METHOD FOR DETECTING DEFECT AND DEFECT DETECTION DEVICE IN CONTINUOUSLY CAST SLAB FOR THIN STEEL SHEET

摘要

PROBLEM TO BE SOLVED: To provide a method for detecting a defect and a defect detection device in a continuously cast slab for a thin steel sheet which can estimate and detect a cracking defect generated on the surface of a slab to be formed into the stock of a continuously cast thin steel sheet with high accuracy in a stage directly after casting.;SOLUTION: In the method for detecting a defect in a continuously cast slab, the temperature distribution in the width direction of the surface of a continuously cast slab is periodically measured; a difference in the highest temperature and the lowest temperature between both the width edge parts in the surface of the slab and a position of 1/3 of the whole width from both the width edge parts is calculated, or a difference in the highest temperature and the lowest temperature between a position of 1/10 of the whole width from both the width edge parts in the surface of the slab and a position of 1/3 in the whole width from both the width edge parts is calculated; and it is decided that a defect is generated on the surface of the slab when the calculated temperature difference lies in a preset threshold value or above in any of the sides of both the width edge parts, or successive frequency that the temperature difference lies in the preset threshold value or above is prescribed frequency of two or more times.;COPYRIGHT: (C)2012,JPO&INPIT