共查询到20条相似文献,搜索用时 15 毫秒
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通过开发用于组织模拟的用户程序,采用有限元软件DEFORM-3D模拟AM50镁合金多道次热轧过程中的组织转变,并通过与实验结果的对比分析证明该用户程序模拟多道次轧制的可行性。结果表明:多道次热轧有助于镁板的晶粒细化及均匀再结晶组织的获得,精轧前的板坯温度对终轧后的晶粒尺寸影响很大,但对晶粒尺寸的分布情况影响不明显。开发的用户程序亦可应用于其他类型多道次热变形过程的模拟研究。 相似文献
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Multi-recrystallizations occurring in a steel billet during hot forging were predicted. The prediction was obtained by coupling rigid thermoviscoplastic finite element analysis and recrystallization modeling equations. The finite element analysis was preformed for nonisothermal deformation as well as heat transfer for the entire forging process. As a result, it was predicted that three or four times of recrystallizations occurred in the billet and that resulting grains varied in size for different locations. The final grain sizes at the locations in the billet were measured and compared with predicted ones. It was found that they were in good agreement. 相似文献
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Rod rolling is a process in which the deformation of the workpiece between the work rolls is quite different from the rod
drawing process, but the area strains (natural logarithm of area reduction ratio) multiplied by a constant have been used
in the calculation of the pass-by-pass evolution of austenite grain size in rod (or bar) rolling without any verification.
Considering that the deformation parameters (strain and strain rate) at a given pass play a crucial role in determining recrystallization
behavior, the calculation method for the deformation parameters associated with rod rolling should be examined. In this study,
a series of numerical simulations has been carried out using an area strain model [5] and an analytic model [6] which calculate
the pass-by-pass strain in the rod rolling process, focusing on the effect of the calculation method for the pass-by-pass
strain on the recrystallization behavior and evolution of AGS (austenite grain size) during a given pass. These have been
investigated for a six-pass rolling sequence (oval-round or round-oval) designed for this study by incorporating the recrystallization
and AGS evolution model being widely used in hot rolling. It was found that the recrystallization behavior and evolution of
AGS during a given pass were significantly influenced by the calculation methods for deformation parameters. The area strain
model lacks mathematical grounds to be used as input to the equations for recrystallization and AGS evolution. 相似文献
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采用物理冶金模型结合二维温度场对ASP(Angang Strip Production)热轧X70管线钢再结晶、相变等物理冶金过程进行了模拟,并结合BP神经网络对最终的力学性能进行了预测.研究表明,实验钢在层流冷却前的奥氏体晶粒尺寸为10~25 pm,板带横断面奥氏体晶粒尺寸分布不均匀,心部的奥氏体晶粒尺寸比角部大15 μm左右;在给定冷却速率的情况下采用前段冷却方式得到的铁素体分数比后段冷却方式大2%~5%;采用BP神经网络可以把伸长率预测结果相对误差标准差提高1.8% ;Si含量0.2%~0.3%成为其对力学性能影响的转折点. 相似文献
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A multiscale modelling framework has been proposed to characterize microstructure evolution during hot strip rolling of transformation-induced plasticity (TRIP) steel. The modelling methodology encompasses a continuum dislocation density evolution model coupled with a lumped parameter heat transfer model which has been seamlessly integrated with a mesoscale Monte Carlo (MC) simulation technique. The dislocation density model computes the evolution of dislocation density and subsequently constitutive flow stress behaviour has been predicted and successfully validated with the published data. A lumped-parameter transient heat transfer model has been developed to calculate the average strip temperature in the time domain. The heat transfer model incorporates the effect of plastic work for different strain rates in the energy conservation formulation. A coupled initial value problem solver has been developed to integrate the system of stiff ordinary differential equations in the time domain to predict dislocation density and temperature profiles simultaneously. The temporal evolution of microstructure during hot rolling of TRIP steel is simulated by the MC method incorporating thermal and dislocation density data from the continuum models. Simulated microstructural maps, kinetics of recrystallization and grain size evolution have been generated in a 200 × 200 lattice system at different strain rates and temperatures. The simulation code has been implemented in a high-performance grid computing network. The predicted temporal evolution of grain size, recrystallized fractions and flow stress have been validated with the published literature and found to be in good agreement, confirming the predictive capability of the integrated model. 相似文献
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通过相图、轧制理论以及对热轧带钢金相组织的观察,对比分析了EF08钢、410S铁素体不锈钢和304奥氏体不锈钢热轧过程中的变形抗力和动态回复再结晶能力。结果表明:EF08钢奥氏体区在900~1 200 ℃,热轧过程处于奥氏体相区,其动态回复再结晶能力较410S铁素体不锈钢和304奥氏体不锈钢强;EF08钢的粗轧过程轧制特性与304奥氏体不锈钢相近,精轧后几道次与410S铁素体不锈钢类似。 相似文献
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通过热压缩实验研究了原始晶粒尺寸为厘米级的EB炉流程纯钛在不同变形温度和变形速率下的热变形行为,并基于电子背散射衍射(EBSD)技术对EB炉流程纯钛的再结晶机制进行了探讨。结果表明:厘米级的EB炉流程纯钛在热变形过程中的加工硬化行为具有典型的“三阶段”特征:第一阶段线性快速下降;第二阶段迅速回升至一个峰值;第三阶段从峰值又开始下降,这与变形过程中的孪生现象有关;EBSD结果表明超粗晶粒纯钛在热变形过程中的再结晶机制主要是非连续动态再结晶。 相似文献
