Abstract: Based on the field investigations and analysis of data obtained, it is evident that the distribution of discontinuities on this pit is considerably identified with the rigional geostructure distribution and may be explained clearly with the geostructural pressure field on this rigion. The stability of the end Slopes, i.e.concave slopes has been analysed with modelling and by means of the finite element method in axial symmetry system. A new method, called 3-D. column method,is proposed with which the stability of the potential failure body in arbitrary configr-ations may be analysed. With this 3-DC the end effect on the failure bod-has been analysed and the slope stability with a range of horizontal curvature radiuses have been calculated. Results obtained show the relationship between the slope safety and curvature radiuses is given by F=a+b/(R0/H0) as R/H<2.
Abstract: Based upon the industrial test and production data, the VOD process formaking stainless steel is discussed in this paper.Temperature varition during VOD treatment was analysed.The result shows that the technical parameters influence the temperature greatly.It is important to control the temperature of oxidation period,which it depend on adjusting oxygen supply system (including lance height, oxygen supply rate and oxygen pressure) and vacuum system reasonably. The temperature dropping during reducing treatment was influe nced by the temperature after oxygen blowing,amount of additions, such as ferroalloy coolants and reduction mix,and redu-cing treatment time.A suitable range of oxygen supply rate was given to avoid splashing of steel.And also,analysing the element variation and dec-arburization reaction on the basis of thermodynamics.
Abstract: The model experiments on the accumlation of large oxide inclusion in the bottom of ingots during pouring were carried out by using NH4C1-water solution and plastic particles.The mechanism for the accumulation of inclusion were proposed. The quantity of inclusions may be indicated by the following equation: $Q = \frac{{A{\rm{\cdot}}b}}{{1 - \alpha }}(\int_{{t_1}}^{{t_0}} {(\overline V - {U_S})} {C_0}dt + \int_{{t_0}}^{t + {t_s}} {(\overline V - {U_S})} k{C_0}dt)$ It was found that the result of experiments were in good agreement with plant practises. Accumulation of the large inclusion on the bottom of ingots is effectively inhibited by the application of the heat-generating agent in the ingot cap but the adding time and method is of very important. For reducing inclusion, it is necessary to cast steel in a suitable temperature.
Abstract: This investigation deals with the effect of Mg on the fatigue-creep interaction behaviour of Ni-base superalloy GH698, and the behaviour of the element Mg under creep stress. The experimental results indicate that Mg has no influence on the pure fatigue property tested at 700℃ 1Hz tension-compression cycling. Mg increases the rupture life for pure creep test due to the prolongation of the steady state creep and the development of the tertiary creep, but has no influence on min. creep rate. Under fatigue-creep interaction the beneficial effect of Mg on fracture life still manifests itself, even though several different wave forms are used for interaction tests.All results indicate that as long as the fraction of creep fracture exists the beneficial effect of Mg on fracture life occurs. The fractographic analysis indicates that the beneficial effect of Mg is directly related to the appearance of intergranular fracture.The inter granular fracture can be found in certain degree for all tests except pure fatigue test. AES analysis illustrates grain boundary segregation of Mg occured after heat treatment. At the beginning of the creep the segregation of Mg redistributes under the effect of creep stress, and the Auger peak of Mg is eliminated.However, as long as the creep voids nucleate the segregation of Mg at the surface of creep voids can be found by AES analysis, and this segregation will increase with increasing the creep time.According to the AES analysis, the conclusion is that the mechanism of the beneficial effect of Mg on the propagation rate of creep void lies in decresi ng the surface diffusion coefficent and grain boundary diffusion coeffic-ent by the segregation of Mg. Another possible effect of Mg determined by AES analysis is that Mg may react with S, and decreases the segregation of S.
Abstract: A new maraging steel,Mn-Mo-co steel,has been made with the aim ofsaving the alloy elements,Co and Ni.Although the strength of the steel can reaoh to or even overtake the strength level of commercial 18Ni maraging steel,the toughness of this steel is quite low.It is probably that the second phases vere precipitated along the grain boundaries before the ageing pro-cess to be carried out. In order to improve the properties of the steel,a rapid solidification technique has been used and the relationships between structures and mechanical properties have been studied as well. The experimental results shown that the rapid cooling thin metal belt has a very fine grain size and high solid solubility of alloy elements.In thls microstructure,the vacancies and dislocation are so high that an homogeneous cell structure are formed.The transverse section of the rapid cooling belt consists of two layers,upper and lower layers.The microstructure of lower layer which is direct contact with the roller surface consists of equiaxed fine crystals with a diameter less than lμm,and the upper layer make up of fine columnar crystals.It has been also found that the rapid cooling layer always has a tough fracture,but columnar crystal layer,i.e.upper layer, usually has a cleavage fracture. In the ageing condition, the hardness of the rapid cooling belt is always higher than that of quenched steel having the same chemical composition. However,other mechanical properties of the mi-crocrystal steel formed by rapid solidification are still remained for further investigation.
