Product Code: ICAL08_1105

Rapid Transformation of Scale on Steel Sheets by Laser Irradiation
Authors:
Koji Hirano, Nippon Steel Corporation; Futtsu-City Chiba Japan
Atsushi Sugihashi, Nippon Steel Corporation; Futtsu-City Chiba Japan
Yasumitsu Kondo, Nippon Steel Corporation; Futtsu-City Chiba Japan
Hirofumi Imai, Nippon Steel Corporation; Futtsu-City Chiba Japan
Naoya Hamada, Nippon Steel Corporation; Futtsu-City Chiba Japan
Presented at ICALEO 2008

Scale, iron oxide on hot strip steel sheets, consists of several kinds of oxides; hematite (Fe2O3), magnetite (Fe3O4) and wustite (FeO) as well as iron (Fe) itself. In this study, controlling of scale properties is studied using laser irradiation, which realizes heating only thin scale layer without changing properties of steel substrate. In our experiment, 2 kW diode laser beam (808 nm) was scanned on scale surface at 0.2 m/sec. The composition analysis reveals that the following reaction takes place in the scale: Fe3O4 + Fe 4FeO. It is known that the reaction occurs at above 580 °C under thermal equilibrium, but the result shows that heating time of just several milliseconds is enough for the reaction. The mechanism investigation will also be presented.