| 摘要 |
PROBLEM TO BE SOLVED: To reliably detect the development of a longitudinal crack defect on a cast billet during continuous casting. SOLUTION: A plurality of temperature measuring elements 18 are embedded in the width direction into the inner part of a mold wall 10 at the equal position from molten steel surface, and a parameter Z defined with Z=√V<SB>C</SB>(T<SB>i+1</SB>-T<SB>i</SB>)/[ä(T<SB>i+1</SB>+ T<SB>i</SB>)/2-T<SB>W</SB>}<SP>2</SP>k√L×Δt] ( wherein the temperature T<SB>i</SB>of an optional temperature measuring element at fixed time t<SB>i</SB>, temperature T<SB>j+1</SB>after timeΔt, the absolute value of the amount of change of both temperatures T<SB>i+1</SB>-T<SB>i</SB>[°C], casting velocity V<SB>C</SB>, distance L between the molten steel surface and the temperature measuring element and the water temperature T<SB>W</SB>[°C] of the mold cooling water are included) is calculated at each temperature measuring element in the width direction. Then, it is judged that the longitudinal crack is developed on the cast billet in the width direction corresponding to this element when the parameter Z exceeds the limiting value in any element. COPYRIGHT: (C)2005,JPO&NCIPI
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