A Continuum Model for the Effect of Dynamic Recrystallization on the Stress⁻Strain Response

Area of Science:

• Materials Science and Engineering
• Computational Materials Science
• Metallurgy

Background:

• Austenitic Stainless Steels and High-Strength Low-Alloy (HSLA) steels undergo significant dynamic recovery and recrystallization (DRX) during hot forming.
• Accurate constitutive models are essential for designing optimal and safe hot-formed steel products.
• Existing models may not fully capture material behavior under transient or high strain rate conditions.

Purpose of the Study:

• To present and validate a new continuum model for predicting the hot forming behavior of steels.
• To accurately describe the stress-strain behavior and dynamic recrystallization (DRX) phenomena.
• To enable predictions under a wide range of deformation conditions, including high strain rates.

Main Methods:

• Development of a new continuum model presented in rate form for transient process analysis.
• Validation of the model against experimental data for AISI 316LN and HSLA steels under hot forming conditions.
• Inclusion of elastic energy due to dynamic stress to model the driving pressure for recrystallization at high strain rates.

Main Results:

• The model accurately describes the stress-strain behavior of AISI 316LN during hot forming.
• High strain rate DRX-induced softening in HSLA steel is accurately predicted.
• The model captures the increased recrystallization rate at high strain rates by incorporating elastic energy.
• Predicted grain sizes follow the reported power-law dependence with steady-state stress.

Conclusions:

• The proposed continuum model provides a robust framework for predicting steel behavior during hot forming.
• The model's ability to account for elastic energy enhances its accuracy in high strain rate scenarios.
• This work contributes to the design of safer and more efficient hot-formed steel products.