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Melt flow,solidification structures,and defects in 316 L steel strips produced by vertical centrifugal casting

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Advances in Manufacturing 2023年第4期11卷 636-646页

作者： Li-Bing Liu Cong-Hui Hu Yun-Hu Zhang Chang-Jiang Song qi-jie zhai Center for Advanced Solidification Technology School of Materials Science and EngineeringShanghai UniversityShanghai200444People’s Republic of China

Vertical centrifugal casting can significantly enhance the filling capability of molten metals,enabling the production of complex thin-walled castings at near-rapid cooling *** this study,the melt flow,solidification structures,and defects in 316 L steel cast strips with a geometry of 80 mm×60 mm×2.5 mm produced by vertical centrifugal casting were numerically and experimentally analyzed under different rotation *** gradually increasing the rotation speed from 150 r/min to 900 r/min,the simulated results showed the shortest filling time and minimum porosity volume in the cast strip at a rotation speed of 600 r/*** a strong turbulent flow was generated by the rotation of the mold cavity during the filling process,experimental results showed that a“non-dendritic”structure was obtained in 316 L cast strip when centrifugal force was involved,whereas the typical dendritic structure was observed in the reference sample without *** areas of the cast strip exhibited one-dimensional cooling,but three-sided cooling appeared near the side of the cast ***,the pores and cracks in the 316 L strips were detected by computed tomography scanning and analyzed with the corresponding numerical *** indicated the existence of an optimal rotational speed for producing cast strips with minimal casting *** study provides a better understanding of the filling and solidification processes of strips produced by vertical centrifugal casting.

关键词： Vertical centrifugal casting Numerical simulation Melt flow Solidification behavior

Review on niobium application in microalloyed steel

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Journal of Iron and Steel Research International 2022年第10期29卷 1513-1525页

作者： Lu-yan Sun Xiang Liu Xi Xu Shu-wei Lei Hui-gai Li qi-jie zhai State Key Laboratory of Advanced Special Steel and Shanghai Key Laboratory of Advanced Ferrometallurgy and School of Materials Science and Engineering Shanghai UniversityShanghai200444China Center for Advanced Solidification Technology(CAST) School of Materials Science and EngineeringShanghai UniversityShanghai200444China Ansteel Group Iron and Steel Research Institute AnsteelAnshan114001LiaoningChina

With the rapid development of high-strength low-alloy(HSLA)steel,Nb as an important microalloying element has received more and more attention in recent *** application and behavior of Nb in HSLA steel,including microstructures optimization,refining grain size,and precipitation behavior of Nb-containing phases,were *** could play an important role in following manners:(1)Nb-containing phases promote ferrite formation,and Nb solute promotes bainite formation.(2)Nb solute atoms and Nb-containing phases can inhibit the growth of austenite grains and austenite recrystallization.(3)Nb(C,N)that precipitates in ferrite/bainite can provide more significant strengthening contribution(more than 300 MPa)than that in austenite(about 100 MPa).Some reasonable suggestions for the production of Nb-bearing HSLA steel with excellent mechanical properties were put forward.

关键词： Niobium Precipitate Microalloying High-strength low-alloy steel

Effects of pulse magneto-oscillation on GCr15 bearing steel continuous casting billet

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Journal of Iron and Steel Research International 2022年第1期29卷 144-150页

作者： Yan-jie Liu Guo-dong Xu Ying-chun Wang Hong-gang Zhong Li-juan Li Biao Wang qi-jie zhai Materials Genome Institute Shanghai UniversityShanghai 200444China Center for Advanced Solidification Technology Shanghai UniversityShanghai 200444China Research Institute China Baowu Steel Group CorporationShanghai 200431China Steel Plant China Baowu Steel Group CorporationShanghai 200431China

Pulse magneto-oscillation(PMO)added during solidification could affect the solidification structure and macrosegregation.A modified thermal simulation equipment was applied to prepare GCr15 bearing steel continuous casting billets with different PMO peak ***,metallographic analysis,component analysis and numerical simulation were adopted to study the influence of PMO peak current and its *** sample with 150 K_(I)A PMO peak current treatment has little difference with the samples without PMO treatment on solidification structure and *** the peak currents are 250 and 350 K_(I)A,the columnar zone increases and macrosegregation *** 450 K_(I)A peak current is selected,the equiaxed grain ratio is enlarged,and the dendritic grains are refined,and the macrosegregation of C,Cr,Si and Mn is decreased *** analyzing,different convections induced by PMO with various peak currents are the key factor to change the solidification structure and macrosegregation.

