By a self-designed and self-built internal pressure creep test system

the interrupted internal pressure creep test was carried out for T92 tubes at 600 ℃ with an internal pressure of 59 MPa

corresponds to a circumferential stress of 130 MPa.The test time was 0h

5 000 h

12 776.5h

18 659.5h

and 24 042.5h(tube leakage)respectively.Mechanical properties including hardness

impact energy and tensile strength at room temperature were tested.The microstructures were characterized by means of optical microscope(OM)

scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results indicate that

the impact energy and hardness of the T92 steel dropped markedly at the beginning of creep

then became relatively stable with further creep.However

the tensile strength declined linearly.Precipitation and rapid coarsening of Laves phase was the main reason for property degradation of the T92 steel.The tensile strength

martensite lath width as well as the size of the Laves phase have a close relationship with the life consumption

which are suggested to be the indicators of condition assessment for the T92 steel.