In-Situ Observation of the Effect of Rare Earth Yttrium Modification on the Capillary Collision of Inclusions in 304 Stainless Steels
摘要
This study combined thermodynamic calculations with laboratory experiments to examine inclusion evolution in 304 stainless steel containing varying yttrium levels. A rare earth element thermodynamic database was established. In-situ observation of inclusion agglomeration and collision in steels with different Y concentrations was achieved by high-temperature confocal scanning laser microscope (CSLM). For Y2O3–Al2O3–SiO2 inclusions with 83 ppm and 120 ppm Y, the critical acceleration distances were 55 and 50 μm, which were larger than the distance of 35 μm observed for Y2O3–Y2S3–Al2O3–SiO2 inclusions (T.Y = 300 ppm) and the distance of 30 μm for Y–O–S inclusions (T.Y = 430 ppm). The attraction of Y2O3–Al2O3–SiO2 complex inclusions was increased from 1.0 × 10−16−5.0 × 10−14 N, which was stronger than 5.0 × 10−17−5.0 × 10−15 N for Y2O3–Y2S3–Al2O3–SiO2 and 1.0 × 10−18−1.0 × 10−16 N for Y2O3–Y2S3 inclusions. As the Y content increased, the attraction between complex inclusions in steel decreased. However, the excessive addition of Y can lead to a large accumulation of inclusions in steel, which was harmful to improving the cleanliness of steel products. It was suggested to control the Y content in steel within the range of 80 to 120 ppm to reduce the collision tendency of inclusions, and avoid a significant increase in the number density of inclusions.