Effect of welding residual stress on type Ⅳ creep failure of P92 steel

Type Ⅳ cracking is considered to be the likely failure mode of P92 steel welds when operated at high temperature for long duration.Type Ⅳ failure often takes place at the intercritical heat affected zone(ICHAZ) or fine grained heat affected zone(FGHAZ).However,the mechanism of type Ⅳ cracking has not yet been understood unequivocally.In order to investigate type Ⅳ failure scientifically,temperature field,welding residual stress and creep strain for welded joint of P92 steel are simulated by ABAQUS code.Experimental result obtained from X-ray diffraction technique is conducted to verify the simulation.The research results show that the locations of ICHAZ and FGHAZ are demonstrated according to the simulation of temperature field.Maximal residual stress concentrates in the ICHAZ and FGHAZ.And axial creep strain is in good agreement with residual stress.So concentration of residual stress that results in accumulation of creep strain and type Ⅳ cracking is regarded as remarkable factor.