Multiscale investigation of the complexity of plastic flow and phase transformation in a duplex medium manganese steel

The objective of this study will be achieved thanks to a combination of various experimental techniques allowing for an access to the hierarchy of scales involved in the collective deformation processes, and also due to application of various kinds of theoretical methods for the analysis of the recorded characteristics. The work on the project will be organized as follows.

• The team has already accumulated data on the evolution of both stress partitioning between different phases (HEXRD) and surface strains (DIC) during tension of a duplex steel containing 4% of Mn and prepared model microstructures with specific heat treatments. These data will allow to the post-doctoral fellow to tame theoretical methods described below.
• A new series of experiments aimed at relating the above-described characteristics to the deformation processes taking place at much finer scales will be implemented by combining DIC with the acoustic emission technique and high-frequency local extensometry.
• The so-obtained various responses of the material to the mechanical loading (fluctuations of the applied stress and internal stresses, evolution of local strain-rate field, acoustic activity) will be analyzed using complementary statistically-based methods including multifractal and rescale-range formalisms, refined composite multiscale entropy analysis, distribution functions, wavelet analysis, and so on.
• These investigations will be supported by the microstructure characterization using electron microscopy. It is also envisaged to propose an appropriate modeling, thanks to collaboration with researchers of LEM3 developing multi-scale plasticity models.