Correlation of hot-microhardness with elevated-temperature tensile properties of low activation ferritic steel

Abstract

Hot microhardness and elevated temperature tensile tests have been performed on 9Cr-2.5W-0.3V-0.15C (GA3X) low activation ferritic steel at temperatures from 20°C to 650°C. The uniform elongation of the tensile test correlated well with the ductility parameter of the microhardness test. The hot-microhardness test showed a sensitive response to the softening and changes in ductility of the GA3X steel. The ultimate tensile strength and 0.2% yield strength of this steel correlated well with hot microhardness data at test temperatures up to 400°C using Cahoon's expressions σ uts = ( H /2.9)( n /0.217) n and σ ys = ( H /3)(0.1) n , respectively, where H is the diamond pyramid hardness and n is the strain hardening exponent. A 20–30% underestimate of tensile strengths were obtained using Cahoon's expressions at temperatures above 400°C, which is probably attributed to creep deformation and may be improved by selecting a proper loading condition during the hardness test.