Mechanical Behavior of Austenitic Steel under Multi-Axial Cyclic Loading

Area of Science:

• Materials Science
• Mechanical Engineering
• Solid Mechanics

Background:

• Low-nickel austenitic steel is crucial in various engineering applications.
• Understanding material behavior under complex loading is essential for design.
• High-pressure torsion fatigue (HPTF) involves combined axial compression and cyclic torsion.

Purpose of the Study:

• To evaluate the suitability of isotropic J2 plasticity versus crystal plasticity for describing mechanical behavior under HPTF loading.
• To investigate the axial creep deformation observed during HPTF experiments.
• To compare the predictive capabilities of different plasticity models.

Main Methods:

• Subjecting low-nickel austenitic steel to high-pressure torsion fatigue (HPTF) loading.
• Implementing and comparing isotropic J2 plasticity models with associated flow rules.
• Utilizing a micromechanical crystal plasticity model with Ohno-Wang kinematic hardening.

Main Results:

• The J2 plasticity model failed to accurately predict the axial creep behavior.
• The crystal plasticity model, incorporating microstructural aspects, demonstrated high accuracy in matching experimental HPTF data.
• Significant discrepancies were observed between the J2 model predictions and experimental axial creep.

Conclusions:

• Crystal plasticity, coupled with microstructural models, is highly effective for predicting material behavior under complex multiaxial cyclic loading.
• Isotropic J2 plasticity is insufficient for capturing the observed axial creep in HPTF of austenitic steel.
• The study highlights the versatility of crystal plasticity in materials under reversing multiaxial stress states.