Creep-fatigue-oxidation interaction in Grade 91 steel weld joints for high temperature applications

► Martensitic lath structure rearranges into cells/subgrains causing cyclic softening. ► Cyclic softening process is highly sensitive to temperature and application of hold. ► Lower CSR of weld joint compared to base metal due to soft zone in the HAZ. ► Failure location of WJ depends upon temperature and direction of hold application. ► Enhanced cracking due to strain localization and creep cavity formation in HAZ. ► Compression dwell sensitivity due to the deleterious effect of the surface oxides.