Thermomechanical finite-element model of shell behavior in continuous casting of steel
- PDF / 1,117,117 Bytes
- 22 Pages / 612 x 792 pts (letter) Page_size
- 32 Downloads / 173 Views
I. INTRODUCTION
COMPUTATIONAL models are important tools to gain insight into thermal and mechanical behavior during complex manufacturing processes such as the continuous casting of steel billets. This process features many interacting phenomena which challenge modeling methods, shown in Figure 1(a). Starting with the turbulent flow of molten steel into the mold cavity, superheat is dissipated during flow recirculation in the liquid pool prior to solidifying a shell against the walls of a water-cooled copper mold. Heat transfer is controlled by conduction through the solidifying steel shell, the mold, and, especially, the size and properties of the interfacial layers between them. After initial solidification at the meniscus, the shell tends to shrink away from the mold walls due to thermal contraction. Over most of the strand surface, internal “ferrostatic pressure” from the head of molten metal maintains good contact between the shell and the mold. However, shrinkage near the corners may create gaps or intermittent contact, which greatly lowers the local cooling rate. The extent of the gap depends on the composition-dependent shrinkage of the steel shell, its creep resistance, the casting speed, taper of the mold wall, thermal distortion of the mold wall, and the thermal properties of the material filling the interfacial gap. The mechanical behavior of the shell also controls the formation of defects such as hot-tear cracks and breakouts and depends on thermal shrinkage, high-temperature inelastic stress-generation rate, solid-state phase transformations, temperature, steel composition, mulCHUNSHENG LI, Postdoctoral Student, and BRIAN G. THOMAS, Wilkins Professor of Mechanical Engineering, are with the Department of Mechanical and Industrial Engineering, University of Illinois at UrbanaChampaign, Urbana, IL 61801. Contact e-mail: [email protected] Manuscript submitted August 18, 2003. METALLURGICAL AND MATERIALS TRANSACTIONS B
tidimensional stress state, and deformation rate. The harsh environment of the steel plant makes it difficult to conduct experiments during the process. To improve insight into these phenomena demands sophisticated mathematical models, to aid the traditional tools of physical models, lab, and plant experiments. A thermal-mechanical finite-element model that incorporates the aforementioned phenomena, named CON2D, has been developed in the Metals Processing Simulation Laboratory at the University of Illinois at Urbana-Champaign over the past decade[1–4] with several applications.[5–12] After a brief literature review, this article describes the features of the CON2D model. It then presents its validation with analytical solutions and a simulation of a continuous steel billet casting process, where plant measurements were available for comparison. II. PREVIOUS WORK Many previous computational models have investigated thermal stress during the continuous casting of steel, including models of billet casting,[13–19] beam blanks,[20] slab casting,[2,6,11,13,14,21–31] and thin-slab casting.[32,3
Data Loading...
