An mixed analytical-numerical modeling for plate under hot rolling
—— Part Ⅰ: Temperature model
Zhen-shan Cui
Jin-ling Zhang Juan Liu
Department of Plasticity Technology, Shanghai Jiao Tong University, Shanghai, 200030, China
Abstract
A temperature model for plate hot rolling is developed by using series function solution. The model is a part of
mixed analytical-numerical modeling aiming at the prediction of deformation variables and microstructure
evolution for plate production by hot rolling. The model takes into account the heat generated by deformation and
the cooling effects resulted from hydraulic descale sprays, work roll chilling, radiation heat flux in interstand areas
and on-line water cooling operations. To accomplish the continuous computation of temperatures in the whole
process, compatible relationships of constants in the solutions are successfully established between passes and
operations. The model is employed in the simulation of an experimental 3-passes rolling of type 304 stainless steel
plate and an industrial 12-passes rolling of Q235A steel plate. The comparison of computed temperature with
measured data demonstrates a favorable coincidence, which verifies the validity of the model. The application also
indicates that the model can be easily employed in simulation of multi-pass rolling and other continuous
operations, with a quite short computational time.
Keywords: Mathematical model, Temperature, Steel plate products, Hot rolling
1. Introduction
To meet the increasingly high requirements on the plate product, many steel plate mills have been or will be
equipped with controlled-rolling and controlled-cooling techniques. The main purpose of these techniques is to
control the microstructure and hence the mechanical properties of the products
[1]
. Recent developments in the
metallurgical theories for the recrystallization, transformation and precipitation and in the computer simulation
technology for deformation and heat transfer make it possible to predict the final microstructure and consequently
the properties of the hot-rolled products
[2]
. Among the processing parameters, temperature is the most important
one to affect not only the deformation resistance but also the microstructure evolution. Many numerical studies on
temperature modeling have been developed for hot rolling, but because of the difficulty in dealing with multi-pass
rolling processes and the huge computational time, very few of these models can be directly applied in the design
of rolling schedule
[3]
. Many empirical temperature models are still currently employed in setting up mills,
therefore, there is a need for developing models based on fundamental knowledge that can be easily used in
multi-pass rolling and cooling processing with satisfactory precision, but with less calculation than finite element
or finite difference method.
In this research work, a mixed mathematical model for plate hot rolling is developed to predict the processing
variables and product microstructures. The model comprises temperature model, deformation and rolling force
model and microstructure model. As a part of the research work, this paper describes the temperature model,
which is developed by using series function method and can be employed for continuous calculation of
temperature variation during multi-pass hot rolling of plates. The model consist of three sub-models each of them
characterizing the feature of heat losing to the environment, contact chilling within the roll-gap, and water cooling
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