Analysis of creep rates of tempered martensitic 9%Cr steel based on microstructure evolution

The creep rates of tempered martensitic 9Cr–3W–3Co–VNb steel with different carbon and boron concentrations were investigated with emphasis on the behavior in the transient creep region. Creep tests were carried out at 650 °C up to about 7 × 104 h and at 700 °C up to about 4 × 103 h. The precipitates were identified as M23C6 carbides and MX carbonitrides after tempering. The movement and annihilation process of excess dislocations in the...