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Cellular automata modelling of grain coarsening during reheating——Ⅱ. Abnormal grain growth

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journal of University of Science and Technology Beijing 2005年第1期12卷 26-32页

作者： WanhuaYu e.j.palmiere S.P.Banks jingtaoHan DepartmentofMaterialsengineering UniversityofScienceandTechnologyBeijingBeijing100083China DepartmentofengineeringMaterials UniversityofSheffieldS13JDSheffieldUK DepartmentofAutomaticControlandSystemsengineering UniversityofSheffieldS13JDSheffieldUK

The 2-dimensional cellular automata (CA) simulation technique has been utilized to investigate the abnormal grain coarsening. The growth of abnormal grains is modelled under this assumption that different grains have different boundary energies and boundary mobilities. As temperature increases, some grains may first get rid of the particle pinning effect. Thus a high probability is obtained for atoms to jump over the boundary, so that they can consume other primary retained grains quickly. From the simulation, the characteristics of the abnormal grain coarsening under different conditions are demonstrated successfully. An experiment has also been carried out to reflect the abnormal grain coarsening on the microalloy steel. Simulation results are quite close to the experimental evidence.

关键词： computer simulation grain growth microstructure reheating

Multi-Pass Simulation of Heavy Plate Rolling Including Intermediate Forced Cooling

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journal of Iron and Steel Research International 2011年第S1期18卷 506-510页

作者： e.j.palmiere A.A.Howe H.C.Carey Institute for Microstructural and Mechanical Process engineering:The University of Sheffield (IMMPeTUS) Sir Robert Hadfield BuildingMappin StreetSheffieldS1 3JDUK Tata Steel Research Development &Technology Swinden Technology CentreMoorgateRotherham S60 3ARUK

Thermomechanical Controlled Processing (TMCP) including accelerated cooling after the final hot rolling pass is a well-established technology,widely applied in HSLA steel plate ***,there are still certain limitations,especially for thicker *** rolling schedule includes a long holding period (HP) after the roughing stage to allow the temperature to fall sufficiently for optimised TMCP during *** Forced Cooling (IFC) applied during the HP can increase productivity by decreasing the required hold time,can restrict austenite grain growth,and can also improve the subsequent strain penetration in thick plate with further metallurgical ***-pass plane strain compression (PSC) tests have been performed on the thermomechanical compression (TMC) machine at Sheffield University including different severities of *** it is impossible to simulate all aspects of the temperature and strain gradients present in thick plates in laboratory specimens,and most of the tests were conducted at temperatures and strains calculated by Finite element modelling as relevant to specific positions through the plate ***,some aspects of the gradients were addressed with tests using cold *** results have indeed shown that IFC can shorten the HP and reduce austenite grain growth and its variation across thick plate.

关键词： Steel plate rolling intermediate forced cooling plane strain compression recrystallisation grain growth finite element modelling temperature and strain distribution

CeLLULAR AUTOMATA MODeLLING OF GRAIN COARSeNING DURING ReHeATING AND VALIDATION WITH THe eXPeRIMeNTAL ReSULTS

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Acta Metallurgica Sinica(english Letters) 2005年第2期18卷 113-120页

作者： W.H.Yu e.j.palmiere S.P.Banks j.T.Han SchoolofMaterialsScienceandengineering UniversityofScienceandTechnologyBeijingBeijing100083China DepartmentofengineeringMaterials UniversityofSheffieldSheffieldS13JDUK DepartmentofAutomaticControlandSystemsengineering UniversityofSheffieldSheffieldS13J-DUK

A novel 2D cellular automata (CA) model has been developed for description of normal grain coarsening and abnormal grain coarsening process. The program reflects the grain coarsening quite well even through the average grain size becomes very large. Follow results have been obtained: (a) The model reflect the normal grain growth kinetics gradually increase with probability and grain growth speed can be controlled. Based on this result, temperature can be coupled in the model. (b) Abnormal grain growth is modelled successfully. (c) Methodology has been put forward to find the relationship between the experiment results and modelling results. The experimental work on the grain coarsening has been carried out. Graphical output matched the realistic microstructure in every detail. Because many physical parameters can be taken into account in the CA programme, this CA model could not only qualitatively demonstrate the grain growth process, but also quantitatively predict and analyse the grain coarsening process.

