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Li Y.-L.,University of Science and Technology Beijing | Cheng S.-S.,University of Science and Technology Beijing | Zhang P.,University of Science and Technology Beijing | Zhou S.-H.,Laiwu Branch Company of Shandong Iron and Steel Co.
ISIJ International | Year: 2015

Based on the survey of two Chinese large blast furnaces (BFs), it was found there were complex relationships between hearth sidewall and bottom temperature. The highest temperature positions for these two BFs were distinctly different, which was indicated that the positions of the most serious erosion were different. Therefore, the mathematical model of molten iron flow in BF hearth bottom was established and the influence of floating state of deadman on molten iron flow and wall shear stress was analyzed. The results showed that the status of molten iron flow was determined by the floating state of deadman so that the erosion position was influenced. The floating height of deadman of BF A was higher than that of BF B obviously, which led to the difference between hearth sidewall and bottom temperature and also the erosion migration. When deadman was sinking at bottom, the molten iron flow was faster and wall shear stress was larger near the bottom corners than that at other bottom positions so that the elephant-foottype erosion occurred easily. When deadman was floating, the erosion position migrated from the hearth bottom corners to the corners between bottom of deadman and hearth sidewall. The permeability of deadman would also affect the erosion. Finally, the erosion profiles and their forming reasons were discussed at different floating heights of deadman. © 2015 ISIJ.

Liu Y.-L.,Laiwu Branch Company of Shandong Iron and Steel Co.
Kang T'ieh/Iron and Steel | Year: 2016

The carbon partitioning behavior and its effect on martensite and retained austenite of Fe-0.24C-0.3Si-1.0Mn-0.56Cr-0.17Mo (mass prcent,%) steel during coolling processes after hot punching were investigated by using fully autodilatometer Formastor-FII. The microstructure characterization was carried out by means of scanning electron microscopy and transmission electron microscopy, and the austenite fraction measurement was determined by X-ray diffraction and electron back scattered diffraction. The results show that martensite and retained austenite were obtained in different cooling processes after hot punching. Using direct fast cooling process after hot punching, the martensite lath was relatively confused and shorter and the amount of retained austenite was less. While using slow cooling process in the end, the martensite lath was longer. It's found that the carbon partition occurred in the slow cooling process. More retained austenite distributed among the martensite lath and formed thin films. High density dislocation distributed within martensite lath. © 2016, Chinese Society for Metals. All right reserved.

Cao Y.-H.,Laiwu Branch Company of Shandong Iron and Steel Co. | Gao Z.-C.,Laiwu Branch Company of Shandong Iron and Steel Co. | Cao Y.-X.,Laiwu Branch Company of Shandong Iron and Steel Co.
Yejin Fenxi/Metallurgical Analysis | Year: 2013

A determination method of seven components in magnetite was investigated by X-ray fluorescence spectrometry with fusion sample preparation. Such influence factors, including dilution ratio, the oxidant dosage (lithium nitrate) and the releasing agent (lithium bromide) dosage, were discussed. Under the optimal conditions, melting temperature and melting time was further selected. After glass sample pieces were prepared by fusion at 1050°C for 10 min with dilution ratio of 1:20, seven components in magnetite, including TFe, CaO, MgO, Al2O3, SiO2, TiO2, were directly determined by X-ray fluorescent spectrometry. Calibration curves were established by magnetite certified reference materials with different iron content, and the linear correlation coefficients were not less than 0.9974. When this method was applied to the determination of actual magnetite sample, the results were consistent with those obtained by chemical method, and the relative standard deviation (RSD) were as follows: 0.29% for TFe, 3.4% for S and 0.29%-2.5% for other elements.

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