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Exact simulation of forming processes using the finite element method requires as precise specification as possible of the prevailing material data and physical boundary conditions. The article presents a method of determining the flow‐stress for sheet metals under hot‐forming conditions. The value is determined in a cylindrical multi‐layer compression test which up to now has been underestimated even for cold testing conditions. This article presents some special adaptations which are necessary for testing under high temperature conditions. The method is able to supply reliable data for FEM simulation, as is demonstrated in some examples. 相似文献
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In the so‐called ferritic rolling the finishing is shifted down into the temperature region of ferrite, which enables a production of thinner hot strips (compared to the conventional hot rolling in austenite) with a changed texture development. The present study is focused on the effect of the process parameters of such initial warm rolled hot strips on the texture formation and hence on the deep‐drawing quality of the final cold strips. A special attention is given to the transmission of the hot strip texture to the cold strip. The investigation was carried out on commercial IF‐ and ELC‐steels by a laboratory simulation with the hot deformation simulator Wumsi (rolling simulated by the plane strain compression test). It was possible to optimize cold rolling and subsequent annealing by means of the measurements of the texture development during the ferritic (warm) deformation as well as the parameters of the processing route of such special production of cold strips by means of the calculation of r‐values. If compared with the conventional processing route, a considerable improvement of deep‐drawability with a diminished earing is achievable especially with the IF‐steel. 相似文献
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To reveal the basic deformation mechanisms under the conditions of high friction, small reduction, and long contact length in thin strip temper rolling process, an elastoplastic finite element analysis of plane strain upsetting was made based on the FEM software Marc. The results indicated that a near flat ‘zero reduction’ region was present in the center of the contact arc. The simulation results about the effect of rolling parameters on the central flat region showed that any change of increasing the rolling force could result in or enlarge the central flat region in the deformation zone. Stress distribution results illustrated that the metal was in triaxial compression state. Although the maximum and minimum principal stresses were all much larger than the yield stress of the strip, the equivalent stress became lower than that, and no further plastic strain, even a small elastic spring back occurred in the central flat region. That was the problem of ‘hydrostatic pressure’ in thin strip temper rolling. 相似文献
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Finite Element Simulation of Hot Strip Continuous Rolling Process Coupling Microstructural Evolution 总被引:2,自引:0,他引:2
Using the nonlinear rigid viscoplastic finite element method (FEM), a finite element simulation of the hot strip continuous rolling process was done, which completely integrates different phenomena such as the metallurgical behavior of the strip and the thermo mechanics in the strip based on the physical metallurgical microstructural evolution law. By combining with the process parameters of certain 2 050 mm hot strip rolling, an actual rolling process of low carbon steel SS400 was simulated using the FEM model. Based on the simulation results, the distributions of the strain field, the temperature field, and the microstructure were presented. Meanwhile, the simulated rolling force, temperature, and microstructure are in good agreement with the measured results. 相似文献
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Reiner Kopp Marc Nutzmann Oliver Ziegelmayer Wolfgang Bleck Roman Diederichs 《国际钢铁研究》2002,73(8):321-326
