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Characteristics of SEN clogging and adhesive behavior of oxide inclusion during continuous casting of Ti-stabilized ultra-pure ferritic stainless steels

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Journal of Iron and Steel Research International 2023年第10期30卷 1939-1951页

作者： Xue-feng Bai yan-hui sun hui-bin Wu Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing100083China

Submerged entry nozzle(SEN)clogging during continuous casting of Ti-stabilized ultra-pure ferritic stainless(Ti-UPFS)steels was systematically investigated via cross-sectional analysis and acid dissolution *** SEN deposit profile was characterized as occurring in three major layers:(1)an eroded refractory layer;(2)an initial adhesive layer comprised an Al_(2)O_(3)-ZrO_(2) composite sub-layer and a dense Al_(2)O_(3)-based deposit sub-layer;and(3)a porous multiphase deposit layer mainly consisting of MgO·Al_(2)O_(3),CaO-Al_(2)O_(3),and *** MgO·Al_(2)O_(3)-rich inclusions did not adhere directly to the eroded refractory but were entrapped during the deposit *** of inclusion characterization in the tundish revealed that the MgO·Al2O3-rich particles present in the tundish served as the primary source of clogging ***,a novel cavity-induced adhesion model by circular approximation was established to explain the effects of complex inclusion characteristics and refractory material type on adhesion force.A high number of small MgO·Al_(2)O_(3) inclusions were expected to accelerate the buildup of clogging *** the modification of MgO·Al_(2)O_(3)-rich inclusions in the size range of 2-4μm by Ca treatment was crucial to minimizing the risk of SEN clogging during the continuous casting of Ti-UPFS steels.

关键词： Ti-stabilized ultra-pure ferritic stainless steel Submerged entry nozzle clogging MgO·Al_(2)O_(3)-rich inclusion Adhesion Continuous casting

Effects of chromium on the microstructure and hot ductility of Nb-microalloyed steel

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International Journal of Minerals,Metallurgy and Materials 2021年第6期28卷 1011-1021页

作者： yang Liu yan-hui sun Hao-tian Wu Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China

It is well-known that the surface quality of the niobium microalloy profiled billet directly affects the comprehensive mechanical properties of the *** effects of chromium on theγ/αphase transformation and high-temperature mechanical properties of Nb-microalloyed steel were studied by Gleeble tensile and high-temperature in-situ observation *** indicated that the starting temperature of the γ→αphase transformation decreases with increasing Cr *** hot ductility of Nb-microalloyed steel is improved by adding 0.12wt% *** atoms inhibit the diffusion of carbon atoms,which reduces the thickness of grain boundary *** number fractions of high-angle grain boundaries increase with increasing chromium *** particular,the proportion is up to 48.7% when the Cr content is 0.12wt%.The high-angle grain boundaries hinder the crack propagation and improve the ductility of Nb-microalloyed steel.

关键词： phase transformation hot ductility chromium high-angle grain boundaries grain boundary ferrite

Analysis of subscription characteristics and user mobility in different types of MMORPGs

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The Journal of China Universities of Posts and Telecommunications 2009年第6期16卷 121-128页

作者： PENG hui sun yan-li WU Hong School of Economics and Management Beijing University of Posts and Telecommunications Beijing 100876 China

Massively multiplayer online role-playing game（MMORPG） is one of the fastest-growing segments of the online game *** subscription refers to game accounts logged in during a certain period of *** user mobility explains the dynamics of subscriber size *** article explores the subscription characteristics and user mobility in different types of *** is found that subscription characteristics in different types of MMORPGs are marked by *** one hand,the curve of competition-based game subscription is linear,and the stability period is short,therefore it is necessary for the game operators to introduce new versions *** the other hand,the gradient rate of subscription in the community-based game is slow at first and then fast,and the stability period is long,hence it will take the game operator a long cycle to launch a new *** difference of subscription curve is caused by the fact that user mobility in competition-based game is higher than in the community-based game,as attractiveness of community-based game can maintain a longer period due to network *** purpose of the study is to help the game operator to understand the development stage and features of the game and to make effective decisions to attract more players.

