Microstructure related failure mechanism of selective laser melted GH4169 with interior fatigue cracking

Abstract The crystallographic facets induced cracking is the typical interior failure mechanism of a selective leaser melting (SLM) GH4169 superalloy under the axial loading with a stress ratio of 0.1 in the very high cycle fatigue. Results show that the formation of facet was related to the activity slip in the grains with high Schmidt factor under shear stress and strain, especially assistant by the inclusions or twins. By the effects of microstructure characteristics, crack growth deflected during the early microcrack growth stage, resulting in the uneven morphology of facets aggregation zone with height amplitude about 83 μm. Furthermore, the fracture of Laves phases occurs during microcrack propagation. Finally, the microstructure related interior cracking mechanism is summarized.