Seawater corrosion resistant structural steel with uniform metallographic structure and production method thereof

Abstract

The invention relates to seawater corrosion resistant structural steel with the uniform metallographic structure and a production method thereof. The seawater corrosion resistant structural steel comprises the following compositions according to percentages by weight: 0.05-0.45% of C, 0.05-0.45% of Si, 1.50-2.50% of Mn, less than or equal to 0.025% of P, less than or equal to 0.006% of S, 0.001-0.0048% of Ti and the rest of Fe and inevitable impurities. The production method comprises the following steps of: smelting, and carrying out vacuum treatment and continuous casting to form a blank; conventionally heating and soaking the casting blank; carrying out subsection rolling, i.e. casting-state structure rolling, rolling of refining grains and homogenization rolling of grain sizes; naturally cooling till reaching room temperature, and setting aside for application. According to the observation of the structural steel by using a 200-times metallographic microscope, in a finished product steel plate, the grains with the size of 10-25mum accounts for 80%-90%, the grains with the size of greater than 25mum is less than or equal to 5%, and the size of the rest of grains is less than 10mum; the seawater corrosion resistant of the steel plate is increased by at least 45%; and the steel plate has good strength and toughness and excellent cold and hot deformation and welding performance.

Description

technical field [0001] The invention relates to iron and steel materials, in particular to seawater corrosion-resistant structural steel and a production method thereof. Background technique [0002] Structural steels such as offshore drilling platforms, especially structural steels located below seawater, not only require good comprehensive mechanical properties and process properties, but also good corrosion resistance to ensure the safety of steel structure engineering. Structural steels such as active offshore drilling platforms are generally DH36, AH36, EH36, D420, E420, D460, E460, E690, etc. stipulated by relevant classification societies. According to relevant literature reports, the above materials have good fatigue resistance during use. The performance cannot meet the requirements, the fatigue life is lower than the design requirements of the service life of the steel structure, and some seawater corrosion resistance cannot meet the requirements, pitting corrosion...

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Problems solved by technology

[0004] The present invention aims to solve the existing problems of low marine corrosion resistance and short service life due to coarse metallographic grains and poor uniformity in the prior art. Under the premise, the marine corrosion resistance rate of steel is increased by at least 45%, the number of steel grains with a grain size of 10-25 μm accounts for 80%-90%, and the steel grain size is uniform seawater corrosion-resistant structural steel and its production method

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