Recent progress toward development of reduced activation ferritic/martensitic steels for fusion structural applications

Significant progress has been achieved in the international research effort on reduced activation ferritic/martensitic steels for fusion structural applications. Because this class of steels is the leading structural material for test blankets in ITER and future fusion power systems, the range of ongoing research activities is extremely broad. Since, it is not possible to discuss all relevant work in this brief review, the objective of this paper is to highlight significant issues that have received recent attention. These include: (1) efforts to measure and understand radiation-induced hardening and embrittlement at temperatures ≤400 °C, (2) experiments and modeling to characterize the effects of He on microstructural evolution and mechanical properties, (3) exploration of approaches for increasing the high-temperature (>550 °C) creep resistance by introduction of a high-density of nanometer scale dispersoids or precipitates in the microstructure, (4) progress toward structural design criteria to account for loading conditions involving both creep and fatigue, and (5) development of nondestructive examination methods for flaw detection and evaluation.