To measure in the noncontact state, the thickness of an oxide film including magnetite formed on the surface of a steel plate.
The thickness of hematite 2b is determined by irradiating a terahertz wave 3 to a hot rolled steel plate 1 having a scale 2 formed on the surface, with a bilayer structure wherein the hematite 2b and magnetite 2a are formed from a surface layer. Then, laser light is irradiated to the hot rolled steel plate 1 to remove the hematite 2b, and the magnetite 2a is transformed into wustite 2c having approximately the same size as the magnetite 2a. Thus, only the wustite 2c is remained in the scale 2, and then, the terahertz wave 3 is irradiated to the hot rolled steel plate 1, to thereby determine the thickness of the wustite 2c. Then, the whole thickness of the scale 2 is calculated from the calculated thickness of the hematite 2b and thickness of the wustite 2c.
HIRANO KOJI
KONDO YASUMITSU
| JPH10206125A | 1998-08-07 | |||
| JP2005214758A | 2005-08-11 | |||
| JP2004028618A | 2004-01-29 |