A Study for Initial Solidification of Sn-Pb Alloy During Continuous Casting: Part II. Effects of Casting Parameters on Initial Solidification and Shell Surface

The initial shell solidification of liquid steel in the mold has significant influence on both surface and internal quality of the final slab, and it is mainly determined by the high transient high temperature thermodynamics occurring in the mold. This study investigated the effects of casting parameters like casting temperature, mold oscillation frequency, and stroke on the initial solidification of a Sn-Pb alloy through the use of a mold simulator to allow the clear understanding of the inter-relationship between irregular shell solidification, heat transfer, negative strip time (NST), and casting conditions. Results suggested that the shell surface oscillation marks (OMs) are strongly depending upon the fluctuations of meniscus responding temperatures and heat flux. An abrupt sudden fluctuation of high frequency temperature and heat flux at the meniscus during the NST would deteriorate the shell surface and leads to deep OMs. The fluctuations of responding temperature and heat flux are determined by the NST, meniscus solidification, and oil infiltration, which in turn are influenced by casting conditions, like casting temperature, oscillation frequency, stroke, etc.     

软接触电磁连铸过程中结晶器及初生坯壳的传热

为了解高频磁场对软接触电磁连铸结晶器及初生坯壳传热行为的影响,用有限元二维数值模拟方法计算了软接触连铸过程中结晶器及初生坯壳的传热.得知在高频磁场（f=20 kHz）作用下,电磁场的感应加热会减少连铸初生坯壳的厚度、提高连铸坯的表面温度,并大幅度提高分瓣结晶器铜壁的温度.     

Mold Simulator Study of Heat Transfer Phenomenon During the Initial Solidification in Continuous Casting Mold

In this paper, mold simulator trials were firstly carried out to study the phenomena of the initial shell solidification of molten steel and the heat transfer across the initial shell to the infiltrated mold/shell slag film and mold. Second, a one-dimensional inverse heat transfer problem for solidification (1DITPS) was built to determine the temperature distribution and the heat transfer behavior through the solidifying shell from the measured shell thickness. Third, the mold wall temperature field was recovered by a 2DIHCP mathematical model from the measured in-mold wall temperatures. Finally, coupled with the measured slag film thickness and the calculations of 1DITPS and 2DIHCP, the thermal resistance and the thickness of liquid slag film in the vicinity of the meniscus were evaluated. The experiment results show that: the total mold/shell thermal resistance, the mold/slag interfacial thermal resistance, the liquid film thermal resistance, and the solid film thermal resistance is 8.0 to 14.9 × 10^?4, 2.7 to 4.8 × 10^?4, 1.5 to 4.6 × 10^?4, and 3.9 to 6.8 × 10^?4 m² K/W, respectively. The percentage of mold/slag interfacial thermal resistance, liquid film thermal resistance, and solid film thermal resistance over the total mold/shell thermal resistance is 27.5 to 34.4, 17.2 to 34.0, and 38.5 to 48.8 pct, respectively. The ratio of radiation heat flux is around 14.1 to 51.9 pct in the liquid slag film.     

Solidification and Particle Entrapment during Continuous Casting of Steel

Avoiding particle entrapment into the solidifying shell of a steel continuous caster is important to improve the quality of the continuous cast product. Therefore, the fluid flow dynamics in the steel melt and mushy zone, heat transfer and solidification of the steel shell, as well as the motion and entrapment of inclusion particles during the casting process were investigated using computational models. Solidification of the strand shell is modelled with an enthalpy‐formulation by assuming a columnar morphology in the mushy zone. The motion of particles is tracked with a Lagrangian approach. When the particles reach the solidification front, they can be entrapped/engulfed into the solid shell or pushed away from the solidification front, depending on the mushy zone morphology and the forces acting on them. The current paper focuses on the mould region at a steel continuous caster, including the submerged entry nozzle (SEN) and 1.2 m length of the strand. The results are validated with plant measurements and demonstrate the potential of the model to predict fluid flow, shell growth and the positions and the amount of entrapped/engulfed particles in the solidifying strand.     

Mold Simulator Study on the Initial Solidification of Molten Steel Near the Corner of Continuous Casting Mold

Metallurgical and Materials Transactions B - Corner cracks are one of the most widespread surface defects of continuous casting slabs, and they are especially severe for peritectic steels and...     

铝合金气滑铸造技术研究

对结晶器结晶结构进行设计，研究和开发油、气、水系统，并进行相应的工艺试验，结果表明，气滑铸造能够提高铸造速度，明显改善铸锭表面和内鄢组织质量。     

Influence of Electropulsing Treatment on the Initial Solidification of Molten Steel During Continuous Casting

Metallurgical and Materials Transactions B - An electropulsing-assisted mold simulator (EPMS) technique was developed to investigate the effect of pulsed electric current on the initial...     

Mathematical Modeling on the Influence of Casting Parameters on Initial Solidification at the Meniscus of Slab Continuous Casting

Metallurgical and Materials Transactions B - In the current study, the two-dimensional mold model was applied to investigate the influence of different casting parameters on the initial...     

