Micromechanical modeling of the viscoplastic behavior of irradiated bainitic steels
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The context of this work is related to the aging of vessel steels in pressurized water reactors. These steels can undergo microstructural changes due to irradiation, having an impact on their behavior. These changes represent the key to understanding and predicting the modification of their response, including the so-called “irradiation hardening” and their fracture properties with irradiation. Recently, a new physically based crystal plasticity law, derived from [1] and specific for vessel steels has been proposed, describing plastic slip rates at the scale of a single crystal in terms of key microstructural characteristics. This law is based on information from smaller-scale simulations generated by molecular dynamics and dislocation dynamics. To calibrate this new law and verify its relevance, numerical simulations were carried out on polycrystalline microstructures using the CraFT calculation code, based on a fast Fourier transform (FFT) method [2]. Comparisons with experimental results were carried out for a range of temperatures, loading speeds and irradiation doses; a good overall agreement was observed. The FFT simulations were finally employed to assess the accuracy of several mean-field homogenized descriptions. Descriptions of the self-consistent type based on a generalized-secant linearization procedure were found to be particularly accurate.
