Effect of creep deformation on Z phase formation in Gr.91 steel

In order to make clear the effect of creep deformation on Z phase formation in Gr.91 steel, creep interrupted tests were performed for 10 000, 20 000, 30 000, 50 000 and 70 000 h at 600°C under 70 MPa. The time to rupture was 80 736·8 h at 600°C under 70 MPa. Z phase was observed in the vicinity of prior austenite grain boundaries in the grip and gauge portions after creep deformation for 10 000 h and more. Number density of Z phase particles...