Abstract: An aspect of the present disclosure may provide a defect detection apparatus and method for a steel plate, in which a defect in a steel plate may be detected, and particularly, only an inner defect in the steel plate may be detected, even with a relatively low amplification rate.

Abstract: An aspect of the present disclosure may provide a defect detection apparatus and method for a steel plate, in which a defect in a steel plate may be detected, and particularly, only an inner defect in the steel plate may be detected, even with a relatively low amplification rate.

Abstract: Provided is a defect inspection device of a steel plate. The defect inspection device according to the present invention includes a plurality of inspection units arranged in a width direction of the steel plate, wherein each of the plurality of inspection units includes a first magnetized pole and a second magnetized pole corresponding to each other. Also, the inspection unit includes: a magnetizing part generating a magnetic flux for magnetizing the steel plate in a direction inclined at a predetermined angle with respect to a rolling direction through the first magnetized pole and the second magnetized pole; and a detection part detecting a leakage flux that leaks due to defects existing in or on the steel plate by using the flux generated by the magnetizing part. Thus, the defects may be correctly detected through the defect inspection device.

Abstract: Provided is a defect inspection device of a steel plate. The defect inspection device according to the present invention includes a plurality of inspection units arranged in a width direction of the steel plate, wherein each of the plurality of inspection units includes a first magnetized pole and a second magnetized pole corresponding to each other. Also, the inspection unit includes: a magnetizing part generating a magnetic flux for magnetizing the steel plate in a direction inclined at a predetermined angle with respect to a rolling direction through the first magnetized pole and the second magnetized pole; and a detection part detecting a leakage flux that leaks due to defects existing in or on the steel plate by using the flux generated by the magnetizing part. Thus, the defects may be correctly detected through the defect inspection device.

Abstract: There is provided an on-line detection system and method for a weld of a steel strip, which can emit a laser beam onto the surface of a steel strip moving at a high speed and measure the reflectivity of the laser beam reflecting from the same, thereby detecting the weld of the steel strip easily on-line. In the on-line detection system, reflectivity measuring means emits a laser beam onto a moving steel strip and continuously measuring the reflectivity of the laser beam returning from the surface of the steel strip, and signal processing means detects a weld of the steel strip based on change in the reflectivity measured on the weld.

Abstract: There is provided an on-line detection system and method for a weld of a steel strip, which can emit a laser beam onto the surface of a steel strip moving at a high speed and measure the reflectivity of the laser beam reflecting from the same, thereby detecting the weld of the steel strip easily on-line. In the on-line detection system, reflectivity measuring means emits a laser beam onto a moving steel strip and continuously measuring the reflectivity of the laser beam returning from the surface of the steel strip, and signal processing means detects a weld of the steel strip based on change in the reflectivity measured on the weld.

Abstract: An apparatus and method for measuring the level of a free surface of molten metal in an electromagnetic continuous casting process using an AC electromagnetic field. A detection coil is provided to detect the sum of a magnetic field applied from an induction coil and an induced magnetic field based on eddy current in the molten metal. An arithmetic unit is provided to detect the surface level of the molten metal by removing a variation of the applied magnetic field with a variation in current to the induction coil from an output signal from the detection coil. The surface level of the molten metal can be accurately measured by determining whether a variation in the output of the detection coil results from a variation in the applied magnetic field or a variation in the surface level of the molten metal.

Abstract: A method of measuring the degree of alloying of galvanized steel sheet through the use of laser beams includes the steps of directing a laser beam on a standard sample and reflecting and splitting the beam and detecting the intensity of specular reflection I.sub.0 (.alpha.) at an angle of reflection (.alpha.) and the intensity of scattering I.sub.0 (.beta.) at an angle of reflection (.beta.) to thus obtain the degree of alloying (X.sub.0) of the standard sample by the formula: ##EQU1## The above steps are repeated to obtain values I.sub.1 (.alpha.) and I.sub.2 (.beta.) to obtain a comparative degree of alloying (X.sub.1) of the standard sample using the above equation form. The arrangement of the laser, mirror and first and second beam splitters are corrected based on a comparison of the X.sub.0 and X.sub.1 values. The above steps are then repeated by directing the laser onto a galvanized steel sheet to obtain the degree of alloying (X.sub.2) of the galvanized steel sheet.