Crack paths in the superalloy IN738 in aged conditions

Microstructural evolution during high temperature dwell-fatigue of austenitic stainless steels

“…Observations and suggestions of similar crack propagation and recrystallization process has been presented before, but for other materials and loading conditions. For superalloys, similar recrystallized grain structures close to the main cracks were observed in [28][29][30][31] and for Kanesund et al [28] and Kuhn et al [29], DRX of crack tip plastic zone during thermomechanical fatigue were due to coarsening of the γ ′ -phase which lost its ability for pinning of the migrating boundaries. Similar loss for pinning functionality of the copper-rich precipitates and Nb-carbides of Sanicro 25 could apply in present study, where this effect only apply to the highly deformed plastic zone of the crack tip and which produce the recrystallized structure around the main cracks and not homogeneously throughout the microstructure.…”

Crack growth mechanisms in an aged superalloy at high temperature

“…Consequently, the crack growth rates for intergranular and transgranular crack extension were comparable and the amount of crack retardation by microstructural barriers decreased. A more detailed discussion of the dependence of the crack growth rate on the microstructure can be found in [8].…”

Influence of Scanning Strategy and Post-Treatment on Cracks and Mechanical Properties of Selective-Laser-Melted K438 Superalloy

“…The primary types of cracking observed in K438 alloys are liquefaction cracking (LC), solidification cracking (SC), and ductility dip cracking (DDC) [22,23]. Liquefaction cracking mainly occurs at grain boundaries, while ductility dip cracking (DDC) results from low-melting eutectics of γ+γ', carbides, and borides [24,25]. DDC complements liquefaction cracking during the growth phase.…”