Contribution of microstructure to yield strength of X-750 alloy used for garter spring in Canada deuterium uranium reactor

The role of microstructures on the overall yield strength of garter-spring coil X-750 alloy used for the fuel channel structure in the Canada deuterium uranium reactor is investigated in this study. We perform a comprehensive characterization of the residual microstructures in the garter-spring coil X-750 alloy and heat-treated plate X-750 alloys using electron microscopy. Simultaneously, we perform small-scale mechanical tests and bulk mechanical tests to evaluate the yield strength of the compact garter-spring coil component. We compare the mechanical property data obtained via the micro-bending measurement method and derive a correlation between each measured data point to assess the increase in yield strength. The γ′ ordering phase contribution is the most crucial factor in strengthening, followed by dislocation density and boundary-decorated precipitates in the garter-spring coil X-750 alloy. We quantitatively evaluate the effects of the γ′ ordering phase and initial dislocation density on the yield strength of the garter spring coil X-750 alloy because they significantly affect the change in the mechanical properties in the irradiation environment.