Abstract: The Sink Field Method（SFM） has been shown to be an acceptable theoretical method for blank development. The autosegment of the outline of a irregular drawn part is investigated in detail in SFM. The blank contours of some irregular drawn parts are given, which are autotracked with the help of SFM computer program.The blank contours of some typical drawn parts autotracked by SFM are tested with drawing process. Based on the test results, guiding function of SFM for arranging drawing beads is discovered, and the accuracy of SFM for blank development is shown theoretically to be improved by adjusting the sink distribution.
Abstract: Based on the investigation of experimental data sampled from φ250×6 semi-continuous bar mill, the mathematical models for continuous rolling steel angles have been studied. The structure of model is identified theoretically and the coefficient of model is estimated by statistical analysis of the experimental data. By the method of dispersing numerically and coinciding with a function, a program of simplifying the shape rolling model is proposed. From the results of off-line simulation, it is proved that the prediction of the model established by the upper method has been found to agree, closely with the experimental data. The accuracy of the model may be further improved by using the adaptive control system.
Abstract: Coal-water slurry (CWS) is a new kind of liquid fuel developed in recent years. In this presentation CWS's firing test and relative facility which is suitable for the furnaces in the metallurgical industry are introduced. The CWS's combustion characteristics analysis is made for some key factors which could have an influence on CWS's combustion efficiencies,and proposition is also made for some essential points by which direct the CWS's combustion at a high efficient. Further, two realizable method of CWS’s ignition are presented. Therefore, a scientific basis has provided for the commercial application of CWS in the metallurgical industry.
Abstract: Giant D. C. motor and generator are widely used in steel plants, but circular runout of their commutator often causes harmful electric spark. In order to solve this problem the amount of circular runout should be precisely detected and measured. However, it is dfficult to attain by conventional measuring method. In this paper, a new measuring system with a non-contacted edd-cur-rent transducer and a TP801 microprocessor is presented. It has good dynamic response and preciseness, data can be measured, processed and recorded simultaneously. The measuring system consists of two parts: analogue measuring and data processing. The function of the measuring system as well as the principle of software and hardware are discribed. The A/D coverting speed is also discussed.
Abstract: This Paper discusses a class of multivarable self-tuning controller with generalized cost-function. Relating to the demands of the engineering application with the cost-function, a generlized minimum-variance control strategy with prespecified closed-loop pole assignment is developed. Meanwhile the polynomial matrix R(Z-1) in the cost-function is so determined as to elimineting the steady state output tracking error of the system. when the parameters of the system are unknown, the parameters of the controller may be estimated directly by using a muitivariable recursive least squares method. The convergent property of the proposed approach is given by using the Martingale convergence theory and the convergence conditions are also given .Simulation results show that the feasibility and the effectiveness of the proposed algorithm.
Abstract: The paper describes a multi-wavelengthes pyrometer. The pyrometer is based on the planck's law. And it is assumed that the logarithm of emissivity is approximated by its polynomial in terms of wavelength. A representation of four-colour pyrometer is designed. The representing temperature of four-colour wavelength pyrometer come from that of ratiocolour wavelength pyrometers.TF-1, reciprocal of four-colour temperature is the linear combination of the TR1-1 and TR2-1 reciprocal of two ratio temperature. The coefficients of the linear combination are decided by the respective wavelengthes. If one of wavelengthes chosed by a ratio is equal to another one of wavelengthes chosed by the other, the four-colour pyrometer is going to become three-colour one. The four-colour（or threecolour） temperature cuts off the error caused by the influence of the emissivity, with 1n ε assumed as being linear in wavelength. A optical fiber is used to transmit the radiation emitted by the measured target. It is the use of technique of optical fiber branch that incoming radiation is distributed to the surface of each dectector. A microprocessor is used to calculated the four-colour signal of radiation. The result of the calibration was gived out by the blackbody furnace. The error of four-colour temperature is compared with that of ratio temperature by the experiment on some metal target. It is said that the technique of multi-wavelength temperature measurement is one. of effective method to decrease the error caused by the emissivity of the measured surface.