关键词： virtual reality online game subscription characteristics user mobility subscription curve life cycle MMORPG

Shape of slab solidification end under non-uniform cooling and its influence on the central segregation with mechanical soft reduction

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International Journal of Minerals,Metallurgy and Materials 2021年第11期28卷 1788-1798页

作者： Jie Li yan-hui sun Hang-hang An Pei-yuan Ni Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China School of Metallurgy Northeastern UniversityShenyang 110819China Hesteel Group Technology Research Institute Shijiazhuang 050000China

In order to study the effect of continuous casting process parameters on the shape of slab solidification end under non-uniform cooling,a solidification model of a continuous-cast slab with non-uniform cooling condition was established with ProCAST *** model was verified by the results of nail shooting tests and the infrared temperature measurement *** characteristic parameters were defined to evaluate the uniformity of the shape of slab solidification *** results showed that the nonuniformity at the beginning and end of solidification,the solidification end length,and the solidification unevenness increased with the rise of casting *** each 10°C increase of superheat,the solidification unevenness increased by about ***,the effect of superheat on the solidification end length can be *** secondary cooling strength showed minimal effect on the nonuniformity at the beginning and end of *** the increase in secondary cooling intensity,the solidification end length decreased,but the solidification unevenness *** addition,the central segregation of the slab produced with and without the mechanical soft reduction(MSR)process was *** transverse flow of molten steel with low solid fraction influenced the central segregation morphology under MSR.

关键词： continuous casting heat transfer model nail shooting shape of solidification end central segregation

Effect of direct charging of hot recycled slag on hot metal pretreatment dephosphorization in a dephosphorization furnace

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Journal of Iron and Steel Research International 2020年第2期27卷 148-159页

作者： Xue-feng Bai yan-hui sun Lei Luo Chang-liang Zhao Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China Shougang Jingtang United Iron&Steel Co. Ltd.Tangshan 063200HebeiChina

Industrial experiments were carried out to investigate the effect of the direct charging of hot recycled slag(DCHRS)on hot metal pretreatment dephosphorization in a dephosphorization *** bulk compositions of semi-steel and slag show that a better dephosphorization effect could be achieved by applying the DCHRS process in the dephosphorization *** with the bulk compositions in normal heats,the mean contents of phosphorus in the semi-steel and total Fe in the final slag were decreased by 0.006 and 1.93 wt.%,respectively,with an increase of approximately 6°C in the semisteel *** to mineralogical observations,the dephosphorization slags in normal heats and test heats were similar in petrographic constituents,but the metal loss was markedly decreased in the DCHRS *** calculations show that even though the dephosphorization slag in the DCHRS process had the same dephosphorization capacity as that in the normal refining process,the phosphorus distribution between slag and hot metal in the new process was slightly higher and closer to the reaction ***,proper operating conditions,including slag basicity,total Fe content in the final slag,bath temperature,slag formation and slag volume,were optimized to improve the dephosphorization efficiency under the condition of the DCHRS *** consumption of lime,light-burnt dolomite and oxygen during blowing was significantly decreased by the DCHRS process.

关键词： Dephosphorization Hot slag Slag recycling Dephosphorization furnace Thermodynamics

Hot Ductility of Ti-V Bearing Microalloyed Steel in Continuous Casting

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Journal of Iron and Steel Research International 2014年第4期21卷 451-458页

作者： yan-hui sun Ya-nan ZENG Kai-ke CAI Metallurgical and Ecological Engineering School University of Science and Technology Beijing

Hot ductility of Ti-V bearing steel was studied by theoretical calculation and thermal simulation experi ment. Meanwhile, microsegregation and precipitates were analyzed. The results showed that elements S, Ti and O were enriched at the grain boundaries, while the hot ductility was deteriorated by inclusions of （Fe, Mn, Si, Al）（S, O） in the interdendritic region. At tbe temperature of 1 100℃, large TiN particles had little effect on hot ductility. In the temperature range from 975 to 925 ℃, reduction of area （R. A） declined rapidly from 81. 88% to 63.16% with the size of particles decreasing from 40 to 20 nm and quantity increasing from 1.4 to 11.9 μm 2, respectively. In the temperature range from 875 to 825℃, R. A reduced unobviously from 35.14% to 28.6% with ferric films thickening gradually. The critical stress, 88.79 MPa, was equal to tensile strength at 825℃. Intergranular fracture was easy to occur with higher critical stress below 825℃.

