Effect of the deformation history on the recrystallisation kinetics of Al-1%Mg alloy.

The literature concerning the industrial hot rolling of commercial
aluminium alloys and the structural modifications that take place
throughout the operations of such processes has been reviewed. Particular attention has been given to the static restoration processes that
occur during the time intervals between deformations of non-heat treatable commercial alloys. Experimental and predictive methods of analysis
of strain and temperature distributions developed during deformation
under plane strain compression conditions have also been surveyed.
Single and multiple deformation tests were performed on specimens of
commercial-purity aluminium, A1-l%Mg and A1-l%Mg-l%Mn alloy using a
plane strain compression testing machine operated by computercontrolled servohydraulic systems, with furnaces and quenching
facilities. Basic stress-strain data derived from such tests in the
range 300-500°C and 1-100 s * were used in conjunction with the
appropriate model to describe previous deformation history, in the
simulation of hot rolling operations carried out on these materials
both on laboratory and industrial scales. However, such a model
required knowledge of the functional dependence of the time to a fixed
recrystallised fraction and the recrystallised grain size, on variables
such as: strain, strain rate, temperature and initial grain size,
which was achieved by means of restoration and recrystallisation
experiments after one deformation. Also, restoration studies carried
out after two deformations allowed the investigation of the effect of
the presence of recrystallisation between the first two deformations on
the kinetics of recrystallisation and the recrystalisation-restoration
relationship during the interpass interval between second and third
deformations. Recrystallisation of the individual fractions with
different accumulated strains seems to take place independently of each
other. Reasonable agreement has been obtained between the computer
predicted load trend and the one found experimentally during the
industrial hot rolling of commercial-purity aluminium and Al-l%Mg
alloy.