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Zhang X.,University of Science and Technology Beijing | Song R.,University of Science and Technology Beijing | Xiong W.,University of Science and Technology Beijing | Xiong W.,Xinyu Iron and Steel Group Co. | And 4 more authors.
7th International Conference on High Strength Low Alloy Steels, HSLA Steels 2015, International Conference on Microalloying 2015, Microalloying 2015 and International Conference on Offshore Engineering Steels 2015, OES 2015 | Year: 2015

The CCT (continuous cooling transformation) curve of the test steel was obtained on Gleeble-1500 thermal mechanical simulator based on the thermal dilation measurement. The test steels were the deformation with 40% under the temperature of 900 °C and then were cooled to room temperature at different cooling rates. The phase transformation law and hardness change rule were emphatically investigated at the cooling rate from 0.05°C/s to 30°C/s by optical microscopy (OM), scanning electron microscope (SEM) and Vickers hardness tester. The regression model of phase transformation was calculated. The results show that the transformation of ferrite and pearlite are inhibited, which cause the dynamic CCT curve shift to the right. The microstructure of the test steel consists of ferrite and pearlite after phase transformation at the cooling rate of 0.05°C/s; the granular bainite appears at the cooling rate of 0.5°C/s due to the interaction of Mo and B; as the cooling rate increases to 2°C/s, the microstructure mainly consists of lath bainite; the martensite is observed at the cooling rate of 2°C/s and there would be total martensite if the cooling rate is higher than 5°C/s and the grain growth rate is faster at the same time. The hardness of test steels increases with the increase of cooling rate, and increases obviously when the cooling rate is lower than 5 °C/s. A theoretical basis is provided to obtain the best bainite/martensite composite microstructure. The martensitic transformation start temperature is 354.6°C and the critical cooling rate is 5°C/s. The test value and the regression model can fit well and reflect the test value trend, showing a high precision of regression.


Qin S.,University of Science and Technology Beijing | Song R.,University of Science and Technology Beijing | Xiong W.,University of Science and Technology Beijing | Xiong W.,Xinyu Iron and Steel Group Co. | And 4 more authors.
7th International Conference on High Strength Low Alloy Steels, HSLA Steels 2015, International Conference on Microalloying 2015, Microalloying 2015 and International Conference on Offshore Engineering Steels 2015, OES 2015 | Year: 2015

The E690 grade offshore platform steel was obtained by top and bottom blowing converter, curved spray continuous casting machine and thermo-mechanical control processing (TMCP). The static continuous cooling transformation curves (CCT curves) of the rolled plate were drawn by adopting thermal expansion method and metallographic analysis. The microstructures at different cooling rates were observed by optical microscope (OM) and scanning electron microscope (SEM). Results showed that the super-cooled austenite in tested steel was relatively stable and there was little high temperature microstructure transformation at the cooling rate of 0.1°C/s. The regression model of phase transformation temperature and cooling rates were obtained. According to the results of orthogonal experiment, the most optimal heat treatment process was firstly heated at 890 °C, wind cooling and then tempered at 630 °C for 60 min.


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.


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.


Zhao H.,Xinyu Iron and Steel Group Co. | Dong F.,Xinyu Iron and Steel Group Co. | Liu X.,Xinyu Iron and Steel Group Co. | Xiong X.,Xinyu Iron and Steel Group Co.
Energy Materials 2014, Conference Proceedings | Year: 2014

This essay introduces the developed high-heat input welding quenched and tempered pressure vessel steel 12MnNiVR for oil storage tank by Xinyu Steel, which passed the review by the Boiler and Pressure Vessel Standards Technical Committee in 2009. The review comments that compared to the domestic and foreign similar steel standard, the key technical index of enterprise standard were in advanced level. After the heat input of 100kJ/cm electro-gas welding, welded points were still with excellent low temperature toughness at -20°C. The steel plate may be constructed for oil storage tank, which has been permitted by thickness range from 10 to 40mm, and design temperature among -20°C-100°C. It studied microstructure genetic effects mechanical properties of the steel. Many production practices indicated that the mechanical properties of products and the steel by stress relief heat treatment of steel were excellent, with pretreatment of hot metal, converter refining, external refining, protective casting, TMCP and heat treatment process measurements. The stability of performance and matured technology of Xinyu Steel support the products could completely service the demand of steel constructed for 10-15 million cubic meters large oil storage tank.


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.


Zhu L.-L.,Chongqing University | He S.-P.,Chongqing University | He S.-P.,Xinyu Iron and Steel Group Co. | Mao J.-H.,CISDI Group Co. | And 3 more authors.
Kang T'ieh/Iron and Steel | Year: 2016

The characteristic differences between traditional mold fluxes for medium or thick slabs continuous casting and ultra-thick slabs continuous casting were analyzed based on the technological characteristics of ultra-thick slabs casting. Then, the systematization of mold fluxes was conducted after the discussion of solidification features of for different grades, and three mold flux groups were proposed: high carbon steels, peritectic steels and micro alloying steels with medium carbon content. Based on the classification, the control ranges of melting temperature, viscosity, break temperature and crystallization ratio of mold fluxes were put forward. Commercial production data reveals that with proposed mold fluxes, smooth and stable casting can be obtained and no sintering is observed. The thickness of liquid slag layer and consumption are suitable. The surface quality of slabs is perfect and the continuous casting process is smooth. © 2016, Chinese Society for Metals. All right reserved.


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.


Chai G.-Q.,University of Science and Technology Beijing | Wang F.-M.,University of Science and Technology Beijing | Fu J.,University of Science and Technology Beijing | Fu J.,Xinyu Iron and Steel Group Co. | Li C.-R.,University of Science and Technology Beijing
Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing | Year: 2010

Local dynamic equilibrium reaction process for the reactions involving complex inclusions, molten steel, slag and refractory materials in steelmaking of high carbon hard wire 82B steel melt was studied and the compositional variation of the inclusions using Mn, Si and Al deoxidation was discussed. The formation condition of plastic inclusions for the Al2O3-SiO2-MgO-CaO-MnO system was calculated and analyzed by the thermodynamic software FactSage. The results reveal that the mass fractions of [Al] and [O] in molten steel are controlled at 25 × 10-6 to 100 ×10-6 and 5 × 10-6 to 20 × 10-6, respectively. In the low-melting point zone, the mass fraction of Si is controlled at 0.1% to 1.5% and that of Mn at 0.2% to 1%.


Guo Y.,University of Science and Technology Beijing | Wang F.,University of Science and Technology Beijing | Huang Q.,University of Science and Technology Beijing | Huang Q.,Xinyu Iron and Steel Group Co. | And 2 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2015

Cracks was found on 510L steel automobile beam during cold bending process, fracture and inclusions morphology, and effect of heat treatment on band microstructure were studied by SEM, EDS and OM to verify the causes of cracking. The results show that iron oxide layer and manganese sulfide in core of the steel plate specimen were the main reasons for the cracks during cold bending, and the ferrite/pearlite band microstructure further promoted the cracks propagation. ©, 2015, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved.

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