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Distribution of TiN inclusions in Ti-stabilized ultra-pure ferrite stainless steel slab

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Journal of Iron and Steel Research International 2019年第9期26卷 962-972页

作者： Hao-jian Duan Ying Zhang Ying Ren Li-feng Zhang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China

In order to clarify and control the silver defect on surface of cold-rolled sheet of the Ti-stabilized ultra-pure ferrite stainless steel, the distribution of TiN inclusions on the cross section of hot-rolled plate was studied using automated scanning electron microscopy/energy-dispersive X-ray spectroscopy inclusion analysis (ASPEX 1020 system). It was found that the number density decreases sharply from the surface to the center of the hot-rolled plate, whereas the average size increases. Then, the distribution of TiN inclusions on the cross section of continuously cast slab was investigated. Similarly, numerous small-sized TiN inclusions were generated at the subsurface of the slab. The average size rapidly increased and the number density dramatically decreased from the subsurface to 1/4 thickness, while from 1/4 thickness to 1/2 thickness, the increase in average size and the decrease in number density were slight. Thermodynamics results showed that TiN inclusion was formed below the liquidus temperature, which indicated that TiN inclusions could not be formed during secondary refining. Considering the microsegregation of solute elements and the equilibrium of TiN formation during solidification, TiN precipitated in the mushy zone when the solid fraction was close to 0.2. The growth of TiN was analyzed based on the diffusion-controlled growth model. With the increase in cooling rate, the time for TiN growth decreased and the size of TiN inclusions was diminished, which revealed the size distribution of TiN inclusions in the cast slab qualitatively.

关键词： TiN inclusion Ti-stabilized ultra-pure ferrite stainless steel Distribution in slab Thermodynamics Diffusion-controlled growth model

AN EXPERIMENTAL STUDY ON VERTICAL HYDRODYNAMIC FORCE ON A CIRCULAR slab NEAR FREE SURFACE BY WATER WAVES

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Journal of Hydrodynamics 2006年第2期18卷 184-191页

作者： LAN Ya-mei LIU Hua XUE Lei-ping CHEN Gang School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030China

An experimental study has been carried out to investigate the vertical force on a slab of sea-crossing bridge piers in the cases of different hydrodynamic conditions. The experimental study is divided into two parts in terms of regular waves and irregular waves. The hydrodynamic loads acting on the slab are measured by a six component balance and pressures on the bottom of the slab are measured by pressure transducers. It turns out that the vertical lbrce patterns can be considered as impact type and bouyant uplili type. For these two different patterns, time series of the vertical hydrodynamic forcc are measured and analyzed. The influences of wave height, wave period, clearance height of slab on the vertical force arc discussed in detail.

关键词： vertical impact forcc bouyant uplift force,waves slab

Material records for Mesozoic destruction of the North China Craton by subduction of the Paleo-Pacific slab

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Science China Earth Sciences 2020年第5期63卷 690-700页

作者： Yazhou FENG Jinhui YANG Jinfeng SUN Jiheng ZHANG State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China

It is well known that the destruction of the North China Carton(NCC)is closely related to subduction of the Paleo-Pacific slab,but materials recording such subduction has not been identified at the peak time of *** paper presents data of whole-rock major and trace elements and Sr-Nd-Hf isotopes and zircon U-Pb ages and Hf-O isotopes for Mesozoic volcanic rocks from the Liaodong-Jinan region in the northeastern NCC,in order to trace the subduction-related materials in their source and *** Mesozoic volcanic rocks in the Liaodong-Jinan region are mainly composed of two series of rocks,including alkaline basaltic trachyandesite,trachyandesite and trachyte,and subalkaline trachyandesite and *** U-Pb dating yields eruption ages of 129–124 Ma for these *** Early Cretaceous volcanic rocks are all enriched in LILEs(such as Rb,Sr,Ba and Th)and LREEs,depleted in HFSEs(such as Nb,Ta and Ti),indicating that they were originated from mantle sources that had been modified by subducted crustal ***,they have relatively heterogeneous and variable isotopic *** alkaline basaltic trachyandesite,trachyandesite and trachyte have enriched whole-rock Sr-Nd-Hf and zircon Hf isotopic compositions and mantle-likeδ18O values,suggesting that they were derived from low-degree partial melting of an isotopically enriched lithospheric mantle *** contrast,the subalkaline trachyandesite and andesite have relatively depleted isotopic compositions with zirconεHf(t)values up to+5.2 and heavy zircon O isotopic compositions with δ18O values of+8.1‰to+9.0‰,indicating that they were originated from a lithospheric mantle source that had been metasomatized by melts/fluids derived from the recycled low-T altered oceanic *** of these geochemical features suggest that the Early Cretaceous volcanic rocks in the Liaodong-Jinan region would result from mixing of mafic magmas with different *** magmas were originated from

