Investigation of meniscus region behavior and oscillation mark formation in steel continuous casting using a transient thermo-fluid model

In the continuous casting of steel, many complex phenomena in the meniscus region of the mold are responsible for the formation of oscillation marks. Oscillation marks are depressions found around the perimeter of continuously cast steel slabs, which if too large can lead to cracking in steel slabs. Therefore, knowledge on how to minimize the size of oscillation marks is very valuable. A computational model was created of the meniscus region, which includes transient multiphase fluid flow of slag and steel, with low-Reynolds turbulence, heat transfer in the mold, slag, and steel, steel shell solidification, mold oscillation, and temperature-dependent properties. This model was first validated using previous experimental and plant data. The model was then used to study the impact of varying casting parameters, including oscillation frequency, stroke, modification ratio, casting speed, molten steel level fluctuations, and temperature-dependent slag properties and surface tension on the oscillation mark shape, and other aspects of thermal-flow behavior during each oscillation cycle, including heat flux profile, slag consumption and mold friction. The first half of oscillation marks were formed during negative strip time as the slag rim pushed molten steel away from the mold wall and that the second half of oscillation marks were formed during positive strip time as the molten steel is drawn near the mold wall due to the upstroke of the mold. Oscillation mark depth was found to decrease with increasing frequency, modification ratio, casting speed, and slag viscosity, while oscillation mark depth was found to increase with increasing stroke. Oscillation mark width was only found to increase due to increases in pitch, which can be contributed to decreasing frequency or increasing casting speed. While many observations were made in this study, in general, oscillation mark depth and total slag consumption increase with increasing negative strip time, while the average heat flux and average mold friction decrease with increasing negative strip time.

Name thesis:degree_name

Master of Science (M.S.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor dc:publisher

Colorado School of Mines. Arthur Lakes Library

Year dc:date.issued

2017

Author dc:creator

• Blaes, Carly M.

Advisor dc:contributor.advisor

• Thomas, B. G. (Brian G.)

Committee members dc:contributor.committeemember

• Bogin, Gregory E.
• Tilton, Nils

• CFD
• marks
• steel
• continuous
• casting
• oscillation

Statement dc:rights

• Copyright of the original work is retained by the author.

Language dc:language.iso

eng, English

Identifier

T 8298

OAI identifier oai:identifier

oai:repository.mines.edu:11124/171023