Effect of Increased Extrusion Ram Speed and Liquid Nitrogen Cooling on the Mechanical Properties of 6060 Aluminum Alloy

This study investigates the impact of increased extrusion ram speed—achieved by utilizing liquid nitrogen as a die cooling agent—on the mechanical properties of a 6060-aluminum alloy. Mechanical characterization of the extruded profiles was performed using both tensile and nanoindentation tests. In addition, nanoindentation was employed to evaluate creep behaviour and to extract key parameters, such as the steady-state creep strain rate. The findings indicate that while the enhanced ram speed has a minimal influence on Ultimate Tensile Strength (UTS) and Yield Tensile Strength (YTS), it has a more noticeable effect on elongation. Finite Element Analysis (FEA) was used in conjunction with nanoindentation data to model the mechanical behaviour of the alloy, showing good agreement with experimental tensile test results. This confirms the effectiveness of FEA-assisted nanoindentation as a reliable tool for mechanical assessment. Moreover, the results demonstrate that creep displacement is significantly influenced by the increased ram speed. However, the steady-state creep strain rate remained largely unaffected by variations in ram speed with the use of liquid nitrogen as a coolant. Notably, the creep stress exponent (n) was found to increase with higher ram speeds enabled by liquid nitrogen cooling.