Advanced Materials Research Vols. 311-313

Abstract: For the thick steel plate 13MnNiMoNbR, submerged arc welding was carried out, three kinds of wires were used H08Mn2MoA, H10Mn2MoA, H10Mn2Ni2MoA and together with two kinds of fluxes which are SJ101, SJ102 .After welding ,normalizing plus tempering heat treatment was added.Using V-shaped notch Charpy impact test and the fracture morphology was observed for researching. The toughness of weld and heat affected zone was lower than 27J at -20 °C,cleavage fracture exited in main proportion. Experiments proved that because of the slow colling speed of weld after normalizing a large amount of the upper bainite produced. When normalizing temperature fell in the critical zone where the ferrite and austenite two-phase can exist together (critical normalizing),upper bainite in weld was eliminated , strength and low temperature (-20 °C) toughness correspond with national standard.

Abstract: In the present work, effects of elements vanadium and niobium on the microstructure of the conventional indefinite chilled rolls made by small vertical centrifugal caster were investigated, using optical microscopy, Scanning Electron Microscopy (SEM, Jeol 6400), Energy Dispersive X-ray Spectroscopy (EDXS, Cu-K radiation) to identify the type, morphology, and to measure the volume fraction and the distribution of carbides and graphites formed during solidification. Microstructural analysis indicates that, the amount of graphite is dramatically reduced by adding V element. The volume fraction of the square-like carbides NbC increases with the Nb content increasing. However, if Nb content is over a critical point, large amount of the square-like NbC carbide can be seriously segregated in the out part of the section.

Abstract: This article makes melting temperature, melting speed, viscosity and Na₂CO₃ relationship curves, and analyses the influence of Na₂CO₃ to melting temperature, melting speed and viscosity of the covering agent, by determining melting temperature, melting speed and viscosity of the covering agent of each formulation. Research results show that, with the contents of Na₂CO₃ increasing, melting temperature and viscosity decrease, melting rate decrease after first increase.

Abstract: Soil as a corrosive medium is probably of greater complexity than other environment. This paper studies the influence of soil engineering properties towards metal loss of buried X70 carbon steel coupons. The study focuses on soil engineering properties which are soil moisture content, clay content and plasticity index. A total of 160 pieces of X70 carbon steel coupon were buried in 5 different locations in Peninsular Malaysia for a period of 12 months to study the effect of the abovementioned parameters towards metal loss caused by soil-corrosion. The samples were retrieved periodically for every 3 months to determine its weight loss and consequently the corrosion rate. It was found that the rapid growth of corrosion is relatively correlated with the high moisture content of soil. Yet, corrosion initiated at a slow pace for high plasticity soil and clayey soil. The highest and the lowest corrosion growth rate were calculated at 0.218mm/year and 0.051mm/year respectively. No strong indication can be found to relate the dominant influence of soil engineering properties towards measured corrosion rate of buried steel coupons.

Abstract: The process of three-phase electroslag furnacefoundry casting  electroslag remelting was used to produce 316L stainless steel ultra-fine wires with a diameter of 0.018mm. Breakage of the wire often occurs during drawing process due to the existence of inclusions in the steel. In order to improve the cleanliness of 316L steel, the deoxidizer and top slag composition were optimized by industrial trials in this production process. As a result, the total oxygen (T.O.) content decreased from 120 ppm to 57ppm. During the electroslag remelting process, the composition of electroslag and the power supply were optimized. Argon protection was used and electrode was washed by acid solution before refining. Finally, the T.O. in the remelting ingot can be controlled below 20 ppm.

Abstract: The microstructure of a bainitic steel after different cooling rates has been investigated by transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD). The effect of cooling rate on the intermediate transformation microstructure was studied. The results showed that the final microstructure contained complex mixture of bainitic ferrite, granular bainite and polygonal ferrite. There was mainly lath-like bainitic ferrite at fast cooling rate (20Ks^-1), while microstructure in samples cooled with intermediate rates (8~15 Ks^-1) contained bainitic ferrite and granular bainite. When cooling rate decreased to less than 5Ks^-1, polygonal ferrite occurred.

Abstract: In this paper, the direct reduction of iron ore pellets was carried out by simulating the typical gas composition in coal gasification process, Midrex and Hyl Ⅲ process, the influence of gas composition and temperature on reduction was studied. Results show that the proportion of H2 increasing is helpful to improve the reduction rate, while when H2/CO>1.6, changes of H2 content will have very little influence on it. Appropriate reduction temperature is about 950°C, higher temperature(1000°C) may unfavorably slowed the reduction rate. From the kinetics analysis at 950°C and 1000°C, when H2/CO=0.4 the prophase of reduction course (~90%) is likely controlled by interfacial chemical reaction mechanism and in the later controlled by gaseous diffusion mechanisms. However, when H2/CO>0.4 the whole reduction course is likely controlled by interfacial chemical reaction mechanism. The reaction rate constant (k) and effective diffusion coefficient (De) at 950°C are both better than those at 1000°C. Research also shows that the coal-water slurry gasification based on Texaco furnace is more suitable for iron ore direct reduction than other coal gasification processes.

Abstract: A industrial strip shaper is developed, which mainly consisted of the shape detecting roller, the collecting ring, the DSP shape signal processing board and the shape control model. The structural form which is different from the international popular segmented detection roller is put forward and the entire detection roller inlayed block is developed to avoid the scratch of the strip surface due to different thermal expansion of the traditional detection roller measuring unit effectively. The signal transmission form which is different form the international popular dry slip ring is put forward, the spray wet slip ring is developed to improve the measuring precision and the service life. The signal processing form which is different form the international popular gathering card is put forward and the embedded DSP shape signal processing hardware system is developed to improve the measuring precision and the anti-interference ability. The shape signal processing software system whose function contains error compensation, pattern recognition, establishment of the target shape and the close loop control calculation is built to implement the intelligentized shape meter. The shape meter has been test chronically on the 1250 mm cold strip mill of Angang Steel Company Limited and the test result indicates that the measuring signals were stable and reliable and the close loop control of shape was implemented.

Abstract: Based on the shape detecting principle and the DSP (Digital Signal Processing) technology, a high-precision shape detecting system of cold rolling strip is developed to meet industrial application. It was successfully used in Angang 1250 mm HC 6-high reversible cold rolling mill. The precision of shape detecting was 0.2 I, the shape deviation was controlled within 6 I after the close loop shape control was input.

Abstract: The influences of non-metallic inclusions on the quality and properties of the steel not only depended on the quantity of inclusions, but also on the type、shape、size、deformation behavior and distribution condition. By means of ANSYS finite element analysis software, the stress field distribution in the inclusions and the matrix around the inclusions are analyzed under the condition of different kinds of types、shapes、distributions with changeable load in heavy rudder arm steel castings, then micromechanics behavior of inclusions is investigated from angle of macro mechanics.