In regard of the reduction of energy consumption during the production of steel slabs and strips different charging procedures are of high economic interest. Especially hot and direct charging procedures are used in modern ways of strip production like CSP and strip casting. For simulation of these procedures and their related effects on the microstructure and the mechanical properties of the material, the complete process chain of melting, casting and hot rolling in one heat has been realised in a pilot scale. In this concept process parameters such as temperature over time are controlled during the complete process. By variation of the thermomechanical process parameters the microstructure and the mechanical properties gained in different processing routes can effectively be simulated. This new set‐up allows the simulation of the casting and rolling processes not only in a laboratory scale by using conventional compression, tensile and quench tests but now also in a pilot scale. The results will be used as input parameters for FEM simulation. In this paper the set‐up of the laboratory facility is described with the measured and controlled parameters. 相似文献
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针对特厚板再结晶型轧制,板坯中心难以变形导致心部晶粒粗大的问题,使用Q345B钢,采用有限元方法建立了特厚板轧制的仿真模型,以研究在特厚板轧制过程中引入厚度方向上的温度梯度对钢板心部应变的影响,并与传统均温轧制进行对比,预测了两种温度场条件下奥氏体再结晶的晶粒尺寸.采用大试样平面应变实验对模拟结果进行验证.研究结果表明,温度梯度轧制有利于增加坯料心部应变量,最大增加了61.35%.计算和实验结果显示温度梯度轧制可以减小特厚板心部晶粒尺寸,晶粒度级别提高了一个等级,说明该工艺对提高特厚板中心区域性能有利. 相似文献
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This work was carried out in context with the development of strip casting with the single‐belt process. In this new process the hot rolling is performed in‐line with considerably lower velocity than in conventional hot rolling. It is of interest to study the effect of low rolling speed on the material properties. Based on a finite element model used to predict the thermomechanical behaviour of the strip in tandem mills, the microstructural evolution of austenite was computed. In order to take account of the non‐isothermal conditions in industrial hot rolling, the material equations for recrystallization and grain growth are modified. The parameter studies were carried out over a wide range of volumetric flow rate extending from that in thin slab casting to that in conventional finishing rolling. They demonstrate that the “slow hot rolling” can produce a fine grain of austenite. Austenite grain evolution was computed for conventional rolling with a seven stand mill and for in‐line hot rolling of strip produced by the single‐belt process. It is found that the final grain size of austenite is about the same for the two processes under the condition that strip thickness behind the last stand is the same. 相似文献
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特厚板厚度方向形变传递规律的仿真分析 总被引:1,自引:0,他引:1
基于Gleeble热压缩试验、有限元方法对一种HSLA钢特厚板轧制过程中厚度方向变形向心部传递的规律进行了仿真研究。首次从有限元角度定量揭示出特厚板生产中高温、低速、大压下量的轧制规范机理。仿真所用材料本构模型由Gleeble试验数据结合Arrhenius方程所构建,研究了轧制速度、压下量、轧制温度以及板坯厚度对特厚板厚度方向应变分布的影响规律。结果表明,轧制速度小于1 m/s时(平均应变速率小于 0.33 s-1),有利于变形向钢板心部传递,削弱截面效应;压下量越大,钢板等效应变越大,且厚度方向最大等效应变出现的位置向心部偏移;轧制温度对等效应变的分布影响不显著,但是高温轧制有利于减小轧机负荷;板坯越厚,变形分布不均匀性越显著。当板坯厚度为500 mm时,截面的最大、最小等效应变差达到0.2。生产中,在设备允许的情况下,建议特厚板的轧制采用高温、低速、大压下量规范。 相似文献
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微制造、微电子行业的小型化、轻量化和移动化的发展方向需要厚度更薄、尺寸精度更高的极薄和超薄金属箔材,极薄和超薄金属箔材制造技术越来越重要。极薄带轧制试验及生产实际中,Stone最小可轧厚度公式有较多不合理之处。通过有限元模拟得到不同厚度极薄箔带在不同压下率时的接触轮廓与轧制压力变化规律,为Stone最小可轧厚度赋予新含义,即表示在极小压下变形量条件下是否存在中性区的临界厚度值;建立了极薄箔带适轧厚度解析计算模型,即根据轧制力条件和箔带厚度可计算出其单道次能够获得的最大压下量,为已有轧机确定产品规格范围并制定轧制规程及为设计轧机时确定轧辊直径和力学参数提供理论指导。 相似文献
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CSP线高强度细晶热轧板的混晶和变形拉长晶粒的成因 总被引:1,自引:0,他引:1
对CSP线生产的高强度细晶热轧板的混晶和拉长晶粒的成因进行了分析,用有限元分析法模拟了热轧带钢的变形区的剪切应变场和温度场,用Gleeble实际模拟轧制工艺和组织变化。结果表明,CSP线高强度细晶热轧板的混晶和拉长晶粒的形成与钢板轧制过程中的钢板表层的变形场及温度场有关,也与先析出铁素体的形成后再进行轧制变形的过程有关;采用奥氏体深过冷轧制,既保证得到细晶粒又避免产生混晶和被变形拉长的晶粒。新的CSP轧制工艺,成功地生产了高强度高成形性细晶粒C-Mn热轧板。 相似文献
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Luis E. Hernandez‐Castillo John H. Beynon Christophe Pinna Sybrand van der Zwaag 《国际钢铁研究》2005,76(2-3):137-141
A modified microgrid technique has been applied to a laboratory‐made duplex stainless steel, to experimentally simulate the local state of deformation of the austenite‐ferrite microstructure of low‐alloy steels subject to intercritical deformation. A sample containing such a microgrid was deformed by plane strain compression at high temperature under conditions representative of hot rolling processes. The distortion of the microgrid after hot deformation revealed, in a quantifiable manner, the plastic flow of both phases and different deformation features. The micro‐strain distributions measured can be used to validate the models predicting the hot deformation of low alloyed C‐Mn steels during intercritical rolling. 相似文献
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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4.3 μm。 相似文献