Enhancement of high temperature low cycle fatigue lifetime of PWA1484 superalloy artificial bicrystals via boron-induced grain boundary strengthening

High temperature fatigue performance plays a critical role in the service of turbine blades, and casting defects like low angle grain boundary (LAGB) in single crystal superalloys would severely affect the service performance of blades. This study demonstrates B-induced pronounced improvement in low cycle fatigue (LCF) lifetime at 980 degrees C for the PWA1484 artificial bicrystal with 6 degrees LAGB. Such an effective increment in LCF lifetime was achieved by stabilising LAGB through a delicate modulation of LAGB composition without boride. Moreover, Binduced matrix softening featured by homogenous distribution of fatigue deform zones with high density of dislocations was evidenced.

Automated summary

This study demonstrates that B-induced improvement in low cycle fatigue (LCF) lifetime in single crystal superalloy turbine blades can be achieved by stabilising low angle grain boundaries (LAGB) through a delicate modulation of LAGB composition without using boride. The Binduced matrix softening featured by homogenous distribution of fatigue deform zones with high density of dislocations was also evidenced.