摘要
CSP(contract strip production)薄板坯连铸连轧技术是20世纪80年代开发成功的生产热轧板卷的全新的短流程工艺，是继氧气转炉炼钢、连续铸钢之后钢铁工业最重大的革命性技术之一。它集科学、技术和工程为一体，将热轧板卷的生产在一条短流程的生产线上完成，充分显示出科学性和先进性，已经成为目前钢铁界的技术热点。
我国的CSP技术均引自国外，其中，生产过程软件(在线控制和离线指导)是引进技术的重要组成部分。为了加快我国CSP引进技术的国产化进程，消化吸收并开发出具有自主知识产权的薄板坯连铸连轧生产工艺过程控制和管理软件，是我国钢铁企业实现跳跃式进步的关键，是实现薄板坯连铸连轧技术自立开发和现有生产线优化管理的重要环节。薄板坯连铸连轧工艺热过程数字化正是这个软件的重要组成部分。
本文主要针对连铸热过程进行研究和数值模拟。连铸热过程主要为铸坯凝固冷却过程，本文依据在线模型的特点，结合包钢CSP生产线的具体特点，考虑多种因素诸如保护渣、二冷区铸坯表面换热系数及凝固率模型对铸坯凝固冷却的影响，首先尝试建立了被细化的连铸过程数学模型，通过数值计算，分析了部分操作、模型参数对板坯温度的影响。
本文在采用热源函数法处理凝固潜热、选用能反映两相区内溶质再分配的凝固率方程、考虑溶质运动的对流热的基础上，通过对连铸热过程模型的简化，建立了描述沿拉坯方向铸坯横断面在各个时刻温度变化的二维数学模型。通过计算，模型对多种操作和模型参数进行了数值模拟研究和分析，数字化铸坯断面上三个典型温度点的变化规律，同时给出结晶器出口处、二冷区和空冷区的出口处断面温度分布。
数值计算结果表明：
(1)模型比较全面地反映了连铸热过程坯壳的生长过程、液芯长度和铸坯温度变化，计算结果较真实，具有一定的实用价值；
门）拉坯速度、二冷区的冷却水量对铸坯温度分布、坯壳厚度和液芯长度影响
较大；钢液浇注温度仅对液芯长度有较大影响。
（3）气隙厚度和保护渣吸收系数对结晶器内坯壳厚度的生长影响较大，并进一
步讨论它们对板坯表面质量的影响，减小气隙宽度、增加保护渣吸收系数
有利于包晶钢的浇铸；凝固率模型仅对液芯长度有一定的影响，而对铸坯
温度的影响可以不计。
The technology of compact strip production is a new techniques with compact process on hot strip rolling which received successful development in 1980's as well as is one of the most important revolutionary technology of steel industry, following making steel with BOF and continuing casting, This technology that finishing rolling hot strip with a short line integrated science, technology and engineering has became the hot topic on iron-steel industry. Sufficient fact has been showed scientific and advanced.
All techniques of CSP used in our country originate from abroad. Process software (controlled on line and offline) is key component of the techniques. Learning, digestion and developing the CSP control system and management software, which have the intellectual asset, are the key step to promoting steel-maMng enterprise. And it is also a very important for developing CSP technology by self-reliant and optimizing management of production line. Therefore the digital model on heat transformation process of CSP is vitally component of this software.
This paper aims at researching process of heat-transfonnation and running numerrical simulation. Heat-transformation process of continuing casting is mainly cooling process on slab's solidification. According to the style of online model, combined with situation of BTCSP line, taking account of many effective factors such as mould powder, heat-transformation coefficient in slab surface of secondary cooling zone and solidification rate model. Through data calculated, we build the differential math model of casting process and analyze partial operation and model data, which effect on slab surface temperature.
We adopt heat source function to deal with potential heat during solidification and select solidification rate equation, which can reflect solute re-distribute in two different phases. We build a planar math model, which describe temperature change of slab section along rolling direction in any time through simplifying heat-transformation process model based on convective heat of planar movement. It analyzed and simulated data as well as the different operation through calculating, as result of getting
the principle of three typical temperature points on the slab section and the temperature distribution of mould exit, secondary cooling zone and the free cooling zone. The results on data calculation indicates:
(1) The model reflects the growing process, the length of liquid core and slab temperature for the heat transformation process completely during casting. This result that is really true has valuable for application.
(2) Casting speed and flow of secondary cooling have influence on distribution of temperature in slab surface, shell thickness and liquid core length. But the steel temperature only effects on liquid core length.
(3) Gap thickness and absorb coefficient of mould powder have much influence on shell thickness and slab surface. Therefore, it will benefit for casting peritectic steel through decreasing the gap thickness or increasing; absorb coefficient of mould powder. The model of solidification rate only influence on liquid core length, but not slab temperature.
引文
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