Advanced Materials Research Vol. 402

Abstract: Heat transfer coefficient has a great influence to the thermal state of the mould copper plate. The coupled visco-elasto-plastic FEM models have been presented for thermal process analysis of steel the mould copper plates. With the understanding to the mould thermal state for different heat transfer coefficient, the characters of mould copper plate thermal state is obtained. It is shown that, when the heat transfer coefficient increasing, the surface temperature of the mould plate would be lower, but the temperature distribution trend is steady, and at same time, the heat transfer coefficient has little influence to the equivalent strain distribution, especially for the nodes nearer to the meniscus. For breakout signal catching of this mould, the thermocouple is better to embedded lower than 300mm to the meniscus by vertical, and less than 30mm to the mould cold side by level.

Abstract: Caustic calcined dolomite based compound desulfurizer by the silicon thermal reduction method was taken as study object. Effect of fluxing agent and heating agent on caustic calcined dolomite based compound desulfurizer melting point was studied. The result showed that heating agent was the major influential factor for the melting point of compound desulfurizer, melting point of the compound desulfurizer gradually reduced with the increase of heating agent. Fluxing agents of CaF₂ and SiO₂ were the minor influential factors for the melting point of compound desulfurizer. The lowest melting point condition for the compound desulfurizer was：7% CaF₂+11% Al₂O₃+17% SiO₂ + 56% heating agent.

Abstract: This paper aims to study the effect of time and pressure on the nitrogen solubility limit through single factor experiment. The experiment is operated in the independent designed device whose main part is high temperature and high pressure reactor, Using high pressure and bottom blowing nitrogen in the furnace, it can gain high nitrogen nickel-free stainless steels whose nitrogen content is more than 1.1%.;The results show that there is solubility limit of nitrogen in 18Mn18CrN steel under certain condition ; The solubility limit of nitrogen in steel increases with the growth of pressure which ranges from 0.4MPa to 1.4MPa.

Abstract: Using the secondary iron bearing dust as raw material, to make high basicity and coal mixed briquette, and then the briquettes are rapid self-reduced to produce iron nuggets at high temperature, at the same time of obtain more pure iron nuggets, the removal rate of alkali metal elements Pb is above 90%,Zn is about removed completely, so as to solve the problem of the damage of alkali metal elements, and this can make great contributions to the energy conservation and emission reduction, and environment protection.

Abstract: To reduce the slag sticking to snorkel and to increase the operation life of snorkel during ladle alloying process, B₂O₃-CaO (mass ratio 1:2) and CaF₂-CaO(mass ratio 1:2) were respectively employed as modifiers added to ladle slag. The effects of modifier on weight of sticking slag and erosion rate were investigated. The results showed that the weight of slag sticking to snorkel is reduced, but the rate of modified ladle slag pervading into snorkel is increased with the increasing of modifier added into ladle slag. The optimal weight of modifier is about 10 percent of total weight of ladle slag. The results of test in practice indicate that the slag sticking to the snorkel has been reduced by the slag modification. At the same time, the industrial applied test results show that the operation life of snorkel is increased by more than 100 percent.

Abstract: The quality of pellet has a great extent effect on the BF smooth operation. In this paper, Self-characteristics of iron ore powers used in pellet process were investigated. Then, the principles of ore-proportioning optimization basing on self-characteristics of iron ore during pelletizing were proposed. Schemes of ore-proportioning optimization were designed and a series of experiments on the schemes have been made for seeking the rational ore-proportioning scheme. The results show that there are great differences in the pelletizing properties of single iron ore podwer, and the object of improving pellet quality is reached through optimizing ore-proportioning, that lays a theoretical foundation and provides technical basis for improving pellet quality.

Abstract: This research penetrated on the transformation of phases in the microstructures of austempered ductile iron with respect to different austempering holding times. Ductile iron samples were constituted in form of Y block double cylinder with dimension of 300m x Ø25mm through CO2 sand casting process in 60 kg capacity furnace. Austempering process were conducted by first austenitizing the samples at temperature of 900°C for 1 hour. The process continues by rapidly quenched the samples inside salt bath furnace at 350°C for three different holding times of 1 hour, 2 hours and 3 hour. Samples were then taken out and cooled at room temperature. Samples were then prepared in accordance to standard metallographic process and observed using Tabletop Scanning Electron Microscopy (SEM) model Hitachi TM3000. Phases were then verified through X-Ray Diffraction analysis (XRD) test by Rigaku diffractometer. The phase structures of as cast ductile iron mainly consisted of graphite nodules embedded in ferrite and pearlite phases Austempering the samples for 1 hour holding time promoted the structures of ferrite platelets and bainitic structures surrounding the graphite. Longer austempering holding times resulted in coarsening of the ferrite platelets structures and transformation from lower bainite to upper bainite structures.

Abstract: Coke is the unique role of supporting material column in blast furnace high temperature region. Therefore the most important property is the high temperature compressive strength after reaction. This paper used decarburization electric furnace, electric mirrors, adjustable atmosphere high temperature compression testing machine and other equipments, study on the relationships between coke carbon loss rate and reactivity and size, the distribution rule between high temperature compressive strength and coke carbon loss rate. The study found that the carbon loss rate was affected by reactivity and size, in the same piece of coke, external rate of carbon loss higher than the internal loss, the surface carbon losses affect on coke strength is less, it make coke size decrease; carbon losses occur inside will not affect the size of coke, but it may affect the coke compressive strength seriously. The compressive strength can be divided into two parts: a constant and an amount proportional to carbon loss rate.

Abstract: The fluid flow in an 800 mm diameter bloom mold from two kinds of submerged entry nozzles (SEN) was investigated numerically with a mathematical model and experimentally in a water model. It was shown from the research results that the impacting depths measured in the water modeling experiments are in good agreement with the ones from the numerical calculation. The impacting depths obtained from the 4-port down 5° SEN are 140~220 mm at immersion depths from 100 to 180 mm, while those from 5-port up 5° SEN are 60~120 mm at immersion depths from 100 to 140 mm. There are an upper and a lower recirculating zone for these two SENs at the vertical section through a port center. Dimension of these two recirculating flow zones varies with the immersion depth of the SENs. At 100 mm immersion depth of the tow SENs the eye of the upper recirculating flow is not evident. The eyes of the upper recirculating flows for 5-port up 5° SEN are close to the SEN, while the ones for 4-port down 5° SEN are close to the mold wall. On the liquid surface in the mold, flow produced with the 4-port SEN creates 8 recirculating flow zones close to the SEN, while 10 recirculating flow zones close to the mold wall are formed with the 5-port SEN.

Abstract: The high nitrogen steel is alloy steel whose nitrogen content is more than solubility limit at atmospheric pressure[1]. Bottom-blowing high-pressure nitrogen smelting nitrogen steel has many advantages, in the paper, from the study of 18Mn18CrN,it can come to a conclusion that in the case of Temperature of 1853K, pressure of 1.0MPa, the bottom-blowing flow of 0.16m³ / h and temperature of 1873K, pressure of 1.4MPa, the bottom-blowing flow of 0.16m³ / h, With the bottom-blowing time of increased the nitrogen content in steel increases, but when the time is more the 10 minutes, the nitrogen content is saturated.