Finite element analysis of strain gradients in aluminium alloy sheets processed by asymmetric rolling

摘要

Gradient microstructures can be achieved due to creating of strain gradient, which can be considered as a mechanism to simultaneous improves the ductility and strength of metallic materials. Asymmetric rolling is one of the methods of severe plastic deformation and this process can be used to fabricate metallic materials with gradient microstructures. Searching the process parameters which provide predetermined strain gradient is very important. This paper presents the distributions of the effective strain through strip thickness of aluminum alloy Al-6.2Mg-0.7Mn processed by a single-pass asymmetric rolling. Effects of thickness reduction per pass (10...60%), rolls speed ratio (1...60%), diameters of the rolls (50...500 mm), contact friction coefficient (0.1...0.4) and initial strip thickness (1...8 mm) were investigated by the rigid-plastic finite-element analysis. The non-linear effect of rolls speed ratio on the strain gradient during asymmetric rolling was found. Extremely high predetermined strain gradient up to e ≈3...6 was reached during a single-pass asymmetric rolling. Finite element analysis of the deformation characteristics, presented in this study, can be used for development of the asymmetric rolling process as a method of fabrication of metallic materials with gradient microstructures.