Abstract
In the current work, a rod deflection method (RDM) is conducted to measure the velocity of molten steel near the surface in continuous casting (CC) mold. With the experimental measurement, the flow velocity and direction of molten steel can be obtained. In addition, a mathematical model combining the computational fluid dynamics (CFD) and discrete phase method (DPM) has been developed to calculate the transient flow field in a CC mold. The simulation results are compared and validated with the plant measurement results. Reasonable agreements between the measured and simulated results are obtained, both in the trends and magnitudes for the flow velocities of molten steel near the mold surface. Based on the measured and calculated results, the velocity of molten steel near the surface in the mold increases with increasing casting speed and the casting speed can change the flow pattern in the mold. Furthermore, three different types of flow patterns of molten steel in the mold can be obtained. The pattern A is the single-roll-flow (SRF) and the pattern C is the double-roll-flow (DRF). The pattern B is a transition state between DRF and SRF, which is neither cause the vortices nor excessive surface velocity on the meniscus, so the slag entrainment rarely occurs. Argon gas injection can slow down the molten steel velocity and uplift the jet zone, due to the buoyancy of bubbles. Combination of the measurement and numerical simulation is an effective tool to investigate the transient flow behavior in the CC mold and optimize the actual operation parameters of continuous casting to avoid the surface defects of the automobile outer panels.
Highlights
The surface defects on the cold rolled sheets for automobile outer panels related to the steelmaking process are mainly the large-sized Al2 O3 clusters, “Ar + Al2 O3 ” typed inclusions and the entrapped mold powder particles [1]
The results showed that the fluctuations included a wide range of flow velocities as large as 0–0.6 m/s and the period of these fluctuations was estimated to be around 15 s based on the water model experiments
Compared the distribution of velocities with and without argon gas injection, it can be found that argon gas injection can slow down the molten steel velocity and uplift the jet zone
Summary
The surface defects on the cold rolled sheets for automobile outer panels related to the steelmaking process are mainly the large-sized Al2 O3 clusters, “Ar + Al2 O3 ” typed inclusions and the entrapped mold powder particles [1]. The non-metallic inclusions and the entrapped mold powder particles produced in the steelmaking and continuous casting (CC) process are firstly crushed down and elongated along the rolling direction during the subsequent rolling process. They are discretely distributed along the rolling direction to form the line-shape defects, such as sliver, scab and blister. The number density of the large inclusions decreases with increasing casting speed when the casting speed is 1.0–2.0 m/min
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