Effect of the Stirring Mode on the Behavior of Al2O3–MgO Particles and Clusters during Ladle Treatment of Ni‐based Alloy 825. Issue 12 (18th September 2017) - Kellner, Hans E. O.
Abstract : It is well known that inclusions affect the properties of alloys. Therefore, the importance of understanding what inclusions exist and how they behave cannot be overstated. This study has examined the behavior of Al2 O3 –MgO particles and clusters in the melt during the ladle treatment of Alloy 825, who is a Ni‐based Alloy. The effect of different stirring directions of electromagnetic stirring in combination with gas stirring is discussed based on three‐dimensional investigations of the clustered particles. More specifically, the composition, size, and number of particles and clusters are determined after electrolytic extraction of metal samples by using SEM in combination with EDS. The results show that the agglomeration of Al2 O3 –MgO particles in the melt is faster for an upward induction stirring combined with a gas stirring in comparison to a downward stirring combined with a gas stirring. However, the total removal of clusters from the melt is more effective when using a downward induction stirring compared to when using an upward induction stirring, especially for large size clusters (>11.2 μm). The effect of the different stirring modes on the behavior of the Al2 O3 –MgO particles and clusters in the melt for the ladle treatment experiments agree with the theoretical predictions based on Stokes', Brownian, and Turbulent collisions. Abstract : The effect of different stirring modes (combination of gas stirring and electromagnetic stirring with upwards or downwards direction) on the agglomeration and removing of Al2 O3 –MgO clusters during the ladle treatment is evaluated. The results show that the cluster number in the melt can drastically decrease (by ≈55–80%) by using gas stirring in combination with a downward induction stirring.