Steel plate for hull structure is referred to as ship plate. Due to the harsh working environment of the ship, the ship shell is subject to the chemical and electrochemical corrosion of seawater and the corrosion of Marine organisms and microorganisms. The hull bears large wind and wave impact and alternating load; The shape of the ship makes the processing method complicated, so the steel for the hull structure is strictly required. First of all, good toughness is the most critical requirement. In addition, high strength, good corrosion resistance, welding performance, processing and molding performance and surface quality are required. In order to ensure quality and toughness, carbon equivalent is also strictly required.