NUCLEATION BEHAVIOR OF Al8Fe4Nd PHASE IN RAPIDLY SOLIDIFIED AI-Fe-V-Si-Nd ALLOY

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INFLUENCE OF NaC1 DEPOSITION ON ATMOSPHERIC CORROSION OF A3 STEEL IN THE PRESENCE OF SO2

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MODELING OF MICROSTRUCTURAL EVOLUTION IN MICROALLOYED STEEL DURING HOT FORGING PROCESS

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第八届铸铁科学与工艺国际会议论文题录

主旨球墨铸铁处理工艺现状C.R.Loper,Jr影响珠光体-贝氏体铸铁舰船发动机缸套凝固结构与机械性能的因素T.Yashida,K.Yamamoto,S.Higashi,K.Ogi中国贝氏体等温淬火球墨铸铁的发展与应用Y.C.Zeng,K.R.Li,Z.C.Zhang铸铁凝固建模工艺现状D.M.Stefanescu第一部分:铸铁的凝固与固态转换的基础研究探究铸铁凝固的一致解释G.L.Rivera,R.E.Boeri,J.A.Sikora硅与锰在多元碳硅铁母合金中的分配系数H.Rivera-Garza,M.Castro-Román,M.Herrera-Trejo,J.López-Cuevas铸铁的激冷和激冷技术趋势E.Fras,M.Górny,W.Kapturkiewicz,H.Lo…     

Some features of welding arc radiation

0IntroductionRadiationisanimportantphenomenonofarcweldingprocess.Essentially,itreflectsthephysicalprocessesoccUrringinthearcregion.Ithasbeennotedthattheinformationconcerningthearcprocess,suchastemperature.componentsandtheirdistributions.canberealizedthroughtheobservationofradiationbyarcself-emissionl'.ZI.Therefore,moreknowledgeaboutthefeatUresoftheradiationisneededtoenhancetheunderstandingofti)eldingarc.Inthisarticle.somephenomenaofweldingarcradiation,suchaspossiblewavelengthrangeoftheradiat…     

NUMERICAL SIMULATION OF TEMPERATURE FIELD FOR COAT OF COAT-CAST TECHNOLOGY

1.IntroductionAsmoreattentionispaidtosurfacereinforcing,differentkindsofsurfacereinforcingtechnologyhavebeendevelopedinthiscentury.Coat-casttechnologyisoneofthem.Coat-castisonekindofcastingtechnology,amethodofbrushingorpastingthebinder,fluxandalloypowderontheinnersurfaceofthecastingmodelsoastoobtainasolid,reliablecoatwithspecialpropertiesonthecastingsurfaceduringcasting.Asearlyas1913,A.D.Momsproposedthethoughts.FOrmerSovietscholarsstartedtostudythecoat-casttechnologyin1970s.Inaddition,Japa…     

1988年冶金学会年会论文题录选译

(该年会系第117次年会,于1988年2月25一28日 在美国亚利桑那州菲尼克斯市召开) 1.拜耳法氧化铝生产100年,Fat饭Habashl,加拿 大 2.英国氧化铝生产的历史,Dan Macfie,英国 3.铝土矿一其在过去100年中的技术与经济历史, J.Regnier,美国4.美国拜耳法实践的评价,Keith Iludson,美国5.高岭土在苛性喊液中的溶解动力学,G.I.D, R。耽h,A.J.Whjte,澳大利亚6.拜耳法工艺的现状,Lest口A.D.C址n,美国7.用部份湿氧化法除去高分子量有机化合物,B. J.Foster,M.L.Roberson,美国吕.一水软铝石型铝土矿的管道化溶出,F.众,ban, K.Solynlar,J.Stein…     

