Thermal and mechanical behavior of copper molds during thin-slab casting (I): Plant trial and mathematical modeling
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I. BACKGROUND
AN important recent trend in the steel industry is the development of processes for casting steel closer to the final product size. The continuous casting of thin slabs with only a few centimeters of thickness allows hot-direct rolling to be performed inline with a conventional finishing mill, eliminating the need for a roughing train. This advanced continuous-casting technology of thin slabs is growing in the steel industry owing to the associated savings in capital cost, energy, and manpower. The mold is the most critical component of the process, which controls initial solidification and determines surface quality. The quantification of heat transfer and distortion of thin-slab casting, copper mold plates has received relatively little attention in previous literature. Furthermore, the difference between the funnel and parallel mold design has not been compared. During operation, the mold distorts due to the steep thermal gradients. Although this distortion is very small, it may affect the size of the gap between the solidified shell and the mold, which, in turn, controls heat transfer. Thin-slab molds are expected to have higher heat flux and temperature owing to the higher casting speed. The accompanying thermal stress may cause permanent creep deformation near the meniscus, which affects mold life as well. Furthermore, maintaining a reliable, crack-free mold within close dimensional tolerances is also crucial to safety and productivity. JOONG KIL PARK, Graduate Student, and INDIRA V. SAMARASEKERA, Professor, are with the Department of Metals and Materials Engineering, University of British Columbia, Vancouver, BC, Canada V6T 1Z4. Contact e-mail: [email protected] BRIAN G. THOMAS, Professor, is with the Department of Mechanical and Industrial Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801. U. SOK YOON, Senior Researcher, is with the Iron & Steelmaking Research Group, Technical Research Laboratory, POSCO, Pohang, Kyungbuk, Korea. Manuscript submitted May 29, 2001. METALLURGICAL AND MATERIALS TRANSACTIONS B
This article is the first part of a two-part study on the thermal and mechanical behavior of thin-slab casting molds. This part investigates the heat-flux profiles based on mold temperature measurements and compares the thermal distortion of thin-slab molds of two different configurations using three-dimensional (3-D) finite-element models. II. PREVIOUS WORK Many mathematical models and plant trials have investigated the thermal and mechanical behavior of conventional slab-casting molds.[1–7] Thomas et al.[1,2] applied a 3-D elastic-plastic-creep finite-element model to predict temperature and distortion of a conventional slab mold during operation. The wide faces were predicted to bend inward (toward the steel) with a maximum distortion on the order of 1 mm on the wide-face centerline between the meniscus and mold midheight. They also studied the effect of design and operating variables, such as slot spacing and shape, copper plate thickness, strand width, clamping
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