Assessing the Irradiation Defect Induced Changes using Dislocation Based Crystal Plasticity Model for BCC Materials

Radiation effects lead to significant reduction in ductility of nuclear reactor components. Body Centered Cubic (BCC) materials exhibits better thermal properties as compared to Face Centered Cubic (FCC) materials, in addition to excellent resistance to helium embrittlement and void swelling under higher dpa levels, making them the promising materials for future nuclear applications. Fracture toughness in BCC has a well defined temperature dependent transition as compared to FCC materials, which is a major concern restricting their application to high dose conditions. In the present paper such strong temperature dependence of strain rate and flow stress in BCC materials is investigated numerically for both non-irradiated and irradiated conditions. In view of dislocations mobility being a fundamental property to determine the plastic behavior, a dislocation based material model is proposed which is based on physical approach rather than phenomenological.