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Precipitation behavior of BN type inclusions in 42CrMo steel

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International Journal of Minerals,Metallurgy and Materials 2013年第1期20卷 28-36页

作者： Yu-nan Wang yan-ping bao Min Wang Le-chen Zhang State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of Metallurgical and Ecological Engineering University of Science and Technology Beijing National Engineering Research Center of Flat Rolling Equipment University of Science and Technology Beijing

Automobile crankshaft steel 42CrMo, which requires excellent machinability and mechanical properties, cannot be manufactured by traditional methods. To achieve these qualities, the formation behavior of boron nitride （BN） inclusions in 42CrMo steel was studied in this article. First, the precipitation temperature and the amount of BN type inclusions with differ- ent contents of boron and nitrogen in molten steel were calculated thermodynamically by FactSage software. Then the mor- phology and the size of BN type inclusions as well as the influence of cooling methods on them were investigated by scanning electron microscopy. Furthermore, the effects of cooling rate and the contents of B and N in molten steel on the morphology, size, and distribution of BN type inclusions were studied quantitatively and detalledly by directional solidification experiments. It is found that different BN inclusions in molten steel can form by controlling the cooling rate and the contents of B and N, which is important for obtaining the excellent machinability of 42CrMo steel.

关键词： steel solidification boron nitride inclusions precipitation

Defect electrons accelerate iron cycle of novel Fe-based Fenton:Long-term effective quinoline degradation

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Chinese Chemical Letters 2023年第6期34卷 598-605页

作者： Weikang Hu Ming yang Qingyun yan Jiahui Ji yan bao Jinlong Zhang Mingyang Xing Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research CenterFrontiers Science Center for Materiobiology and Dynamic ChemistryInstitute of Fine ChemicalsSchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China Shanghai Engineering Research Center for Multi-media Environmental Catalysis and Resource Utilization East China University of Science and TechnologyShanghai 200237China

Heterogeneous Fenton has been widely used in the disposal of organic pollutants,however,slow regeneration of≡Fe(II)remains limitation for its practical application of long-term ***,we come up with a novel Fe-based heterogeneous Fenton catalyst named as FeS_(x)O_(y)-X(X is the ratio of ethylene glycol to N,N-dimethylformamide).With the help of the abundant defect electrons in Sulfur vacancies,≡Fe(Ⅱ)regeneration on the surface of FeS_(x)O_(y)-1:1 was accelerated,resulting in a stable proportion of≡Fe(Ⅱ)on the surface,which maintained continuously stable generation of hydroxyl radical(·OH)and singlet oxygen(^(1)O_(2)).Thus,without any organic reagents or cocatalysts,FeS_(x)O_(y)-1:1 based Fenton system achieved effective long-term degradation of 560 mg/L quinoline within only 7 days,which was evidently better than reported Fe S and SV-Fe S_(2)(SV:Sulfur vacancy).The system had excellent adaptability to water quality and the COD removal rate of biochemical wastewater was as high as 79.8%.

关键词： Fenton reaction Quinoline Defect electron Iron cycle Heterogeneous catalyst

Comparison of surface integrity for dry and wet drilling of 49Fe-49Co-2V alloy

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Chinese Journal of Aeronautics 2022年第6期35卷 325-338页

作者： Yuan ZHANG Zhigang DONG yan bao Renke KANG Xin HUANG Dongming GUO Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education School of Mechanical EngineeringDalian University of TechnologyDalian 116024China AVIC Xi’an Flight Automatic Control Research Institute Xi’an 710076China

Working performances of the components made out of 49Fe-49Co-2V alloy are closely related to the surface integrity of the drilled holes,which are influenced remarkably by the cooling *** present study focuses on the surface integrity differences between wet and dry drilled 49Fe-49Co-2V alloy *** drilled hole surface roughness and topographies,metallurgical and mechanical properties,and the exit characterizations were obtained using optical microscopy(OM),scanning electron microscopy(SEM),electron backscatter diffraction microscopy(EBSD),transmission electron microscopy(TEM),energy dispersive spectroscopy(EDS)and Vickers hardness techniques,*** effects of cooling conditions on the surface integrity were concluded and the influence mechanisms were analyzed based on the force and temperature differences in drilling process with different cooling *** is found that the surface roughness and the thickness of refined-grain region of the dry drilled holes are larger than those of wet drilled holes;work hardening induced by wet drilling is more serious than dry drilling;chippings occurred in the exits of the wet drilled holes due to the material brittleness,which could be avoided by dry *** surface integrity differences of wet and dry drilled holes are closely related to the force and temperature differences in drilling process with different cooling conditions.

