Comparison of Static and Dynamic Mechanical Response of Aluminum 6061 Subjected to Multi-Directional Forging

Abstract

The present investigation focuses on the implementation of the multi-axial forging process, recognized as a severe plastic deformation (SPD) technique, with the aim of elevating the mechanical features of the widely employed Al 6061 alloy. Specifically utilized in the automotive and aviation industries, this alloy's behavior was meticulously examined through a series of quasi-static and dynamic tests. To achieve this objective, the multi-directional forging (MDF) process was implemented for up to three cycles, involving a total of nine passes, at a raised temperature of 200 °C. Subsequently, the severely deformed material underwent utilizing high strain rate loading for the Split Hopkinson Pressure Bar (SHPB) test system. After MDF, the grain size is refined down to below 11 microns with a starting grain size of 13 microns. This is reflected as increased hardness and yield strength in the quasi-static regime. For SHPB characterization, increased dynamic strength is also observed. However, although the yield strength showed about 60% increase with decent ductility, the maximum dynamic strength increased about 10% after SPD with a relatively brittle behavior.