ARTIFICIAL NEURAL NETWORKS-MODELING, PROGRAMMING AND APPLICATION IN MATERIAL HOT WORKING

1.IntroductionNeuralnetworksarecomposedofsimpleelementsoperatinginparallel.Theseelementsareinspiredbybiologicalnervoussystems.Asinnature,thenetworkfunctionisdeterminedlargelybytheconnectionsbetweenelements.Wecantrainaneuralnetworktoperformapedicularfunctionbyadjustingthevaluesoftheconnections(weights)betweenelements.Commonlyneuralnetworksareadjusted,ortrained,sothataparticularinputleadstoaspecifictargetoutput.Suchasituationisshownbelow.There,thenetworkisadjusted,basedonacomparisonoftheoutput…     

金属材料冲裁过程的有限元模拟

介绍了利用弹性有限元对金属冲裁加工模拟的基本原理,包括弹塑性大变形木匠,裂破坏模拟以及网格重划分等技术,利用商业化有限元程度DEFORM－2D^TM对不锈钢（AISI304）板料的冲裁工艺进行了模拟,模具采用刚体模型,工件采用弹塑性模型,材料断裂破坏采用Cockroft-Latham破坏准则,分析了冲裁过程中裂纹生成、扩展以及材料断裂分离的过程,冲载力的变化等,模拟结果中的材料断裂和冲裁力的变化与已发表文献中的实验结果一致。     

Finite element modeling of power spinning of thin-walled shell with hoop inner rib

A 3D elasto-plastic finite element（FE） model of power spinning of thin-walled aluminum alloy shell with hoop inner rib was established under software ABAQUS. Key technologies were dealt with reasonably. The reliability of the FE model was verified theoretically and experimentally. The forming process was simulated and studied. The distribution of the thickness and stress, and the variations of spinning force were obtained. The workpiece springback was analyzed with ABAQUS/Standard. The results show that the FE model considering elastic deformation can not only be used to analyze the workpiece springback in the complex spinning process, but also serve as a significant guide to study the local deformation mechanism and choose the reasonable parameters.     

筒形件冲压缩口成形工艺的数值模拟研究

应用有限元分析软件中的显式动力学求解器模拟筒形零件缩口成形工艺过程中应力、应变和位移流向的分布云图,分析了工件成形时的塑性变形特点及其对成形质量的影响关系.研究表明:筒形件冲压缩口成形工艺主要失效形式是缩径区的裂纹、定径区的起皱和传力区部分的失稳等;工件失效的主要原因是塑性变形区材料流动速度不均匀导致的应力集中;冲压缩口力随着摩擦系数和模具锥角的增大而增大,但是会随着模具型腔内圆角半径的增大而减小.     

曲面形件拉延变形过程数值模拟

运用有限元模拟软件MSC.Marc对不锈钢带凸缘半球面形件和抛物面形件进行了数值模拟研究.首先采用拉延成形方式对半球面形件和曲面形件进行数值模拟,模拟了它们在不同工艺参数下的成形过程.从模拟结果中分析应力、应变和材料厚度的分布与变化,分析了凹模圆角半径、凸模形状对拉延成形过程的影响,得出在拉延成形方式下,凹模圆角半径R=10 mm时成形性与成形质量最佳;为了比较不同成形工艺对曲面形件成形的影响,对半球面形件进行了胀形成形模拟,采用相同的分析方法得出,胀形时的变形程度较大,胀形后的材料厚度较薄,坯料没有增厚现象.     

真空吸附铣削夹具的设计及其应用

工件变形是影响薄板零件加工精度的主要问题。采用高速铣削加工可减小切削力、切削热、切削振动等产生的工件变形;利用真空吸附铣削夹具装夹工件,使其受到均匀分布的夹紧力,可大大减小因夹紧力造成的工件变形,提高零件的加工精度和表面粗糙度。在介绍真空吸附夹具结构设计与工作原理的基础上,重点阐述薄板零件高速铣削加工真空吸附夹具的设计要点及其应用。     

点焊过程热膨胀变形分析

用有限元方法模拟了低碳钢点焊过程的热膨胀变形，给出了正常焊接、工件受约束和极限条件下的热膨胀变形的理论计算结果，分析了热膨胀对电极的作用和各种机械约束对热膨胀行为的影响，结果表明：焊接区热膨胀以电极有很在的推动作用，最大位移量在电极轴线方向；焊接热膨胀变形受工件的约束条件，电极压力及焊机机械参数的影响，变形规律有所不同，研究结果为热膨胀法点焊质量实时控制提供了理论指导。     