Effect of Induction Heat on Initial Solidification During Electromagnetic Continuous Casting of Steel

 Aiming at the process of electromagnetic continuous casting (EMCC), a three dimensional finite element model on electromagnetic field and temperature field was developed through the commercial software ANSYS to investigate the effects of induction heat of high frequency electromagnetic field on the early solidification process of molten steel in soft contact mold under various conditions of exciting current parameters. The results show that the induction heat has significant effects on the early solidification process, which appear as increasing the billet surface temperature, thinning the initial solidified shell and lowering the starting point of the initial solidification. The increases of exciting current frequency and density make the effects of induction heat on solidification process increased remarkably. Especially, with the increase of exciting current frequency, the early solidification process and shell growth become non-uniform in billet circumferential direction. Morever, if the exciting current density exceeds a certain value, there occurs a high temperature region in the top of molten steel column, and then the initial solidification rate is decreased greatly.     

小方坯连铸坯壳凝固行为的研究

通过分析、测定拉漏坯壳和大生产中铸坯的情况,计算出连铸小方坯凝固坯壳的厚度及凝固系数,揭示了165mm×165mm小方坯连铸坯壳的生长规律和不均匀性,指出坯壳生长的不均匀性是造成连铸小方坯变形和角裂漏钢的前提条件,并为评价二冷系统的冷却能力、制定合理的二冷配水制度和高拉速条件下的工艺参数提供了重要依据。     

凝固末端轻压下技术在连铸中的应用

文章阐述了凝固末端轻压下技术的原理，介绍了这种技术的几种不同方式，并对其主要工艺参数轻压下的位置、压下率、总压下量、压下速率和拉速等等的确定进行了讨论和分析。对比了一些厂家使用末端轻压下技术的效果。末端轻压下技术对减少中心偏析很有效，对提高产品质量、生产高附加值产品有重要意义。     

方坯高效连铸凝固冷却的研究

建立了适应方坯高效连铸特点的凝固冷却数学模型,应用所建立的模型进行模拟计算,获得了高效方坯连铸的二次冷却制度和铸坯温度场等的变化规律。研究所获得的结果,应用于重庆钢铁设计研究所设计的方坯高效连铸机上进行生产获得了较好的效果。     

连续定向凝固过程铜铬合金的组织与缺陷

研究了铜铬合金的连续走向凝固的工艺条件及相互之间的匹配关系,以及铜铬合金的显微组织及其表面缺陷形成的原因.结果表明:结晶器高度10~25mm,冷却距离25 mm,合金温度1210~1280℃,牵引速度0.2~1.0mm/s,冷却水量720L/h时,可制得Cu-0.6% Cr合金材料.     

Microstructure and Properties of Cu-Fe-Cr-Ag Alloy Prepared by Directional Solidification and Upward Continuous Casting

A Cu-Fe-Cr-Ag alloy was prepared by directional solidification (DS) and upward continuous casting (UCC) to study the effect of different casting methods on the structure and properties of Cu-Fe-Cr-Ag. The results showed that the directionally solidified Cu-Fe-Cr-Ag alloy had excellent mechanical properties and conductivity. After cold drawing and isothermal aging, the peak tensile strength (789 MPa) and peak conductivity (65.5 pct IACS) of directionally solidified Cu-Fe-Cr-Ag alloy were 21 MPa and 4.7 pct IACS higher, respectively, than those that of the upward continuously casted Cu-Fe-Cr-Ag alloy. Compared to upward continuously casted Cu-Fe-Cr-Ag alloy, the Fe dendrites in directionally solidified Cu-Fe-Cr-Ag alloy were much finer, more uniform, and arranged along the direction of the magnetic field. Cu and Ag formed a Cu-Ag eutectic structure at the edge of the directionally solidified Cu-Fe-Cr-Ag alloy rod. After multi-stage thermomechanical treatment, Ag was mainly distributed around the material and formed a structure similar to Ag-clad Cu. The directionally solidified Cu-Fe-Cr-Ag alloy had a smaller lattice constant and finer Fe fibers. The small lattice constant and Fe fibers and the special distribution of Ag lead to the excellent comprehensive performance of the directionally solidified Cu-Fe-Cr-Ag alloy.

     

水平连铸中断面圆坯凝固过程的数学模拟

应用凝固传热数学模型水平连铸圆坯的生产工艺进行模拟，找出合理的二次冷却工艺，并在实际生产中进行了验证，应用所选定的合理二次冷却工艺，提高了铸坯质量。     

结合射钉实验与数值模拟对凝固进程精确预测研究

结合大方批连铸机设备和工艺特点与要求,采用射钉法测量不同工艺条件下40CrA和GCr15两个钢种的铸坯凝固坯壳厚度,并将测量结果与数值模拟结果进行了综合验证。结果表明,结合射钉实验和数值模拟能更精确跟踪铸坯的凝固进程,为轻压下工艺提供可靠的凝固信息。