Irradiation creep and microstructural changes of ODS steels of different Cr-contents during helium implantation under stress

Abstract

Irradiation creep and microstructural changes of two ferritic ODS steels with 12% and 14% Cr have been studied by homogeneously implantation with helium under uniaxial tensile stresses from 40 to 300MPa. The maximum dose was about 1.2dpa (5000appm-He) with displacement damage rates of 1×10−5dpa/s at a temperature of 300°C. Irradiation creep compliances were measured to be 4.0×10−6dpa−1MPa−1 and 10×10−6dpa−1MPa−1 for 12 and 14Cr ODS, respectively. Subsequently, microstructural evolution was studied in detail by TEM observations, showing dislocation loops and bubbles distributed homogenously in the matrix. Some bubbles were attached to ODS particles. Finally, the effects of Cr content on irradiation creep and microstructural changes are discussed, including earlier results of a 19Cr ODS and a PM2000 ferritic steel.