Residual stress state after the laser surface remelting process

Residual stresses are a result of elasto-plastic deformations induced in the workpiece material during the heat treatment process. The extent and magnitude of internal stresses depend on temperature conditions in heating and cooling and physical properties of the workpiece material. This contribution discusses the extent and distribution of residual stresses after laser remelting a thin surface layer on ductile iron 80-55-06 (ASTM specification) or Gr 500-7 according to ISO. Residual stresses are not only induced by temperature differences but also result from stresses due to microstructural changes between the surface and the core of the specimen subsequent to cooling to the ambient temperature. The distribution and extent of residual stresses in the remelted thin surface layer depend mostly on melt composition and cooling conditions. Different rates of solidification and subsequent cooling of the remelted layer are reflected in the volume proportions of the created cementite, residual austenite, and martensite in the microstructure. The rate of heating and cooling of the thin surface layer is a function of laser power, beam diameter on the workpiece surface, and interaction time. In addition, the number of passes of the laser beam over the workpiece surface and different degrees of laser trace overlapping were increased to see how these can affect the thermal conditions in the workpiece. To determine the residual stresses, the relaxation method was used. This is based on measuring the specimen strain during electrochemical material removal.     

A verification of the thermal stress analysis,including the furan sand mold,used to predict the thermal stress in castings

The restraint exerted on a casting by a furan sand mold on the casting and the contraction of the casting during cooling was dynamically and simultaneously measured using a device that we developed. The measurements were compared during cooling with thermal stress analyses. The thermal stress analyses were based on the representative mechanical models for the furan sand mold, i.e., the elastic and elasto-plastic models used in previous studies. The comparison demonstrated that the elasto-plastic model simulates the restraint force more accurately than the elastic model. In the thermal stress analysis, it was important to describe the development of inelastic deformation and the fracture of the sand mold. However, the simulated restraint force was still twice as large as the measured force even in the elasto-plastic model. This error is most likely attributable to using the temperature-independent mechanical properties of the furan sand mold and the mechanical model of the casting alloy, which neglected the viscoplasticity at high temperature in the thermal stress analysis.     

7050铝合金等温模锻坯料设计

设计合适的锻压坯料是保证锻压后锻件具有良好综合性能的基础,通过改进锻压坯料的尺寸来改善锻件各部位的变形程度以获得具有良好组织及性能的锻件。运用有限元模拟软件Deform-3D模拟联接轴等温模锻过程,对不同尺寸的坯料模拟等温锻造过程,随着坯料在Z向厚度尺寸的增加,模锻后锻件的等效应变随之逐渐增加。选择成形效果较佳且模锻后锻件变形程度逐渐增加的锻压坯料进行实验。对热处理后的等温模锻件进行室温拉伸、硬度、电导率、疲劳以及金相实验检测。结果显示:对于横截面沿长轴突变的联接轴锻件,锻件各部位间性能差异较大;等温模锻后,变形程度大的锻件能够获得更好的微观组织和力学性能。     

基于网格重剖分的搅拌摩擦焊接数值模拟及搅拌头受力分析

采用自适应网格方法,建立搅拌摩擦焊接过程的完全热力耦合热刚粘塑性有限元模型,模拟搅拌摩擦焊接过程中工件的温度场、变形场和搅拌头的受力。计算结果表明,温度场关于搅拌头的分布为非对称,焊接在前行侧的有效应变高于其返回侧;沿焊缝区域的温度场、应变场分布是由工件的上表面至底面,呈自上而下的顺序递减。对搅拌头反力曲线的研究表明,在相同的转速下,焊接速度越快,其反力越大;在相同的焊接速度下,转速越大,其反力越小;搅拌头的受力峰值产生在预热阶段结束和搅拌头开始移动的时刻,在给定搅拌头倾角的情况下,搅拌头的最高温度产生在搅拌头的后侧。