A steel plate resistant to seawater dry and wet alternating corrosion in marine environment and its manufacturing method

Abstract

A steel plate resistant to alternating wet and dry seawater corrosion in marine environments and its manufacturing method, based on an alloy system with low C-low Mn-high (P, Cu and Ni) alloying-micro (Nb, Ti) treatment, the control 9.23 (%P)×[3.13(%Cu)+1.67(%Ni)+0.37(%Cr)]≥2.35, [(%P)×H] / [(%Cu)+(%Ni)+0.33(% Cr)]≤2.65; Ca treatment, and the Ca / S ratio is between 1.0 and 3.0 and (%Ca)×(%S) 0.28 ≤1.5×10 ‑3 ; Optimize the TMCP process, so that the microstructure of the finished steel plate is uniform and fine ferrite + dispersed bainite, the average grain size of the microstructure is below 15 μm, and P fails to form excessive segregation at the grain boundary; While ensuring that the steel plate has excellent strength and toughness / strong plasticity matching, excellent cold / thermal mechanical processing characteristics and good weldability, the steel plate is also excellent in resistance to seawater alternating wet and dry corrosion.

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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