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Analysis of cracking phenomena in co.tinuous casting of 1Cr13 stainless steel billets with final electromagnetic stirring

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International Journal of Minerals,Metallurgy and Materials 2016年第5期23卷 534-541页

作者： Yu Xu Rong-jun Xu Zheng-jie Fan Cheng-bin Li An-yuan Deng En-gang Wang Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education) Northeastern University Research Institute Baoshan Iron & Steel Co. Ltd.

Solidification cracking that occurs during co.tinuous casting of 1Cr13 stainless steel was investigated with and without final elec- tromagnetic stirring （F-EMS）. The results show that cracks initiates and propagates along the grain boundaries where the elements of carbon and sulfur are enriched. The final stirrer should be appropriately placed at a location that is 7.5 m away from the meniscus, and the appropri- ate thickness of the liquid co.e in the stirring zone is 50 ram. As a stirring current of 250 A is imposed, it can promote co.urnnar-equiaxed transition, decrease the seco.dary dendrite arm spacing, and reduce the segregation of both carbon and sulfur. F-EMS can effectively de- crease the amount of cracks in 1Cr13 stainless steel.

关键词： stainless steel cracking solidification co.tinuous casting electromagnetic stirring

Visco.s properties of new mould flux based on aluminate system with CeO_2 for co.tinuous casting of RE alloyed heat resistant steel

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Journal of Rare Earths 2016年第3期34卷 328-335页

作者：亓捷刘承军李春龙姜茂发 Key Laboratory for Eco.ogical Metallurgy of Multimetallic Ores (Ministry of Education) Northeastern University Baotou iron and steel (Group) co. Ltd.

The co.ventional mould fluxes can not be applied to the co.tinuous casting of RE alloyed heat resistant steel, because severe slag-metal interface reactions occur generally in the mold. To restrain the interface reaction and improve co.ditions for co.tinuous casting, a new mould flux based on aluminate system was devised. The visco.s properties were investigated. Scanning electron microsco.y and X-ray diffraction were applied to detect and characterize the crystalline phases in the co.tinuous co.ling process. The results showed that appropriate addition of CeOco.ld avoid the precipitation of CaO and decrease the visco.ity of the mould flux. Increasing the mass ratio of CaO /AlO, especially to a value exceeding 1, co.ld worsen the stability of the mould flux. With a co.tent of less than 14 wt.%, LiO co.ld reduce the visco.ity and breaking temperature, but its effect co.ld be weakened for the promoted precipitation of LiAlO. To obtain a mould flux with stable visco.s properties, such as visco.ity and breaking temperature, appropriate co.tents of CeOand LiO should be co.trolled to around 10 wt.% and 14 wt.%, while the mass ratio of CaO /AlOshould not be more than 1.

关键词： mould flux aluminate melt visco.ity rare earth steel heat resistant steel

Performance co.parison for oil-water heat transfer of circumferential overlap trisection helical baffle heat exchanger

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Journal of Central South University 2016年第10期23卷 2720-2727页

作者：王伟晗程道来刘涛刘颖昊 co.lege of Urban co.struction and Safety Engineering Shanghai Institute of Technology Energy and Environment Research Institute Baoshan Iron & Steel Co. Ltd

The performance tests were co.ducted on oil–water heat transfer in circumferential overlap trisection helical baffle heat exchangers with incline angles of 12°, 16°, 20°, 24° and 28°, and co.pared with a segmental baffle heat exchanger. The results show that the shell side heat transfer co.fficient h_o and pressure drop Δp_o both increase while the co.prehensive index h_o/Δp_o decreases with the increase of the mass flow rate of all schemes. And the shell side heat transfer co.fficient, pressure drop and the co.prehensive index ho/Δpo decrease with the increase of the baffle incline angle at a certain mass flow rate. The average values of shell side heat transfer co.fficient and the co.prehensive index h_o/Δp_o of the 12° helical baffled scheme are above 50% higher than those of the segmental one co.respondingly, while the pressure drop value is very close and the ratios of the average values are about 1.664 and 1.596, respectively. The shell-side Nusselt number Nu_o and the co.prehensive index Nu_o·Eu_(zo)^(-1) increase with the increase of Reynolds number of the shell side axial in all schemes, and the results also demonstrate that the small incline angled helical scheme has better co.prehensive performance.

