【作者】 陈斌斌；

【导师】 关绍康；

【作者基本信息】 郑州大学 ， 材料加工工程， 2011， 硕士

【摘要】 哈兹列特双带连铸连轧工艺具有流程短,能耗低,成本低,效率高等优点,引起了世界范围内铝合金板带生产企业越来越多的关注。高效率和环境友好型的连铸连轧工艺逐渐成为铝合金板带生产工业发展的一个主要趋势。直冷铸锭热轧工艺是常规的铝板带生产工艺,它是一种多工序工艺,其工序包括熔化(合金化)、直冷铸造、锯头、铣面、预热和热轧(含热粗轧和热精轧),所生产的热轧卷经过冷轧后才能达到最终的厚度。双辊铸轧工艺的工序包括熔炼(合金化)、铸轧和卷曲。铸轧带坯需冷轧方能达到最终厚度,而采用哈兹列特双带连铸工艺时铸造之后接在线热连轧,其热轧带较铸轧带坯要薄,所需的冷轧工作量自然要少。哈兹列特连铸板坯的质量对终轧产品的性能有很大的影响。而哈兹列特双带凝固传热的数值模拟研究对提高连铸坯的表面质量、机械性能,改善微观组织非常重要,而且对哈兹列特利用余热进行热连轧节能非常有帮助。因此哈兹列特双带凝固传热的数值模拟研究非常有必要。本文运用有限元法对哈兹列特连铸坯的凝固传热过程进行了数值模拟,在适当的假设条件下,建立了哈兹列特连铸过程的二维传热数学模型,并用热焓法建立了适用于固相、液相和固液两相区的统一能量方程。用热阻串联模型描述并计算了哈兹列特复杂的气隙层的传热,求解了哈兹列特连铸坯的凝固传热过程的两维稳态温度场,给出了连铸坯表面、中心以及连铸机出口处断面的温度分布,研究了不同过热度,连铸速度,双带涂层对哈兹列特连铸坯温度场的影响。数值计算结果表明：(1)该传热模型比较全面的反映了哈兹列特连铸传热过程温度的变化、两相区和液芯长度的变化、坯壳的生长过程；(2)连铸速度、双带涂层对两相区长度和铸坯温度变化,尤其是连铸机出口断面温度,有较大的影响,而过热温度则对坯壳形成位置有明显的影响；(3)连铸速度、过热温度和双带涂层对连铸坯中心和表面的温差影响不大,它主要受双带冷却强度影响。更多还原

【Abstract】 Hazelett twin-belt continuous casting and rolling process is absorbing more and more attention of aluminum alloy plate and strip producers of the world for its advantages, such as short procedure, low energy consumption, low production cost and high productivity. Environment-friendly and high productivity continuous casting and rolling process is becoming main trend of aluminum alloy plate and strip processes. The conventional DC casting/hot mill process route include melting and alloying, DC casting, sawing, surface milling, rolling ingot preheating, and hot rolling(both roughing and finishing). The hot rolled strip is subsequently cold rolled to finish gauge. With twin-roll casting, the steps include melting and alloying, casting and coiling. The strip is subsequently cold rolled to finish gauge. In the twin-belt process, casting is followed by in-line hot rolling to produce a hot rolled strip that is thinner than twin-roll cast strip, requiring less subsequent cold rolling.The quality of Hazelett twin-belt continuous casting has big influence on the property of finished hot-rolled aluminum strip. The numerical simulation study on solidification and heat transfer of the twin-belt continuous casting is important to improve the surface quality, microstructure, and mechanical property of continuous casting aluminum strip and very helpful to take advantage of the heat in the as-cast strip to save energy and reduce the environmental impact, which is the biggest advantage of the Hazelett process. So it is very necessary to do some numerical simulation research on solidification and heat-transfer of Hazelett twin-belt continuous casting process.In this paper, a two-dimensional heat-transfer model which considers a generalized energy equation that is valid for the solid, liquid, and mushy zones in the Hazelett continuous cast was developed to simulate the solidification and heat transfer of twin-belt continuous casting of aluminum alloy slab by the finite element method under some assumptions. The heat transfer of Hazelett caster mold interface was described by an overall thermal resistance model. The steady state temperature field during the continuous casting was computed and the temperature distribution of slab surface, center and continuous casting exit was also computed when casting was close to steady state. the influence of process parameters such as casting speed, superheat and belt coat on temperature distribution was investigated. The result of calculation indicated as follows:(1) The Hazelett heat-transfer model built in this paper reflects mushy zone evolution, the length of liquid core and slab temperature distribution for the heat transformation process completely during Hazelett twin-belt continuous casting.(2) Continuous casting speed and twin-belt coat have big influence on temperature field, especially twin-belt caster exit temperature, super heat has much influence on the formation position of shell(3) Process parameters such as continuous casting speed, super heat, twin-belt coat have little influence on the temperature difference between center and surface of Hazelett casted slab, which is mainly influenced by twin-belt cooling condition更多还原