TTP Diagrams of Z Phase in 9–12% Cr Heat-Resistant Steels

Time-Temperature-Precipitation diagrams of Z phase were investigated in crept samples of 9–12% Cr heat-resistant steels. The Z phases were formed around the prior austenite grain boundaries at 823 K, 923 K, and 973 K—temperatures similar to the 873 K reported in a previous paper. The time required for Z phase formation was shorter in higher Cr steels, indicating that to avoid Z phase formation the Cr content of the steel should be reduced as far...