Modelling of deformation inhomogeneity in the angular accumulative drawing process—multiscale approach

Abstract

This study presents a multiscale finite element modelling strategy to predict deformation and microstructure inhomogeneity in the drawn wires. Recently developed AAD (Angular Accumulative Drawing) method is used as a powerful tool to accumulate the deformation energy and optimise the properties and microstructure of the drawn product. The AAD process is characterised by a complex strain path history that is a result of various modes of deformation (drawing, bending, burnishing, shearing and torsion). The main idea of the AAD is producing wires with high plastic strain inhomogeneity. In consequence, this leads to increased deformation energy accumulated in the drawn product and, in turn, to much higher tensile strength and ductility. It was shown in the present study that the inhomogeneity of microstructure refinement plays an important role in the texture formation. Also, combination of regions characterised by different features contributes to the final properties of the product. The analysis of drawn by AAD products starts to be especially complicated in the case of microalloyed steels. Strain and microstructure inhomogeneities that exist in the drawn wire were predicted using multiscale computer model. In order to make the model strain path sensitive, non-linear hardening rule was applied. Necessary parameters were identified using inverse analysis based on the cyclic torsion tests. The texture inhomogeneity existing in the drawn wires was predicted using crystal plasticity based modelling. It has been shown that the effect of complex strain path history that exists in the AAD process can be effectively controlled by computer simulation.