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Severe plastic deformation is now recognized the most efficient way of producing ultrafine grained metals and alloys. At the present time a lot of severe plastic deformation methods have been proposed and developed. They differ in the deformation schemes. Unlike such severe plastic deformation methods as high pressure torsion and equal-channel angular pressing, rolling with the velocity asymmetry is a continuous process. It helps to solve the problem of the limited length of manufactured bars with semi ultrafine structure. Rolling process with roll velocity asymmetry generates high shear strain necessary for obtaining ultrafine structures of the processed material. A new process of asymmetric rolling of profiles in multi-roll passes has been developed. This process can be used for production of high-strength profiles such as circles, hexagons, wire rods, etc. Compression of the bar in multi-roll passes can be done not only from two, as usual, but from three or four sides. In case of a multi-crimped bar, a uniform compression scheme with large hydrostatic pressure is created in the deformation zone. It enhances the ductility of the material and allows increasing the strain intensity. Simulation in DEFORM 3DTM proved that the process of asymmetric rolling in multi-roll calibers allows to obtain higher values of shear strain and strain effective.

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The paper gives a mathematical model of grain evolution and dislocation density during asymmetric cold rolling of aluminum alloy 7075 in an SPD mode. Correlations between the effect of equivalent and shear strain on Al 7075 structure are obtained. An agreement of simulation results with experimental data is shown.

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