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Liu S.,Tangshan College | Zhao Z.,Shougang Jingtang United Iron & Steel Co. | Hao Y.,Tangshan College | Zhao X.,Tangshan College | And 2 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2014

For the pitting defect on the strip surface during cold rolled continuous annealing process, integrated with the equipment and technology, the cause of pitting defect was analyzed and the prevention measures were proposed. The results show that the O2, the dew points in the annealing furnace and the pulling force out of control lead furnace roller to slip and nodule, which are the main reason of the strip pitting. In actual production, the O2 in furnace holds within 0.003%-0.005% and the dew point in the furnace holds within -30--45 ℃, and combined with pulling force control, keep the original strip cleanliness and the furnace roller cleaning online can prevent the strip surface from pitting.

Deng X.-X.,University of Science and Technology Beijing | Deng X.-X.,Shougang Institute of Technology | Wang X.-H.,University of Science and Technology Beijing | Li L.-P.,University of Science and Technology Beijing | And 4 more authors.
Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing | Year: 2014

The effect of ladle change process (the 4th heat to the 5th heat) on the surface cleanliness of IF steel continuous casting slabs was investigated by total oxygen measurement and automatic feature analysis equipped on ASPEX. A comparison of surface cleanliness was performed between transition slabs (cast during ladle change process) and normal slabs (cast under normal condition). It is found that inclusions larger than 20 μm are classified into three types: (1) cluster alumina (including bubble + cluster alumina inclusions); (2) cluster TiOx-Al2O3 inclusions; and (3) mold powder inclusions. In terms of surface inclusions in normal slabs, most of the inclusions detected in the scanning area are cluster alumina, and no mold powder inclusions are found. While for transition slabs, the total oxygen content increases from 14×10-6 to 17×10-6, and the number density of Type 2 inclusions goes up since the cast start of the 5th heat, indicating re-oxidation of the steel melt during ladle change process. Furthermore, level fluctuation in the mold is also severe since the cast start of the 5th heat, leading to mold powder entrapments. The affected length of cast slabs during ladle change process is about 11 m under the present casting condition.

CHENGREN-BAO,University of Science and Technology Beijing | YONGLIN-KANG,University of Science and Technology Beijing | YAN-LI,Shougang Jingtang United Iron & Steel Co.
Surface Review and Letters | Year: 2016

In hot-dip galvanizing process, air jet wiping control is so crucial to determine the coating thickness and uniformity of the zinc layer on the steel strip. A numerical simulation of gas-jet wiping in hot-dip galvanizing was conducted to minimize the occurrence of edge over coating (EOC). The causes of EOC were identified by contrasting and analyzing the airflow fields on the strip edge with and without a baffle. The factors influencing the airflow field on the strip edge during the change in the gap between the baffle and the strip edge were also analyzed. The effect of the distance between the air knife and the strip was evaluated. Technological parameters with on-site guidance role were obtained by combining them with the actual production to elucidate the role of the baffle in restraining the occurrence of EOC. The uniform distribution of pressure and coating thickness on the strip is achieved when the distance of the baffle from the strip edge is about 0.3 times of the jetting distance. © 2017 World Scientific Publishing Company

Zhang X.-F.,University of Science and Technology Beijing | Zhang X.-F.,Shougang Jingtang United Iron & Steel Co. | Lu X.-F.,University of Science and Technology Beijing | Zhang Q.-D.,University of Science and Technology Beijing
Gongcheng Lixue/Engineering Mechanics | Year: 2015

The analytical calculation of local arbitrary buckling deformation under a local arbitrary non-uniform load is established by using an energy variational method which considers the elastic restraint of the flat part on the buckling region and its strain energy. On the basis of the principle of stationary potential energy, the critical conditions are obtained by searching the buckling region. The simulation calculation is developed by the ABAQUS finite element method (FEM) and the mode of local arbitrary buckling and critical conditions, which are verified by the analytical method, are obtained. Factors affecting the buckling critical conditions, such as the elastic restrained coefficient, the distance between the center of the buckling region and the free edge, the width of non-uniform load, and average tension are analyzed. Results show that the critical conditions of local arbitrary buckling are the same under the same initial conditions when the buckling region does not exceed the width of the strip. ©, 2015, Tsinghua University. All right reserved.

Zhong J.,University of Science and Technology Beijing | Zhang J.,University of Science and Technology Beijing | Li K.,University of Science and Technology Beijing | Liu Z.,University of Science and Technology Beijing | And 3 more authors.
Ironmaking and Steelmaking | Year: 2016

Alkali metals are one of the important factors promoting the degradation of coke in blast furnace. Previous studies usually focused on the properties of coke affected, respectively, by K and Na separately, while K and Na will simultaneously affect coke performance in the actual production of blast furnace. Through simulating the actual situation where coke is affected by K and Na vapours simultaneously in blast furnace, the evolution of coke structure and thermal properties (CRI, CSR) after alkalisation with different proportions of K and Na vapours are revealed in this study. Results showed that coke structure was broken when the proportion of alkali vapours reached 3%, and coke fine formation rate increased with the increase of K vapour, indicating that K vapour caused a great damage to coke structure; CRI of coke reached the highest and CSR the lowest when K/Na ratio was 3/7. It was observed with SEM/energy dispersive spectrometer that K and Na existed in both mineral matters and carbon matrix; nepheline, generated when coke reacted with alkaline (K, Na) vapours, was determined by XRD. The content of K and Na in nepheline is dependent on the ratio of alkaline (K, Na). © 2016 Institute of Materials, Minerals and Mining

