Crystal-Plasticity-Based Micro-Mechanical Model for Simulating Plastic Deformation of TC4 Alloy

Area of Science:

• Materials Science
• Mechanical Engineering
• Computational Modeling

Background:

• Titanium alloy (Ti-6Al-4V or TC4) is crucial in aerospace and biomedical fields due to its high strength-to-weight ratio and corrosion resistance.
• Plastic deformation in TC4 is significantly influenced by microstructural features, especially grain size.

Purpose of the Study:

• To develop and validate a crystal plasticity model for simulating TC4 plastic deformation.
• To explicitly account for the effect of grain size on slip resistance and material behavior.
• To establish a failure criterion predicting macroscopic failure strain dependence on grain size.

Main Methods:

• Development of a crystal plasticity model incorporating a Hall-Petch relationship.
• Utilization of a thermally activated flow rule to model slip system kinetics.
• Calibration and validation using experimental stress-strain data from uniaxial tensile tests on TC4 with varying grain sizes.

Main Results:

• The model successfully simulated the grain-size strengthening effect in TC4.
• Accurate prediction of flow stress, strain hardening, and local strain heterogeneity evolution.
• Establishment of a critical local equivalent plastic strain criterion that predicts macroscopic failure strain dependence on grain size.

Conclusions:

• The developed crystal plasticity model provides a physically based computational tool for TC4.
• The model enables optimization of TC4 processing parameters and prediction of deformation behavior under service conditions.
• This research enhances the understanding of grain size effects on the mechanical performance of titanium alloys.