Transient Evolution of Nonmetallic Inclusions in a Si–Mn‐Killed Stainless Steel with Cerium Addition

Laboratory experiments are performed to study the transient evolution of inclusions in Si–Mn‐killed stainless steels with additions of 40, 100, and 400 ppm cerium. With the increase of the cerium content in the molten steel, the evolution path of inclusions is Al 2 O 3 –SiO 2 –MnO–CaO → Ce 2 O 3 –Al 2 O 3 –SiO 2 –MnO–CaO → Ce 2 O 3 → Ce 2 O 3 –CeS. The addition of 40 ppm cerium gradually increases the Ce 2 O 3 content in liquid oxide inclusions. After the addition of 100 ppm cerium, inclusions first evolve to Ce 2 O 3 –Al 2 O 3 –SiO 2 –CaO–CeS, then to Ce 2 O 3 . The CeS is generated as a transient product then disappears. After the addition of 400 ppm cerium, liquid Al 2 O 3 –SiO 2 –MnO–CaO inclusions are modified to solid Ce 2 O 3 –CeS ones. The addition of 40 ppm cerium into the steel lowers the size from 1.74 to 1.53 μm. After the addition of 100 and 400 ppm cerium into the steel, the size of inclusions immediately decreases due to the formation of small Ce 2 O 3 –CeS inclusions and then increases owing to the collision of solid inclusions. A higher cerium content in the steel promotes the collision of Ce‐rich inclusions.