Characterization of Inclusion Size Distributions in a Large Forged Shaft Using X‐ray Micro‐Computed Tomography Imaging

The presence of nonmetallic inclusions in steel considerably affects the material's properties. This study investigates these effects by sampling six locations along the radial direction of a large forged shaft to analyze the distribution characteristics of inclusions. Scanning electron microscopy and optical microscopy are used to identify the types and morphologies of the inclusions. X‐ray micro‐computed tomography scanning provides detailed distribution data, including the length, width, equivalent diameter, and shape of the inclusions. This approach allows for a comprehensive understanding of the radial distribution characteristics of inclusions in the forged shaft. The results reveal that both the quantity and size of inclusions in the large forged shaft increase progressively from the edge toward the center. Additionally, the fatigue strength is estimated based on the inclusion distribution at various locations. The prediction shows a relative error exceeding 15%, indicating that the heterogeneity of the components considerably affects their fatigue performance. Finally, a novel method for predicting the maximum inclusion size within the heterogeneous large forged shaft is introduced.