High-heat-input welding thick steel plate and manufacturing method thereof

Abstract

Disclosed are a high-heat-input welding thick steel plate and a manufacturing method thereof. The manufacturing method includes following steps: a) smelting, refining and continuous casting; b) rolling; and c) cooling. Steel consists of components including, by weight percentage, from 0.05 to 0.09% of C, from 0.10 to 0.30% of Si, from 1.3 to 1.7% of Mn, from 0.005 to 0.03% of Ti, from 0.003 to 0.025% of Nb, from 0.001 to 0.01% of S, smaller than or equal to 0.015% of P, smaller than or equal to 0.006% of N, from 0.0005 to 0.01% of Mg, smaller than or equal to 0.01% of Al, smaller than or equal to 0.003% of Ca, more than one of smaller than or equal to 0.3% of Cu, smaller than or equal to 0.4% of Ni and smaller than or equal to 0.002% of B, and the balance Fe; and Ti / Nb is larger than or equal to 1.2, deoxidant Mn, Si, Al, Ti, Ca and Mg are successively added in a steel liquid deoxidizing process, wherein (Mg+Ca) / Mn is larger than or equal to 0.3 for micrometer impurities with the grain size larger than or equal to 1.0 micrometer in the steel, (Mg+Ca) / Mn is larger than or equal to 0.1 for sub-micron impurities with the grain size ranging from 0.1 micrometer to 1.0 micrometer in the steel, and Ti / Mn is larger than or equal to 0.07. A large quantity of impurities which are distributed in a dispersion manner are formed, growth of austenite grains in a welding heat affected zone can be restrained, growth of intra-granular ferrite is promoted, and the high-heat-input welding performance of the thick plate is greatly improved.

Description

technical field [0001] The invention relates to a method for manufacturing a steel plate for welding, in particular to providing a thick steel plate for high heat input welding and a manufacturing method thereof. The thick steel plate can be used in fields such as shipbuilding, construction, bridges, oil and gas pipelines, and offshore platforms. The invention can greatly improve the toughness of the welding heat-affected zone of the thick steel plate in the process of large heat input welding. Background technique [0002] In recent years, with the enlargement of welding structures such as shipbuilding, construction, pressure vessels, oil and gas pipelines, and offshore platforms, improving the large heat input welding performance of thick steel plates can improve welding efficiency, shorten manufacturing hours, and reduce manufacturing costs. become an increasingly urgent requirement. [0003] After high input energy welding, the structure of the steel in the welding heat...

AI Technical Summary

Problems solved by technology

With the increase of welding line energy, the grain size of prior austenite becomes larger, the structure of side lath ferrite and upper bainite is more developed, the size of grain boundary ferrite also increases correspondingly, and the welding heat-affected zone The Charpy impact energy will be significantly reduced, which reduces the toughness of the welded heat-affected zone

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