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

• The effect of recrystallization (RX) on fatigue life was studied by in situ SEM.
• The discrete RX grains were most detrimental to the fatigue life of DZ4 alloy.
• DZ4 with surface layer of multiple refined RX grains showed improved fatigue life.
• Short crack behaviors in DZ4 alloy and RX layer were examined by in situ SEM.
• Crack initiation and crack growth rate explain the effect of RX on fatigue life.

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.

Figure optionsDownload as PowerPoint slide