双辊薄带钢铸轧过程的流场温度场耦合数值模拟

采用有限元法模拟了双辊铸轧不锈钢过程的流热耦合问题;分析了铸轧速度对熔池内流场,、温度场的影响以及流民温度场与温度场之间的相互影响,给出了凝固过程中熔池与铸轧辊之间的热流密度变化趋势及随铸连的变化规律,并把此模拟的结果与试验的结果相比较,吻合较好;通过熔池内温度场及温度梯度分析了熔池内凝固的发展及其对热流密度变化的影响。此     

双辊铸轧工艺温度场和流场耦合的数值模拟

 双辊铸轧过程中熔池内金属的流动状态及温度分布直接影响着铸轧过程的稳定性与铸带产品的质量。针对实验室双辊铸轧试验的特点,采用三维有限元法模拟了双辊铸轧过程的热流耦合问题,利用热平衡计算、铸轧实验和模拟相结合的反向方法分段建立了凝固过程中凝壳与铸辊之间热传导系数与铸轧速度、熔池位置之间的关系模型,并分析不同工艺条件下熔池内凝固变化的情况。     

不锈钢薄带铸轧过程中的流动特性

采用有限元法模拟了双辊铸轧不锈钢过程的流热耦合问题,分析了铸轧速度对熔池内流场、温度场遥影响以及流场与温度场之间的相互关系,给出了大过程中熔池与铸轧辊之间的热流密度变化趋势及帮轧速度的变化规律,并比较了模拟与试验的结果;给出了薄带表面温度在铸轧过程中的变化及其随铸轧速度变化的趋势。     

连续铸轧过程中的热-力耦合模型及数值计算

提出了具有强温变耦合特性的界面接触热导模型,采用第三类边界条件对铸轧过程中铸坯和铸轧辊辊套的温度场和轧制力分布进行了仿真,仿真结果与实测数据比较吻合。     

铸轧铝合金带坯横纹缺陷产生原因分析及其控制

采用铜辊套双辊连续铸轧生产3系铝合金,通过分析铸轧板材横纹缺陷暗纹和亮纹的枝晶组织特点,以及铸轧过程中结晶前沿的动态变化特点,研究了铸轧生产过程中板面出现横纹缺陷的原因,并提出了控制措施。结果表明：凝固壳与轧辊表面反复接触和脱离造成轧辊对熔体的冷却不连续,从而导致带坯表层结晶的不连续,最终形成了板面横纹缺陷,而光亮晶的形成加剧了横纹缺陷的严重程度。当铸轧速度提高到一定值时,轧辊向凝固壳的靠近速度(V_a)大于或等于凝固壳的收缩速度(V_s),初始凝固壳与轧辊表面之间不产生气隙,同时抑制光亮晶的形成,可以显著减轻甚至消除铸轧板横纹缺陷。     

基于MARC二次开发的连续铸轧热力耦合分析

综合考虑辊套与铸轧板的弹塑性变形对温度场和应力场的影响，建立铝带坯双辊连续铸轧过程的二维动态热力耦合计算模型；为了建立铸轧过程复杂的边界条件和热接触条件，采用纯铝高温本构关系和接触热阻数值模型，用Fortran对MARC进行二次开发；采用更新的拉格朗日方法进行分析，得出铝带坯连续铸轧过程的温度场和应力场的分布；分析比较不同铸轧速度对铸轧板坯和铸轧辊温度场和应力场的影响。     

双辊铸轧薄带钢组织特点及其形成机理分析

通过对双辊铸轧熔池的特点和薄带在熔池中凝固变形过程的特点进行分析，探讨了不锈钢铸轧薄带的组织结构分布特点及其形成机理，并用结晶热力学做出了解释。     

双辊铸轧薄带钢温度场的有限元分析

针对实验室现有的实验设备条件,建立了双辊铸轧薄带钢过程的有限元数学模型,通过程序开发对熔池内的温度场进行了模拟;给出了各工艺参数对凝固终点位置及铸带表面温度的影响规律,为铸轧过程的分析和控制提供了理论依据.     

双辊板带铸轧凝固过程的数值模拟

根据双辊板带铸轧工艺中金属熔池内的传热特点,建立了笛卡尔坐标系下的传热数学模型,并利用有限差分法对其凝固过程进行了数学求解,从而对双辊板带铸轧凝固过程的传热特点及其影响因素进行总结,并对其加工工艺提出了一些见解,最后将该方法的求解结果和文献中的结果进行了对比。通过本方法的研究,为控制带钢铸轧的凝固过程提供了理论基础。     

双辊铸轧薄带钢温度场的有限元分析

针对实验室现有的实验设备条件,建立了双辊铸轧薄带钢过程的有限元数学模型,通过程序开发对熔池内的温度场进行了模拟;给出了各工艺参数对凝固终点位置及铸带表面温度的影响规律,为铸轧过程的分析和控制提供了理论依据。     