关键词： computer simulation grain growth microstructure reheating

The Use of a Fe-30%Ni and Fe-30%Ni-Nb Alloy as a Model Systems for Studying the Microstructural evolution during the Hot Deformation of Austenite

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The Use of a Fe-30%Ni and Fe-30%Ni-Nb Alloy as a Model Syste...

技术创新与循环经济——第二届宝钢学术年会

作者： W.M.RAINFORTH P.CIZeK F.BAI R.POTHS e.j.palmiere IMMPeTUS:Institute for Microstructural and Mechanical Process engineering:The University of Sheffield Sheffield S1 3JDUnited Kingdom

＜正＞The development of physically-based models of microstructural evolution during thermomechanical processing of metallic materials requires knowledge of the internal state variable data,such as microstructure, texture and dislocation substructure characteristics,over a range of processing *** is a particular problem for steels,where transformation of the austenite to a variety of transformation products eradicates the hot deformed *** paper reports on a model Fe-30%Ni based alloy,which retains a stable austenitic structure at room temperature,and has therefore been used to model the development of austenite microstructure during hot deformation of conventional low carbon-manganese *** also provides an excellent model alloy system for microalloy *** of the microstructure and crystallographic texture was characterised in detail using optical microscopy,XRD,SeM,eBSD,and *** dislocation substructure has been quantified as a function of crystallographic texture component for a variety of deformation conditions for the Fe-30%Ni base *** extension to this study,as the use of a microalloyed Fe-30%Ni-Nb alloy in which the strain induced precipitation mechanism was studied *** work has shown that precipitation can occur at a much finer scale and higher number density than hitherto considered,but that pipe diffusion leads to rapid *** implications of this for model development are discussed.

关键词： microalloyed steels strain induced precipitation microbands texture

来源： cnki会议评论

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加工条件对管线钢组织影响的实验研究

中国冶金 2007年第5期17卷 37-40页

作者：杨雄飞 e.j.palmiere 付俊岩中信金属公司微合金化技术中心北京100004 谢菲尔德大学IMMPeTUS研究所

管线钢的最终组织和性能与控轧工艺以及加速冷却直接相关。采用一种新型的模拟轧制过程设备来研究X70级别管线钢在热变形冷却后的组织;设计了一系列的平面应变压缩实验来模拟板带轧制过程参数特别是精轧温度和冷却速率对最终组织的影响... 详细信息

管线钢的最终组织和性能与控轧工艺以及加速冷却直接相关。采用一种新型的模拟轧制过程设备来研究X70级别管线钢在热变形冷却后的组织;设计了一系列的平面应变压缩实验来模拟板带轧制过程参数特别是精轧温度和冷却速率对最终组织的影响。采用恒定的变形速度70 s-1以及恒定的道次间隙时间,在850、900、950℃温度下的单道次和多道次压缩变形,随后研究2种不同冷却速率(3℃/s,6℃/s)获得的最终微观组织。观察发现,对于950、900、850℃的变温变形,出现了严重的混晶现象,而850℃下进行的3次压缩试样在6℃/s冷却到660℃后铁素体晶粒尺寸达到4.3μm。

关键词：平面应变压管线钢应力-应变曲线晶粒

Are hydrides under high-pressure-high-temperature superconductors?

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National Science Review 2024年第7期11卷 9-12页

作者： j.e.Hirsch Department of Physics University of California

Contrary to the current consensus, I argue that the existing evidence for high-temperature superconductivity in hydrides under high pressure is not compelling. I suggest that the focus of the field should urgently shift to establish unequivocally experimentally whether or not superconductivity in pressurized hydrides exists, instead of continuing to search for new materials that might show elusive signals of unproven superconductivity at ever higher temperatures. The implications of a negative finding for the theoretical understanding of superconductivity are discussed.

