CSP连轧过程变形的有限元分析

借助Marc商用软件,采用弹塑性大变形热力耦合有限元法,对薄板坯CSP连轧过程的变形过程进行模拟,分析了轧制过程中各道次轧件等效应力、等效应变、等效应变速率和轧制力的变化．结果表明：在轧制变形区内,等效应变沿轧制方向逐渐增大,在轧件出口处达到最大值;而在轧件入口表面附近等效应力和等效应变速率最大;在轧制稳定阶段．轧制力在微小范围内波动;轧制力模拟值与实测值基本一致．分析结果可以为工业生产提供参考．     

基于神经网络的微合金钢热轧奥氏体晶粒尺寸预报模型

基于神经网络原理，对微合金钢热轧控制参数的选取进行了研究。制订了一套获取样本数据的实验方案。该方案利用Gleeble-1500热力模拟机提取了轧制温度、应变量、应变速率和相应的应力应变曲线，并通过显微观察获取了实验后样品断面的奥氏体晶粒尺寸。通过归一化把实验所得数据进行必要的处理。采用改进BP算法训练网络，对热轧控制参数（轧制温度、应变量、应变速率）和描述微合金钢组织性能的参数（奥氏体晶粒尺寸）之间的映射关系进行了函数逼近，建立了奥氏体晶粒尺寸流变应力神经网络模型，实践证明，将该神经网络模型运用于热轧控制预报，提高了预测精度并取得较好的效果。     

铝热连轧温度场模拟在Marc中的实现

通过Gleeble-1500热模拟机等温压缩试验研究了1235铝合金流变本构模型．在此基础上,建立铝板带热轧二维MSC．Marc有限元模型,对热连轧过程温度场进行了模拟仿真,并分析了热连轧过程中的温度场变化规律．     

热连轧圆钢成品孔型的有限元分析

根据ф16 mm圆钢的轧制规程,运用有限元分析软件ANSYS中的LS-DYNA大变形弹塑性显式分析动力学模块,对终轧机架在分别采用双半径圆弧和切线扩张角两种成品孔型条件下的热连轧过程进行有限元模拟。对比分析了同一轧件在不同孔型中的金属流动特性和应力应变分布规律。结果表明,有限元模拟结果与实际生产过程相吻合;对同样采用30°扩张角的两种孔型而言,轧件在双半径圆弧成品孔型中的表面受力和总体应变分布更为均匀;轧件在成品孔型的圆弧扩张部位受到的应力较大,使轧辊轧槽表面磨损不均;采用材质硬度更高的成品轧辊,可以降低轧槽表面的磨损程度,延长轧辊孔型的使用寿命,节约生产成本。     

高速棒材热连轧过程温度场数值模拟

通过对高速棒材轧制、水冷和输送等各个环节热传导及边界条件的分析,应用有限差分法建立高速棒材热连轧过程温度场模型,并对整个连轧过程进行了温度模拟计算,获得轧件表面及其内部温度分布规律。结果表明,计算值和实测值有较好的一致性。     

金属层合板轧制复合工艺国内外研究进展

金属层合板发挥了组元材料各自的优势,实现了单一金属不能满足的综合性能,是近年来国家重点发展的金属结构材料之一,被广泛应用于航空航天、国防军工、交通运输和装备制造等领域.轧制法是金属层合板的主要制备方法之一,具有稳定连续化生产的优势. 本文主要综述了金属层合板轧制复合工艺国内外的研究进展,简述了机械啮合理论、金属键理论等目前被学者认可的几种金属层合板轧制复合假说,分类总结了热轧、冷轧、异温轧制、累积叠轧、异步轧制等复合工艺的优缺点及适用范围,同时通过工程法、流函数法和上限法等理论解析,分析了金属层合板轧制复合工艺技术方面的特点. 针对数值仿真中的待复合界面连接问题,归纳了粘合模型、共节点模型等界面处理模型及应力场、应变场、速度场等相关物理量定值或函数关系的复合判据.基于目前轧制复合工艺存在的不足,提出了研究团队国际首创的残余应力小、板形好且结合强度高的波纹轧制复合工艺,并对轧制复合工艺今后的研究重点作了展望.     

热连轧工艺对GH4648合金棒材组织与性能的影响

研究了连轧生产线生产的GH4648合金热轧棒材的组织与性能.采用热连轧过程的自动化控制系统调整棒材的轧制速度、保持稳定的终轧温度,从而获得晶粒组织均匀、α-Cr相形态与分布合理的热轧棒材.与传统的横列式轧机相比,工艺更稳定、可控,热轧棒材的组织稳定、性能提高.     

