软接触结晶器电磁连铸中拉坯阻力的实验研究

软接触结晶器电磁连铸可以改善铸坯的表面质量,但其电磁场对拉坯阻力的影响以及拉坯阻力与铸坯表面质量间的关系仍值得研究。笔者设计并制作了悬臂梁应变仪,在小型连铸机上测定了软接触结晶器电磁连铸过程中结晶器内的拉坯阻力,并对连铸坯的表面质量进行了分析。结果表明：①在本实验条件下,随着拉坯速度的提高,无论有、无保护渣或连续的高频电磁场,拉坯阻力均增加,铸坯表面质量下降;②施加保护渣或连续的高频电磁场都能显著降低拉坯阻力,而且拉坯速度越大,拉坯阻力下降的幅度越大;③随着磁场强度的增加,拉坯阻力减小,铸坯表面质量提高。但当磁场强度达到一定程度时,拉坯阻力开始增大,相应的铸坯表面质量下降。这表明,铸坯表面质量与拉坯阻力直接相关。     

电磁软接触连铸技术对连铸坯表面振痕的影响及原因探讨

电磁软接触连铸技术是一门新兴技术．讨论了电磁软接触连铸技术的产生背景和发展过程;分析了其作用原理;综述国内外学者利用电磁软接触连铸技术实验的冶金效果;实验研究了有无电磁场作用下弯月面区域结晶器壁温的温度变化规律．结果表明：电磁软接触连铸技术可以提高结晶器内壁和金属熔池温度,改善铸坯的初始凝固过程,减轻振痕,提高铸坯的表面质量．最后提出了电磁软接触连铸技术研究中还需进一步研究的关键问题．     

软接触结晶器电磁连铸技术研究现状

 从磁场分布和结晶器设计、磁场对铸坯表面质量改善的机理、电磁场作用下结晶器内弯月面的行为、磁场施加方式的演变等几个方面,综合论述了软接触结晶器电磁连铸技术的发展现状,并指出了该技术未来发展过程中值得注意的几个方面。     

高频调幅磁场下无结晶器振动电磁连铸技术的实验研究

为了在连铸过程中用电磁力的振动代替结晶器的机械振动,成功研制了可以产生方波、正弦波、三角波3种波形的高频调幅磁场发生器,并对其在结晶器内产生的磁场进行了测量.进行了3种波形高频调幅磁场下的无结晶器振动电磁连铸实验,结果表明①在方波、三角波和正弦波调幅磁场作用下的无结晶器振动电磁连铸过程中,当调制波频率略低于系统固有频率时,弯月面与结晶器器壁间断接触距离最大,保护渣润滑效果最好,连铸过程拉坯阻力最小,连铸坯表面质量相对较好.②在3种高频调幅磁场中,从减小拉坯阻力和改善铸坯表面质量的角度讲,正弦波在整体上要稍优于三角波和方波.     

软接触结晶器连铸实验与电磁场分析

软接触结晶器连铸准三维电磁场数值模拟,结合锡等低熔点金属的软接触连铸实验,分析了软接触结晶器连铸中电磁场频率及感应圈电流等与铸坯表面磁感应强度、电磁力及电磁压力的关系。     

日本在软接触电磁连铸方面的最新研究进展

主要介绍了软接触电磁连铸的原理和日本最近几年来在软接触电磁连铸方面的研究进展,分析了电流强度、焦耳热、结晶器形状和早期凝固壳形态对铸坯表面质量的影响,提出了该技术还需进一步研究的关键问题.分析认为：感应线圈产生的焦耳热是决定铸坯表面质量的首要因素;电流强度存在一个最佳值,过大或者过小均会对铸坯表面质量产生不利影响;连铸条件相同时,角部形状为圆角的结晶器所生产出来的铸坯表面质量要好于角部形状为直角的结晶器.     

连铸坯表面质量的改善

为了改善连铸坯的表面质量，发展了两项新的浇铸技术，一是在结晶器外面，外加间歇式高频磁场，另一技术是同时外加间歇式高频磁场和结晶器振动。用熔融镓模拟钢须的动态变化，并根据数字解析弯月面的变形，表现这处新技术的特征。在结晶器用锡模拟钢液观察表面质量。高频磁场的外加，减少结晶器振动对熔融金属与结晶器间的流体通路里的动压力影响和抑制弯月面形状的变化。     

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.     

