Static recovery of tempered lath martensite microstructures during long-term aging in 9–12% Cr heat resistant steels

Static recovery of tempered lath martensite microstructures of strength enhanced ferritic steels has been investigated during very long-term aging up to 2 × 10 4 h at 650 °C for 3 steels containing 9 to 12% Cr. Static recovery of tempered lath martensite microstructure occurs after an incubation period for 1–2 × 10 3 h in the steels. The static recovery is controlled by the loss of strengthening due to M 23C 6 precipitates, and disappearance of MX carbonitrides cannot be the main cause of the static recovery.