Q420B高强度铁塔角钢高温力学性能研究

采用Gleeble-3500D对Q420B连铸坯试样进行热模拟实验,分析应变速率分别为1,5,10s-1时,温度对其高温力学性能的影响,并对高温脆性区间温度范围和脆化机理进行研究。结果表明,Q420B连铸坯在轧制过程中,抗拉强度随温度的升高而逐渐降低,在1150℃左右出现低塑性区。为了得到良好的面缩率,避免在热变形过程中形成裂纹等缺陷,建议轧制温度避开1150℃。     

Static and dynamic finite element analysis of 304 stainless steel rod and wire hot continuous rolling process

Three-dimensional finite element models were developed to analyze 304 stainless steel rod and wire hot continuous rolling process with the help of MSC.Marc software. The entire 30-pass deformation process and the actual parameters of production line were taken into account. Static and dynamic procedures were used to study the continuous rolling process with the aid of the thermo-mechanical coupled FEM of elastic-plasticity. The properties of billets, such as deformation, temperature field and rolling force, were mainly discussed. The simulation results of temperature agree well with the measured values. Comparisons of the analysis results obtained using static implicit method and dynamic implicit method were presented. It is shown that static implicit procedure is more accurate than dynamic implicit procedure and is able to simulate the rolling process with a lower speed, such as a roughing mill. Whereas, dynamic analysis shows a higher efficiency than static analysis and is fit for simulating the rolling process with a higher speed, such as a finishing mill.     

Research on constitutive equation of DIWA353 steel used in hemisphere head of power station nearby recrystallization temperature

To simulate the DIWA353 steel used in boiler nearby recrystallization temperature accurately by using finite element,the high temperature constitutive model of this material must be researched firstly....     

Formation mechanism in alloy steel rolling process using thermo-mechanical coupling method

Based on the theory of elastic-plastic finite element method, the high-speed hot continuous rolling process of a billet is simulated and analyzed in vertical and horizontal passes. The billet is dragged into the passes by contact friction force between the billet and rollers. The rollers and billet are represented by respectively rigid and deformable bodies, and three-dimensional models are developed for the billet and rollers. The distribution of deformation field, effective strain, rolling force and temperature field are accurately calculated for the whole rolling process (including unstable and stable stages). In addition, the rolling pressure on the width symmetry center is compared with that in the in-situ experimental measurements. It is revealed that various heat exchange phenomena among the billet, rollers and surroundings can result in unbalanced temperature distribution on the cross section. Rolling force and strain can change significantly when the billet is moved towards or away from the roller gap, and keep almost invariable in the stable stage. It is expected that the simulation results would be useful for practical manufacture and provide the theoretical foundation for improvement of process planning and optimization of process parameters.     

Flow stress behavior and processing map of Al-Cu-Mg-Ag alloy during hot compression

The hot deformation behavior of Al-Cu-Mg-Ag was studied by isothermal hot compression tests in the temperature range of 573-773 K and strain rate range of 0.001-1 s^-1 on a Gleeble 1500 D thermal mechanical simulator. The results show the flow stress of Al-Cu-Mg-Ag alloy increases with strain rate and decreases after a peak value, indicating dynamic recovery and recrystallization. A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate and temperature, the flow stress equation is estimated to illustrate the relation of strain rate and stress and temperature during high temperature deformation process. The processing maps exhibit two domains as optimum fields for hot deformation at different strains, including the high strain rate domain in 623-773 K and the low strain rate domain in 573-673 K.     

82B高碳钢热变形行为研究

采用单道次热压缩实验方法,在Thermomaster-Z型热模拟试验机上模拟高碳钢高速线材热轧变形过程动态再结晶行为,测定82B高碳钢在变形温度为800～1 100℃、变形速率为0.1～50 s-1、变形程度为0～0.60条件下的真应力-应变曲线,利用曲线特征值确定高应变速率下的变形激活能,根据实验结果分析动态再结晶变形条件,建立动态再结晶状态图。     

热连轧过程中力能参数的三维仿真分析

借助大型商品有限元软件MSC.MARC及其先进的接触求解方法,采用真实工艺尺寸,以热力耦合大变形理论为基础,真实地模拟出了高速线材预精轧区六机架热连轧过程,计算并分析了轧制过程中的应力场、轧制力与轧制力矩等力能参数随时间增量步的变化规律,计算结果对现场轧制工艺参数的调整优化有重要的参考价值,对实际生产也有重要的指导意义.     

