How to properly investigate recrystallization in wrought aluminum alloys

During the production of wrought aluminum alloys, depending on the material
recrystallization may occur at several stages in the process chain, affecting the final
microstructure. Since microstructure is directly related to material properties, an
understanding of recrystallization is of great importance. Investigations are challenging due
to the rapid transformation and multiple mechanisms interacting at the microscale. Adequate
characterization is not easy and the method used must be carefully selected depending on
the research question. In this work, different methods such as hardness measurements,
optical microscopy, in situ electron backscatter diffraction (EBSD) and ex situ EBSD have
been tested and their applicability to the problem has been evaluated. Each method has its
advantages and disadvantages, and there are limitations that are not obvious at first glance.
An industrial AA8079 foil stock alloy was used to test the methods. The recrystallization
kinetics were determined using the different methods and the results are compared and
discussed. In addition, the initial phase of recrystallization was studied in more detail using in
situ EBSD. The interaction between subgrain growth and nucleation of new grains was
recorded and the results are discussed. Recrystallization and concurrent precipitation were
studied in an industrial AA6016 alloy for automotive applications. Precipitation was found to
have a strong influence on the recrystallization kinetics depending on the heating rate.