关键词： 49Fe-49Co-2V alloy Cooling condition Drilling Exit chipping Microstructure Surface integrity Surface quality Work hardening

A study on bearing characteristic and failure mechanism of thin-walled structure of a prefabricated subway station

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Frontiers of Structural and Civil Engineering 2022年第3期16卷 359-377页

作者： Lianjin TAO Cheng SHI Peng DING Sicheng LI Shang WU yan bao Key Laboratory of Urban Security and Disaster Engineering of the Ministry of Education Beijing University of TechnologyBeijing 100124China Department of Hydraulic Engineering Tsinghua UniversityBeijing 100084China China Construction Science&Technology Group Co. LtdBeijing 100195China

In order to study the bearing performance of a new type of prefabricated subway station structure(PSSS),firstly,a three-dimensional finite element model of the PSSS was established to study the nonlinear mechanics and deformation ***,the bearing mechanism of a PSSS was investigated in ***,the development law of damages to a thin-walled prefabricated component and the failure evolution mechanism of a PSSS were *** results showed that this new type of the PSSS had good bearing *** top arch structure was a three-hinged arch bearing system,and the enclosure structure and the substructure were respectively used as the horizontal and vertical support systems of the three-hinged arch structure to ensure the integrity and stability of the overall ***,the tongue-and-groove joints could effectively transmit the internal force between the components and keep the components deformed in *** rigidity degradation of the PSSS caused by the accumulation of damages to the spandrel,hance,arch foot,and enclosure structure was the main reason of its loss of bearing *** existing thin-walled components design had significant advantages in weight reduction,concrete temperature control,components hoisting,transportation and assembly construction,which achieved a good balance between safety,usability and economy.

关键词： prefabricated subway station thin-walled components finite element analysis bearing characteristic failure mechanism

Graphene-Based Photo-Fenton Catalysts for Pollutant Control

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Transactions of Tianjin University 2021年第2期27卷 110-126页

作者： yan bao Qingyun yan Jiahui Ji Bocheng Qiu Jinlong Zhang Mingyang Xing Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research CenterSchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China Jiangsu Key Laboratory of Pesticide Sciences Department of ChemistryCollege of SciencesNanjing Agricultural UniversityNanjing 210095China

Water pollution is a global environmental issue with multi-dimensional infl uences on human *** strategies,such as photo-Fenton reaction,have been employed to remove recalcitrant ***-dimensional(2D)graphene and its threedimensional(3D)confi gurations have attracted considerable attention as emerging carbon-based catalysts in photo-Fenton fi elds owing to their alluring properties in electron transfer,reactant adsorption,and light *** review summarizes the recent developments in 2D and 3D graphene-based catalysts for photo-Fenton *** structures,characteristics,activity,and mechanisms are *** conclusions and outlooks are proposed for the profound understanding of challenges and future directions.

关键词： Photo-Fenton Graphene Pollutant control Aerogel Hydrogel

Coordinated control of carbon and oxygen for ultra-low-carbon interstitial-free steel in a smelting process

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International Journal of Minerals,Metallurgy and Materials 2015年第12期22卷 1252-1259页

作者： Min Wang yan-ping bao Quan yang Li-hua Zhao Lu Lin State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing National Engineering Research Center of Flat Rolling Equipment University of Science and Technology Beijing

Low residual-free-oxygen before fmal de-oxidation was beneficial to improving the cleanness of ultra-low-carbon steel. For ultra-low-carbon steel production, the coordinated control of carbon and oxygen is a precondition for achieving low residual oxygen during the Ruhrstahl Heraeus （RH） decarburization process. In this work, we studied the coordinated control of carbon and oxygen for ultra-low-carbon steel during the basic oxygen furnace （BOF） endpoint and RH process using data statistics, multiple linear regressions, and thermodynamics computations. The results showed that the aluminum yield decreased linearly with increasing residual oxygen in liquid steel. When the mass ratio of free oxygen and carbon （[O]/[C]） in liquid steel before RH decarburization was maintained between 1.5 and 2.0 and the carbon range was from 0.030wt% to 0.040wt%, the residual oxygen after RH natural decarburization was low and easily controlled. To satisfy the requirement for RH decarburization, the carbon and free oxygen at the BOF endpoint should be controlled to be between 297 × 10^6 and 400 × 10^-6 and between 574 × 10^-6 and 775 × 10^-6, respectively, with a temperature of 1695 to 1715℃ and a furnace campaign of 1000 to 5000 heats.