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Zhuo-han CAO Yu SUN Chen ZHOU Zhi-peng WAN Wen-hua YANG Li-li REN Lian-xi HU 《中国有色金属学会会刊》2019,29(1):98-111
The deformation behavior of V-10Cr-5Ti alloy was studied on the Gleeble-1500 thermomechanical simulator at the temperatures of 950-1350 °C, and the strain rates of 0.01-10 s?1. Based on the Arrhenius model, dislocation density model, nucleation model and grain growth model, a numerical cellular automaton (CA) model coupling simulation of hot deformation is established to simulate and characterize the microstructural evolution during DRX. The results show that the flow stress is fairly sensitive to the strain rate and deformation temperature. The error between the predicted stress by the Arrhenius model and the actual measured value is less than 8%. The initial average grain size calculated by the CA model is 86.25 μm, which is close to the experimental result (85.63 μm). The simulations show that the effect of initial grain size on the dynamic recrystallization microstructure evolution is not significant, while increasing the strain rate or reducing the temperature can refine the recrystallized grains. 相似文献
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有限元模拟技术在板带钢轧制中的应用 总被引:8,自引:1,他引:8
介绍了板带钢轧制过程中常用的有限元模拟方法的类型,及其近年来在揭示轧制力能参数、温度场、板形控制及板带轧制新技术和新工艺开发中的一些应用实例,并指出其存在的问题和发展前景。 相似文献
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Zhen Zhang Ming-pu WangZhou Li Nian JiangShimeng Hao Jing GongHailong Hu 《Journal of Alloys and Compounds》2011,509(18):5571-5580
Hot-rolling experiments with a reduction from 10% to 60% in single pass were conducted on AZ31B twin-roll cast sheets. Optical microscope (OM), electron backscattered diffraction (EBSD) tests and transmission electron microscope (TEM) were used to investigate twinning and DRV/DRX behaviors at different stage in the hot-rolling process. Two types of twinning occurred in the initial stage of hot-rolling process. DRV and discontinuous recrystallization dominated at moderate strain while continuous DRX took place homogeneously throughout original grains at the largest strains. 相似文献
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A study of pore closure and welding in hot rolling process 总被引:5,自引:0,他引:5
The design of processing conditions to eliminate porosity in steel during hot rolling has become more critical with the advent of continuously cast feed stock. To predict appropriate process parameters, experiments were performed in which holes were drilled in steel slabs, at different depth below the surface perpendicular to the rolling direction. After hot rolling, the state of the deformed holes was examined by optical microscopy. The fracture surfaces of tensile specimens notched in the plane of the closed holes were examined under a scanning electron microscope to investigate the bonding ( welding ) between the surfaces of the closed holes because this bonding is the most important factor indetermining the transverse mechanical properties of the rolled product. The deformation of such holes in the roll gap was modelled as an clastic / plastic plane strain problem using the FE software ABAQUS to investigate the strain and stress around holes and to analyze the conditions required to promote pore closure and welding between the closed surfaces.
Experiment results showed that the rate of pore closure was affected by the parameters of rolling process and the position of holes relative to the rolling contact surfaces. FE simulation of pore closure showed a good agreement with experimental results and showed that a certain level of hydrostatic pressure resulted in the closure of pore and that the holding period of the pressure in the compressive state determined the degree of welding of surface of pores; shear is favourable to this welding. 相似文献
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《Journal of Materials Processing Technology》2006,171(1):83-92
This study presents the application of parameters design to improve both the product quality and the equipment performance in a hot sheet rolling plant. Three empirical models were developed to predict and explain the relationship between variation in some process parameters and the type and range of product defects together with equipment disorders observed. The investigation is based on the analysis of the results of a set of designed experiments.The most critical process parameters were set at specified values and the effect of the change in these parameters, on rolled sheets quality and rolling equipment performance is evaluated. The three process parameters considered are the reduction ratio (Rd), the slab temperature (Ts), and the exit strip speed (Sp). The quality characteristics considered are: profile and flatness of rolled sheets and distance between chatter marks, the performance indicators considered are: rolling force, vibration measurements, and the rolling mill wear rate.Through optimization of process parameters, it was possible to reduce chattering. Consequently, chatter marks and roll wear were greatly reduced. Product flatness and profile were improved. Plant down time and production scrap was considerably reduced. This investigation proved that it is possible to improve both product quality and equipment performance in the hot rolling plant through the parameters design approach. 相似文献