To provide a thick steel plate which has improved laser cuttability, and is used for general structures, welding structures, machine structures or the like in the fields of construction equipment, buildings, bridges, shipmaking, pressure vessels or the like.
The thickness of scale in the surface of the steel plate is controlled to 10 to 50 μm for improving the laser absorptivity in the surface of the steel plate. In the steel components, the content of C is increased, and the content of Mn and the content of Mn are reduced for optimizing the heat generation by oxidation in the steel, and the viscosity of molten steel. The ratio of the peeling in the boundary between a scale layer and ferrite is controlled to ≤10%, and the area of vacancies present in the scale layer is controlled to ≤5% for optimizing the flow of assist gas.
| JPH0615301 | FORMING METHOD FOR SHAPE STEEL |
WATABE YOSHIYUKI
CHIJIIWA RIKIO
