Macrosegregation induced interface structure and its effect on creep failure in dissimilar metal welds between Ni-based alloy and 10% Cr martensitic steel

This study reported the evolutionary behavior of macrosegregation induced interface structure during post weld heat treatment (PWHT) and its effect on creep failure in dissimilar metal welds (DMWs) between Ni-based alloy and 10%Cr martensitic steel with Ni-based filler metal. During welding, macrosegregation led to formation of partially mixed beach-like lath martensite interface structure on the steel side. The beach-like structure transformed to rod-like Ni-rich and C-rich martensite accompanied by Ni-depleted and C-depleted martensite/ferrite after PWHT due to partial austenization and diffusion of austenite-stabilizing elements like Ni and C. Interfacial creep failure occurred along the interface between steel and the beach-like interface structure, which was related to creep voids nucleation at the BCC/FCC interface between steel and the beach-like structure during creep at 600 degrees C. Hence, the relationship between macrosegregation, interface structure and creep failure in the DMWs was clarified.

Automated summary

This study elucidated the influence of macrosegregation on interface structure and the effect of this influence on creep failure during post weld heat treatment in dissimilar metal welds.