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Zhang L.,Xian University of Architecture and Technology | Zhang L.,Xinyu Iron and Steel Group Co. | Yang X.,Xian University of Architecture and Technology | Zhang J.,Xinyu Iron and Steel Group Co. | Zhao Z.,University of Science and Technology Beijing
Jinshu Rechuli/Heat Treatment of Metals | Year: 2013

Following the reduction principle, the low cost chemical components system of XG600 was designed, on the basis of the C-Mn steel components, the content of precious Nb was reduced and the V, Cr, Mo were relieved and the content of cheaper Ti was increased. The influence of the chemical composition and process parameters on the microstructure and properties was researched. The results show that by optimized rolling technology and controlling cold strip process technology, the hot-rolling coils grade 600 MPa have fine and uniform ferrite in majority and fine mechanical properties. Source


Tao S.-F.,University of Science and Technology Beijing | Wang F.-M.,University of Science and Technology Beijing | Yu Q.-M.,University of Science and Technology Beijing | Sun L.-F.,Xinyu Iron and Steel Group Co. | Li C.-R.,University of Science and Technology Beijing
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2013

The expansion curves of EQ70 steel for offshore platform were measured by using a DIL805A dilatometer, combined with metallography and Vickers hardness measurement, the curves of continuous cooling transformation(CCT) were determined for the steel. The results show that with the cooling rate below 0.5°C/s, the microstructure is mainly granular bainite, with the cooling rates between 0.5°C/s and 2°C/s, the microstructure consists of granular bainite and lath bainite, and martensite forms as the cooling rate is 2°C/s, when cooling rate is up to 5°C/s, the microstructure is completely martensite. Source


Sun L.-F.,University of Science and Technology Beijing | Sun L.-F.,Xinyu Iron and Steel Group Co. | Wang F.-M.,University of Science and Technology Beijing | Tao S.-F.,University of Science and Technology Beijing | Gou X.,University of Science and Technology Beijing
Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing | Year: 2014

Metallographic microscopy and intercept method were adopted to investigate the austenitic grain growth behavior of locomotive wheel steel at different heating temperatures and holding time. On the basis of analyzing the effects of heating temperature and holding time on the austenite grain size, a simple kinetic model was used to analyze the austenite grain growth process, and the influence of the evolution of second phase particles on the austenite grain growth was also discussed. It is found that the austenite grain size increases with the rise of heating temperature and the prolonging of holding time, but the influence of heating temperature is more obvious. The kinetic time exponent of austenitic grain growth increases with temperature rise and the value is close to the theoretical value of 1/2. Austenite grain growth and the volume fraction and size variation of second phase particles AlN in the steel have a significant correlation. Source


Gu Y.,Beijing Institute of Petrochemical Technology | Ning C.,South China University of Technology | Yu Z.,South China University of Technology | Li H.,South China University of Technology | And 2 more authors.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2014

The corrosion behavior of microarc oxidation (MAO) coatings prepared on AZ31 Mg alloys at 50, 100, 300, 500, 1000 and 3000 Hz was studied in simulated body fluid (SBF). The microstructure, porosity, and chemical phase composition of the samples before and after corrosion were analyzed. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were employed to characterize the corrosion performance. The results show that pulse frequency plays an important role on the corrosion resistance of the MAO coating. The corrosion current density decreases and electrochemical impedance increases with the increase of the pulse frequencies, which result from the dense microstructure at high frequency. The coating produced at 3000 Hz exhibits the largest corrosion resistance with the densest morphology in the present study. Copyright © 2014, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved. Source


Tao S.-F.,University of Science and Technology Beijing | Wang F.-M.,University of Science and Technology Beijing | Yu Q.-M.,University of Science and Technology Beijing | Sun L.-F.,Xinyu Iron and Steel Group Co. | Chai G.-Q.,General Research Institute for Nonferrous Metals, China
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2013

Effects of austenitizing temperature and holding time on prior austenitic grain size and its distribution were studied based on optical microscope observation and Image J analysis software. The results show that the prior austenite grain size increases with the increasing of austenitizing temperature, the coarsening temperature of austenitic grain is 950°C and the phenomenon of mixed grain occurs at 1000°C. Austenite grain size of EQ70 steel increases with the increasing of holding time as austenitized at 850°C, but with the increase of holding time over 2 h, the increasing rate of austenite grain size is reduced. Source

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