SURFACE STATE DETERMINATION METHOD AND SURFACE STATE DETERMINATION DEVICE

To provide a surface state determination method and a surface state determination device which can accurately determine a surface state of a hot-rolled steel sheet after pickling.SOLUTION: A surface state determination method according to the present invention determines a surface state of a hot-rolled steel sheet after pickling. The surface state determination method comprises: an irradiation step of performing irradiation of a surface of the steel sheet with non-single-wavelength light; a light receiving step of receiving reflected light of the irradiation emitted from the surface of the steel sheet; and a determination step of determining the surface state on the basis of the reflected light obtained in the light receiving step. In the determination step, a color tone index which is an index of a color tone of the reflected light is calculated and acceptance/rejection of the surface state of the hot-rolled steel sheet after pickling is determined from a result of a comparison between the calculated color tone index and a threshold value of the color tone index set for each of pickling conditions of the hot-rolled steel sheet.SELECTED DRAWING: Figure 3 【課題】本発明は、酸洗後の熱延鋼板の表面状態を正確に判定できる表面状態判定方法及び表面状態判定装置を提供することを課題とする。【解決手段】本発明に係る表面状態判定方法は、酸洗後の熱延鋼板の表面状態を判定する判定方法であって、上記鋼板の表面に単波長でない光を照射する工程と、上記鋼板の表面から発せられた上記照射の反射光を受光する工程と、上記受光工程で得られた反射光に基づき上記表面状態を判定する工程とを備え、上記判定工程で、上記反射光の色調の指標である色調指標を算出し、上記熱延鋼板の酸洗条件ごとに設定された上記色調指標の閾値と算出した上記色調指標とを比較した結果から酸洗後の熱延鋼板の表面状態の良否を判定する表面状態判定方法である。【選択図】図３