Effect of Eliminating the Solution Heat Treatment on the Mechanical Properties and Microstructure of Hot-Forged Aluminum Alloys

The EN AW 6082 aluminum alloy stands out as a highly favored material in automotive, aerospace, defense, and general engineering sectors, chiefly owing to its excellent strength-to-weight ratio, formability, and heat treatment capabilities. This study introduces an integrated manufacturing route specifically designed for fabricating 6082 aluminum cooker valves by completely eliminating the traditional post-forging solution heat treatment. In this streamlined approach, the components undergo direct water quenching straight after hot forging, which is immediately followed by artificial aging. The primary objective of this approach is to reduce the number of processing steps in the production line, shorten the overall cycle time, decrease energy consumption, simplify the process flow, and improve manufacturing efficiency. Within this scope, the conventional process and the proposed integrated process were comparatively evaluated in terms of both microstructural and mechanical properties. Microstructural characterization was performed using optical microscopy, and similar overall morphologies were observed for both processes. However, the samples produced via the integrated route exhibited greater cross-sectional microstructural stability, characterized by a uniform grain structure from the surface to the core. In contrast, the conventional process showed indications of microstructural heterogeneity in certain regions, including local variations and features associated with a tendency for abnormal grain growth that was attributed to the additional solution heat treatment step. These adverse effects were found to be more limited in the integrated process, where microstructural stability was better preserved. Mechanical performance evaluation revealed that the Brinell hardness values of both production routes were very close, both hovering around 100 HB. The findings indicate that eliminating the post-forging solution heat treatment does not significantly degrade the overall mechanical performance of the material. In conclusion, the proposed integrated forging process emerges as a more efficient and streamlined manufacturing alternative, offering reduced processing steps, energy and time savings, while maintaining product performance.