Improving Mechanical Properties of EP823 Ferritic/Martensitic Steel via Increasing Silicon Contents

EP823 ferritic/martensitic (F/M) steels, as one of the most promising structure materials for nuclear reactor applications, have been widely investigated in recent decades. The comprehensive mechanical properties of EP823 need to be evaluated and further improved. In this study, several types of EP823 with different Si contents doping are carefully prepared, and the effects of Si content on microstructures, tensile properties, and wear resistance are systematically discussed. Results indicate that the EP823 with higher Si content exhibits higher yield strength, which is mainly attributed to the increase in the density of the punched-out dislocation pile-ups and the enhanced solid solution strengthening effect. The wear resistance of EP823 is significantly improved with the increase in Si content, and the increase in surface hardness is detected as the basis for the improvement of wear performance. In addition, unique Si-containing M₂₃C₆ carbides with lattice distortion are found in this study, and their positive effects on mechanical properties of EP823 are revealed. Consequently, our work proposes an effective strategy of regulating Si content to improve the mechanical properties of EP823 steel and contributes to the ongoing development of EP823 F/M steels for nuclear applications.