Steel plate resistant to alternate dry-wet corrosion of marine environment seawater and manufacturing method of steel plate

Abstract

The invention relates to a steel plate resistant to alternate dry-wet corrosion of marine environment seawater and a manufacturing method of the steel plate. An alloy system with low C, low Mn, high (P, Cu and Ni) alloying and micro (Nb, Ti) treatment is adopted as the basis, 9.23(%P)*[3.13(%Cu)+1.67 (%Ni)+0.37(%Cr)] is controlled to be larger than or equal to 2.35, and [(%P)*H] / [(%Cu)+(%Ni)+0.33(%Cr)] is controlled to be smaller than or equal to 2.65. Ca treatment is carried out, and the Ca / S ratio is 1.0-3.0 and (%Ca)*(%S)0.28 is less than or equal to 1.5*10-3. The TMCP process is optimized, so that a microscopic structure of the finished steel plate is of uniform and fine ferrite and dispersedly distributed bainite, the average grain size of the microscopic structure is 15 microns or below, and P cannot form excessive segregation at the grain boundary. The steel plate is ensured to have excellent obdurability / strong plasticity matching, excellent cold / hot machining characteristics and better weldability, and meanwhile, and the steel plate is resistant to alternate dry-wet corrosion of seawater excellently.

Description

technical field [0001] The invention relates to the technical field of corrosion-resistant steel, in particular to a steel plate resistant to alternating dry and wet corrosion of seawater in a marine environment and a manufacturing method thereof. Background technique [0002] As we all know, low-carbon (high-strength) low-alloy steel is one of the most important engineering structural materials, widely used in oil and gas pipelines, offshore platforms, shipbuilding, bridge structures, boiler containers, building structures, automobile industry, railway transportation and machinery manufacturing. The physical and mechanical properties of low-carbon (high-strength) low-alloy steel depend on its chemical composition and manufacturing process, among which strength, toughness, plasticity, corrosion resistance (atmosphere, industrial atmosphere and marine atmosphere, etc.) The most important performance of low-carbon (high-strength) low-alloy steel is ultimately determined by the...

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Problems solved by technology

[0008] The above-mentioned developed steel types not only contain a large amount of alloying elements such as Cu, Ni, Cr and Ti, but also have a high content of precious alloying element Ni and weather-resistant element Cr, of which the content of Ni and Cr basically reaches more than 1.00%, resulting in high steel plate manufacturing costs 1. There are many cracks and defects on the surface of the steel plate, and the quality control of the steel plate surface is also difficult; more importantly, these developed steel types are mainly aimed at corrosion resistance to marine atmospheric atmosphere, that is, salt spray corrosion resistance (chloride ion corrosion resistance), and do not involve seawater in the splash zone. The steel plate is corroded under the alternating dry and wet conditions, and the seawater in the splash zone is the most corrosive to the steel plate, which is directly related to the service life, maintenance cost and safety and reliability of the marine steel structure.

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