Double aging enabled paint-baking hardening in AA7075 aluminum alloy
Journal
Materials Science and Engineering: A
Journal Volume
972
Start Page
150627
ISSN
09215093
Date Issued
2026-10
Author(s)
Abstract
This study demonstrates a novel double-aging strategy, which enables superior thermal stability against softening during automotive paint baking in AA7075 alloy subjected to Hot Form Quench process. This new strategy involves a pre-aging at 120 °C for 2 h followed by a high-temperature aging at 180 °C for 20 min, significantly reducing processing time compared to the typical T6 tempering. Integrated characterizations via transmission electron microscopy and atom probe tomography reveals the metallurgical origins of this enhanced stability. The DA process promotes Cu to partition into η′ nanoprecipitates at elevated temperatures, leading to a higher density of fine precipitates after paint baking. The outcome achieves a high yield strength of 548 MPa and a high ultimate tensile strength of 614 MPa, avoiding the property degradation seen in T6 condition. This novel strategy offers an efficient heat-treatment approach for high-volume manufacturing and property optimization for aluminum alloys.
Subjects
Aluminum alloy
Double aging
Paint baking
Thermal stability
η′ nanoprecipitate
Publisher
Elsevier Ltd
Type
journal article