Effect of Silicon on Mechanical Properties of 9Cr-1.5WVTa Low Activation Martensitic Steel

Based on the new Chinese low activation martensitic (CLAM) steel being developed as for fusion reactors, the effect of silicon adding on the mechanical properties of 9Cr-1.5WVTa steels was investigated. The results show that adding 0.2% silicon leads to higher tensile strength, and more excellent plasticity and impact toughness. The ductile-brittle transition temperature (DBTT) is decreased from -13 ℃ to -30 ℃. The 9Cr-1.5WVTaSi steel has a smaller prior-austenite grain size, but microstructures are similar, both fully martensitic steels free of δ-ferrite. It was summarized that the improved tensile and impact properties of the 9Cr-1.5WVTaSi steel were attributed to adding 0.2% silicon, refined the prior-austenite grain size.