventional heating method, the temperature rise characteristics of carbon-containing chromite ore fines in the microwave field were investigated using microwave heating in a microwave metallurgical furnace. The experimental results show that the carbon-containing chromite ore fines have better temperature rise characteristics in the microwave field at a frequency of 2. 45 GHz. After heated in the microwave field of 10 kW, the temperature of 1 kg carbon-containing chromite ore fines rose up to 1 100 ℃ in 7 min, at a temperature rise rate of 157. 1 (℃ • min~(-1) • kg~(-1)), whereas the temperature of 1 kg carbon-containing magnetite ore fines rose only up to 1 000 ℃ in 10 min, at a temperature rise rate of 100 (℃• min~(-1) • kg~(-1)). With increasing carbon-fitting ratios and by adding calcic lime, their heating effects changed regularly.
查看更多>>摘要：To study the combustion characteristics of the polyethylene (PE) particle and coal powder at blast temperature of the blast furnace, the contents of CO and CO_2 of off-gas during the combustion of PE particle and coal powder at the 1 200 ℃ and 1 250 ℃ were measured using carbon monoxide and carbon dioxide infrared analyzer, and then the corresponding combustion ratio was calculated. The results showed that when the temperature is high, the combustion speed of PE and coal powder is high and the corresponding combustion ratio is high. Whereas, the combustion speed and ratio of PE are much higher than those of coal powder.
查看更多>>摘要：Liquid-phase enhanced sintering of powder metallurgy (P/M) 316L stainless steel by addition of sintering aids was studied. 2% - 8% of pre-alloyed Fe-Mo-B powder with two different particle sizes was added as sintering aids, and the specimens were sintered in vacuum at 1 200 - 1 350 ℃. The results show that the fine Fe-Mo-B powder (5 - 10 μm) has stronger activated effect. The sintered density increases with the increase in sintering aid content or sintering temperature. Warm compaction has a better effect on the control of dimensional precision of compacts. The prealloyed Fe-Mo-B powder deviated from Mo_2FeB_2 component can also be sintering aid of P/M 316L stainless steel.
查看更多>>摘要：The contrast experiment of different stirring modes, which includes a new type of stirring-injection with the method of pulse and rotation, and the initial one-way stirring method, is done through physical simulation in the laboratory. The stirring methods of pulse and rotation are of two kinds. One is pulsed and rotary stirrer with positive and opposite directions. The other is pulsed and rotary stirrer with rotation-stop-rotation. The results show that the stirring mode of pulse and rotation has better effects than the one-way stirring method. The specific effects are that the mixing time of the melting bath is apparently shortened, the number of grains involved in the liquid surface is increased, and the residence time of air bubble in water is doubled.
查看更多>>摘要：To design a power source system and mold for electromagnetic soft-contact continuous casting process and to theoretically estimate the heat losses from the charges and the system power, the effect of structure parameters on system power and magnetic flux density distribution was calculated using finite element method. The results show that as for electromagnetic soft-contact continuous casting system with partial-segment type mold, the power consumption is much more than that with a full-segment type mold; about 62% of electric power is dissipated in the mold, and the effective acting range of magnetic field is relatively narrow. Optimizing mold structure is a crucial measure of remarkably reducing mold power consumption and saving electric energy. Increasing slit number, width, and length can remarkably increase the magnetic flux density in the mold and can reduce the electric energy consumption. Among structure parameters, slit number and slit width are relatively more effective to reduce energy consumption. For a round billet electromagnetic continuous casting system with diameter of 178 mm, the reasonable slit number, width, and length are about 24 - 32, 0. 5 - 1. 0 mm, and 160 mm, respectively.
查看更多>>摘要：The distributions of heat flux along the height and the circumferential direction of round billet mould were measured continuously. The influence of casting speed, carbon content, powder, and pouring temperature on the average longitudinal and circumferential heat flux in the "high heat flux region" was discussed. The experimental and analytical results provide a basis for an intelligent mould with online detection of defects, adjustment of operational parameters, optimization of the monitoring system, and even prediction of abnormal heat transfer.
查看更多>>摘要：The acting force on the roll system of Sendzimir mill was analyzed using 3D FEM. The roll gap pressure distribution and the acting force between rolls S and O, rolls O and I, rolls O and J, rolls I and A, rolls I and B, as well as rolls J and B were analyzed. The results showed that the roll gap pressure mainly affected the roll surface layer, 50 mm for backup roll; the roll gap pressure distribution is of double peaks among the work roll, the 1st intermediate roll (IMR) , and the 2nd IMR; the maximum value of the roll gap pressure between the backup roll and the second IMR appears on the edge of the barrel of rolls; the component force presents the in-para-curve distribution. These are important for reducing the wear of rolls and the break of the backup roll and guiding for production.
LI Yu-guiHUANG Qing-xueSHEN Guang-xianXIAO Hong...
p.34-38页
查看更多>>摘要：With rollers as elastic bodies and workpieces as elastoplastic bodies, the rolling problem can be viewed as a friction elastic-plastic contact problem. With fewer assumptions in the simulation of strip-rolling process, a boundary element method (BEM) for two-dimensional elastoplastic finite strain and finite deformation analysis of contact problems with friction was presented. All the equations for contact problems, which include multi-nonlinearities, were obtained. Incremental and iterative procedures were used to find contact pressure and friction stress. Moreover, initial strain rate algorithm and work-hardening material behavior can be assumed in the plastic analysis. Several examples were presented, and the results of contact pressure and friction stress were in excellent agreement with those of analysis.
查看更多>>摘要：To promote effectively dynamic recrystallization and obtain a homogeneous distribution of ultrafine grain size in strip finish rolling process, the behavior of static and dynamic recrystallization must be appropriately designed to provide an ultrafine austenite microstructure without mixed grain size. The design of rolling schedule was analyzed based on the control of the recrystallization behavior to achieve ultrafine grain size in the strip rolling process of niobium microalloyed steel. The experimental simulations were presented to validate the twice dynamic recrystallization design to achieve ultrafine grain size control.
查看更多>>摘要：Owing to smelting vanadium-titanium magnetite ore, the amount of iron entrainment in slag as droplets is far higher than that in conventional BF slag. However, the iron droplets can be easily settled by blowing air into the molten slag. The results show that more than 80% of iron droplets in titania bearing slag can be settled and separated after treatment. The temperature rise of molten slag during the oxidizing process and the decreased viscosity caused by the component change of slag as well as air stirring in slag both accelerate the iron droplets settling. The vanadium content in the settled iron droplets and the original iron droplets was obtained by chemical analysis. The possible reason for the increased vanadium in the settled iron droplets was discussed by thermodynamic principles.
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