Papers by Keyword: Molten Steel

Abstract: A mathematical model has been constructed for simulating the RH degasser of an iron and steel Co. Ltd. The flow field of molten steel in the ladle has been investigated; in addition, it is also investigated through physical modeling study. The main objective of the investigation was to assess the influence of gas flow rate and immersion depth on dead zones in the ladle. The results show that the flow pattern of molten steel in RH degasser can be well represented by the mathematical model and the physical model. Except the areas close to the free surface and the zones between the two snorkels and the sidewall in the ladle, these dead zones can be reduced by increasing of gas flow rate and immersion depth. These dead zones were marked with 1, 2, 3, results calculated by mathematical modeling are in good agreement with which obtained by means of physical modeling (water modelling) study increasing of immersion depth could markedly reduce the area of dead zone 3, yet the area of dead zone 1 and 2 could be markedly reduced by increasing the gas flow rate, hence indicate that mixing of dead zones could be intensified through improving gas flow rate and immersion depth.

Abstract: The flow pattern and temperature distribution of molten steel in tundish were calculated by CFD and heat transfer method. Comparing the tundish flow field and the temperature field of empty packet and turbulence inhibitor installed, the role of turbulence inhibitor in tundish was analyzed, and the advantages and disadvantages of turbulence inhibiter were illuminated. The results show that: the turbulence inhibitor can eliminate the short circuit flow at tundish bottom, stabilize flow, and homogenize molten steel composition; but the turbulence inhibitor can consume energy of molten steel, and reduce the temperature of molten steel in the tundish. Without the turbulence inhibitor, the surface minimum temperature is far from the narrow corner, it is not easy to knot cold steel; installing turbulence inhibitor can raise the molten steel temperature near inlet, steel flow will scour inlet refractory intensively, service life of which shortens.

Abstract: High purity AL₂O₃-MgO carbon-free refractories for ladle lining were investigated, this paper compared with the properties of bricks with different bond system and different production process, and study the wear mechanism, the TOC and hydrogen content change; analyzing the microstructure of residual bricks and the impact of refractories on quality of molten steel;Conclusions:The two kinds of bricks have different wear mechanism, the bricks bonded by a-bond was damaged mainly by penetration and erosion while the bricks bonded by resin was damaged by structure spalling and they have different effect on cleanness of molten steel.

Abstract: In this work, the design of a new technology for nanoparticle addition into molten steel that improves the mechanical properties of the material, as well as the upscale of the process, was pursued. The process was scaled from laboratory to industrial level starting from first experiments carried out in pure iron bath, in order to analyze the behavior of nanoparticles in molten metal environment, and finishing with the addition of nanoparticles into microalloyed steel bath as industrial trials. The first steps of the research were performed in the levitation furnace at Tecnalia R&I installations that can cast samples up to 1 kg, continuing with a high vacuum furnace with a capacity up to 35 Kg. By the end of the investigation, the process was scaled up to industrial level at Gerdau facilities.

Abstract: A mathematical model for the RH refining process was developed and validated by the measured molten steel temperature in situ. It is showed that the model predicted temperature matched the measured value well and the average errors within ±5°C were 86.9%. The model results also showed that for every increase of 100°C of the initial temperature of the chamber inwall , the average molten steel temperature increased by about 8°C. For every blowing extra 50m³ oxygen, the steel temperature increased by about 7°C.

Abstract: Quick analysis of chemical composition is very important for process control and quality assessment in metallurgical industry, especially in steelmaking process. A prototype equipment for online analysis of molten steel composition was developed based on laser-induced breakdown spectroscopy. The effect of steel temperature on different spectral line intensities was studied, and calibration curves of Cr, Ni, Si and Mn were built. Results show that most line intensities are greatly enhanced when steel temperature is higher than 1200°C, and the detection capability of minor elements in molten steel is higher than in normal solid steel. Line intensity, however, is easier saturated in molten steel, leading to narrow linear ranges of calibration curves for molten steel. Furthermore, for online analysis, by using a median filter the abnormal points were inhibited and the changing compositional concentrations were successfully monitored.

Abstract: Using finite element method, the molten steel flow process in soft-contact electromagnetic continuous casting mold is simulated. The results show that the molten steel surface were affected by the electromagnetic force and shrink to the centre, near meniscus zone the flow velocity of steel increases and appears an obvious circumfluence, a large number of inclusion float and are absorbed by flux; on the other hand, the turbulent kinetic energy significant increases in circumfluence area, this exacerbates the reaction between flux and liquid steel, the initial size of the solidification organization are refined, and the surface quality of slab are enhanced.

Abstract: By establishing finite element mathematical model for heat transfer in the ladle to simulate transient temperature distribution field, this paper, with typical value method and energy conservation method, studies effect of ladle preheating temperature and insular linings of the ladle on molten steel temperature drop in the 210 t ladle used by Chongqing Iron & steel Co., Ltd. Furthermore, decrease rate of molten steel temperature is forecasted under different working conditions. These predicted results are compared to those obtained by temperature measurements on the site, which shows that ladle preheating temperature affects the rate of molten steel temperature drop a lot, and the decrease rate of molten steel temperature in casting state is greater than in holding state of molten steel. Actual temperature decrease rate of molten steel on the site is between one obtained by energy conservation method and one obtained by typical value method. These studied conclusions provide good reference for molten steel temperature control in Chongqing Iron & Steel Co, Ltd.

Abstract: Using finite element method, the molten steel flow process in soft-contact electromagnetic continuous casting mold is simulated. The results show that the molten steel surface were affected by the electromagnetic force and shrink to the centre, near meniscus zone the flow velocity of steel increases and appears an obvious circumfluence, a large number of inclusion float and are absorbed by flux; on the other hand, the turbulent kinetic energy significant increases in circumfluence area, this exacerbates the reaction between flux and liquid steel, the initial size of the solidification organization are refined, and the surface quality of slab are enhanced.

Abstract: Steel is a kind of important material. The accurate control about the end temperature of molten steel has significant impact on the quality of steel material. Case Based Reasoning (CBR) is used to predict the end temperature of molten steel in Argon Oxygen Decarburization (AOD). Grey Relational Degree (GRD) with different weights of attributes is adopted to calculate the similarity between cases. Analytic Hierarchy Process (AHP) is taken to determine the weights of attributes. Multiple Linear Regression (MLR) is applied to compute the relative weight of two different attributes for AHP. Two methods, CBR using AHP with Equal Weights (CBR_AHP_EW) and CBR using AHP with Different Weights (CBR_AHP_DW), are employed to for a comparison. The results show that CBR_AHP_DW is effective in predicting the end temperature of molten steel in AOD and CBR_AHP_DW outperforms CBR_AHP_EW.