Numerical investigation of factors affecting creep damage accumulation in ASME P92 steel welded joint

The present study mainly investigated Type IV cracking occurring in the fine grained heat affected zone (FGHAZ) in the welded joint of ASME P92 steel at high temperature and low applied stress by numerical simulation method. Based on the modified Karchanov–Rabotnov constitutive equation, the user defined material subroutine (UMAT) was complied and the creep damage accumulation was carried out by finite element method using ABAQUS codes for the welded joint at 650 °C and 70 MPa. Calculated results revealed that the most severe creep damage and the highest equivalent creep strain occurred in the FGHAZ because of high maximum principle stress and high maximum principle stress. Furthermore, the effect of groove angle and HAZ width on the creep damage accumulation was investigated. It indicated that a small groove angle and a narrow FGHAZ width could deteriorate the creep damage accumulation because of the degradation of maximum principle stress and stress triaxiality in the FGHAZ.