Analysis of Mold Level Hunching by Unsteady Bulging during Thin Slab Casting.

Abstract

In order to analyze the phenomenon of mold level hunching (MLH) during thin slab casting process, the variation of the mold level and the bulging of strand were measured and analyzed using Fast Fourier Transform (FFT) spectrum analysis. Both of mold level hunching and bulging had the same frequency and the specific frequency corresponded to the main roll pitch of the thin slab caster. The unsteady bulging was found to be a main reason of mold level hunching. The unsteady bulging profile through the full range of the caster and the height of mold level hunching were calculated using a heat transfer model and a continuous beam model. The effects of process variables on mold level hunching and the process condition of reducing mold level hunching were studied. The amount of mold level hunching increased as unsteady bulging increased due to the hunching of casting speed. An aperiodic roll pitch between segments could be effective in reducing mold level hunching.KEY WORDS: mold level hunching (MLH); unsteady bulging; FFT analysis; continuous beam model; thin slab casting; aperiodic roll pitch.

Modeling Solidification Phenomena in the Continuous Casting of Carbon Steels

“…Involving an expression for the local heat-transfer coefficient inside the mold (Yoon et al, 2002) a more realistic formula was derived that exhibited good results in the present study: …”

“…Consequently, internal structure problems could be identified and verified in practice. The unsteady bulging was found to be (Yoon et al, 2002) the main reason of mold level hunching during thin slab casting. A finite difference scheme for the numerical solution of the heat transfer equation together with a continuous beam model and a primary creep equation were developed in order to match experimental data.…”

Generation Mechanism of Unsteady Bulging in Continuous Casting-2 -FEM Simulation for Generation Mechanism of Unsteady Bulging-

“…As the generation mechanism of unsteady bulging, it is considered that the plastically deformed solidified shell does not remain in its original shape, and the shell is pushed back by the rolls, as Yoon et al 9) reported. In this simulation, as shown in Fig.…”

“…Yoon et al 9) have reported that unsteady bulging was suppressed by adoption of a non-cyclic roll pitch.…”

Comparative Analysis of Bulge Deformation between 2D and 3D Finite Element Models

“…However, bulge deformation measurement has been a very difficult problem to be solved due to the production feature of continuous casting. Only a few papers [1,2] presented experimental data of bulge deformation. In recent years, some measurement methods and patents have been proposed, but these methods applied in bulge deformation measurement have not been reported.…”