Modelling of Melt Flow and Solidification in the Twin‐Roll Strip Casting Process

A three‐dimensional mathematical model has been developed to simulate turbulent fluid flow, heat transfer and solidification in the pool of a twin‐roll strip caster. A Darcy‐porosity approach was used to study the fluid flow within the mushy solidification zone in the pool. The effect of the heat transfer coefficient and permeability constant on the flow and solidification was also predicted. It was shown that an even flow and temperature distribution of the pool can be obtained by using a suitable feeding system. The heat transfer between the rolls and the solidifying metal has a big influence on the location of the solidification end point. The permeability of the mushy zone is a key factor which affects the flow and solidification in the twin‐roll strip casting process.     

双辊铸轧过程轧制力计算的研究

 在对熔池内金属凝固和变形的机理分析的基础上,将铸轧区域分为2个求解区域。采用流体力学中Navier Stokes方程并引入流函数,对液相区、糊状区的流变特性进行分析并建立相应的速度场,同时引入固相百分率计算模型和粘度计算模型,根据速度边界条件推导出该区域单位压力分布解析式。对于凝固区的铸轧力建模仍沿用传统热轧模型。利用上述模型进行铸轧力计算,计算结果与实测结果吻合较好,为建立双辊铸轧过程铸轧力控制策略的提供了有力的支撑。     

The key technologies of controlling low carbon steel as-cast strip surface quality

This article is try to explain or analyze the key technologies of controlling the surface quality of low carbon steel as cast strip through investigation of interface heat transfer between solidified shell and liquid steel.The one of the key technologies of controlling surface quality of low carbon steel as cast strip is through the casting roll surface texture in order to achieve the homogeneous solidification on the casting roll.Another is through forming a thin film on the casting roll surface in order to achieve a balance between rapid solidification and homogeneous solidification.This film formed between the twin roll and the molten steel can be controlled by adjusting the chemical composition and inclusion in liquid steel through controlling the amount of all[O]and free[O].     

Numerical analysis of fluid flow and heat transfer in pool of twin roll strip caster

Abstract

Twin roll strip casting is regarded as a prospective technology offering many economic benefits. The control of fluid flow in the pool is, however, particularly difficult due to the high casting speed and small pool volume. In the present study, a three-dimensional mathematical model has been developed for the coupled analysis of fluid flow, heat transfer and solidification in the pool using the finite difference method. The characteristics of transport phenomena in the pool of a twin roll strip caster using a wedge type melt delivery system were analysed by numerical simulation. The results show that it is desirable for the wedge melt delivery system to provide the uniformity of flow and temperature in the pool to maintain the casting process and improve the strip quality.     

Two-dimensional model for twin-roll continuous casting

A numerical algorithm for the two-dimensional solidification problem in the twin-roll continuous casting system is presented in this paper. Attention is focused on the elucidation of heat transfer and flow characteristics in both the liquid and the solid phases. The present mathematical model can be applied to general full Navier-Stokes and energy equations, thereby covering the wide range of twin-roll casting conditions. The boundary fixing method (BFM) is adopted to handle the moving boundary, and the resultant transformed governing equations for the solid and liquid regions are solved separately by using a usual explicit-type finite difference method. In this paper, a general numerical methodology is presented, and the quantitative relationships between the important control parameters in continuous casting of twin-roll type (such as the roll speed, the roll gap, the initial temperature of molten materials, the material properties, the solidification profile, and the endpoint of solidification) are clarified in detail. The present numerical results have been compared with experimental results obtained separately to check the validity of the proposed method.     

双辊薄带凝固组织的数值模拟(Ⅱ)--数学模型的应用

双辊薄带凝固组织中柱状晶区所占比例对薄带质量有非常重要的影响，本在已建数学模型的基础上，模拟预测了浇铸温度、铸辊转速、熔池高度等工艺参数对双辊薄带凝固组织中柱状晶区比例的影响。模拟结果表明：在全凝固点位置位于铸辊出口处和保持带厚不变的条件下，工艺参数对薄带凝固组织中柱状晶区比例的影响是不同的。     

基于反算热流的结晶器内流动--传热--凝固耦合模拟

基于Navier-Stokes动量方程和湍流低雷诺数k-ε方程,综合考虑能量守恒和钢液凝固与糊状区对流动过程的影响,建立了描述结晶器内钢液流动、传热及凝固过程的三维耦合数学模型.以实测温度和结晶器反问题模型计算出的热流为边界条件,模拟计算了结晶器内钢水的流动、传热和凝固行为.钢液流动决定结晶器内的温度和热流分布,铸坯凝固受钢液流动和结晶器热流双重因素的影响.建立的模型以及由此得到的铸坯凝固非均匀特征可为进一步考察浇铸过程中纵裂和其他表面缺陷提供借鉴和参考.