Investigation on creep rupture of 3W-3Co ferrite blade steel at 620 .DEG.C.

Effect of microstructure evolution and creep rupture behavior on 3W-3Co ferrite steel creep strength was investigated by using SEM and TEM.The results show that the stress vs service time curves of the tested sample accord with lgσ=2.64941-0.05472lgτ equation under different stress at 620 ℃.The main creep fracture mechanism of the steel is transgranular fracture under the high stress and short-term creep conditions.The ZrO2 and NbC forming in smelting process is the main source of crack.The tested sample maintain higher creep rupture strength in early creep at 620 ℃.