关键词： Hydrides

Malargüe Site Remediation:A Successful Solution for Uranium Mill Tailings

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原子能科学技术 2024年第10期58卷 2088-2094页

作者： BARARI e DíAZ j G GIOMIA KeMPF R A National Atomic energy Commission Av.Del Libertador 8250Ciudad Autónoma de Buenos AiresC1429BNPArgentina

Comisión Nacional de energía Atómica (CNeA) has the responsibility for restoring uranium mining facilities once the operations have ***,within its environmental Program and in compliance with its legal responsibilities,decides to implement a restoration project for all sites related to the mining and processing of uranium *** Malargüe Site is located within the Province of Mendoza in the city of Malargü*** is the first site to successfully complete its *** activities consist of relocation of tailings to an engineering *** tailings management(encapsulation) and rehabilitation of the area was finished in june *** remediation alternative for the ore tailings was selected after conducting comparative studies and submitted the project to the society for *** objective of the encapsulation of the mineral tails is to isolate them from the environment,also proceeding with the decontamination and rehabilitation of the area (landscaping,post-closure monitoring and 20 years monitoring period).encapsulation consisted of the construction of a containment cell for the mine tailings,to isolate them and prevent pollutants from entering the environment through the transfer *** clean the impacted areas,the soil was removed,it was incorporated into the encapsulation,and the filling was carried out with natural soils from the *** prevents radon transfer to the environment,as ^(222)Ra is an alpha emitter with a half-life of four days,which produces its own radioactive *** progeny are solids,and when a ^(222)Ra nucleus emits an alpha particle into the air,the resulting ^(218)Po nucleus,momentarily electrically charged,adheres to any dust *** prevents the discharge into the air containing radon and also containing dust particles charged with intensely radioactive radon *** tasks mentioned make it possible to decrease radon emanation,reduce radiological risks to the public and pre

关键词： remediation radionuclide transfer tailings encapsulation solution sustainable

Annual variation of adult survival of a south-temperate House Wren population in Argentina

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Avian Research 2024年第2期15卷 229-237页

作者： Gustavo j.Fernandez Mariana e.Carro Paulo e.Llambías Grupo de Investigacion en ecofisiología de Fauna Silvestre INIBIOMA-CONICETAsentamiento Universitario San Martín de los Andes(AUSMA)Universidad Nacional Del ComahuePasaje de la Paz 235(8370)San Martín de los AndesNeuquenArgentina Grupo de Investigacion de Biología de Aves IADIZA CCT-MendozaUniversidad Nacional de CuyoAvenida RuizLeal s/n Parque General San Martin5500MendozaArgentina

Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population *** numerous studies on this subject in north-temperate environments,there is a lack of equivalent studies at similar latitudes in the ***,we used a 14-year dataset of capture,banding,and resighting to estimate the annual variation in the apparent adult survival probability of a south-temperate population of House Wrens(Troglodytes aedon bonariae).We evaluated temporal variation in sur-vival and the effect of environmental(climatic)and demographic variables(adult abundance,total number of fledglings produced during each breeding season)on survival *** found that the probability of adult survival decreased as the abundance of breeding adults *** density-dependent effect could be related to the resident lifestyle of southern House Wrens,which could determine an intense competition for territories and resources that ultimately would affect their survival.

关键词： Annual variation CjS Density-dependence Survival Troglodytes aedon bonariae

Insm1:orchestrating cellular mimicry in the thymus medulla

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Cellular & Molecular Immunology 2024年第4期21卷 414-416页

作者： K.D.james j.e.Cowan UCL Institute of Immunity and Transplantation The Pears BuildingRowland Hill StreetLondonNW32PPUK

The thymus is the primary production site for a functional and self-tolerant T-cell *** establishment of immune tolerance is mediated by the generation and presentation of tissue-restricted self-antigens(TRAs)by medullary thymic epithelial cells(mTeCs),which screen T-cell receptors for self-reactivity to eliminate autoreactive T *** studies have extended our understanding of mTeC heterogeneity by examining the mechanisms by which mTeCs mimic the peripheral self[1].

关键词： medullary eliminate restricted