Hot tensile properties of 9Cr-2WVTa reduced-activation ferritic/martensitic steel

Abstract

Reduced-activation ferritic/martensitic steels have been developed by replacing molybdenum by tungsten and niobium by tantalum in commercial elevated-temperature Cr–Mo steels to reduce half-life of radioactive isotopes. The objective of this study was to investigate tensile properties of a reduced-activation ferritic/martensitic steel (9Cr-2WVTa) in normalized-tempered (NT) and quenched-tempered (QT) conditions have been studied over the temperature range of room temperature to 600 C. The increase in temperature led to reduction in yield and ultimate tensile strengths in both conditions. Furthermore, the strengths of NT samples were similar to those of QT samples. Variations of elongation and reduction of area with temperature revealed that both properties initially decreased up to 400 C but thereafter increased as the temperature increased. Since fracture surfaces of all tensile samples were dominated by dimples, it was presumed that the decrease in elongation and reduction of area in the intermediate temperature range was related to Dynamic Strain Ageing (DSA). In addition, NT samples exhibited superior elongation at all temperatures except 500 C.