关键词： low carbon steel smelting decarburization cleanness

Optimization of flow control devices in a single-strand slab continuous casting tundish

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International Journal of Minerals,Metallurgy and Materials 2011年第3期18卷 292-296页

作者： Ning Ding yan-ping bao Qi-song Sun Li-feng Wang School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China Shougang Research Institute of Technology Beijing 100041 China

The optimization of flow control devices in a single-slab continuous casting tundish was carried out by physical modeling, and the optimized scheme was presented. With the optimal tundish configuration, the minimum residence time of liquid steel was increased by 1.4 times, the peak concentration time was increased by 97%, and the dead volume fraction was decreased by 72%. A mathematical model for molten steel in the tundish was established by using the fluid dynamics package Fluent. The velocity field, concentration field, and the resi-dence time distribution （RTD） curves of molten steel flow before and after optimization were obtained. Experimental results showed that the reasonable configuration with flow control devices can improve the fluid flow characteristics in the tundish. The results of industrial applica-tion show that the nonmetallic inclusion area ratio in casting slabs is decreased by 32% with the optimal tundish configuration.

关键词： tundish flow control simulation optimization residence time

Simulation of the Northern and Southern Hemisphere Annular Modes by CAMS-CSM

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Journal of Meteorological Research 2019年第5期33卷 934-948页

作者： Sulan NAN Junli yanG yan bao Jian LI Xinyao RONG State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081 National Meteorological Center China Meteorological AdministrationBeijing 100081 Numerical Prediction Center National Meteorological CenterChina Meteorological AdministrationBeijing 100081 Binjiang College Nanjing University of Information Science&TechnologyWuxi 214105

As leading modes of the planetary-scale atmospheric circulation in the extratropics, the Northern Hemisphere(NH)annular mode(NAM) and Southern Hemisphere(SH) annular mode(SAM) are important components of global circulation, and their variabilities substantially impact the climate in mid-high latitudes. A 35-yr(1979-2013) simulation by the climate system model developed at the Chinese Academy of Meteorological Sciences(CAMS-CSM) was carried out based on observed sea surface temperature and sea ice data. The ability of CAMS-CSM in simulating horizontal and vertical structures of the NAM and SAM, relation of the NAM to the East Asian climate, and temporal variability of the SAM is examined and validated against the observational data. The results show that CAMS-CSM captures the zonally symmetric and out-of-phase variations of sea level pressure anomaly between the midlatitudes and polar zones in the extratropics of the NH and SH. The model has also captured the equivalent barotropic structure in tropospheric geopotential height and the meridional shifts of the NH and SH jet systems associated with the NAM and SAM anomalies. Furthermore, the model is able to reflect the variability of northern and southern Ferrel cells corresponding to the NAM and SAM anomalies. The model reproduces the observed relationship of the boreal winter NAM with the East Asian trough and air temperature over East Asia. It also captures the upward trend of the austral summer SAM index during recent decades. However, compared with the observation, the model shows biases in both the intensity and center locations of the NAM's and SAM's horizontal and vertical structures. Specifically, it overestimates their intensities.

关键词： CAMS-CSM model evaluation annular mode Northern Hemisphere Southern Hemisphere

Effect of main inclusions on crack initiation in bearing steel in the very high cycle fatigue regime

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International Journal of Minerals,Metallurgy and Materials 2018年第6期25卷 623-629页

作者： Chao Gu yan-ping bao Peng Gan Min Wang Jin-shan He State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Steel Institute RWTH Aachen University

This work aims to investigate the effect of main inclusions on crack initiation in bearing steel in the very high cycle fatigue（VHCF） regime. The size and type of inclusions in the steel were quantitatively analyzed, and VHCF tests were performed. Some fatigue cracks were found to be initiated in the gaps between inclusions（Al2 O3, Mg O-Al2 O3） and the matrix, while other cracks originated from the interior of inclusions（Ti N, Mn S）. To explain the related mechanism, the tessellated stresses between inclusions and the matrix were calculated and compared with the yield stress of the matrix. Results revealed that the inclusions could be classified into two types under VHCF; of these two, only one type could be regarded as holes. Findings in this research provide a better understanding of how inclusions affect the high cycle fatigue properties of bearing steel.

关键词： very high cycle fatigue bearing steel inclusions tessellated slress crack initiation