He Y.,CAS Institute of Process Engineering | He Y.,University of Chinese Academy of Sciences | Wei L.,CAS Institute of Process Engineering | Zhang X.,CAS Institute of Process Engineering | And 5 more authors.
Journal Wuhan University of Technology, Materials Science Edition | Year: 2014

A kind of ceramic slurry was prepared and sprayed onto the surface of 9Ni steel at room temperature. The coating layer will not only reduce the depth of the formed Ni-enriched entanglement at high temperature but also have an excellent ability to resist oxidation of the 9Ni steel. Compared to bare specimen, the depths of the entanglement of the coated 9Ni specimen could be successfully reduced by 74.1% and the oxidation loss be decreased by 62.3% by heating at 1 250 °C for 60min. In addition, the coated specimen indicates no trace of oxide pegs. It proves that the coating has outstanding improvement to internal oxidation resistance. Some characterization methods such as metalloscopy, XRD, XPS, SEM and EDX have been used to reveal a possible protective mechanism. The result shows that the coating layer reacts with the iron oxide to form MgFe2O4on the surface of the coated specimen, which could provide a smaller diffusion coefficient rate of Fe ion. The coating with a low cost and easy implementation is promisingly applicable in the slab-reheating process of the 9Ni steel. © 2014, Wuhan University of Technology and Springer-Verlag Berlin Heidelberg.

Wang C.,University of Science and Technology Beijing | Zhang J.L.,University of Science and Technology Beijing | Zhang H.S.,Shougang Jingtang United Iron & Steel Co. | Jiao K.X.,University of Science and Technology Beijing | And 2 more authors.
Ironmaking and Steelmaking | Year: 2016

The viscosity of CaO–SiO2–Al2O3–MgO–CaCl2 slags (C/S = 1.12) were investigated to elucidate the effects of chlorine ranging from 0.02 to 0.53 mass% on the blast furnace slags at high temperatures. Moreover, the Raman spectra of the quenched slags and the X-ray diffraction patterns of the slags cooled in air after viscosity measurement were thoroughly analysed to interpret the transformation of the structures of the slags with increasing the content of chlorine. The viscosity was found to decrease slightly with the increase of chlorine at a given temperature higher than 1673 K, and the critical temperature (TCR) decreased from about 1660 to 1590 K simultaneously which was possibly deriving from the precipitation of Ca2Al2SiO7, Ca3Al2(SiO4)3–xCl4x and SiO2 in higher chlorine content. The degree of polymerisation for silicon–oxygen tetrahedra was found to decrease estimating from the decrease of the average amount of bridging oxygen calculated from the deconvolution results of the Raman spectra of the quenched slags, which provided the explanation for the decrease in viscosity. And that the apparent activation energy of the slags was commonly reduced by chlorine increasing demonstrated the decrease in the degree of polymerisation of molten slags simultaneously. © 2016 Institute of Materials, Minerals and Mining

Wang J.-J.,University of Science and Technology Beijing | Hao J.-J.,University of Science and Technology Beijing | Guo Z.-M.,University of Science and Technology Beijing | Wang Y.-M.,Shougang Jingtang United Iron & Steel Co.
Rare Metals | Year: 2015

Spherical tungsten and titanium powders were prepared by radio frequency inductively coupled plasma torch with irregular shaped tungsten and titanium hydride (TiH2) powders, respectively. The effect of the feed rate on spheroidization efficiency was investigated. The phase composition, oxygen content, morphology, and particle size distribution of the powders before and after spheroidization were characterized by X-ray diffraction (XRD), nitrogen/oxygen analyzer, scanning electron microscopy (SEM), and laser micron sizer (LMS). The results show that both kinds of plasma-processed powders have good dispersity, smooth surface, and single phase. A maximum of 100 % of spheroidization efficiency can be achieved at a lower feed rate. The spherical titanium powder obtained by the plasma treatment consists of particles with mean diameter of 33.34 μm, while the mean diameter of original TiH2 powder is 136.56 μm. The apparent density and flowability of the spherical tungsten powder are 6.3 g·cm−3 and 0.16 s·g−1, respectively. The apparent density and flowability of the spherical titanium powder are 2.8 g·cm−3 and 0.52 s·g−1, respectively. With the increase of the feed rate, the spheroidization efficiency of raw powders drops gradually. © 2014, The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg.

Peng Z.,University of Science and Technology Beijing | Bao Y.-P.,University of Science and Technology Beijing | Mei N.,Shougang Jingtang United Iron & Steel Co. | Yang L.-K.,Hangzhou Iron and Steel Group Co. | Zhang F.,Hangzhou Iron and Steel Group Co.
Gongcheng Kexue Xuebao/Chinese Journal of Engineering | Year: 2015

A two dimensional coupled model of fluid flow and heat transfer of liquid steel and water in a mold was established to investigate the influence of inlet cooling water temperature and velocity on the mold tube temperature field and average mold heat flux. Solved by Fluent, this model simulated the flow and heat transfer of liquid steel and cooling water, solidified shell growth, and heat transfer across air gap and mold fluxes by conduction and radiation. The model's accuracy was verified by comparing the shell thickness and copper tube temperature field with other researches. Model results suggest that the inlet cooling water temperature notably affects the cold face temperature of the copper tube. If the inlet cooling water temperature exceeds 313 K, the highest temperature of the cold face will surpass the boiling point of water. However, an increase of 0.49 m·s-1 in water velocity can diminish the adverse effects of an increase of 4 K in inlet cooling water temperature. ©, 2015, The Editorial Board of CHINESE JOURNAL OF ENGINEERING. All right reserved.

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