Mechanical Properties and Microstructure of Aluminum Alloy Al-6061 Obtained by the Liquid Forging Process

Abstract

The liquid forging process has the flexibilities of casting in forming intricate profiles and features while imparting the liquid forged components with superior mechanical strength compared to similar components obtained via casting. Additionally, liquid forging requires significantly lower machine loads compared to solid forming processes. Currently, components that are formed by liquid forging are usually casting alloys of aluminum. This paper investigates the suitability of liquid forging a wrought aluminum alloy Al-6061 and the mechanical properties after forming. The proper handling of the Al-6061 alloy in its molten state is important in minimizing oxidation of its alloying elements. By maintaining the correct alloying composition of Al-6061 after liquid forging, these Al-6061 samples can subsequently undergo a suitable heat treatment process to significantly improve their yield strengths. Results show that the yield strengths of these liquid forged Al-6061 samples can be increased from about 90MPa, when they are in the as-liquid forged state, to about 275MPa after heat treatment. This improved yield strength is comparable to that of Al-6061 samples obtained by solid forming processes. As such, the liquid forging process here has been shown to be capable of forming wrought aluminum alloy components that has the potential for structural applications.