Effects of recrystallization on the low cycle fatigue behavior of directionally solidified superalloy DZ40M

The effects of recrystallization on low cycle fatigue behavior were investigated on directionally solidified Co-base superalloy DZ40M. Optical microscopy and SEM were used to examine the microstructure and fracture surface of the specimens. The mechanical testing results demonstrated that the low cycle fatigue property of DZ40M significantly decreased with the partial recrystallization. Fatigue cracks initiate near the carbides and the grain boundaries with slip-bands. Both the fatigue crack initiation and propagation can be accelerated with the occurrences of recrystallized grain boundaries.