Effect of Cu Contents on Microstructure and Creep Property of High Chromium Ferric Steels

The microstructure and creep property before and after creep of three high chromium ferric steels with 0wt%Cu, 0.6wt%Cu and 3wt%Cu were studied under the conditions of 650 ℃ and 140 MPa. The results show that the creep fracture time increasing from 1 172 h to 1 620 h and the creep rate decreased from 2.2×10-9 s-1 to 1.2×10-9 s-1 with the Cu content increasing from 0wt% to 3wt%. The addition of Cu effectively suppressed forming high temperature δ-ferrite phase adverse to the creep property.Numerous Cu-rich phases with the size of 50-100 nm dispersedly precipitated in the matrix of the tested steel with 3wt%Cu, which could effectively restrain the motion of dislocation and thus increase the creep resistance of the steel.