Z-phase Formation during Creep and Aging in 9–12% Cr Heat Resistant Steels

The precipitation behavior of the Z phase was investigated after long-term creep exposure in ASME-T91, T92, T122 without δ-ferrite, and T122 with δ-ferrite through elemental mapping using EF-TEM. The Z phase was identified by comparing the Cr map with the V map. Most of the Z phase was observed around prior austenite grain boundaries and/or packet boundaries in all of the steels examined. In T122 with δ-ferrite, the Z phase also precipitates...