关键词： Bearing steel Numerical simulation Thermal simulation Pulse magneto-oscillation

Improving ingot homogeneity by modified hot-top pulsed magneto-oscillation

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Journal of Iron and Steel Research International 2022年第12期29卷 1939-1950页

作者： Fan Zhang Hong-gang Zhong Yu-qian Yang Ming-xu Pan Ren-xing Li qi-jie zhai Center for Advanced Solidification Technology Shanghai UniversityShanghai 200444China Daye Special Steel Co. Ltd.Huangshi 214429HubeiChina

Heavy ingots,especially the ingot of more than 10 t,often contain detrimental heterogeneous defects,such as macrosegregation,shrinkage pipes,and ***-top pulsed magneto-oscillation(HPMO)can refine the solidified structure of ingot and improve their ***,it may exacerbate the positive segregation at the upper part of the ingot ***,a round table HPMO riser with a feeding part was designed,and the microstructure and macrosegregation of Al–Si alloy ingots solidified with and without HPMO were *** simulation and experimental results indicated that round table HPMO riser could enable fine and uniform solidified structures in the whole ingot body;in the meantime,feeding part allowed the melt with enriched solute to gather in the upper part of the riser until the last solidification stage of *** provides an effective approach for obtaining highly homogenized ingots.

关键词： Homogeneity Hot-top pulsed magneto-oscillation Heavy ingot Macrosegregation Simulation

An accelerated aging assisted by electric current in a Fe-Mn-Al-C low-density steel

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China Foundry 2022年第5期19卷 395-402页

作者： Zhi-gang Wang Chu-lun Shen Jian-lei Zhang Chang-jiang Song qi-jie zhai Center for Advanced Solidification Technology(CAST) School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

An aging method assisted by electric current was applied to a Fe-18Mn-9Al-1C(wt.%)low-density *** improves the microstructure and therefore significantly increases both the yield strength and ductility of the *** current-assisted aging method can increase the yield strength by 178 MPa and elongation by 1.16 times in only 0.5 min at 450℃.However,the yield strength is increased only 90 MPa by the traditional aging method(heat conduction)at 450℃ for 180 min,and the elongation is even decreased from 42.0%to 31.6%.The obvious improvement in yield strength by the current-assisted aging for a short time is resulted from the fact that the current-assisted aging promotes a rapid precipitation of nano-scaleκ-carbides inγ-austenite by reducing the thermodynamic barrier and accelerating the atomic *** work demonstrates that this current-assisted aging method is significantly time saving and cost-effective for low-density steels,with potential for various industrial applications.

关键词： low-density steel current-assisted aging κ-carbide

Distributions of Electromagnetic Fields and Forced Flow and Their Relevance to the Grain Refinement in Al–Si Alloy Under the Application of Pulsed Magneto-Oscillation

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Acta Metallurgica Sinica(English Letters) 2022年第2期35卷 254-274页

作者： Yan-Yi Xu Jing Zhao Chun-Yang Ye Yan-Ping Shen Xin-Cheng Miao Yun-Hu Zhang qi-jie zhai Center for Advanced Solidification Technology Shanghai UniversityShanghai 200072China Key Lab of Intelligent Equipment Digital Design and Process Simulation Tangshan UniversityTangshan 063000Hebei ProvinceChina School of Materials Science and Engineering University of Science and Technology LiaoningAnshan 114051China

Distributions of electromagnetic fields and induced forced flow inside a metal melt are crucial to understand the grain refinement of the metal driven by pulsed magneto-oscillation(PMO).In the present study,PMO-induced electromagnetic fields and forced flow in Ga-20 wt%In-12 wt%Sn liquid metal have been systematically investigated by performing numerical simulations and corresponding experimental *** numerical simulations have been confirmed by magnetic and melt flow *** to the simulated distribution of electromagnetic fields under the application of PMO,the strongest magnetic field,electric eddy current and Lorentz force with inward radial direction inside the melt are concentrated adjacent the sidewall of cylindrical melt at the cross section of middle height of *** a result,a global forced flow throughout the whole cylindrical column filled with Ga-20 wt%In-12 wt%Snmelt is initiated with a flow structure of two pair of symmetric *** PMO-induced electromagnetic fields and forced flow in Al-7 wt%Si melt have been numerically *** contribution of electromagnetic fields and forced flow to the grain refinement of Al-7 wt%Sialloy under the application of PMO is *** indicates that the forced flow may play a key role in the grain size reduction.

