ORIGINAL ARTICLE
An investigation of descaling spray on microstructural
evolution in hot rolling
F. Wang
&
L. Ning
&
Q. Zhu
&
J. Lin
&
T. A. Dean
Received: 18 December 2006 / Accepted: 7 May 2007 / Published online: 5 June 2007
#
Springer-Verlag London Limited 2007
Abstract High pressure water spray is used to remove
oxide scales in hot rolling of steel plate. This would reduce
the temperature temporarily on the workpiece surface. To
investigate the effect of temperature variation due to the
descaling spray on the microstructural evolution, a thermal-
mechanical coupled FE model has been established. The
heat loss due to the spray is experimentally measured and
modelled using the established FE model. The heat transfer
coefficient is determined using an inverse engineering
method. A set of unified viscoplastic constitutive equations
is implemented into the commercial FE solver MARC
through the user-defined subroutine CRPLAW. The effect
of descaling water spray on the surface temperature
variation is numerically studied. Furthermore, the effect of
surface temperature variation on the evolution of disloca-
tion density, recrystallisation and grain growth is investi-
gated for various hot rolling conditions.
Keywords Hot rolling
.
Thermal-mechanical modelling
.
Microstructural evolution
.
Unified constitutive equations
.
Materials modelling
1 Introduction
Mechanical properties of hot rolled plates are strongly
influenced by their microstructural features, which are
controlled by dynamic and static recrystallization, grain
growth, etc, in hot rolling processes. The temperature and
deformation are the two main factors that determine how
and when the microstructure evolves [1]. Over the past
decade, the technology of thermo-mechanical control
process (TMCP) is a very popular method in steel
production to control austenite recrystallisation and grain
size, especially in plate rolling. It improves the mechanical
properties of low carbon micro-alloyed steels, allowing
lower costs and higher productivities to be achieved, in
comparison to heat-treatment after rolling. By carrying out
various deformation conditions, microstructural evolution
of metal materials can be controlled. It is thus essential to
study the effects of controlled rolling on the microstructural
evolution, to ensure the desired properties are achieved.
FE simulation has been used to investigate the micro-
structure variation in a hot forming process, with the use of
mechanism-based material models, which can describe the
interactive effect of deformation, deformation rate and
microstructural evolution [1–14]. For example, Glowacki
[3] has developed a coupled-thermo-mechanical-micro-
structural model to predict static recrystallisation and
austenite grain growth. Rebelo et al. [4] developed a finite
element model that coupled microstructural factors with the
temperature and velocity fields. Bontcheva [5] combined
the thermal-mechanical FE model with microstructural
relationship to investigate recrystallisation mechanisms
and phase transformation so as to obtain a reasonable
rolling condition in shape rolling of steel rod. A set of
mechanism-based unified viscoplastic constitutive equa-
tions has been developed by Liu and Lin [7]and
implemented into an FE solver to predict recrystallisation
and grain size evolution in multi-pass hot rolling. Wang [8]
simulated the static and dynamic recrystallisation of
austenite during hot rolling using a macro-micro combined
Int J Adv Manuf Technol (2008) 38:38–47
DOI 10.1007/s00170-007-1085-x
F. Wang
:
L. Ning
:
Q. Zhu
Shougang Technology Institute, Shougang Group,
Beijing 100041, People’s Republic of China
J. Lin (*)
:
T. A. Dean
Department of Mechanical & Manufacturing Engineering,
School of Engineering, University of Birmingham,
Edgbaston, Birmingham B15 2TT, UK
e-mail: j.lin@bham.ac.uk