Experimental and Numerical Investigation of Heat Assisted Incremental Sheet Forming Process of Magnesium Alloy

Abstract

Magnesium alloys possess exceptionally good mechanical properties, primarily their excellent high strength to weight ratio, and have attracted many applications in the automobile and aerospace industries. However, their use is limited by the poor formability at room temperature when processed through conventional processes because the crystal lattice structure of magnesium is hexagonal closed packed (hcp), due to which there are limited sliding planes. At the elevated temperature ranges of 200–300 °C, more sliding planes get activated, which increases the ductility and decreases the flow stress. It leads to enhanced formability at a higher temperature for magnesium alloys. Therefore, several methods of heat-assisted single point incremental forming process (HA-SPIF) have been established by many researchers in order to improve the forming limits of such hard-to-deform materials. In this study, a new method of the heat-assisted single-point incremental forming process (HA-SPIF) is developed by using cartridge heaters to enhance the forming limits. The influence of higher temperature on fracture depth and thickness distribution of AZ31B magnesium alloy sheet is studied in detail. Experimental results indicate that the fracture depth and thickness distribution increases as the temperature increases. A coupled thermo-mechanical numerical simulation model using ABAQUS/EXPLICIT® is developed to predict forming limits; it was validated using the experimental results. The Johnson-Cook model was implemented as the constitutive model and also to define the fracture criterion. A reasonably good agreement between the results of the numerical simulation and those of the experiment is observed.