| 摘要 |
PROBLEM TO BE SOLVED: To provide a thick steel plate excellent in laser cuttability and a method of manufacturing the same.SOLUTION: After a steel material, which has a composition containing, by mass%, 0.3% or less of C, and further containing 0.05-2.0% of Si, 0.02-2.0% of Ni, and 0.03-2.0% of Cu so as to satisfy 0.10%≤Si+Ni+Cu≤3.00%, is heated and subjected to hot rolling to produce a thick steel plate, descaling by high-pressure water having a collision pressure of 1 MPa or more is performed at a surface temperature of the thick steel plate in a range of 700-950°C, and then the thick steel plate is cooled to a room temperature so as to be held for 500 s or more at a surface temperature of the steel plate in a range of 300-650°C, whereby a scale layer having an average thickness of 15 μm or less and having a specific specular gloss and lightness is formed on the surface of the thick steel plate. An interface between the scale layer and base iron has an arithmetic average roughness Ra of 2.5 μm or more. As a result, a thick steel plate excellent in laser cuttability can be easily manufactured with small restriction on the manufacturing of the steel plate. |
