Stress-corrosion-resistant high-strength steel and controlled rolling and controlled cooling technology thereof

Abstract

The invention provides stress-corrosion-resistant high-strength steel and a controlled rolling and controlled cooling technology thereof, and belongs to the technical field of metal materials. The high-strength steel comprises the following chemical components of, by mass percentage, less than or equal to 0.06% of C, 0.20-0.30% of Si, 1.5-1.9% of Mn, less than or equal to 0.010% of P, less than or equal to 0.006% of S, 0.20-0.50% of Cr, 0.20-0.30% of Ni, 0.20-0.50% of Cu, 0.03-0.06% of Nb, 0.004-0.01% of N and the balance Fe, wherein the mass percent of Nb and N meets the condition that Nb/N is greater than or equal to 6 and less than or equal to 8. The controlled rolling and controlled cooling technology for the high-strength steel comprises the steps of firstly, carrying out heating and heat preservation on a continuous casting blank, then carrying out first-stage rolling and controlled cooling; and then carrying out second-stage rolling and cooling after rolling. The high-strength steel and the controlled rolling and controlled cooling technology have the advantages that through reasonable alloy composition design and the controlled rolling and controlled cooling technology, the mechanical property and the stress corrosion resistance of the steel can be improved; and according to the chemical components and the rolling process, the steel with the yield strength greater than 550MPa can be produced, in the steel, the size of a large number of nano particles is less than 10nm, the Nb(C,N) precipitated phase is uniformly distributed, and therefore the mechanical property and the stress corrosion resistance of the steel can be obviously superior to the mechanical property and the stress corrosion resistance of E550 steel produced by common components and technologies.

Description

technical field [0001] The invention relates to the technical field of metal materials, in particular to a stress-corrosion-resistant high-strength steel and a controlled rolling and cooling process thereof. Background technique [0002] With the accelerated exploitation of marine resources, the demand and performance requirements for steel for offshore platforms continue to increase. High-strength steel plates for offshore platforms must have high strength, high toughness, lamellar tear resistance, fatigue resistance, corrosion resistance, and excellent weldability, etc. features. In addition, due to the harsh marine service environment, it is necessary to take cathodic protection measures for offshore platforms. When the cathodic protection potential is not controlled properly, hydrogen precipitation may occur, and the precipitated hydrogen will permeate into the interior of the steel. There is a certain amount of hydrogen in the steel, so that the high-strength steel has...

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Problems solved by technology

In addition, due to the harsh marine service environment, it is necessary to take cathodic protection measures for offshore platforms. When the cathodic protection potential is not controlled properly, hydrogen precipitation may occur,

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