METHOD OF DETERMINING CAUSE OF DEFECTS ON STEEL MATERIAL SURFACE

摘要

A method for detecting a cause of an abnormal portion present on a surface of a steel product, which comprises the steps of: condensing a pulsed laser beam, irradiating the pulsed laser beam thus condensed onto an abnormal portion present on a surface of a steel product and a vicinity thereof, limiting pulse energy density of the pulsed laser beam at an irradiation point of the pulsed laser beam on the surface of the steel product within a range of from 10 kW/mm<2> to 100 MW/mm<2>; causing the irradiation point of the pulsed laser beam to zigzag-move throughout the entire region containing the abnormal portion and the vicinity thereof, to vaporize a surface portion of the steel product in the zigzag-moving region of the irradiation point, and converting the resultant vapor into fine particles, so as to collect samples of the abnormal portion and the vicinity thereof on the surface of the steel product in the form of fine particles; and continuously analyzing chemical compositions of the thus collected samples in the form of fine particles to detect a cause of an abnormal portion present on the surface of the steel product. <IMAGE>