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Abstract:
The effect of severe plastic deformation (SPD) during cyclic multi-axis compression on grain refinement and strain hardening in interstitial free (IF) steel is studied quantitatively. In the experimental part, the material samples were cold deformed in the MAXStrain(R) system by successive compression in two mutually orthogonal directions. The electron backscatter diffraction (EBSD) technique was used to measure the average spacing of the dislocation cell (low angle) and cell-block (high angle) boundaries. In the modelling part, the decrease in size of dislocation cells and cell blocks was expressed in terms of the effective plastic strain defined such that strain-rate reversals slow down its accumulation. The strengthening effect of microstructural evolution was included in the continuum mechanics framework of finite strain plasticity. Examples of simulation of the behaviour of IF steel severely deformed by multi-axis compression are calculated and compared to experimental data.

Keywords:
Modelling, Microstructure, Hardening, Severe plastic deformation