A NON-SCHMID CRYSTAL PLASTICITY FINITE ELEMENT APPROACH TO MULTI-SCALE MODELING OF NICKEL-BASED SUPERALLOYS

Area of Science:

• Materials Science
• Mechanical Engineering
• Computational Mechanics

Background:

• Nickel-based superalloys are critical for high-temperature applications.
• Accurate constitutive models are needed to predict their thermomechanical behavior.
• Existing models often lack multi-scale capabilities and detailed microstructural representation.

Purpose of the Study:

• To develop and integrate non-Schmid crystal plasticity models across two length scales (sub-grain and homogenized grain).
• To capture the thermomechanical behavior of nickel-based superalloys from 300K to 1223K.
• To incorporate orientation dependencies and tension-compression asymmetry.

Main Methods:

• Developed a size-dependent, dislocation density-based FEM model for the sub-grain Representative Volume Element (RVE).
• Created an Activation Energy based Crystal Plasticity (AE-CP) model for single crystals.
• Bridged sub-grain and homogenized grain scales within a multi-scale framework.

Main Results:

• The models accurately represent orientation dependencies and tension-compression asymmetry.
• The homogenized AE-CP model's parameters are linked to microstructural features (γ' shape, volume fraction, channel-width).
• Simulations show distinct trends for yield stress and hardening in stronger tension/compression directions.

Conclusions:

• The multi-scale framework provides an accurate and efficient approach for simulating nickel-based superalloys.
• The homogenized model significantly speeds up crystal plasticity FE simulations.
• The approach retains accuracy while enabling faster computational predictions.