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Li N.,University Of Science And Technology Liaoning | Zhang J.,University Of Science And Technology Liaoning | Xu Q.,Tianjin Iron and Steel Group Co Ltd | Zhai L.,University Of Science And Technology Liaoning | And 2 more authors.
Journal of Materials Science and Technology | Year: 2013

Low carbon steels with B and P additions were remelted by electromagnetic levitation and solidified in a vacuum drop tube. The droplet volumes were set to be 2mm×2mm×2mm (TM) and 5mm×5mm×5mm (FM), respectively. The microstructure of rapidly solidified steel droplets (cooled in silicon oil) with P and both B and P addition was observed. The microstructures of B-bearing droplet samples were more uniform than those of B-free ones, for both TM and FM samples. The distribution of C and P along the diameter of each sample was detected. The well-distribution of C and P was detected in B-bearing droplet samples. So it could be deduced that B was also well distributed in the steels. It was B atoms that promoted the well-distribution of C and P, which further improved the uniformity of microstructure under the condition of rapid solidification. The micro-hardness of B-bearing samples was higher than that of B-free samples, and the hardening mechanism was discussed in detail. © 2013.

Lu Y.H.,Hebei University of Technology | Lu Y.H.,Tianjin Vocational Institute | Liu X.M.,Tianjin Iron and Steel Group Co Ltd
Advanced Materials Research | Year: 2013

According to analysis of operation condition and failure mechanism of converter hood, we designed a protective coating material and sprayed on the converter hood of Tianjin Iron & Steel Group Co. Ltd. by supersonic arc spraying technology, extended the working life of the converter and increased the output and benefit. © (2013) Trans Tech Publications, Switzerland.

Liu Z.,Northeastern University China | Gao X.,Northeastern University China | Du L.,Northeastern University China | Li J.,Northeastern University China | And 2 more authors.
Applied Surface Science | Year: 2015

The immersion experiment was carried out to study the corrosion behavior of low-alloy steel with martensite/ferrite microstructure at vapor-saturated CO2 and CO2-saturated brine conditions. The characteristics of corrosion behavior are investigated by the microstructure of tested steel, corrosion rate, corrosion phase, surface morphology and cross-section morphology. The results demonstrate that the microstructure of tested steel consists of tempered martensite and ferrite, and ferrite may dissolve preferentially in corrosion process. The corrosion products comprising of inner layer and outer layer at both vapor-saturated CO2 and CO2-saturated brine conditions are Cr-rich compound and FeCO3, respectively. The corrosion rate at vapor-saturated CO2 condition is tremendously lower than that at CO2-saturated brine condition. The corrosion rate and scale morphology show that the compact and dense outer layer plays an important role on corrosion resistance, although the inner layer appears firstly. Based on the results of this experiment, the underlying mechanisms of low-alloy steel with martensite/ferrite microstructure are proposed to illustrate carbon dioxide corrosion behavior. © 2015 Elsevier B.V. All rights reserved.

Xu L.,Control Iron and Steel Research Institute, China | Chen Q.,Control Iron and Steel Research Institute, China | Chen Q.,Jiangxi University of Science and Technology | Pan Y.,Tianjin Iron and Steel Group Co Ltd | Lai C.,Jiangxi University of Science and Technology
Jinshu Rechuli/Heat Treatment of Metals | Year: 2015

Both cleavage section and ductility section along the grain of boron micro-alloyed steel were analyzed by Auger electron spectroscopy. The results show that the segregation of boron in the grain boundaries is more than 300 times, some microdomains boron atomic percent reaches 38.65%. Thermodynamic analysis shows that BN precipitation temperature is higher than AlN, which precipitates priority and inhibits the precipitation of AlN. Specimens made of boron micro-alloyed steel slab were observed by SEM. The BN precipitates sized in 2-5 μm were found only in ferrite grain boundaries and within the grain. Most BN precipitates were found combining with MnS and formed BN+MnS composite precipitates which take MnS as the nucleating center and to grow during high temperature quenching experiment. ©, 2015, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved.

Zeng J.-Q.,Control Iron and Steel Research Institute, China | Pan Y.-F.,Tianjin Iron and Steel Group Co Ltd | Wang L.-P.,Shijiazhuang Iron and Steel Co. | Liang M.,Shijiazhuang Iron and Steel Co. | Li S.-Q.,Tianjin Iron and Steel Group Co Ltd
Kang T'ieh/Iron and Steel | Year: 2014

Based on review of development about the processes of clean steel production at home and abroad, the technical principles and their necessities of low-cost and high-efficient clean steel production by combined blowing converter were analyzed, including low-temperature dephosphorization by combined blowing converter, the coordination of top and bottom blowing, the continuous implementation of the new process, the high-efficient oxygen blowing in decarburization period, and the reutilization method of slag been rich in P2O5, and so on. In order to obtain good implementation effect of the new process, the comprehensive and objective technical key points of the new process must be known well, and also the solid foundation of technical and management would be needed. According to related problems occurred in practice, the improved proposals were put forward.

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