关键词： hot ductility microalloyed steel solute segregation precipitate critical stress

Formation mechanism and control of MgO·Al_2O_3 inclusions in non-oriented silicon steel

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International Journal of Minerals,Metallurgy and Materials 2014年第11期21卷 1068-1076页

作者： yan-hui sun Ya-nan Zeng Rui Xu Kai-ke Cai School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

On the basis of the practical production of non-oriented silicon steel, the formation of Mg O·Al2O3 inclusions was analyzed in the process of ＂basic oxygen furnace（BOF） → RH → compact strip production（CSP）＂. The thermodynamic and kinetic conditions of the formation of Mg O·Al2O3 inclusions were discussed, and the behavior of slag entrapment in molten steel during RH refining was simulated by computational fluid dynamics（CFD） software. The results showed that the Mg O/Al2O3 mass ratio was in the range from 0.005 to 0.017 and that Mg O·Al2O3 inclusions were not observed before the RH refining process. In contrast, the Mg O/Al2O3 mass ratio was in the range from 0.30 to 0.50, and the percentage of Mg O·Al2O3 spinel inclusions reached 58.4% of the total inclusions after the RH refining process. The compositions of the slag were similar to those of the inclusions; furthermore, the critical velocity of slag entrapment was calculated to be 0.45 m·s^-1 at an argon flow rate of 698 L·min^-1, as simulated using CFD software. When the test steel was in equilibrium with the slag, [Mg] was 0.00024wt%–0.00028wt% and [Al]s was 0.31wt%–0.37wt%; these concentrations were theoretically calculated to fall within the Mg O·Al2O3formation zone, thereby leading to the formation of Mg O·Al2O3 inclusions in the steel. Thus, the formation of Mg O·Al2O3 inclusions would be inhibited by reducing the quantity of slag entrapment, controlling the roughing slag during casting, and controlling the composition of the slag and the Mg O content in the ladle refractory.

关键词： silicon steel steelmaking inclusions deoxidation slag entrapment thermodynamics kinetics

Solidification structure simulation and casting process optimization of GCr15 bloom alloy

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China Foundry 2022年第1期19卷 63-74页

作者： Jie Li Hao-tian Wu yang Liu yan-hui sun Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China

Based on the solidification heat transfer model and CAFÉmodel,the solidification structure of GCr15 bloom alloy was *** nail shooting and acid etching experiments,the solidification models were *** secondary dendrite arm spacing(SDAS)model of GCr15 was obtained by simulation calculation and metallographic *** the increase of casting speed,the SDAS,equiaxed crystal ratio(ECR)and average grain size *** the rise of superheat,the SDAS increases in the 20-70 mm of thickness and decreases in the 80-160 mm of *** ECR decreases and the average grain size increases with the increase of *** the increase of specific water flow,both the SDAS and ECR *** minimum average grain size is obtained when the specific water flow is 0.20 L·kg^(-1).The central carbon segregation index is reduced from 1.11 to 1.075.

关键词： numerical simulation continuous casting equiaxed crystal ratio secondary dendrite arm spacing carbon segregation

Mismatch negativity,social cognition,and functional outcomes in patients after traumatic brain injury

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Neural Regeneration Research 2015年第4期10卷 618-623页

作者： hui-yan sun Qiang Li Xi-ping Chen Lu-yang Tao Department of Forensic Medicine Soochow University Department of Forensic Medicine Chifeng University

Mismatch negativity is generated automatically, and is an early monitoring indicator of neuronal integrity impairment and functional abnormality in patients with brain injury, leading to decline of cognitive function. Antipsychotic medication cannot affect mismatch negativity. The present study aimed to explore the relationships of mismatch negativity with neurocognition, daily life and social functional outcomes in patients after brain injury. Twelve patients with traumatic brain injury and 12 healthy controls were recruited in this study. We examined neurocogni-tion with the Wechsler Adult Intelligence Scale-Revised China, and daily and social functional outcomes with the Activity of Daily Living Scale and Social Disability Screening Schedule, re-spectively. Mismatch negativity was analyzed from electroencephalogram recording. The results showed that mismatch negativity amplitudes decreased in patients with traumatic brain injury compared with healthy controls. Mismatch negativity amplitude was negatively correlated with measurements of neurocognition and positively correlated with functional outcomes in patients after traumatic brain injury. Further, the most signiifcant positive correlations were found be-tween mismatch negativity in the fronto-central region and measures of functional outcomes. The most signiifcant positive correlations were also found between mismatch negativity at the FCz electrode and daily living function. Mismatch negativity amplitudes were extremely positive-ly associated with Social Disability Screening Schedule scores at the Fz electrode in brain injury patients. These experimental ifndings suggest that mismatch negativity might efifciently relfect functional outcomes in patients after traumatic brain injury.

关键词： nerve regeneration brain injury cognition disorders diagnostic techniques Wechsler Intelligence Scale event-related potential neuronal plasticity electrophysiology neuropsychology activity of daily living work capacity evaluation electroencephalogram neural regeneration NSFC grant