On the changes in the low-cycle-fatigue life and cracking mechanism of P91 cross-weld specimens at elevated temperatures

A significant reduction in the fatigue life of cross-weld P91 specimens was observed in tests at 538 and 566 degrees C compared to that at 25 degrees C. The remarkable reduction of the fatigue strength was directly correlated to the shift of the fatigue cracking locations from the BM region at 25 degrees C to the interface between the intercritical heat-affected zone (ICHAZ) and BM at elevated temperatures. The low-cycle fatigue (LCF) resistance deterioration mechanisms were attributed to synergic interactions between a high rate of microstructure deterioration accompanied by severe plastic deformation and lower strain hardenability in the ICHAZ region at elevated temperature.

Automated summary

A significant reduction in the fatigue life of cross-weld P91 specimens was observed at elevated temperatures. The fatigue strength reduction was directly linked to the shift of fatigue cracking locations and the deterioration mechanisms in the intercritical heat-affected zone.