Warm Forming Characteristics of AA7075: Microstructure Interaction Mechanisms and Constitutive Models

Area of Science:

• Materials Science
• Mechanical Engineering
• Computational Materials Science

Background:

• AA7075 is vital in aerospace engineering.
• Understanding its behavior during warm deformation is key to optimizing manufacturing processes.

Purpose of the Study:

• To investigate the microstructure evolution and constitutive relationships of AA7075 during warm forming.
• To develop and compare predictive models for flow stress behavior.

Main Methods:

• Isothermal compression experiments at varying temperatures and strain rates.
• Microstructural characterization using Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM).
• Development of a phenomenological Hensel-Spittel-Garofalo (HSG) model and a hybrid Harris Hawks Optimization-Long Short-Term Memory (HHO-LSTM) machine-learning model.

Main Results:

• Dynamic recovery was identified as the primary softening mechanism under warm forming conditions.
• Flow stress is sensitive to temperature and strain rate, decreasing with temperature and increasing with strain rate.
• Both HSG and HHO-LSTM models showed predictive accuracy, with HHO-LSTM demonstrating superior performance in capturing nonlinear relationships.

Conclusions:

• The HHO-LSTM model offers a highly accurate and robust method for predicting AA7075 flow behavior during warm forming.
• This advanced predictive tool can aid in optimizing engineering applications for aerospace components.