Seawater-corrosion-resistant steel and manufacturing method thereof

Abstract

The invention discloses seawater-corrosion-resistant steel and a manufacturing method thereof. The mass percentage contents of carbon, silicon, manganese, phosphorus, sulphur, chrome, molybdenum, niobium, titanium and aluminum in the steel are well controlled. Qualified molten steel obtained through converter smelting is subjected to LF + RH + aluminum treatment and then subjected to continuous casting, the obtained billet steel is heated to 1150-1250 DEG C in a heating furnace and then is rolled into a steel sheet, and the final rolling temperature is 850-950 DEG C; and the steel sheet is cooled rapidly at the cooling speed of 100-300 DEG C / s in the first place and then is cooled to 650-750 DEG C in a laminar cooling method at the cooling speed of 10-25 DEG C / s, and the final cooling steel sheet is coiled into a steel coil at the temperature of 650-750 DEG C. The steel coil is spirally welded into a pile pipe through a twin-wire, the pile pipe has good mechanical performance, yield strength is 400-500 MPa, tensile strength is 510-630 MPa, the elongation ratio is larger than 23%, and impact power is larger than 250 J. The pile pipe has good welding performance, the tensile strength obtained after welding is larger than 510 MPa, requirements for 3a and 180 degrees can be met through forward bending, back bending and side bending while integrity is maintained, the impact power obtained after welding is larger than or equal to 110 J, and the corrosion rate of the pile pipe is smaller than 1.30 mm per year.

Description

technical field [0001] The invention relates to a seawater corrosion-resistant steel and a manufacturing method thereof. By adopting the design idea of ​​low-carbon and low-alloy chemical composition system, the steel has excellent mechanical properties, welding properties and seawater corrosion resistance. Background technique [0002] Corrosion of steel in marine environments is one of the typical natural environment corrosions. Since seawater is a typical electrolyte solution, traditional steel materials are easily corroded in seawater, causing great economic losses. Therefore, steel materials used in marine environments must be coated to improve its corrosion resistance. However, the coating on the steel surface is easily damaged by the complex conditions of the ocean, especially in the ocean splash zone, which is easily damaged by the impact of waves or floating objects. Once the coating is damaged, the steel will be damaged much faster than in the atmosphere. Corrosi...

AI Technical Summary

Problems solved by technology

The corrosion-resistant steel involved in JP08073986 belongs to Ca-treated steel, but its Ni content is as high as 2.5%, which greatly increases the manufacturing cost of steel

The corrosion-resistant steel mentioned in the above-mentioned several patent documents contains precious alloy element Ni. In order to ensure the toughness and corrosion resistance of the steel, the Ni content in the corrosion-resistant steel disclosed in some patent documents is as high as 4% (such as JPII001745), This greatly increases the manufacturing cost of steel