Effect of the Stirring Mode on the Behavior of Al₂O₃–MgO Particles and Clusters during Ladle Treatment of Ni‐based Alloy 825

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 Al 2 O 3 -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 Al 2 O 3 -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 mm). The effect of the different stirring modes on the behavior of the Al 2 O 3 -MgO particles and clusters in the melt for the ladle treatment experiments agree with the theoretical predictions based on Stokes', Brownian, and Turbulent collisions.

TiN Particles and Clusters during Ladle Treatments of Ni-based Alloy 825 using Different Stirring Modes

“…However, for downwards stirring (EMS/D + GS) the number of clusters for all sizes decreased. 13) Furthermore, more detailed studies (in 2D) have been done on 3 heats for each stirring method. Despite some variations, the obtained results showed similar tendencies for Al 2 O 3 -MgO and TiN clusters in the heats with the same stirring parameters.…”

“…During these studies, several parameters influencing the agglomeration and removal of inclusions (such as stirring conditions and inclusion characteristics) were considered and discussed. [2][3][4][5][6][7][8][9][10][11][12][13][14] A overview of the obtained results at different stirring modes and conditions were done in a separate article. 13) It was reported that the turbulent dissipation energy rate (ε), as a parameter of intensity of melt stirring in the ladle, can be varied in very wide range (from 0.0002 to 0.7 m 2 s − 2 ).…”

“…15) The behaviors of Al 2 O 3 -MgO clusters in the melt for dif-ferent stirring modes during ladle treatment were discussed in separate article. 13) However, the formation and behavior of TiN inclusions and clusters in the melt of Ni-base alloys have not been considered up to now.…”

“…1) Several previous studies have proven that the characteristics of non-metallic inclusions in liquid steel can be modified during the ladle treatment. [2][3][4][5][6][7][8][9][10][11][12][13][14] Both model calculations [2][3][4][6][7][8][9][10]12,14) and experimental investigations 5,[11][12][13] have…”

Assessment of a Simplified Correlation Between Wettability Measurement and Dispersion/Coagulation Potency of Oxide Particles in Ferrous Alloy Melt

“…[4][5][6][7][8][9] Moreover, there is a concept, inclusion engineering, that deals with the control of the amount, morphology, size distribution, and composition of nonmetallic inclusions formed in the liquid steel during refining and solidification. [10] To better understand the mechanism of inclusion agglomeration behavior, the experimental studies using both in-situ [11][12][13][14][15] and ex-situ [16][17][18][19] methodologies have been performed. However, the current in-situ characterization research by high-temperature confocal laser scanning microscope (HT-CLSM) limits the inclusion behavior on the liquid steel surface or named steel-gas interface, which is a much different mechanism with the case of inclusion agglomeration at the bulk of the liquid steel.…”