Effect of Varied Solidification Methods on Characteristics of Nonmetallic Inclusions in 304 Stainless Steel

This research examines the impact of varying solidification methods on the behavior of nonmetallic inclusions in 304 stainless steel during the solidification process. Five sets of cooling experiments are carried out to systematically characterize and analyze the inclusion features. The findings indicate that when the cooling rate is reduced from 45.33 to 1.21 K s −1 , the average inclusion diameter increases from 1.64 to 3.31 μm, while the number density declines from 31.97 to 16.47 mm −2 . Specifically, the percentage of small‐sized inclusions (<3 μm) drops sharply from 93.8% to 41.4%. In terms of composition, as the cooling rate diminishes, the average contents of MnO and SiO 2 in the inclusions rise, whereas the Cr 2 O 3 content decreases. Morphologically, the inclusions undergo a gradual transition from spherical or ellipsoidal homogeneous‐phase particles to irregular multiphase structures. Building upon a solute segregation model, a kinetic model for inclusion growth is developed. Calculations performed with this kinetic model reveal a notable inverse relationship between the size of the inclusions and the rate of cooling, as described by the fitted equation: . The predictions generated by the model show a strong correlation with the experimental results.