Cathodoluminescence Analysis of Nonmetallic Inclusions in Steel Deoxidized and Desulfurized by Rare-Earth Metals (La, Ce, Nd)

The injection of misch metal, which primarily consists of La, Ce, and Nd, into molten steel can reduce the size of nonmetallic inclusions, suppress the formation of harmful nonmetallic inclusions, and reduce the content of oxygen and sulfur in steel. To investigate the impact of misch metal on these effects, we propose a method for identifying inclusions in steel that has been deoxidized and desulfurized by misch metal using cathodoluminescence (CL) analysis within 1 minute. Based on the CL images and spectra of model steel samples that were deoxidized and desulfurized by La, Ce, or Nd metal, we demonstrate that La₂O₃, La₂O₂S, CeO₂, Ce₂O₂S, Nd₂O₃, and Nd₂O₂S inclusions can be identified by the emitted luminescence color using cameras with sensitivity ranges of 420 to 680 and 350 to 1000 nm. La₂O₃, La₂O₂S, CeO₂, Ce₂O₂S, Nd₂O₃, and Nd₂O₂S inclusions emitted blue-green, yellow-orange, yellow-orange, violet, blue-violet, and red luminescence, respectively when observed by a camera with a sensitivity range of 420 to 680 nm. CeO₂ and Nd₂O₃ inclusions emitted red-orange and red-violet luminescence, respectively when observed by a camera with a sensitivity range of 350 to 1000 nm.