STEEL HAVING HIGH STRENGTH AND METHODE FOR MANUFACTURING THE SAME

摘要

PURPOSE: A high strength steel plate and a manufacturing method thereof are provided to prevent crack or breaking of a plate, and to offer efficient physical property due to uniform structure of a first and a second layers in which nitrogen is diffused. CONSTITUTION: A high strength steel plate includes a first layer(1), a second layer(2), and a third layer. The first layer is made of extra-low-carbon steel. The second layer is located on a position adjacent to the first layer. The second layer has a first surface(21) located on an opposite side of the first layer. The second layer has the same organization with the organization of the first layer. The third layer is formed on the second layer. The third layer is formed to prevent corrosion of the surface of the first layer.