Effect of Al Content on Non‐Metallic Inclusions in Fe–13Cr– x Al–0.02Y Alloys

To investigate the effects of aluminum (Al) content addition on the morphology, type, quantity, and evolution patterns of nonmetallic inclusions in Fe–13Cr– x Al–0.02Y alloys, a series of laboratory experiments and thermodynamic calculations were conducted by varying the Al addition amount. The results indicate that at an Al content of 3.68 wt%, the transformation sequence of inclusions follows: Al 2 O 3 → Y 2 O 3 + YAlO 3 → Y 2 O 3 + YAlO 3 + Y 2 O 2 S; When Al content increased to 4.62 wt%, the transformation pathway primarily follows: Al 2 O 3 → Y 2 O 3 + YAlO 3 + Y 2 O 2 S → YAlO 3 + Y 2 O 2 S; Further increasing Al content to 5.41 wt% results in a transformation process mainly of: Al 2 O 3 → YAlO 3 + Y 2 O 2 S. Higher Al content suppresses the precipitation of Y 2 O 3 inclusions and further reduces the average size of overall inclusions. As Al content rises from 3.68 to 5.41 wt%, the average inclusion particle size decreases from 2.21 to 2.08 μm. The recommended Al addition is 4.62−5.41 wt%. These experimental observations are in good agreement with the thermodynamic calculations.