高频磁场作用下软接触电磁连铸初生坯壳的变形行为

结晶器内初生坯壳的变形行为直接决定着连铸坯的表面质量。笔者运用Reynold润滑方程推导出渣膜内的动压力分布,建立了初生坯壳的二维弹塑性变形有限元模型,研究了施加电磁场前、后坯壳的变形行为。研究结果表明：高频磁场(20kHz)下的感应加热作用会降低保护渣的粘度;电磁压力将增加渣缝的宽度,使施加电磁场后连铸坯初生坯壳的变形行为受到影响,进一步解释了软接触电磁连铸技术改善坯壳表面振痕的机理。     

方坯软接触电磁连铸实验研究

利用低熔点 Sn- 10 Pb合金进行高频磁场作用下 10 0 m m× 10 0 m m方坯软接触电磁连铸实验研究 ,考察电源功率、弯月面位置以及感应线圈匝数对铸坯表面质量的影响 ,以确定软接触电磁连铸工艺所需最佳工艺参数。在此基础上成功地进行了钢的软接触电磁连铸实验 ,在高频磁场作用下 ,所得钢坯表面振痕明显减轻 ,角部裂纹基本消失。     

Solidification in Soft-Contact Continuous Casting Mold with Alternating Electromagnetic Field

Ａｓａｎｅｆｆｅｃｔｉｖｅｔｅｃｈｎｉｑｕｅ ,ｓｏｆｔ ｃｏｎｔａｃｔｅｌｅｃｔｒｏ ｍａｇｎｅｔｉｃｃｏｎｔｉｎｕｏｕｓｃａｓｔｉｎｇｔｅｃｈｎｏｌｏｇｙｉｓｒｅｃｅｎｔｌｙｉｎｔｒｏｄｕｃｅｄｉｎｔｈｅｃｏｎｔｉｎｕｏｕｓｃａｓｔｉｎｇｐｒｏｃｅｓｓｔｏｃｏｎ ｔｒｏｌｔｈｅｉｎｉｔｉａｌｓｏｌｉｄｉｆｉｃａｔｉｏｎａｎｄｉｍｐｒｏｖｅｔｈｅｑｕａｌｉｔｙｏｆｂｉｌｌｅｔ[1,2 ] .Ｔｈｅｈｉｇｈｆｒｅｑｕｅｎｃｙｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｆｉｅｌｄｉｓｕｓｅｄｍａｉｎｌｙｔｏｃｏｎｆｉｎｅｔ…     

特殊钢的连铸

特殊钢一般含有一定的合金元素,冷却凝固状态不同于普通碳素钢,在连铸坯中更易产生成分 和组织偏析,和表面裂纹等缺陷。所以冶炼特殊钢时应提高钢水的纯洁度,减少夹杂物含量和改善夹杂物形 态,连铸时采用钢液二次氧化和污染,以减少铸坯低过热度(10～15℃)浇注和保护浇铸技术,防止成分和组 织偏析,提高铸坯表面质量和内部致密度。叙述了连铸保护浇铸技术,中间包冶金,电磁搅拌、凝固末端轻压 下特殊钢连铸专用覆盖剂、保护渣和自动化技术。讨论了特殊钢连铸工艺参数,存在的问题和对策。     

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.     

电磁软接触方坯连铸实验研究

简要介绍了软接触电磁连铸技术的原理,分别从电源功率、结晶器切缝形式、弯月面位置、线圈匝数四个方面阐述了其对结晶器内磁感应强度和作用范围的影响,在此基础上进行了Sn-10%Pb合金和0.8%C钢拉坯实验,结果表明铸坯表面质量明显改善,振痕为传统连铸的10%,角部裂纹消失.     

