Effect of heat treatment on the microstructure and mechanical properties of AZ80M magnesium alloy fabricated by wire arc additive manufacturing

Abstract

To maximize the benefits of wire arc additive manufacturing (WAAM) processes, the effect of post-deposition heat treatment on the microstructure and mechanical properties of WAAM AZ80M magnesium (Mg) alloy was investigated. Three different heat treatment procedures (T4, T5 and T6) were performed. According to the results, after T4 heat treatment, the microsegregation of alloying elements was improved with the eutectic structure dissolved. Samples after T5 heat treatment inherited the net-like distribution of secondary phases similar to the as-deposited sample, where the eutectic structure covering the interdendritic regions and the β-phase precipitated around the eutectic structure. After T6 heat treatment, the tiny β-phases re-precipitated from the matrix and distributed in inner and outer of the grains. The hardness distribution of the samples went through T4 and T6 heat treatment was more uniform in comparison to that of T5 heat treated samples. The tensile test showed that the T6 heat treatment improved the strength and ductility, and the anisotropy between horizontal and vertical can be eliminated. Moreover, T4 treated samples exhibited highest ductility.

Keywords

• Wire arc additive manufacturing
• AZ80M magnesium alloy
• Heat treatment
• Microstructure
• Mechanical properties