采用中等厚度连铸板坯＋“Coilplate”工艺生产中板——一种短流程、高效化的中板生产新工艺

介绍了国内外最新型的短流程、高效化中板生产新工艺、新技术，即采用中等厚度连铸板坯 “coilplate”工艺生产中板的工艺技术。结合国内外新建生产线的工艺及设备配置，对该工艺的主要技术特点、优势及生产方式进行了详尽的阐述。     

Properties of High Basicity Mold Fluxes for Peritectic Steel Slab Casting

 In high speed continuous casting of peritectic steel slabs, mold fluxes with high basicity are required for less surface defect product. However, the basicity of remaining liquid slag film tends to decrease in casting process because of the crystallization of 3CaO·2SiO2·CaF2. Thus, a way is put forward to improve mold fluxes′ properties by raising the original basicity. In order to confirm the possibility of this method, the effect of rising original basicity on the properties of mold fluxes is discussed. Properties of high fluorine based mold fluxes with different basicities and contents of CaF2, Na2O, and MgO were measured, respectively. Then, properties of higher basicity mold fluxes were discussed and compared with traditional ones. The results show that increasing the basicity index can improve the melting and flow property of mold fluxes. With the increasing basicity, crystallization rate of mold fluxes increases obviously and crystallization temperature tends to decrease when the basicity exceeds 1.35. The method presented before is proved as a potential way to resolve the contradiction between horizontal heat transfer controlling and solidified shell lubricating for peritectic steel slab casting. But further study on improving the flow property of liquid slag is needed. This work can be used to guide mold fluxes design for high speed continuous casting of peritectic steel slabs.     

直流焦耳处理对Co718Fe49Nb08Si75B15玻璃包覆非晶丝非对称巨磁阻抗效应的影响

 研究了Co718Fe49Nb08Si75B15玻璃包覆非晶丝经直流焦耳处理后的非对称巨磁阻抗效应。结果表明，随着处理电流的增加，阻抗最大变化率随之增大，并在处理电流为70 mA时达到最大值。在15 MHz的驱动电流下，阻抗最大变化率为335%，线性区域的灵敏度达1%/(A·m-1)。进一步提高处理电流，导致阻抗最大变化率减小。对钴基玻璃包覆非晶丝的AGMI性能特征用表面阻抗张量进行了讨论。     

中薄板坯连铸包晶钢结晶器液面波动原因分析

针对采用中薄板坯连铸机生产包晶钢时出现的结晶器液面波动大、铸坯废品率高等问题,分析认为,结晶器液面控制系统精度不高、包晶钢反应、夹杂物种类控制不当是主要影响因素。通过全面维护结晶器液面控制系统、优化脱氧合金制度,控制转炉终点氧化性等相应措施,结晶器液面波动由8～10mm降至3mm,改善了连铸坯的质量。     

中薄板坯高速连铸保护渣的研制开发

详述了中薄板坯连铸机的特征,以及保护渣设计过程中,为适应这些特征所必须遵守的原则.对开发出的保护渣试验结果进行了介绍,并对此作了比较详尽的分析和总结.     

含Cu钢连铸高温延塑性研究

含Cu钢因具备良好的强度、耐蚀性、焊接性能,被广泛地应用于船舶、压力容器、石油生产平台及工程机械。但由于选择氧化,Cu在钢表面富集,易导致含Cu钢在生产过程出现热裂纹。针对含Cu钢的这一特性,采用热拉伸试验研究了Cu含量对钢高温塑性的影响,对相同Cu含量、不同Ni含量的钢种热塑性也进行了对比,并结合其显微组织及断口形貌对试验钢种的脆性断裂机理进行探讨。同时,还利用Thermocalc软件计算了试验钢种的塑性低谷对应温度,提出了含Cu钢的连铸工艺优化建议。     

Numerical Simulation on Thermal Stress Field in a Wide Slab Mould of Peritectic Steel Continuous Casting

A numerical simulation of the thermal stress field of the solidified shell in the mold during continuous casting of peritectic steel slab was calculated.The results showed,owing to the volume contraction caused by the peritectic reaction,the thermal stress on the wide surface of the solidified shell was larger for the peritectic steel slab than that for the non-peritectic steel,and the maximum thermal stress on the wide face was at the 200-400mm position away from the central line.With increment of slab width,the thermal stress increased and the maximum value moved towards the central line.In addition,the thermal stress was also affected by the casting operation parameters.In the present work,the proper drawing speed was around 1.2m/min for the wide slab of 3200mm×150mm,with the cooling intensity of 5500L/min and the superheat degree of 15℃to 25℃.     

The Influence of Peritectic Reaction/Transformation on Crack Susceptibility in the Continuous Casting of Steels

The work presented here examines the surface cracks that can form during the continuous casting of near peritectic steels due to the volume changes during the peritectic reaction/transformation. The investigated samples were collected during plant trials from two different steel grades. The role and mode of the peritectic reaction/transformation are found to depend on the composition of the alloy, resulting in different types of surface cracks. The effect of the local variation in the cooling rate on the formation of the different types of cracks present in each steel grade, which can be due, for example, to the formation of oscillation marks, is demonstrated. The enhanced severity of the surface and internal oxidation, both of which depend on the alloy composition and consequent peritectic reaction, is highlighted. Experimental and theoretical studies show that different types of surface cracks can occur in peritectic steels depending upon the alloy composition and cooling rate, both of which define the fraction of the remaining liquid upon completion of the peritectic reaction/transformation.     

Thermodynamic Modeling as a Strategy for Casting High Alloy Steels

Strategies based on thermodynamic calculations can be used to overcome the problems associated with oxides encountered in steel plant operations, which can lead to certain difficulties in the process such as clogging of submerged entry nozzle during continuous casting. Approaches to producing high alloy steels by continuous casting have been taken. One of the strategies to avoid the oxidation of chromium is to add a small amount of other elements (subject to other constraints), which do not cause subsequent problems. The problem has been studied using the Thermo-CalcR software, with related databases; and the results obtained for different process conditions or generic com-positions have been presented.     

板坯连铸凝固过程微观组织参数的模拟研究

通过数学模型研究了在不同的凝固条件下中碳钢和300系列奥氏体不锈钢在凝固过程中的微观组织参数的变化关系,对枝晶生长速率、枝晶半径、二次枝晶臂间距、枝晶尖端温度、温度梯度等参数随坯壳生长的变化以及不同参数的改变对上述微观参数的影响进行了研究,并对两种钢种的微观组织参数进行了比较。结果表明由于不锈钢所具有的特殊组分和凝固特性使得其微观参数均比碳钢小,符合枝晶生长规律。     

亚包晶钢板坯连铸结晶器液面波动与控制

 针对亚包晶钢板坯连铸结晶器内经常出现的严重液面波动问题,从机制认识出发,进行了工艺试验研究。指出液面驻波和二冷区坯壳的非稳定鼓肚是导致结晶器液面波动的主要因素。通过调整亚包晶钢的化学成分,使其碳含量与实际包晶点的计算值接近,并适度增加二冷前区的冷却强度,可有效抑制液面波动。结果表明,亚包晶钢连铸突出的液面波动是因为其不均匀坯壳生长所造成的非稳定鼓肚。亚包晶钢实际碳含量距包晶点越近,相变收缩比例越小,坯壳厚度不均匀度以及后续坯壳非稳定鼓肚量的变化也将越小,有助于减小液面波动程度。