关键词： North China Craton Early Cretaceous volcanic rocks Zircon Hf-O isotopes Subduction of the Paleo-Pacific slab

Water modeling of mold powder entrapment in slab continuous casting mold

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Journal of University of Science and Technology Beijing 2007年第5期14卷 399-404页

作者： Qiaotong Lu Rongguang Yang Xinhua Wang Jiongming Zhang Wanjun Wang Metallurgical and Ecological Engineering School University of Science and Technology Beijing Beijing 100083 China

The optimal parameters were determined by the water modeling of slab casting. It was found that there are mainly three types of mold powder entrapment in slab continuous casting, i.e., the entrapment caused by the shearing flow near the narrow face of mold, the entrapment caused by vortexes around the submerged entry nozzle （SEN）, and the entrapment caused by the Ar bubbling. Both the velocity of the surface flow and the level fluctuation of the liquids are enlarged with increasing the casting speed, reducing the submersion depth of SEN, decreasing the downward angles of the nozzle outlets, and increasing the Ar flowrate, all of which increase the tendency of mold powder entrapment. Among the four above-mentioned factors, casting speed has the largest effect.

关键词： continuous casting slab mold mold powder water model

Abnormal mold level fluctuation during slab casting of peritectic steels

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Journal of Iron and Steel Research International 2020年第2期27卷 160-168页

作者： Zhong-kuai Jiang Zhi-jian Su Cheng-qian Xu Jin Chen Ji-cheng He Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern UniversityShenyang 110004LiaoningChina Shanghai Meishan Iron and Steel Co. Ltd.Nanjing 210039JiangsuChina School of Metallurgy Northeastern UniversityShenyang 110004LiaoningChina

Abnormal mold level fluctuation is frequently observed in high-speed casting,especially for peritectic steels,which has been shown to severely deteriorate product *** an online electromagnetic sensor and an ibaAnalyzer are used to analyze the frequency and amplitude of massive mold level fluctuation data from the slab casting process of different steel grades using different casting speeds,slab widths and physical parameters of mold *** results show that in the slab continuous casting process of peritectic steels,the main frequency and equivalent amplitude of abnormal mold level fluctuations first increase and then decrease with increasing the carbon *** the production of various grades of steel,the main frequency of abnormal mold level fluctuation and the equivalent amplitude increase with increasing the casting speed,while the main frequency of abnormal mold level fluctuation changes little with increasing the casting *** main frequency of abnormal mold level fluctuation is positively related to the surface tension of the mold *** on these results,a new mechanism has been *** is shown that the abnormal mold level fluctuation is mainly induced by shell bulging while moving through the rollers,and resonance occurs when the frequency approaches the natural frequency of the molten steel in mold,which results in a large amplitude of the abnormal mold level *** on this mechanism,a new equation for the resonance frequency of molten steel is *** improved method based on this mechanism has proved to be effective in controlling abnormal mold fluctuations.

