Effect of Rare‐Earth Cerium on Nonmetallic Inclusions in Fe–Mn–C–Al Twinning‐Induced Plasticity Steel

Abstract

The effect of Ce treatment on nonmetallic inclusions in Fe–Mn–C–Al twinning‐induced plasticity steel is studied by adding different content of rare‐earth cerium. scanning electron microscopy, energy‐dispersive spectroscopy, and electron probe X‐ray microanalyzer analysis show that the main inclusions in Ce‐treated steel change from Al 2 O 3 –MnS to CeAlO 3 –Ce 2 S 3 . With the increase of Ce content, the number, size, and density of inclusions in steel decrease, and the morphology of irregular inclusions is closer to the spindle. In this experiment, the size of inclusions in the test sample with 0.0048% Ce addition is the smallest and the distribution of inclusions is the most uniform. Based on the classical thermodynamics and Factsage thermodynamics software, the evolution rule of Ce addition on inclusions is calculated. The thermodynamic calculation results are in good agreement with the experimental results. In addition, combining the experimental phenomena and thermodynamic calculation results, it is revealed that the transformation path of the main inclusions Al 2 O 3 –MnS to CeAlO 3 –Ce 2 S 3 in the Ce‐treated steel is as follows: the outer layer of MnS → CeS → Ce 3 S 4 → Ce 2 S 3 ; inner layer Al 2 O 3 → CeAlO 3 +Ce 2 O 2 S. The anisotropy difference between inclusions and iron matrix after Ce treatment is reduced, which reduces the damage of inclusions to steel.