Effect of Chromium, Aluminum and Nickel on Microstructure and Reverse-S type Creep Rupture Strength of High Cr Ferritic Heat Resisting Steels

Microstructure and creep strength at 650°C of two high-Cr ferritic heat resisting steels were investigated. 11Cr steel containing relatively high carbon, aluminum and nickel showed a significant drop in creep strength after 1000 h while 9Cr steel containing relatively low carbon, aluminum and nickel showed a recovery of creep strength after a slight drop. The 11Cr steel contained M23(CB)6, Z phase and relatively coarsened Laves phase as...