双辊薄带-铸辊界面平均换热系数的测定

双辊薄带 铸辊界面平均换热系数是双辊薄带连铸过程数值模拟研究的重要计算参数 ,对它的测定进行研究具有非常重要的理论意义和实用价值。通过试验和数值计算相结合的方法 ,测定了薄带 铸辊界面的平均换热系数 ,实际测定过程表明 :设计的试验装置和采用的计算方法对于测定双辊薄带 铸辊界面平均换热系数是简便易行的 ,可应用到各种不同尺寸的双辊铸机上     

双辊薄带-铸辊界面换热影响因素的研究

综述了各因素对双辊薄带-铸辊界面热流的影响规律,归纳了前人研究模型和方法的特点,为进一步研究双辊薄带-铸辊界面的热交换行为提供参考.     

双辊连铸铝合金薄带凝固组织模拟的微观模型

在研究双辊连铸铝合金薄带工艺凝固过程的基础上,运用金属凝固的基本原理,并运用现代计算机仿真技术,建立了双辊连铸铝合金薄带凝固的异质形核、枝晶尖端的生长动力学、柱状晶向等轴晶转变(CET)的解析模型,同时建立了基于元胞自动机(CA)的双辊连铸铝合金薄带凝固组织的仿真模型,为双辊连铸薄带凝固组织形成的仿真模拟奠定了基础.     

镁合金双辊薄带连铸技术的研究现状及进展

双辊薄带连铸技术作为一种有潜力的镁合金板带材生产技术,其研究开发正受到国内外的关注。本文总结了镁合金双辊薄带连铸技术的研究概况,尤其是镁合金双辊薄带连铸工艺开发、薄带组织和性能研究以及薄带凝固过程的数值模拟等方面取得的进展,指出了该技术目前还存在的问题,并对今后的发展进行了展望。     

双辊快速凝固AZ31镁合金薄带试验研究

在等径双辊连铸机上进行了AZ31镁合金薄带连铸的试验研究，掌握了诸如浇铸温度、铸辊转速、辊缝和侧封等合理的工艺参数，成功地铸出了AZ31镁合金薄带并对其显微组织进行了分析。     

双辊薄带连铸自动控制系统辊速控制优化建模

为对武钢双辊薄带连铸自动控制系统辊速进行检测和控制,保持工艺稳定,提高薄带成品质量,提出了凝固终点坯壳厚度反馈修正铸辊主速度给定的数学模型。对辊速与凝固终点坯壳厚度相互关系进行了研究:辊速与凝固终点坯壳厚度近似线性关系。辊速越大,坯壳厚度越小且易断带或漏钢;辊速越小,坯壳厚度越大且易裂纹或轧卡。据此通过射钉法测量凝固终点坯壳厚度,建立最优凝固终点位置模型和凝固终点坯壳厚度反馈修正铸辊主速度给定数学模型,解决了凝固终点不能测量以及因换规格而不能准确修正主速度给定的问题。此模型为实现武钢双辊薄带连铸产业化提供了前期理论准备。     

双辊薄带连铸布流系统的模拟优化研究

采用数学模拟的方法研究了不同结构布流系统对双辊薄带连铸熔池内流体流动状态的影响,优化设计了新型的布流系统。同时根据Fr和Re准数相似的原则,建立了双辊薄带连铸机的1∶1水模型,分析了不同连铸操作参数对液面波动的影响。结果表明,新型布流系统可使钢液在熔池内均匀分布,有利于薄带坯的均匀凝固。     

双辊薄带连铸技术的研究与发展

双辊连铸技术是一种新型近终形连铸技术,近年来受到普遍关注。本文综述了该项技术在国内外的研究与发展,介绍了侧封、轧辊运行状况和工艺参数等双辊连铸技术中的关键问题及研究热点。双辊连铸技术将广泛应用于不铸钢薄带的连续铸造生产、其它高合金特种钢双辊连铸技术的研究与应用也指日可待。     

双辊连续铸轧凝固过程数学模型的建立及验证

以等价比热容法处理结晶潜热和以假设的流线边界划分网格节点,建立了双辊连铸薄带凝固过程的宏观速度场、传热、溶质传输和凝固组织形成的微观数学模型以及双辊连铸薄带凝固过程的宏观-微观耦合数学模型.同时,以固相率为媒介,采用宏微观不同的网格尺寸和时间步长,实现了宏观模型与微观模型的耦合,并对建立的双辊连铸薄带凝固组织形成的数学模型进行了验证.     

双辊薄带钢连铸工艺参数的选择

双辊薄带钢连铸是连铸领域中一项新的技术,具有节约能源、降低成本和节约投资等优点,由于其特有的优势而越来越被重视.该项技术也日趋成熟,很具开发潜力.简要描述了双辊薄带连铸的原理和特点,并对双辊薄带钢连铸工艺参数,如产品规格、浇注辊直径等的选择进行了分析.同时介绍了世界上几个典型的、具有一定工业化规模的薄带铸轧机的主要工艺参数.     

