Ultrasound-assisted in-situ characterization of precipitation kinetics for tailoring mechanical properties in high-strength aluminum components
Year: 2025
Type: article
Abstract: High-strength aluminum alloys, such as AA7075, offer exceptional lightweighting potential due to their high specific strength. However, their limited formability at room temperature necessitates thermally assisted forming strategies to ensure failure-free shaping. As performance demands increase, components must exhibit tailored mechanical properties. Tailored Quench Forming (TQF) presents a promising route by integrating forming, quenching, and local property adjustment into a single process step. Yet, the identification of suitable process parameters remains experimentally intensive and lacks clarity in the microstructure behavior during forming. This study introduces a nondestructive, contact free in-situ characterization method for the precipitation-hardenable alloy AA7075, enabling real time monitoring of precipitation behavior during variable cooling and subsequent artificial aging. A high-resolution laser ultrasound system is used to track the influence of local cooling rates on precipitation evolution, which is then correlated with post-process hardness and nanometer-scale Scanning Transmission Electron Microscopy (STEM) analysis. The approach defines critical process windows and precipitation regimes. These parameters are transferred to a forming process, producing components with local tailored properties. Deep drawing and microstructural analysis confirm the formation of property gradients, ranging from high strength to increased ductility, driven by controlled precipitation morphologies. Beyond AA7075, this work establishes a transferable approach for microstructure and property design in precipitation-hardenable alloys via thermal process control during forming. The findings contribute to a fundamental understanding of precipitation kinetics under thermomechanical conditions and support the development of adaptive forming strategies for functionally graded aluminum components. • A novel in-situ laser-ultrasonic methodology for in-situ tracking of precipitation kinetics during thermomechanical processing • Demonstration of a quantitative correlation between ultrasonic signal evolution and precipitation behavior verified via STEM analysis • Identification of critical quench rate and precipitation regimes enabling targeted mechanical property tailoring in AA7075 • Validation of tailored quench blanks via local thermal tool control achieving functional gradients in strength and ductility • Establishment of a transferable process design framework for tailoring local microstructures in precipitation-hardenable aluminum alloys
Authors: Nikolaos Rigas, Henrik Zieroth, Nicolas Karpstein, Erdmann Spiecker, Marion Merklein
Institution: Friedrich-Alexander-Universität Erlangen-Nürnberg
Language: English
Subfield: Aerospace Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,980
Funder: Deutsche Forschungsgemeinschaft
OpenAlex ID: W7092283496