Research Initiation: Thermomechanical Treatment of Moving Metal Strips in Rolling Processes

提出了一种实验与数值相结合的方法来研究运动金属带材在轧制过程中的热机械处理。为了提高产品质量，降低生产成本，采用了控制冷却的TMT工艺。然而，关于冷却过程的传热行为的信息很少。因此，对带钢轧制的热行为进行了研究。特别强调了在移动带材上射流沸腾的局部对流换热系数的测量。三种冷却系统将被调查和比较：喷雾冷却，层流射流和水帘。具有快速响应时间（微秒级）的表面热电偶和薄膜热流计将用于测量瞬时表面温度和热流。有限差分方法将使用欧拉和拉格朗日方法来分析数据并预测轧制条件下的带钢温度。研究了带钢材料、带钢温度、带钢移动速度以及射流速度和射流构型对局部换热系数的影响。控制冷却技术是近年来发展起来的一种对热连轧机脱模台上的带钢进行在线热处理的技术。其结果是在轧制条件下连续生产出高质量的产品。然而，目前的冷却系统设计主要是基于试错法，因为传热行为还没有得到很好的理解。在提出的研究中，需要更好地理解带钢冷却过程的热学和力学行为。

A combined experimental and numerical research program is proposed to study the thermo-mechanical treatment (TMT) of moving metal strips in rolling processes. TMT using controlled cooling has been adopted to improve product quality and to reduce production cost. However, very little information is available on the heat transfer behavior of the cooling process. Therefore, this research is initiated to study the thermal behavior of strip rolling. Particular emphasis is placed on the measurement of the local convective heat transfer coefficients for jet boiling on moving strips. Three cooling systems will be investigated and compared: spray cooling, laminar jets, and water curtains. Surface thermocouples and thin film heat flux gages with fast response times (on the order of microseconds) will be used to measure the instantaneous surface temperatures and heat fluxes. Finite difference methods will be developed using Eulerian and Lagrangian approaches to analyze data and to predict strip temperatures in rolling conditions. The effect of strip material, strip temperature, and moving speed as well as the jet velocity and jet configuration on the local heat transfer coefficients will be investigated. Controlled cooling technology has recently been developed to perform on-line thermo-mechanical treatment (TMT) of the strips on the run out tables of hot-strip-mills. The result is a continuous process for producing high quality products in the as- rolled conditions. At present, however, the cooling system design is primarily based on a trial-and-error approach because the heat transfer behavior is not well understood. A better understanding of thermal and mechanical behavior of the strip cooling processes as described in the proposed research is needed.