Micromodel of Simulation on Twin-Roll Continuous Casting Thin Strip Solidification Structure

在研究双辊连铸铝合金薄带工艺凝固过程的基础上,基于金属凝固的基本原理,建立双辊连铸铝合金薄带凝固的异质形核、枝晶尖端的生长动力学(KGT)、柱状晶向等轴晶生长的转变(CET)的解析模型,同时建立基于元胞自动机(CA)的双辊连铸铝合金薄带凝固组织的仿真模型,为双辊连铸薄带凝固组织形成的仿真模拟奠定基础,从而为双辊薄带连铸工艺提供一定的理论指导。同时利用铝合金双辊薄带连续铸轧组织凝固过程验证了数学模拟的可行性。     

铝双辊连续铸轧凝固微观组织的数值模拟(英文)

在研究双辊连铸纯铝薄带凝固过程的基础上,基于金属凝固的基本原理,并运用现代计算机仿真技术建立双辊连续铸轧纯铝薄带凝固的异质形核,枝晶尖端的生长动力学(KGT),柱状晶向等轴晶生长的转变(CET)的解析模型;建立基于元胞自动机(CA)的双辊连铸纯铝薄带凝固组织的仿真模型,为双辊连铸薄带凝固组织的仿真模拟奠定基础,从而为双辊薄带连铸工艺提供一定的理论指导。同时,利用双辊薄带连续铸轧纯铝凝固微观组织过程验证数学模拟的可行性。     

Heat transfer behavior of top side-pouring twin-roll casting

The interfacial heat transfer between the casting and the substrate from liquid/solid contact to solid/solid contact with pressure was investigated using a set of equipment designed according to the characteristics of the top side-pouring twin-roll casting process. The interfacial heat transfer behavior of this process consists of 4 stages: chilling, solidification shrinkage, compression and cooling. High values of the IHTC ranging from 50,000 to 90,000 W/m² °C were detected in the chilling stage, followed by a sharp decrease in solidification shrinkage stage (4000–8000 W/m² °C). Due to the pressure, which modeled the effect of rolling in twin-roll casting, the IHTC bounced back to 6000–20000 W/m² °C, according to different conditions. The influence of process variables such as pressure magnitude, compress speed, pouring temperature, surface roughness and alloy composition had been discussed. Because of the compress action, the influence of these variables performed in a different way, but it was concluded that the way to improve the contact conditions always accompanied with an increase in the IHTC.     

双辊薄带连铸凝固组织模拟微观模型的验证

以双辊薄带连续铸轧工艺凝固过程为基础,基于金属凝固的基本原理,并运用现代计算机仿真技术建立了双辊薄带连铸凝固过程的异质形核、修正的枝晶尖端生长动力学、柱状晶向等轴晶生长转变(CET)的解析模型以及基于元胞自动机(CA)的双辊薄带连续铸轧凝固组织的仿真模型,为双辊薄带连续铸轧凝固组织形成的仿真模拟奠定了基础,同时利用铝合金双辊薄带连续铸轧组织凝固过程验证了数学模拟的可行性。结果表明:可用建立的数学模型模拟预测铸轧工艺参数对双辊连续铸轧薄带凝固组织的影响。     

Numerical Simulation Of Molten Pool And Control Strategy Of Kiss Point In A Twin-Roll Strip Casting Process

Coupled turbulent flow, temperature fields of the twin-roll casting strip process were simulated by three-dimensional finite element method. Based on the heat balance calculation and using inverse methods between the simulations and real experiments, the relational models among casting speed, location, and coefficient of heat transfer between molten metal and rolls in different regions are given. In the simulation, the calculated surface temperatures are in good agreement with the measured values. An on-line model of kiss point is derived by simulations and the geometry of molten pool, corresponding control strategy is also proposed.     

3D Numerical Simulation on Thermal Flow Coupling Field of Stainless Steel During Twin-Roll Casting

The surface crack and lateral crack of the AISI 304 stainless steel thin strip produced by twin-roll casting were observed. The temperature at the center of outlet during twin-roll-casting process was determined by infrared thermometer. In order to avoid the surface cracks of the casting strip, the thermal flow coupling field of AISI 304 stainless steel during twin-roll-casting process was simulated by a 3D fluid-structure coupling model. According to the simulation result, the effect of the casting speed on thermal flow field was analyzed and the process parameters were optimized. Moreover, by studying heat flux curves, the heat transfer mechanism between molten pool and roll was analyzed. The results show that, with the increase of the casting speed, the temperature of the molten pool increases and the solidification point moves toward the outlet. Meanwhile, the whirlpool above gets larger. Based on the solidification front position, the optimized process parameters are 1500 °C and 0.37 m/s. The heat transfer mechanism between molten pool and roll contains direct contacting heat transfer and air gap heat transfer.     

Continuous fabrication of bulk amorphous alloy sheets by twin-roll strip casting

Twin-roll strip casting was utilized to fabricate the sheet products of Zr- and Cu-base bulk amorphous alloys with quite different glass forming abilities (GFAs). Simulation of the solidification behavior of the these amorphous forming alloys during twin-roll strip casting shows that suitable cooling rate can be achieved by twin-roll strip casting to form amorphous structure through the thickness of sheet. Optimum twin-roll strip casting conditions have been suggested based on the simulation results. Actual twin-roll strip casting shows that both Zr-base alloy with high GFA and Cu-base alloy with much less GFA can be strip cast forming amorphous structure. The results indicate that the twin-roll strip casting is a viable process for continuous fabrication of sheets of bulk amorphous alloys with a wide range of critical cooling rates.     

An Investigation of Heat Line Formation in Roll-cast Aluminium Alloys

Abstract

An experimental study has been made of the factors affecting heat line formation in twin roll-cast aluminium alloys. Strip has been cast over a wide range of thickness, casting velocity and alloy composition. Heat lines are classified as large, medium and minor ones. Heat line formation is discussed in terms of the heat transfer between the strip and the roll within the contact region in the twin-roll casting process.