Effects of Temperature and Microstructure on Short Crack Growth of Laser Powder Bed Fusion Ni‐Based Superalloy

ABSTRACT This paper utilized an in‐situ electron microscopy technique along with high‐temperature fatigue tests conducted at 298, 573, and 923 K to observe the initiation and propagation of short fatigue cracks (SFC) in the nickel‐based superalloy GH4169 and to examine changes in grain boundaries. The study examined how temperature and local microstructure affect the growth behavior of SFC in GH4169, which was fabricated using laser powder bed fusion (LPBF). The growth rate of SFC increased with higher temperature and stress amplitude, while the GH4169 alloy exhibited a combination of intergranular and transgranular fractures. Using the modified Paris model, the SFC growth model with Young's modulus ( E ) as an independent variable successfully predicted the crack propagation rate under various temperature loading conditions.