Materials Science and Engineering A293 (2000) 173 – 184
Dynamic recrystallisation in a copper/stainless steel
pseudo-two-phase material
A. Manonukul, F.P.E. Dunne *
Department of Engineering Science, Uniersity of Oxford, Parks Road, Oxford OX13PJ, UK
Received 29 November 1999; received in revised form 22 May 2000
Abstract
The initiation and development of dynamic recrystallisation in a pseudo-two-phase material have been investigated to study the
effect of area fraction and distribution of the pseudo-second phase. Hot compression tests have been conducted at 400°C on
specially fabricated pseudo-two-phase copper test specimens and single-phase copper test specimens. A material model has been
implemented into finite element software coupled with the recently proposed criterion for initiation of dynamic recrystallisation
in single-phase materials. Micro-mechanical models have been employed to predict deformation, the initiation of dynamic
recrystallisation and microstructural change in the pseudo-two-phase specimens. Good agreement is observed between the
experimental results and the model predictions. It is found that an increase in area fraction of pseudo-second phase accelerates
the initiation of dynamic recrystallisation but reduces the spatial development of recrystallisation. Furthermore, the intensity of
localised deformation and the constraint imposed by different configurations of rigid pseudo-second phase influence the initiation
of dynamic recrystallisation and its spatial development. A distribution with lower intensity of localised deformation and less
constraint has a later initiation of dynamic recrystallisation and a larger spatial development of recrystallisation. The bonding
condition between matrix/fibre interfaces influences the nominal strain to initiation, locations where dynamic recrystallisation first
occurs and the spatial development of recrystallisation. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Dynamic recrystallisation; Modelling; Two-phase materials; High temperature deformation
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1. Introduction
Dynamic recrystallisation (DRX) is important in a
range of metal forming processes and particularly so
for materials in which their mechanical properties are
largely determined by their microstructure. Whilst con-
siderable attention has been given to DRX in single-
phase materials, it is not the case for DRX in
two-phase materials. Better understanding of DRX
during hot deformation can help engineers to improve
the quality of their products. Computer process simula-
tion is increasingly popular as a tool for optimisation of
product design and product quality. Much of the re-
search on DRX modelling has been focused on single-
phase materials or ignores the effect of second-phase
particles. Many commercial alloys, however, are two-
phase materials, and form an important class of materi-
als used, for example, in aero-engine components, and
this is the driving force for this research.
Investigation of DRX in single-phase materials has
covered a large range of materials with low to medium
stacking fault energies. The influence of each deforma-
tion parameter, e.g. temperature, strain, strain rate and
initial microstructure, has been individually investi-
gated. The effect of deformation conditions on the
DRX behaviour is well understood. In contrast, two-
phase systems have received less attention. There are a
significant number of experimental studies for two-
phase systems undergoing static recovery. However,
fewer data for DRX in two-phase systems are available.
Some investigations are based on two-phase alloys, in
which it is difficult to vary each second-phase parame-
ter independently. In many cases, both phases deform
and the effect of one phase on the behaviour of the
other phase is not clearly understood. On the other
hand, in metal matrix composites, most investigations
* Corresponding author. Tel.: +44-1865-273140; fax: +44-1865-
273905.
E-mail address: fionn.dunne@eng.ox.ac.uk (F.P.E. Dunne).
0921-5093/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
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