Abstract: The rates of the reduction of carbon-bearing pellets have been determined with a thermalbalance test instrument and heating method of a single pellet. The effects of heating temperature, carbon contents of pellet, composition of furnace gas, additives, and the kinds of raw materials on the rates of reduction, final metallizing rates and metallurgical characteristics of carbon-bearing pellets have also been investigated. The results of the experiments show that the softening temperature and melting temperature of the pellet are higher than coventional pellet's temperature. There is a procedure of gas-releasing when the pellets containing >15%C are heated in the temperature range of 1000℃ to 1350℃.The pellets can be self-reduced rapidly in the furnace gas with a high temperature and high contents of CO2. A high metallizing ratio can be obtained. The final metallizing ratio of pelletes increases with the increase of heating temperature. This new type of pellet with very good metallurgical characters can be used directly as a raw material of ironmaking shaft furnace, in which coke can be replaced by a wide ranges of raw coals.
Abstract: The reasonableness of direct alloying with chrome ores is discussed with thermodynamical analysis as well as the influencing factors, such as the burden of chrome ores, basicity of slag and reductants. The results of experiments have shown that the basicity of slag should be around 1.5 and the chrome ore burden was limited up to 30% of Cr2O3 in slag. Carbon was used as reductant first and then silicon to continue for better metallurgical effect.
Abstract: By analysing and disposing the experimental data from Shanghai NO. 5 I&S Works, comparing these data with the results undertaken by some investigators, the equilibrium conditions of [C]-[O], [Cr]-[O], [C]-[Cr] during stainless steel making in STB combined-blown converter are approached. The results show that the [C]-[Cr] equilibrium relation is different from Hilty's equation which is suitable for the stainless steel making in electrical furnace. Therefore, it is not very accurate to measure the [C]-[Cr] equilibrium conditions in STB combined-blown converter.
Abstract: Calcium aluminate-based fluxes are widly used nowadays in refining of steels because molten calcium aluminate enhances the extent of deoxi-dization of liquid steel and has a high sulphide capacity. By means of this fact, a new deoxidant of steel in which aluminium wire is wraped with high CaO content flux (AWF) is used in this study. Compared with the deoxidizing results of aluminium alone in liquid steel, it is concluded that the final oxygen content is lowered 40-300 ppm, the number and size of inclusions decrease by 226 and 1.9μm respectively. At the same time, the desulphurization ratio reaches 50%.
Abstract: The rules of stength and ductility for 45 steel under temperature range from solidus to 600℃ were measured by a thermal stress/strain simulator Gleeble 1500. The influence of thermal history, strain rate and cooling rate on strength and ductility at solidifying region, Austenitic region and γ→α region was studied. The mechanism of cracking in these three regions was investigated.
Abstract: The body tensile strengh of the centrifugal-casting gray cast iron pipes treated with RE can be improved to 25.9%(pouring of ladle) or 42.4% (spraying process), while their average values are 214N/mm2, and 242N/mm2 respectively. Both surpass the (ISO13-78) specification (180N/mm2) and reach the requirement of metal mold centrifugal-casting gray cast iron pipes. The cast iron pipe thickness is 2.2mm(14.1%) thinner than the international standard.
Abstract: In order to investigate the possibility of improving the wear resistance of ZA-27 alloy, the influence of RE on the properties and structure of alloy has been studied. The experimental results show that RE refines grain size, shortens secondary dendrite arm spacings, increases the areal fraction of phase. When the RE addition is larger than 0.1%, hard phase containing RE appears in the metal matrix. The morphology of this phase varies with the increase of RE addition. The above mentioned behavior of RE enhances tensile strength and hardness slightly, decreases toughness and increeases wear resistance of ZA-27 alloy remarkably.
Abstract: On the basis of three structure criteria of hardenability (DI90%M,DI99.9%M and DI50%M) of 20CrMnTi, 20MnVB and 20CrNiMo steel, according to the case hardenability structure criterion (90%M), established regressive equations which contained the term of interaction effect between alloy elements on hardenability, and could continuously calculated the values of case hardenability(JD90%M——on the top-quenched specimen,the distance from the top to the 90% martensitezone). The calculated values by these equations have shown satisfactory agreement in comparision with the experimental data of aforementioned three steels.
Abstract: It has been found that main factors effecting on the forming property are the total reduction of cold rolling and the annealing temperature.The results obtained shows that optimum process parameters for deep drawing lCr13 stainless steel sheet are: the total ruduction is 60%,the annealing temperature is 750℃ followed with the air-cooling, The aspect of metallurgical structure and texlure was also discussed.
Abstract: With concise analysis methods, the mathematical model of the flying shear kinematics and its operating program in the computer have been developed, which is specially used for analysing the synchronous cutting characteristics of crank rotating flying shear with the radial equal speed mechanism both in its adjusting or running station on line and in the design of a new shear. The exactiude of the system has been indicated by comparing the calculated results with the situations of the shear's cutting operation.
Abstract: To assure the stableness of quality of the products, the computer control system adjusts the quantity of water, depending on the temperature of rod after rolling, in order to reach the predetermined temperature of rod's self-temper. This paper introduced the analysis of this computer control system which has been used in Tangshan Iron and steel mill, constitution of the hardware and software of this system, the inferring of mathematical model and the self-learning of model. The results of controlling were also given.
Abstract: The friction coefficent(μ)-time(t) transients of anodic film on 7070 Al Alloy were measured in the process of the film being worn by a small steel ball. It was found that the friction coefficent tended to increase during wearing. A phenomenon of periodic change of the friction coefficent, which increased steply and then changed slowly, occured repeatly. The friction coe-ffient were related not only to the abrasion of the sample surface but also to the fibre-boundies cracking in the subsurface layer of the anodic film.
Abstract: The flow characteristics of Coal-Water Slurry (CWS) and the movement of coal powder in the pipeline transportation of CWS are analysed. Then, the calculation method of CWS pipe wearing has been got by analysing the rub process of coal powder with inner surface of pipe. It has been proved by the calculation results that the pipe wearing is very slight in proof of the feisibility of long distance pipeline transportation of CWS. Detailed measures are also analysed to reduce pipe wearing of CWS.
Abstract: A mathematical model of the unsteady flow pipe section has been built up while CWS is transported in a long pipe. By solving the model, length of the unsteady flow pipe section, pressure gradient at every cross-section and the gross energy losses can be predicted. Through a small modification of the model the transition process of the pressure gradient in response to a sudden change of flow quantity may be revealed. Experimental results proved the model's reliability.
Abstract: The flow of fluid in the entrained slagging coal powder combustor are analysed. Specially, the center reflux area and its effects on the flow of fluid slag are analysed. The main factors which affect the center reflux area are investigated. The experimental results of the axal velocity and the tangential velocity in combustor have been given. Some suggestions for improvement have been made.
Abstract: In the paper designed four complex detectors and observed their background counting rates in balloon space environment. The primary crystal is Nal(Tl) scintillator of each complex detector. Its veto crystal is BaF2, BGO, CsI(Tl) and Nal (Tl) separately. The results shown that the integral background counting rates of four complex detectors in region of energy 30~350keV at altitu-de31~36km are near. There is no obvious difference each other on y background noise level in space environment. The differential counting rates of Nal/BGO and NaI/BaF2 detectors are lower than Nal/CsI and Nal/Nal detectors.
Abstract: the stochastic instability of Ito's stochastic differential systems isstudied. The Has'minskii theorem on stochastic instability is obviously improved. The comparison criterion of q-instability is established. Furthermore, the q-instability theorem is developed by means of the sufficient conditions reduced such that suited to applications.
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