Abstract: The hyperfine parameters for 57Fe in Fe1-xVx(0 ≤ x ≤ 0.843) alloy systems have been studied by means of Mossbauer spectroscopy. For x<0.1 the hyperfine field Hhf(n, x) and the isomer shift IS(n, x) on Fe site with the number of V atoms in the vicinity of the Fe nuclein and V concentration x can be described by the following equations; Hhf(n,x)=(331-n·ΔHhf)+k1x IS(n,x)=-n·ΔIS+k2x Where △Hhf and △IS, the change in the hyperfine field and isomer shift found per one V atom in the neighbour shell, are 24.5kOe and 0.016 mm/s, respectively. These expression indicate that the influence of V atoms on the hyperfine field and isomer shift can be divided into two parts: short range effect and long range effect. The former, the effect of the neighboured V atoms, is additive. The later is attributed to the expansion of lattice. In the Fe1-xVx（0≤x≤0.843） alloys the hyperfine field distributions and the average value of hyperfine field and isomer shift are obtained. The average isomer shift as a function of V concen-tration x can be written as follow: IS= -0.19x The hyperfine field distributions show that two state of Fe atoms seem to exist in the Fe1-xVx alloys for x≥0.5.
Abstract: The passivity and pitting mechanisms of Fe-Cr alloys which contain 13%Cr, 17%Cr and 28%Cr in 3.5%NaCl solution have been presented by AES, EPMA technique and rotating disc-ring electrochemical measurement, especially, the behaviour of element Cr was investigated. By experiments and analysis, the following conclusions have been obtained:(a) The most important factor that control corrosion resistance of Fe-Cr alloys is the ratio Cr/Fe in passive film. (b) For diffenent Fe-Cr alloys, dissolution of Cr within pit is different. For alloys of Fe-13Cr and Fe-17Cr, dissolution of Cr follow dissolution-deposition reaction but following adsorption-desorption reaction is occurred for Fe-28Cr alloy.（c） Based on the experimental results and analytical discussion,models of pitting propagation mechanism for Fe-13Cr, Fe-17Cr alloys and for Fe-28Cr alloy have bene proposed respectively.
Abstract: In this paper, we first prove the elastic/viscoplastic variational principle and regard the rigid/viscoplastic, elastic-plastic and rigid-plastic va-riational principle as its special case, then derive the finite element formulas. The constitutive equations of elastic/viscoplastic material are eq. (2-14), (2-16). Suppose the strain-hardening function of material is H=H($\mathop \varepsilon \limits^{\rm{\cdot}} $VP, $\mathop \varepsilon \limits^{\rm{\cdot}} $) then have eq. (2-17). Usually, d $\mathop \varepsilon \limits^{\rm{\cdot}} $ is rather small, we can obtain eq. (2-18).Finally, we have eq. (2-22). The elastic/viscoplastic variational principle says:Among all the possi-ble vi, $\mathop \varepsilon \limits^{\rm{\cdot}} $ij, the actual solution renders the functional (2-23) a stationary value. From dynamic tests at different strain rate, eq. (2-27) is obtained by regression. Work rate functions are eq. (2-28) and (2-29). The rigid/viscoplastic conventional variational principle is that among all the possible vi, $\mathop \varepsilon \limits^{\rm{\cdot}} $ij, the actual solution renders the functional (2-23) a stationary value. According to the Fig. 3-1, we suppose the stress-strain relations for complicated stress state are eq. (3-5).The work rate functions are eq. (3 -6) and (3-7).The variational principle concerning non-plastic region and unloadingproblems can be discribed as follow:among all the vi, εij, the actual solu-ion renders the functional (2-23) a stationary value. Nadai's constitutive equation (4-4) can be extended to elastic-plastic deformation case. We futher define eq. (4-5), and let eq. (4-7), then we obtain eq. (4-8). Under the condition of εij<1,wwe obtain eq.(4-9).Since the constitutive equation (4-8) is a homogeneous function of time, the functional (2-23) can be rewritten as eq. (4-10). The variational principle of Nadai's deformation theory says. Among all the ui,εij,the actual solution renders the functional (4-10) a stationary value. According to the experimental results, a variational principle based on the general functional (2-23) is proved on the some proper handling of the constitutive equations for different materials. Some other variational principle which mentioned above and in our other papers can be regarded as special cases of the variational principle discussed here.
Abstract: A.Charnes and W.W.Cooper presented an algorithm for liner fractional programming.We prove that the liner fractional programming is an equivalent of a certain liner programming;then we use Karmarkar algorithm for the liner programming to get the polynomial-time algorithm for liner fractional programming.
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