关键词： performance experiments helical baffled heat exchangers circumferential overlap of baffles incline angle of baffle heat transfer enhancement

Experiment of Microwave Heating on Self-Fluxing Pellet co.taining co.l

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Journal of iron and steel Research International 2003年第2期10卷 1-4页

作者： CHEN Jin LIU Liu ZENG Jia-qing LIU Jin-ying REN Rui-gang Central iron and steel Research Institute Beijing Vacuum Electronics Research Institute Xuanhua iron and steel Group co

Based on the phase diagrams and the mass action law in co.bination with the co.xistence theory of metallic melts structure, the calculation model of mass action co.centration for Mg-Al, Sr-Al and Ba-Al was built, and their thermodynamic parameters were determined. The agreement between calculated and measured results shows that the model and the determined thermodynamic parameters can reflect the structural characteristics of relevant melts. However, the fact that the thermodynamic parameters from literature don ′t give the value agree with the measured result may be due to unco.formity of these parameters to real chemical reactions in metallic melts.

关键词： activity mass action co.centration mass action law co.xistence theory thermodynamic parameter

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Technological investigation on the Short Stroke Width co.trol Rolling in the Rougher Mills of Hot Strip co.tinuous Rolling Mill Train

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Journal of iron and steel Research International 1995年第1期2卷 22-25页

作者： SUN Ben Rong SHUAI Min YANG Xin Fa FAN Mei Guang LI Yi Ying ZHOU Ren Yi SHEN Jian Guo Central iron and steel Research Institute MMI Baoshan iron and steel co.

Acco.ding to technological requirement of hot charge rolling and hot direct rolling,in this paper,we investigated the technology of the width co.trol rolling in the rougher mills of hot strip co.tinuous rolling mill *** the basis of improving width range of co.tinuous casting of slab,we obtained a good result of greatly increasing the yield of slab→co.l is achieved.

关键词： hot charge rolling hot direct rolling short stroke width co.trol rolling

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Numerical distortion and effects of thermostat in molecular dynamics simulations of single-walled carbon nanotubes

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Chinese Physics B 2008年第11期17卷 4253-4259页

作者：李瑞胡元中王慧张宇军 State Key Laboratory of Tribology Tsinghua University Advanced Technology Institute of Technology Center Baoshan Iron & Steel Co. Ltd.

In this paper, single-walled carbon nanotubes （SWCNTs） are studied through molecular dynamics （MD） simulation. The simulations are performed at temperatures of 1 and 300K separately, with atomic interactions characterized by the seco.d Reactive Empirical Bond Order （REBO） potential, and temperature co.trolled by a certain thermostat, i.e. by separately using the velocity scaling, the Berendsen scheme, the Nose-Hoover scheme, and the generalized Langevin scheme. Results for a （5,5） SWCNT with a length of 24.5 nm show apparent distortions in nanotube co.figuration, which can further enter into periodic vibrations, except in simulations using the generalized Langevin thermostat, which is ascribed to periodic boundary co.ditions used in simulation. The periodic boundary co.ditions may implicitly be applied in the form of an inco.sistent co.straint along the axis of the nanotube. The co.bination of the inco.sistent co.straint with the cumulative errors in calculation causes the distortions of nanotubes. When the generalized Langevin thermostat is applied, inco.sistently distributed errors are dispersed by the random forces, and so the distortions and vibrations disappear. This speculation is co.firmed by simulation in the case without periodic boundary co.ditions, where no apparent distortion and vibration occur. It is also revealed that numerically induced distortions and vibrations occur only in simulation of nanotubes with a small diameter and a large length-to-diameter ratio. When MD simulation is applied to a system with a particular geometry, attention should be paid to avoiding the numerical distortion and the result infidelity.

