Effect of deformation speed on the microstructure and mechanical properties of AA6063 during continuous extrusion process

Abstract

Experiments and numerical simulations were conducted to analyze the continuous extrusion of AA6063 aluminum alloy under extrusion wheel angular velocities of 0.52, 0.78, 1.04 and 1.3rad/s. Simulation results indicate that variations in extrusion wheel velocity directly affect material deformation and significantly influence the maximum extrusion temperature. This work also reveals that deformation and temperature have opposing effects on the microstructure of the resulting product. A greater wheel velocity causes a higher strain rate and extrusion temperature. Increasing the wheel velocity, at an initially low speed, causes a large increase in strain rate. This results in a decrease in grain size. In contrast, at high wheel velocities, further increases to wheel velocity have much less effect on the strain rate, leading to an increase in grain size as the increased extrusion temperature dominates the mechanics of grain growth. Tensile test results demonstrate that the tensile strength of the resulting aluminum extrusions mainly depends on the exit temperature, which is decided by the deformation speed. Tensile strength and hardness slightly increase with increased deformation speed. Extremely high extrusion temperature results in brittle failure and low mechanical properties of the resulting product when the extrusion speed reaches 1.3rad/s. This paper suggests that an optimum extrusion wheel velocity, which will generate products with good mechanical properties, exists.