Abstract:Confocal laser scanning microscopy was used to perform experiments with various cooling rates for the solidification of Al-Ti deoxidised steel. The effects of cooling rate on the morphology, size distribution of observed with typical inclusions, Al 2 O 3 , TiS, and Al 2 O 3 -TiS in the steel were investigated. The experimental results demonstrate that the inclusion morphology is significantly influenced by the cooling rate. With an increase in cooling rate, the number of inclusions smaller than 3 μm rises whil… Show more
“…[1,2] It is a key technology for producing ultralow carbon, oxygen, nitrogen, and other impurity elements. [3] Generally, the liquid steel, after degassing, is deoxidized with aluminum at the end of the RH refining process and alloyed with titanium; [4][5][6][7] subsequently, the alumina inclusions are generated during the deoxidation process due to adding aluminum. [8,9] The control of alumina inclusions is crucial for ensuring that a steel product performs its designed functions in a structural component.…”
Understanding the aggregation‐floating behavior of alumina inclusions, which is influenced by the interface properties between inclusions and molten steel, is crucial to controlling the purity of IF (interstitial‐free) steel in the refining process. This work attempts to investigate the effect of aluminum and titanium concentrations on the aggregation‐floating behavior of alumina inclusions in the interior of IF molten steel based on the interface properties between molten steel and alumina inclusions. The interface properties between the molten steel and alumina inclusions were measured using an improved sessile drop method. And the aggregation‐floating behavior of inclusions in the interior of molten steel has been quantitatively discussed by an aggregation model based on the attractive force between alumina inclusions, which was combined with the interface properties. The results show that the attractive forces between alumina inclusions, ranging from 6.96×10‐6 to 5.41×10‐5 N, increase and decrease, respectively, with increasing aluminum and titanium concentrations. Furthermore, the terminal floating speeds of alumina inclusions, ranging from 0.0510 to 0.0873 m/s, increase and decrease, respectively, with increasing aluminum and titanium concentrations.This article is protected by copyright. All rights reserved.
“…[1,2] It is a key technology for producing ultralow carbon, oxygen, nitrogen, and other impurity elements. [3] Generally, the liquid steel, after degassing, is deoxidized with aluminum at the end of the RH refining process and alloyed with titanium; [4][5][6][7] subsequently, the alumina inclusions are generated during the deoxidation process due to adding aluminum. [8,9] The control of alumina inclusions is crucial for ensuring that a steel product performs its designed functions in a structural component.…”
Understanding the aggregation‐floating behavior of alumina inclusions, which is influenced by the interface properties between inclusions and molten steel, is crucial to controlling the purity of IF (interstitial‐free) steel in the refining process. This work attempts to investigate the effect of aluminum and titanium concentrations on the aggregation‐floating behavior of alumina inclusions in the interior of IF molten steel based on the interface properties between molten steel and alumina inclusions. The interface properties between the molten steel and alumina inclusions were measured using an improved sessile drop method. And the aggregation‐floating behavior of inclusions in the interior of molten steel has been quantitatively discussed by an aggregation model based on the attractive force between alumina inclusions, which was combined with the interface properties. The results show that the attractive forces between alumina inclusions, ranging from 6.96×10‐6 to 5.41×10‐5 N, increase and decrease, respectively, with increasing aluminum and titanium concentrations. Furthermore, the terminal floating speeds of alumina inclusions, ranging from 0.0510 to 0.0873 m/s, increase and decrease, respectively, with increasing aluminum and titanium concentrations.This article is protected by copyright. All rights reserved.
The experiment of Al‐deoxidized steel coupling with Mg treatment is conducted under three cooling methods to observe the size and morphology of MgAl2O4. Most of MgAl2O4 in the water‐cooled steel are sphere or ellipsoid‐like shape, in the furnace‐cooled steel are cubic or octahedral‐like shape, and in the air‐cooled steel are irregular shape. The quantity of inclusions in the size of 1–3 μm increases with the increasing cooling rate, whereas the quantity of the other size decreases with the increasing cooling rate. The result shows that the changing of cooling methods has little effect on the critical size and the nucleation rate of MgAl2O4. The growth of MgAl2O4 is effected by diffusion, Ostwald, and collision growth, and the increasing cooling rate leads to the decreasing growth time. The size of MgAl2O4 is decided by the diffusion of Mg and the growth time of MgAl2O4. Four possible morphological transformation paths of MgAl2O4 in steel are found, and the shape of MgAl2O4 can evolve from sphere or ellipsoid to octahedron via truncated octahedron or cubic‐like shape. The final morphology of MgAl2O4 is controlled by the transformation path which has a close relationship with the cooling rate.
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