Influence of Process Parameters on Distribution of Shear Strain through Sheet Thickness in Asymmetric Rolling

Abstract

Materials with ultrafine grain structure and unique physical and mechanical properties can be obtained by methods of severe plastic deformation, which include asymmetric rolling processes. Asymmetric rolling is a very effective way to create ultrafine grain structures in metals and alloys. Since the asymmetric rolling is a continuous process, it has great potential for industrial production of ultrafine grain structure sheets. Basic principles of asymmetric rolling are described in detail in scientific literature. Focus in the well-known works is on the possibility to control the structure of metal sheets. However the systematic data on the influence of the process parameters (e.g., ratio of rolls velocity mismatch, reduction per pass, friction and diameter of rolls), and the shear strain rate required to achieve a significant grain refinement in asymmetric rolling are lacking. The influence of ratio of rolls velocity mismatch, reduction per pass, friction and the rolls diameter on the distribution of shear strain through the sheet thickness in asymmetric rolling has been studied in DEFORM 2D. The results of the study will be useful for the research of evolution of ultrafine grain structure in asymmetric rolling.

Simulation of nonmonotonic metal flow during asymmetric sheet rolling with different velocities of the rolls

“…Перспективным методом ИПД с точки зрения возможности его практического применения явля-ется метод асимметричной тонколистовой прокат-ки [4][5][6][7][8][9][10][11]. Целенаправленная асимметрия процесса достигается за счет рассогласования окружных скоростей валков, при этом холодную прокатку осуществляют в условиях высокого контактного трения с большими разовыми деформациями.…”

Finite Element Modeling of Roll Wear during Cold Asymmetric Sheet Rolling of Aluminum Alloy 5083

“…In all cases, the three lubrication regimes were identified. The To obtain a high uniform shear strain [12] and ultrafine grain structure through the sheet thickness during asymmetric rolling of aluminum alloys is necessary: 1) contact friction should be very high (friction coefficient is about 0.32); 2) thickness reduction per pass should be very high (about 50% or more); 3) mismatch factor of roll velocities should be equal to thickness reduction per pass and should be no less then 2. However it can be the reason of a high depth of roll wear.…”

Heat transfer modeling in asymmetrical sheet rolling of aluminium alloys with ultra high shear strain

“…Influence of process parameters on distribution of shear strain through sheet thickness during asymmetric rolling was investigated by FEM in [20]. It was found that shear strain strongly depends on opposite contact friction forces operated in the deformation zone.…”