Abstract: In accordance with the coexistence theory of slag structure and by means of regression analysis, the presence of MnSiO3 and Mn2SiO4 in the slag system MnO-SiO2(and that both of them take part in the reaction of this system) has been determined, therefore the structural units of this system can be expressed as simple ions Mn2+ O2- and molecules SiO2, MnMnSiO3, Mn2SiO4 and the calculating model of mass action concentrations can also be written. At 1600℃ the calculated values of NMnO are identical with the measured αMnO, but the differences; between them at high concentrations of MnO and ower temperatures are due to the coexistence of liquid and solid in the slag system MnO-SiO2, which makes it departure from equilibrium.
Abstract: The oxide inclusions in steel have a important influence on the qualities of rolled product. In this paper, the quantity, morphology,composition and dimensional distribution of oxide inclusions for the strand of horizontal continuous casting has been studied.As well as the origin of oxide inclusions in the strand of continuous casting is discussed.
Abstract: Chrysanthemum-like morphology of quasicrystal with long-range orientational order and no translational symmetry in rapidly solidified Al-12 at%Mn and Al-10 at% Mn-2 at%Fe alloys, is observed by the Hitachi-800 TEM. This result shows that the growth of quasicrystal exhibits a mechanism in between those of noncrystalline and crystalline.The Hitachi-800 EDXS has shown that the stoichiometry of the Al-Mn quasicrystal is very close to Al4Mn6More-over, formation of quasicrystals in Al-Mn alloy is promorted by adding Feto the alloy.
Abstract: High carbon steel containing Cr and Si is designed by lowering carbon content level in ultrahigh carbon steel and adding Cr and Si to it.This steel has of excellent superplasticty and other properties. Compared with other superplastic steels, this steel can keep the superp-tasticity at much higher strain rate(>0.49/min) and can be superplasticity formed more quickly.Because of its wide plastic range of temperature(>150K), 1his steel can be used to form parts in industry conveniently.Its forming stress is low and the superplastic fine grain is easy to be produced. Otherwise, this steel is of good hardenability and its mechanical properties at ambient temperature is better than some die steels (eg.9CrSi steel).
Abstract: This paper describes an experiment on a four-high cold strip mill with dri ven back-up roll. By using the unequal diameter back-up rolls an asynchronous rolling condition can be obtained, An experiment on asynchronous cold rolling for low carbon steel strip shows that it may bring the following advantages, such as decrease in rolling load, increase in reduction, abolishment of the intermediate annealing,raising the output,decrease in cost etc.
Abstract: By one-dimensional model, the flame jets are simulated as a flat flame layer lying between upper and lower exhaust gas layers. Then (he Hottel method of uni-dimensionat system is used to calculate the radiative transfer between these layers. On the bases of Ricou-Spalding empirical formula for the free jet entrainment the mass transfer between the flame and its surrounding gas is calculated, then the mean temperature tf is determined according to the heat balance equation. The heat transfer in the billet described as one-dimensional heat conduction problem is solved by using the finite difference method. A simplified heat transfer simulation model is also developed for determination of the mean charge temperature or billet center temperature per unit grad of furnace temperature increment in each furnace zone as represented by ?θm/?Ti or ?θs/?Ti. The weight factors of the minimum fuel consumption function in different zones Wi are also obtained. An example is given to show the optimal control of furnace zone temperature according to the above mentioned linear programming system.
Abstract: Based on the industrial application of two new type suction pyrometers in good quality, the different factors increasing the accuracy of gas temperature measurement industrial furnace have been analysed.an approach of designing high accuracy suction pyromter is proposed,and the methods adopted for measuring and estimating the heat transfer errors, velocity errors and the accuracy of the suction pyrometers are introduced.
Abstract: Using the high speed cam plastomatry the cylindrical samples with th concave at butt end, filled with glass powders which has different melting poing as lubricate, are pressed. Under the following conditions,deformation temperature is 850 to 1150℃, rate of deformation is 5 to 80 s-1,amount of deformation(Ln(h0/h1)) is 0 to 0.693,the experiments for four kinds of alloy structure steels are taken place. The results show that they not only give the calculating diagram of resistance to deformation, but compare two kinds of curve fitting, finally,a mathematical modle that is higher fitting precision for resistance to deformation is presented
Abstract: This paper proposes a signal transforming system of pyrometrc, which program-controlled by 8039, a single-chip microcomputer. This system is designed to complet higher bit anaiog-to-digital conversion using a 8-bit A/D converter,automatic compensating of zero shift,automatic changing of temperature range, as well as linearity of input voltage. This system covers the temperature range from 1000℃ to 1800℃, totalled 800℃. The error of the system is less than 1℃. The circuit of signaltransforming and the block diagram of program is given out. There is notany parameter of linearity in the program. It can meet the demand of all kindof input functions. Then, the errors of all parts of the system and its influnces arc discussed. Finally, the results of experiments are given out. A optical fiber pyrometer included the signal transforming system has beenturn out. The pyrometer was calibrated by the blackbody furnace. The result of calibration shows that the maximum error is less than 2℃. The pyrometer has been installed on the blast furnace, which used to measure molten iron. It is shown that, combining hardware with software, digital circuit with analog circuit, the signal transforming system is more flexible and the construction of the system is simpler. This signal transforming system can meet the demand of the signal inputed, which not only temperature, but also some other sensors.
