To reveal the distribution of crack tip stress of the superheater applying T92 steel in an ultra supercritical unit boiler with outer diameter crack under the combined effects of both thermal stress and internal pressure

the finite element software ANSYS was employed to establish the finite element model for superheater outer wall with radial crack

by considering the effects of elastic modulus E of the T92 steel varies with temperature.Thus the change rules of the stress intensity factor under internal pressure-heat coupling effect were obtained.According to the vector super position principle

the reasons for crack tip stress field changes were analyzed comprehensively

under the effects of both thermal stress and internal pressure.The results show that

with the same temperature difference

the stress intensity factor increases with the internal pressure

but the thermal stress will lead to crack tip stress field changes of the T92 superheater pipe outer wall with radial cracks under the individual effect of internal pressure.Under the effect of internal pressure-heat coupling

the stress intensity factor reduces with the increasing temperature difference.