Effect of Remelting and Recasting on Microhardness Distribution and Microstructural Evaluation of Aluminum Alloy 6061-T6

Azwar Yunus, Akhyar Akhyar, Iskandar Hasanuddin, and Agus Sasmito

DOI: https://doi.org/10.64486/m.66.2.8
Online publication date: August 27, 2026

Abstract: Aluminum Alloy 6061-T6 is widely used in engineering applications because of its favorable mechanical properties, corrosion resistance, and formability. This study investigated the effect of a single remelting and recasting cycle on the microstructure and spatial distribution of microhardness of Aluminum 6061-T6. The alloy was remelted at approximately 800 °C and gravity cast into a metal mold. Microstructural characterization was performed using optical metallurgical microscopy, while Vickers microhardness was measured at multiple locations across the casting. The wrought material exhibited a relatively homogeneous microstructure with fine and uniformly distributed microstructural features and an average hardness of 134 HV0.5. After remelting and recasting, the average hardness decreased to approximately 89 HV0.5, with values ranging from 80 HV0.5 to 103 HV0.5. Optical microscopy showed a coarser and more heterogeneous microstructure after recasting, together with features consistent with casting-related imperfections. The observed reduction and spatial variation in microhardness were associated with the transition from the original precipitation-hardened T6 condition to a more heterogeneous as-cast microstructure.

Keywords: aluminum alloy 6061-T6; remelting; recasting; microstructure evolution; hardness distribution; precipitation hardening

This article is published online first and will appear in Metalurgija, Vol. 66, Issue 2 (2027).