Effects of heat treatment on the microstructure and mechanical properties of CLF-1 steel for fusion blankets

CLF-1 steel has been recognized as a preferred structural material for fusion reactor blanket modules. Its standard heat treatment involves normalization followed by tempering. This study examines the effects of various heat treatment conditions on the microstructure and mechanical properties of CLF-1 steel, providing critical data to support blanket component fabrication. The results indicate that normalization at 980 °C or 1100 °C, followed by tempering at 700 °C or 760 °C, produces a lath martensitic structure, with primary precipitates including short rod-like M 23 C 6 and fine spherical MX-type carbides. Higher normalization and tempering temperatures result in reduced dislocation density. A comprehensive analysis demonstrates that variations in heat treatment parameters significantly influence grain size, tensile strength, and impact energy absorption. For practical manufacturing, normalization at 1100 °C combined with tempering at 700 °C should be avoided.