High-strength ultra-thick steel plate and production method thereof

Abstract

The invention relates to a high-strength ultra-thick steel plate and a production method thereof. The chemical components of the steel plate include, by weight, 0.0025-0.025% of C, 0.16-0.36% of Si, 0.85-1.15% of Mn, 2.1-4.5% of Ni, 0.8-1.2% of Cu, 0.008-0.035% of Ti, 0.8-1.2% of Al and the balance Fe and unavoidable impurities. The high-strength ultra-thick steel plate adopts an ultra-low carbon component, the alloy contents of Ni, Cu, Al and Ti are reasonably configured, a normalizing plus tempering process is adopted, and three nanoscale intermetallic compounds of Ni3Al, Ni3Cu and Ni3Ti and a Cu-rich phase are sufficiently formed in the tempering process. The thickness of the steel plate made from the components and through the process is larger than or equal to 100 mm, the yield strength Rp0.2 is larger than or equal to 900 MPa, the tensile strength Rm is larger than or equal to 1000 MPa, the percentage elongation after fracture is larger than or equal to 12%, the welding performance, cold bending performance and a plate profile are good, the grain performance in the thickness direction is uniform, and a plate thickness effect is avoided. The steel plate produced through the method can be widely applied to various large-thickness steel plate application fields such as heavy engineering machinery, large building structures and bridge structures.

Description

technical field [0001] The invention belongs to the technical field of metallurgy and relates to a high-strength extra-thick steel plate and a production method thereof, in particular to a multi-phase nano-precipitation composite strengthened ultra-low carbon high-strength extra-thick steel plate and a production method thereof. Background technique [0002] High-strength steel is one of the important engineering structural materials, widely used in various construction machinery, mining machinery, bridge structures, building structures and other fields. With the vigorous rise of infrastructure such as high-rise buildings, cross-sea bridges, deep-sea oil production platforms, and large-scale hydropower stations, steel structures are constantly developing towards large-scale and heavy-duty. The larger the steel plate is, the steel plate with ordinary strength level and thickness level can no longer meet the construction needs of steel structure, and the market demand for high...

AI Technical Summary

Problems solved by technology

However, for large-thickness steel plates, there are also problems such as poor plate shape and uneven structure and properties in the thickness direction.

[0004] At present, there are many patents for the manufacture of high-strength extra-thick steel plates. From the perspective of composition, patents CN101463449A, CN102080190A, etc., in order to obtain high strength, they all use a medium-carbon composition system. Excessive carbon content is not good for the welding performance of steel plates. From the perspective of technology, the existing high-strength extra-thick steel plate patents basically use off-line / on-line quenching + tempering heat treatment process to obtain high strength, such as patent CN101633996A, etc., the quenching process is limited by the thickness of the steel plate, the steel plate The thicker it is, the hardened core cannot be hardened, and there is a thickness effect on the performance of the steel plate. At the same time, for high-strength extra-thick steel plates, the alloy content is high, and cracking is easy to occur after quenching; from the perspective of the strengthening mechanism, the existing patents are obtained through Martens Solid phase transformation strengthening to achieve high strength, such as patent CN102226255A, etc., while the martensitic transformation is accompanied by volume expansion, there will be a large structural stress in the steel plate

[0005] Therefore, there are the following problems in the existing production technology of extra-thick plates: 1) The steel plate is produced by on-line / off-line quenching / controlled cooling process. Uniform, the structure and properties of the core and the surface are quite different; 2) Due to the high alloy of the steel plate, the internal stress of the steel plate after water cooling is relatively large, easy to crack, and the shape of the plate is difficult to guarantee; 3) In the production of extra-thick plates, in order to ensure Hardenability of steel plate, high carbon content, unfavorable for welding

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