W9高速钢的电磁连续铸造研究

 研究了W9高速钢的电磁连续铸造工艺和铸坯的凝固组织特征,并与普通的模铸高速钢中共晶碳化物的类型和分布情况进行了比较,测定了在不同制备条件下高速钢莱氏体网的厚度和凝固冷却速度。结果表明：电磁连续铸造得到的高速钢铸坯表面光滑、振痕轻微、外观形状规整、内部组织致密无缺陷,莱氏体网明显变薄,晶粒明显细化;M2C和MC型碳化物的析出量增多,M6C型碳化物的析出量减少,合金碳化物变得细小、均匀和弥散;铸坯边部的凝固冷却速度为3.4×104 K/s,r/2处为6.5×103 K/s,心部为3.9×102 K/s,冶金质量明显优于普通模铸。     

Effect of Structure Parameters on Power and Magnetic Field in Electromagnetic Soft-Contact Continuous Casting System

To design a power source system and mold for electromagnetic soft-contact continuous casting process and to theoretically estimate the heat losses from the charges and the system power, the effect of structure parameters on system power and magnetic flux density distribution was calculated using finite element method. The results show that as for electromagnetic soft-contact continuous casting system with partial-segment type mold, the power consumption is much more than that with a full-segment type mold; about 62% of electric power is dissipated in the mold, and the effective acting range of magnetic field is relatively narrow. Optimizing mold structure is a crucial measure of remarkably reducing mold power consumption and saving electric energy. Increasing slit number, width, and length can remarkably increase the magnetic flux density in the mold and can reduce the electric energy consumption. Among structure parameters, slit number and slit width are relatively more effective to reduce energy consumption. For a round billet electromagnetic continuous casting system with diameter of 178 ram, the reasonable slit number, width, and length are about 24--32, 0. 5--1.0 mm, and 160 mm, respectively.     

Effect of exciting current of high frequency electromagnetic field on initial solidification of steel during electromagnetic continuous casting

Abstract

A three-dimensional finite element model of the electromagnetic field and temperature field of electromagnetic continuous casting (EMCC) process was developed. The aim was to investigate the effects of induction heat of high frequency electromagnetic field on the early solidification process of molten steel in mould 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 in exciting current frequency and density make the effects of induction heat on solidification process increase remarkably. Especially, with the exciting current frequency increase, the early solidification process and shell growth become non-uniform in billet circumferential direction. Furthermore, 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 greatly decreased. As a conclusion, the effects of induction heat on initial solidification process must be considered when the exciting current frequency and density are adjusted during the electromagnetic continuous casting process.     

1Cr13半马氏体不锈钢连铸坯纵裂纹形成机理及控制

针对1Cr13半马氏体不锈钢包晶反应凝固组织不均匀、高温力学性能差等特点,分析了邢钢炼钢厂6#连铸机1Cr13半马氏体不锈钢连铸坯纵裂纹形成的机理,从过热度、拉速、冷却制度、结晶器电磁搅拌、保护渣选择等方面,使连铸坯表面纵裂纹得到了有效控制,连铸坯修磨损失率降低了3.4％.     

A mold simulator for the continuous casting of steel: Part I. The development of a simulator

Surface defects, such as oscillation marks, ripples, and cracks that can be found on the surface of continuously cast steel, originate in the continuous casting mold. Therefore, a detailed knowledge of initial solidification behavior of steel in a continuous casting mold is necessary because it determines the surface quality of continuously cast slabs. In order to develop an understanding of the initial solidification of continuous cast steels, a “mold simulator” was designed and constructed to investigate heat-transfer phenomena during the initial phase of strand solidification. The mold simulator was used to obtain solidified steel shells of different grades of steel under conditions similar to those found in industrial casting operations. The resulting cast surface morphologies were compared with industrial slabs and were found to be in good agreement, indicating that it is possible to simulate the continuous casting process by a laboratory scale simulator.     

电磁搅拌对石油管用圆坯内部质量的改善

针对P110级石油管用圆坯27Mn2Cr钢连铸坯凝固组织差、中心缩孔严重等缺陷,结合实际生产工艺进行分析,发现不适宜的电磁搅拌工艺及与拉速匹配性差是引起上述问题的主要原因。因此,对结晶器和末端电搅强度进行测量及优化,同时建立?220 mm规格圆坯凝固传热模型,以确定合理的连铸机拉速。通过分析表明,拉速由1.30 m/min提高至1.70 m/min并搭配合理的电搅工艺,铸坯中心等轴晶所占比例由16%提高至25%,中心缩孔消失;同时铸坯内部碳偏析指数范围由0.938~1.062缩小至0.951~1.038,改善了石油套管用圆坯的内部质量。