In situ SEM studies of the low cycle fatigue behavior of DZ4 superalloy at elevated temperature: Effect of partial recrystallization

The influence of partial recrystallization (RX) on the low cycle fatigue (LCF) behavior of directionally solidified DZ4 superalloy was studied using in situ scanning electron microscopy. Three typical recrystallization microstructures were prepared on the fatigue samples, via shot peening and subsequent heat treatment. The effect of RX on LCF life is evidently related to the specific RX microstructure. The RX layer does not necessarily reduce the LCF life. The fatigue crack initiation and short crack propagation behaviors for both raw DZ4 and recrystallized samples were in situ examined, which rationalized the observed effect of recrystallization on the LCF life variation.