CAUSE JUDGING METHOD OF SURFACE APPEARANCE ABNORMALITY OF HOT DIP GALVANIZED STEEL SHEET

摘要

PROBLEM TO BE SOLVED: To provide an evaluation method having resolving power and sensitivity sufficient to evaluate the extremely slightly difference of the concentration of a component in the depth direction and face direction up to the matrix interface of a steel sheet from the surface of a plating layer and capable of rapidly and certainly specifying the cause of the local surface appearance abnormality in a hot dip galvanized steel sheet. SOLUTION: Each of the visually observed appearance abnormal part and appearance normal part on the surface of the hot dip galvanized steel sheet is irradiated with a pulse laser at least at one analyzing point and an emission spectrum is subjected to spectroscopic analysis at every pulse with respect to each analyzing point to respectively measure the emission intensity of a plating principal component and the emission intensity of the principal component of the steel sheet. The data related to the plating thickness obtained from the pulse time series profile of the emission intensity of the plating principal component is compared with the data related to the concentration distribution in a depth direction of the component at every analyzing point to judge the cause of the appearance abnormality on the surface of the hot dip galvanized steel sheet. COPYRIGHT: (C)2007,JPO&INPIT