关键词： slab continuous casting Abnormal mold level fluctuation Resonance frequency Peritectic steel Surface tension

Heat-transfer model on the improvement of continuous casting slab temperature

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Journal of University of Science and Technology Beijing 2004年第1期11卷 18-22页

作者： HongmingWang GuirongLi JunjieWang SchoolofMaterialsScienceandEngineering JiangsuUniversityZhenjiang212013China WuhanIron＆SteelCorpration Wuhan430081China

A heat transfer model on the solidification process has been established onthe basis of the technical conditions of the slab caster in No.3 steel works of Wuhan Iron & SteelCorporation, and the temperature field in the solidifying slab was calculated which was verified bythe measured slab surface temperature. The influences of the main operating factors includingcasting speed, spray cooling patterns, superheat of melt and slab size on the solidification processwere analyzed and the means of enhancing the slab temperature was brought forward. Raising thecasting speed to 1.3 m/min, controlling the flowrate of secondary cooling water and improving thecooling pattern at the lower segments of secondary cooling zone could improve the slab temperatureeffectively. And the increasing the superheat is adverse to the production of high temperature slab.

关键词： heat transfer continuous casting slab solidification mathematical model

slab Storage Calculation Method for Continuous Casting-Hot Rolling

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Journal of Iron and Steel Research International 2004年第1期11卷 33-36页

作者： PENGQi-chun LIUQing TIANNai-yuan WuhanUniversityofScienceandTechnology Wuhan430081China UniversityofScienceandTechnologyBeijing Beijing100083China

Based on load-oriented manufacturing control theory,different combining modes and slab storage calculation method for continuous casting and hot rolling were *** buffer capacity index of continuous casting-rolling was introduced,and the reasonable slab storage under different combining modes was calculated with buffer capacity index of 120.00 hfor CCR,79.20 hfor HCR,19.68 hfor DHCR and 3.84 hfor *** slab is 1.20 h,and the strip is *** gist was provided for steel enterprise to decrease storage.

关键词： continuous casting hot rolling production control slab storage

Behavior of Transversal Crack on slab Corner During V-H Rolling Process

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Journal of Iron and Steel Research International 2006年第6期13卷 31-37页

作者： YU Hai-liang LIU Xiang-hua LI Chang-sheng Y. Kusaba State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China Sumitomo Metal Industries Ltd Fuso-cho 660 AMAGASAKI Japan

The behavior of transversal cracks on the surface of the slab corner during vertical and horizontal （V-H） rolling process with flat vertical roll and groove vertical roll was simulated by explicit dynamic finite element method. The closure and growth of crack and the contact pressure on surfaces of the crack in contacting zone between slab and roll during rolling process were analyzed. The results showed that during vertical rolling process, when the groove vertical roll is used, the maximum contact pressure on surfaces of the crack is 115 MPa, and the closure of crack is stable when the flat vertical roll is used, the maximum contact pressure on surfaces of the crack is 70 MPa, and it fluctuates greatly. During horizontal rolling process, when groove vertical roll is used, the contact pressure becomes zero which may accelerate the growth of crack when flat vertical roll is used, there is still contact pressure. The cal culated results are in good agreement with the results of test.

关键词： slab crack V-H rolling process FEM

Numerical simulation of 3D electromagnetic–thermal phenomena in an induction heated slab

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Journal of Iron and Steel Research International 2020年第4期27卷 420-432页

作者： He-ping Liu Xian-hui Wang Liang-ying Si Jian Gong Central Iron and Steel Research Institute Beijing 100081China Shougang Zhixin Qian’an Electromagnetic Material Co. Ltd.Qian’an 064404HebeiChina

A mathematical model was developed to get an insight into 3D electromagnetic–thermal phenomena in an induction heated steel slab with a large width/thickness ratio by solving a fully coupled Maxwell equations and energy conservation *** spatial heat radiation between the slab surface and the refractory wall in an induction furnace was *** electromagnetic induction and temperature distribution features inside the slab with time evolution were *** effects of electromagnetic induction parameters,thermal conductivity of the material and process parameters on the induction heating process were theoretically *** results show that the spatial distribution of induction heat generation inside the slab is *** high work frequency and the low heat conductivity of slab increase the non-uniformity of slab induction heating *** radiative heat loss and heat transfer between the slab and the metal parts used for holding the slab have an important effect on the slab surface *** is necessary to separately control the current input in the multi-layer coil windings along the height direction of furnace and adopt the multi-step heating strategies with time evolution to improve the homogenization of the slab temperature.

关键词： slab Electromagnetic feld Induction heating Numerical simulation