关键词： molecular dynamics simulation single-walled carbon nanotube (SWCNT) thermostat numerical distortions

A Model for Diagnosing the Formation of Internal Cracks in co.tinuously CastSlabs

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International Journal of Minerals,Metallurgy and Materials 1999年第4期13卷 268-271页

作者： Zhiqiang Han1 theixia Yuan2 Kaike Cai1(l Metallurgy School, University’ of Science and Technology Beijing, Beijing 1 00083, China2 Wuhan iron and steel co., Wuhan 430080, China) Metallurgy School University of Science and Technology Beijing Beijing 100083 China Wuhan iron and steel co. Wuhan 450080 China

The internal cracks in co.tinuously cast slabs are attributed to the excessive tensile strain occurring at the solidifying frontduring the co.tinuous casting process. Based on the understanding, a model for diagnosing the formation of the internal cracks was established, in which the strains at the solidifying front caused by' bulging, straightening or unbending, and roll misalignment were calculated and co.pared with a critical strain value to estimate whether the internal cracks form. Moreover, the established model was appliedto a real slab caster to reveal the distribution of the strains in casting direction and its effect on the internal cracks. It was proved that themodel was reliable and useful for optimizing the operation of co.tinuous casting.

关键词： co.tinuous casting slab, internal crack, diagnosis model

Austenite grain growth of medium-carbon alloy steel with aluminum additions during heating process

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International Journal of Minerals,Metallurgy and Materials 2019年第3期26卷 282-290页

作者： Zi-yi Liu Yan-ping Bao Min Wang Xin Li Fan-zheng Zeng State key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Xiangtan iron & steel co. Ltd.of Hunan Valin

In this study, the effects of heating temperature(850–1100°C) and holding time(30–150 min) on the grain growth behavior of austenite in medium-carbon alloy steel were investigated by co.ducting experiments. The abnormal grain growth and mixed grain structure phenomenon are explained using an equilibrium precipitation phase diagram calculated by Thermo-Calc software package. The Al N particles were observed by field-emission scanning electron microsco.y(FESEM), and the amount of AlN precipitations was detected by electron probe microanalysis(EPMA). Based on the research results, it was found that the average grain size of austenite in the test steel increased co.tinuously with the increase of temperature and holding time. Furthermore, the abnormal growth of austenite occurred in the test steel at 950°C, and the heating temperature affected the austenite grain size more significantly. In addition, the decline in the amount of AlN seco.d-phase particle in the test steel, which weakened the "pinning" effect on austenite grain boundaries, resulted in abnormal growth and the development of mixed austenite grain structures. The prediction model for describing the austenite grain growth of medium-carbon alloy steel during heating was established by regression analysis of the experimental data, and the model was verified to be highly accurate.

关键词： alloy steel austenite grain AlN growth model

Effects of co.ling rate on microstructure and microhardness of directionally solidified Galvalume alloy

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China Foundry 2024年第3期21卷 213-220页

作者： Ji-peng Li De-gao Qiao Jian Li Xiao-yang Luo Peng Peng Xian-tao Yan Xu-dong Zhang Gansu Jiu steel Group Hongxing iron and steel co. Ltd.Jiayuguan 735111GansuChina School of Materials and Energy Lanzhou UniversityLanzhou 730000China

The influences of co.ling rate on the phase co.stitution,microstructural length scale,and microhardness of directionally solidified Galvalume(Zn-55Al-1.6Si)alloy were investigated by directional solidification experiments at different withdrawal speeds(5,10,20,50,100,200,and 400μm·s^(-1)).The results show that the microstructure of directionally solidified Galvalume alloys is co.posed of primary Al dendrites,Si-rich phase and(Zn-Al-Si)ternary eutectics at the withdrawal speed ranging from 5 to 400μm·s^(-1).As the withdrawal speed increases,the segregation of Si element intensifies,resulting in an increase in the area fraction of the Si-rich *** addition,the primary Al dendrites show significant refinement with an increase in the withdrawal *** relationship between the primary dendrite arm spacing(λ_(1))and the thermal parameters of solidification is obtained:λ_(1)=127.3V^(-0.31).Moreover,as the withdrawal speed increases from 5 to 400μm·s^(-1),the microhardness of the alloy increases from 90 HV to 151 *** is a co.bined effect of grain refinement and seco.d-phase strengthening.

关键词： Galvalume alloy directional solidification microstructure length scale microhardness