Effect of Temperature on Mechanical Properties of 9%Cr Ferritic Steel

Mechanical properties of a 9%Cr-ferritic steel grade P92 experimental alloy are studied. The effect of cooling rate on the hardenability was determined by means of continuous cooling diagrams and data provided by hardness measurements and microstructure observations. A fully martensitic microstructure after the solubilization treatment over a wide range of cooling rates was revealed. As this grade of steels is mostly supplied in tempered condition, tensile tests to determine the variation of the strength and ductility at temperatures ranging from 20 to 650°C were carried out after a treatment of 3 h at 760°C. In addition, Charpy V-notch tests were conducted to characterize the impact toughness of the steel and the ductile-brittle transition temperature. Finally, the creep strength was determined from creep tests in the range 550 to 650°C.