Developing of containing Ta, Zr reduced activation ferritic/martensitic (RAFM) steel with excellent creep property.

A reduced activation ferritic/martensitic (RAFM) steel with perfect creep property at elevated temperature (600 °C) was designed by implementing adding trace amount of Ta, Zr elements. In order to reveal the mechanism of creep property enhancing through adding Ta, Zr elements, the microstructural and mechanical evolution behaviors of RAFM steels, with and without containing Ta, Zr elements, were analyzed. It was found that Ta, Zr can not only refine the M 23 C 6 carbide particles, but also can increase the mean size of MX particles in RAFM steels, especially for Zr element. Furthermore, both of Ta and Zr can contribute to increasing the amount of MX particles. Through combining with experimental results and excluding the influence behavior of parent austenite grain (PAG) size on the mechanical property of RAFM steel, it is not the M 23 C 6 particles, but is the precipitation amount of MX carbide particles that promoted by adding Ta, Zr, which can have a significant effect on enhancing the strength and decreasing the creep rate of RAFM steel at 600 °C condition. In addition, the synergistic effect of Ta and Zr elements can significantly increase the creep-resistance breaking time of RAFM steel under the same conditions comparing with other RAFM steels, and then the mechanism of it was revealed in this work. • A reduced activation ferritic/martensitic (RAFM) steel with excellent creep property by changing Ta, Zr elements was developed. • Based on containing Ta element, adding Zr can slightly increase the size and amount of MX carbide particles in RAFM steel, which enhances the microstructure stability of RAFM steel at elevated temperatures. • M 23 C 6 particles have limited influences on increasing the tensile strength and creep properties of RAFM steels at 600 °C, but MX particles can do well with it. [ABSTRACT FROM AUTHOR]