Abstract: It has been considered that the boron segregation at austenite grain boundaries is responsible for the effect of boron addition on the properties of the steel, such as hardenability, creep fracture, etc.By means of particle tracking autoradiograph (PTA) the grain boundary segregation of boron has been investigated in Fe-30% Ni alloys, quenched from 550-1200℃ at different cooling rates.It is shown that two kinds of grain boundary segregation, equilibrium and aonequilibrium segregation, caused by different mechanisms take place.The nonequilibrium grain boundary segregation during cooling with boron depleted zone adjacent to the grain boundary is very sensitive to e cooling rate, and can be inhibited by rapid quenching. The temperature effects on these two kinds of grain boundary segregation are different.As the quenching temperature increases, the grain boundary segregation of boron due to equilibrium adsorption decreases, while the non-equilibrium segregation brought to the grain boundaries kinetically increases. The nonequilibrium segregation therefore dominates in the specimens quenched from high temperatures, and the equilibrium segregation dominates in those cooled from low temperatures. For the cooling used in the work described above, the transition temperature for the dominance of cither segregation in the alloys lies in the range of 650-750℃9 increasing with increasing cooling rate.
Abstract: A calculation method of gas fugacity,traditional a function method,has been discussed on its complexity and error.The error of a function method consists in the inequality between its value and that value when the pressure is close to zero. The substitution of Z function for a function, it shows that the deficiency of a function can be overcomed. The conditions and range of applications of Z function are also explained.One of the advantages is to estimate the field of pressure that obeies the perfect gas law so that it is used widely in practice.
Abstract: Some methods for controlling the quality of electroplates can be found out by making study on electrochemical nucleation and growth,which are of importance for electroplating from molten salts The basic relations between electrochmical nucleation and growth used to be derived from those of gas-Liquid ani liquid-solid phase transformations. In this paper, the thermodynamic relations between electrochemical nucleation and growth arc derived using the general condition of equilibrium between two simple charged phaser,i. e. the electrochemical potentials between themare eqtat to each other, and a equation of nuelous density is got based on statistic theorv. Potentiostatie traasients for hemispherical nicleation with diffusion coatroiled growth are also developed by making use of hemispherical diffusion equation of ions in solution.
Abstract: When freshly generated stainless steel surface is passivating in the chloride solution, the true current decay law, i (t), that is independent of the methods of mechanically removing the oxide film on the metal surface and of parameters selected in experiment, follows i (t)=C1exp(-a1t) + C2exp(-a2t) The first term in this equation is associated mainly with the growth of MeOH adsorbed film, the second term is related to the growth of oxide film. At potentials above a critical potential that is well below the pitting potential measured from the surface covered by oxide film, corrosion pit would occur on the freshly generated surface. The film growth on the stainless steel in MgCl2 solution follows the high field ion conduction mechanism.
Abstract: In this paper the process of rust prevention on seamless steel pipe by hot-dipping paraffins has repoted,and the experimental results, resistance to atmosopheric corrosion for seamless steel pipe after dipping in paraffins, has described and analyzed economically. The results show that the rust prev-enttion process by dipping paraffins is not only convenient to operate and to have low cost, but also good effective on rust prevention. It is of great value to improve surface quality and to life of seamless steel pipe.
Abstract: In this article, the synthesis and characterisation of pure tephroite are discussed. At room temperature, the synthesized pure tephroise be decomposed completely by dilute hydrochloric acid,salphuric acid or phosphoric acid. It is found by calorimetry that the reaction of tephroite with hydrochloric acid releases the heat to be 160.1±3.5 kJ per mole. The determined value of heat of reaction is close to the calculated value of △H°298 based on deta from literature. From the deterarined value of the heat of reaction, the laitice enargy of Mn2SiO4 is calculated to be -8045 kJ·mol-1, the enthalpy of hydration of SiO44- (g) is -4439.3 kJ.mol-1.
Abstract: The mixed ligand complex in the system of "Titanium (Ⅳ)-5 -Br-PADAP-Hydroxylamine-Chloroacetate" is suitable for the spectrophotometric determination of low titanium.The deep blue complex has a maximun absorption at 585nm and the molar absorptivity of 7.24×104.It is stable and can be kept unchanged at least one week after developing.The interference of coexist-ing ions and their diminution are studied. Beer's law is obeyed over the concentration range of 0-25μg titanium per 25 ml. A procedure for the determination of titanium in alloy sleels has developed.
Abstract: In this paper, we discussed the lateral motion of a container along the rope guides. The motion of a container compressed two parts:the oscillation of the center of mass and the rotational vibration round that center of mass. For this dynamic system, the differential equations are established, and determined the numerical solutions by Rung-Kutta method,Analysed these solutions find that (1) The amplitude of the oscillation of container is proportional to the lateral force given by hoist rope, and it is also proportional to the length of rope guides, but is inversely proportional to the weight. (2) If the length of container is kept constant, increasing the distance between two ears of cage, then the shaking of container will decreases. But, if the length of container and the distance between two ears of cage are increasing similarly, the shaking of container can not decreases.
Abstract: Let fij (i, j=1, 2……, r) are continuous, the autonomous nom-lineararge-scale system with equatiom $\frac{{{\rm{d}}{{\rm{x}}_{\rm{i}}}}}{{{\rm{dt}}}}=\sum\limits_{{\rm{i}}=1}^{\rm{r}} {{{\rm{f}}_{{\rm{ij}}}}({\rm{xj}})({\rm{i}}=1, \ldots,{\rm{r}})} $ are considered,where Xi is ni vectors and, assume it has a null solution. Some rather well conditions,under which the null solution of above system is uniformly asymptotically stable in the large,is obtained
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