关键词： Pulsed magneto-oscillation(PMO) Electromagnetic field Forced flow Solidification Grain refinement

Corrosion mechanism research and microstructure analysis of Baosteel No.3 blast furnace hearth

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Journal of Iron and Steel Research International 2017年第10期24卷 1016-1022页

作者： Xun-fu Wang qi-jie zhai School of Materials Science and Engineering Shanghai University Ironmaking Plant of Baoshan Iron & Steel Co. Ltd.

Baosteel No.3 blast furnace hearth was divided into tuyere area,taphole area,taphole upper side wall and taphole lower side wall according to different working *** chemical composition analysis,scanning electron microscopy,X-ray diffraction,energy dispersive spectrometry and other means,chemical composition and microstructure of different parts of hearth carbon brick were analyzed and markedly different corrosion mechanisms of these areas were *** element in form of ZnO mainly deposited on the hot side of carbon *** was no obvious evidence that Zn permeates into carbon bricks and erodes *** for taphole area,K,Na,and Fe contents from hot side to cold side gradually rise and fall,resulting in the decrease of apparent porosity,the increase of density and the higher thermal conductivity compared with those of new carbon *** higher content of Fe in carbon brick leads to more serious erosion because Fe has greatly changed the physical properties of carbon *** the taphole area,the contents of Si and Al present obvious concentration gradient because of the mechanical souring of molten iron and *** SiO;and Al;O;particles that have different expansion factors with carbon brick damaged the carbon substrate because of temperature *** graphitized carbon found on H4 where is the most serious corrosion site means that the carbon brick ever directly contacts with molten iron.

关键词： Blast furnace side wall Chemical component Mierostructure Corrosion

Effects of Thermal Gradients and Rotational Flows on Grain Growth in 22 t Steel Ingots

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Journal of Iron and Steel Research International 2016年第9期23卷 973-980页

作者： Zheng CHEN qi-jie zhai jie-yu ZHANG Hong-gang ZHONG State Key Laboratory of Advanced Special Steel School of Materials Science and EngineeringShanghai University Mechanical Department Tongling University

Heavy ingots are widely used in many industrial fields. The coarse grains formed during the process of in- got solidification influence the properties and fracture behaviors of the final products. The coarse grain growth was simulated under different thermal gradients. A 30Cr2Ni4MoV steel ingot was melted in a cubic crucible with dimen-sions of 15 cm×10 cm×23 cm, and the cooling conditions on each side of the crucible were controlled by different thermal curves. The influences of thermal gradients and rotational flows on grain growth in heavy steel ingots were then investigated both numerically and experimentally. The results showed that when the amplitude of the rotation angle was 60°, the metal was solidified under a reciprocating horizontal rotational condition when the angular velocity was 10 （°）/s or 20 （°）/s. As the thermal gradient increased, the lengths of the primary columnar grains in- creased, and the diameters of equiaxed grains decreased. When the direction of flow rotation was perpendicular to the direction of grain growth, the columnar grain zone was nearly eliminated, and the average diameter of equiaxed grains was 0.5 mm.

关键词： heavy ingot thermal simulation method thermal gradient rotational flow grain refinement

Quantum correlations in a chain-type quantum network

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Communications in Theoretical Physics 2024年第6期76卷 77-91页

作者： Xiaofei qi Aihong zhai Lihua Yang School of Mathematical Science Shanxi UniversityTaiyuan 030006China Key Laboratory of Complex Systems and Data Science of Ministry of Education Shanxi UniversityTaiyuan 030006China School of Mathematics and Information Technology Yuncheng UniversityYuncheng 044000China

A quantum network concerns several independent entangled resources and can create strong quantum correlations by performing joint measurements on some *** this paper,we discuss an n-partite chain network with each of two neighboring observers sharing an arbitrary Bell state and all intermediate observers performing some positive-operator-valued measurements with parameterλ.The expressions of all post-measurement states between any two observers are obtained,and their quantifications of Bell nonlocality,Einstein-Podolsky-Rosen steering and entanglement with different ranges ofλare respectively detected and analyzed.

关键词： quantum correlation nonlocality entanglement chain-type quantum network