Q235小H型钢轧制过程温度场有限元分析

小H型钢成品的组织性能与轧制过程的温度紧密相关,特别是终轧的温度.结合现场测量结果,应用有限元分析软件对轧制过程的温度场进行模拟,并通过对Q235小H型钢轧制过程各轧制阶段温度的实际测量,与有限元分析结果进行比较,两者误差较小,验证了有限元分析结果的正确性,得到了各阶段H型钢断面温度分布特点以及内外温差值.分析结果对制定加热温度、轧制过程冷却参数、轧制工艺参数和进行轧后控冷等提供了有效参考     

热轧温度对Zr-4合金力学性能和耐腐蚀性能的影响

热加工工艺对Zr-4合金板材的力学性能及耐腐蚀性能有极其重要的影响,将Zr-4合金板在800℃和960℃两种温度条件下热轧开坯至2.4 mm厚度,经退火后冷轧加工成为1.2 mm和0.6 mm厚的带材,研究了热轧温度对Zr-4合金板材室温力学性能和腐蚀性能的影响.研究表明,800℃热轧后所制备板材的强度低于960℃热轧后的板材,而延伸率大于960℃热轧后的板材;800℃热轧所制备的0.6 mm厚的Zr-4合金板材的腐蚀性能优于960℃热轧所制备的板材.由研究结果可得：Zr-4合金板材在实际生产过程中需合理地控制热加工温度.     

大棒材热轧工艺的数值模拟

大棒材轧制属于高温大变形塑性成形过程,为了研究轧制过程中轧件温度场、应变场及微观组织演变的规律,在热模拟实验的基础上建立了大棒材初轧道次热-力-组织耦合的有限元模拟模型。模拟结果显示,轧制过程中轧件由于发生再结晶使晶粒得到细化,初轧完成后,轧件平均晶粒尺寸由芯部到表层逐渐减小;由于大棒材初轧过程中轧件芯部变形量较小,不利于轧件芯部孔隙性缺陷的压实,因此提高热轧连铸坯的芯部致密度是改善大棒材芯部质量的重要措施之一。     

宽厚复合板热轧成形轧制力模型

为了有效提高宽厚复合板热轧成形质量,以不锈钢与低合金钢层状复合结构材料为研究对象,针对宽厚复合板结构复合及加工协同变形的技术要求,制定宽厚复合板热轧成形工艺路线,并对热轧宽厚不锈钢复合板成形轧制力模型进行研究.将热轧复合变形区分成Ⅰ、Ⅱ两个区段,并依据热轧过程中轧制区间内金属流动变形规律,确定各界面上摩擦切应力τ的方向,进而推导出热轧不锈钢复合板成形轧制力计算公式.研究结果表明:该轧制力模型可准确预测轧制力的大小,有效提高轧制力的计算精度.经轧制成形制造的不锈钢复合板满足设计技术要求,制定工艺路线合理,可用以指导生产实践.     

Flow stress behavior of Al-Cu-Li-Zr alloy containing Sc during hot compression deformation

The flow stress behavior of Al-3.5Cu-1.5Li-0.25（Sc＋Zr） alloy during hot compression deformation was studied by isothermal compression test using Gleeble-1500 thermal-mechanical simulator. Compression tests were preformed in the temperature range of 653-773 K and in the strain rate range of 0.001-10 s^-1 up to a true plastic strain of 0.7. The results indicate that the flow stress of the alloy increases with increasing strain rate at a given temperature,and decreases with increasing temperature at a given imposed strain rate. The relationship between the flow stress and the strain rate and the temperature was derived by analyzing the experimental data. The flow stress is in a hyperbolic sine relationship with the strain rate,and in an Arrhenius relationship with the temperature,which imply that the process of plastic deformation at an elevated temperature for this material is thermally activated. The flow stress of the alloy during the elevated temperature deformation can be represented by a Zener-Hollomon parameter with the inclusion of the Arrhenius term. The values of n,α and A in the analytical expressions of flow stress σ are fitted to be 5.62,0.019 MPa^-1 and 1.51×10^16 s^-1,respectively. The hot deformation activation energy is 240.85 kJ/mol.     

热轧带钢轧机工作辊热应力的有限元分析

热轧带钢轧机工作辊在工作过程中承受交变热应力,掌握变化的热应力的大小和规律非常重要.热应力的大小目前无法使用实验的方法得到,而采用数值模拟求解是一种行之有效的方法.采用ANSYS 8.0软件对热轧带钢轧机工作辊的温度场和热应力进行了有限元分析,通过计算分析得出工作辊温度场的分布规律,这对于工作辊寿命分析、设计及现场使用都有参考价值.