Abstract
In the present work, the flow field in a slab continuous casting mold with thicknesses of 180 and 250 mm are compared using high temperature quantitative measurement and numerical simulation. The results of the numerical simulation are in agreement with those of the high temperature quantitative measurement, which verifies the accuracy and reliability of the numerical simulation. Under the same working conditions, the velocities near the mold surface with the thickness of 180 mm were slightly higher than those of the mold with the thickness of 250 mm. The flow pattern in the 180 mm thick mold maintains DRF more easily than that in 250 mm thick mold. The kinetic energy of the jet dissipates faster in the 250 mm thick mold than in the 180 mm mold. For double-roll flow (DRF), as the argon gas bubbles can be flushed into the deeper region under the influence of strong jets on both sides, the argon bubbles distribute widely in the mold. For single-roll flow (SRF), as the argon bubbles float up quickly after leaving the side holes, the bubble distribution is more concentrated in the width direction, which may cause violent interface fluctuation and slag entrainment. The fluctuation at the steel-slag interface in the mold with 180 mm thickness is greater than that in the mold with 250 mm thickness but less than 5 mm. The increase of mold thickness may lead to a decrease of the symmetry of the flow field in the thickness direction and uniformity of mold powder layer thickness. In summary, the steel throughput should be increased in the 250 mm thick mold compared with that in the 180 mm thick mold.
Highlights
Automobile exposed panels involve many manufacturing processes, including steelmaking processes, such as hot metal pretreatment, converter blowing, secondary refining, continuous casting, hot rolling, cold rolling and hot-dip galvanizing
In the final quality inspection stage, the surface defects formed in the various production stages are interwoven, which increases the difficulty of the determination of the formation-related causes of the defects and the optimization of the corresponding processes
The results show that with the increase of the argon gas flow rate, the double-roll flow (DRF) first changes into an unstable flow (UF) and develops into a single-roll flow (SRF), and two mechanisms of vortex formation near the surface are observed: uniform shear and non-uniform shear
Summary
Automobile exposed panels involve many manufacturing processes, including steelmaking processes, such as hot metal pretreatment, converter blowing, secondary refining, continuous casting, hot rolling, cold rolling and hot-dip galvanizing. As far as we know, it is difficult to use a continuous caster with a thickness smaller than 175 mm to produce automobile exposed panels to satisfy their strict surface quality requirement This is the reason why two types of slab mold thickness (i.e., 180 and 250 mm) were selected for the comparison of mold flow fields under the same steel throughput, which was not reported before. The industrial high temperature quantitative measurement of the velocity near the mold surface and a numerical simulation were combined to analyze the flow field in slab molds with section sizes of 1800 × 180 mm and 1800 × 250 mm, respectively. The volume of fluid method (VOF) was employed to track the steel-slag interface, and the argon gas bubbles were simplified as Langrangian particles
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