Low-temperature-resistant and lamellar-tearing-resistant super-thick steel plate and manufacturing method thereof

Abstract

The invention discloses an extra-thick steel plate resistant to low temperature and lamellar tearing and a manufacturing method thereof. The chemical composition in steel is by weight percentage: C: 0.09% ~ 0.15%, Si: 0.15% ~ 0.45%, Mn: 1.05% ~ 1.45%, S≤0.003%, P≤0.010%, V: 0.06% ~ 0.08% , Als: 0.015% ~ 0.040%, N: 0.008% ~ 0.015%, Ni: 0.25% ~ 0.45%, the steel also contains one or one of Cr≤0.15%, Cu≤0.15%, Ti≤0.04% The above elements, the balance being Fe and unavoidable impurities. The production process of the steel plate is: die casting → billet rolling → finished product rolling → controlled cooling → normalizing treatment → weak cooling after being released from the furnace. The 180-250mm thick steel plate produced has excellent low temperature resistance and lamellar tear resistance in welded structures.

Description

technical field [0001] The invention belongs to the field of iron and steel material preparation, in particular to a steel plate for welding structures with low temperature resistance, lamellar tear resistance, 36kg grade, 180-250mm large thickness and a manufacturing method thereof. Background technique [0002] In recent years, with the rapid development of large-scale equipment industries such as wind power, hydropower, nuclear power, offshore platforms, and petrochemical pressure vessels, the market is demanding large-thickness (thickness 180mm and above), low-temperature shock resistance (-40°C), and large The demand for lamellar tear-resistant (Z35 performance) steel plates is increasing year by year. For a long time, due to the lack of necessary production and technical equipment, large-thickness lamellar tear-resistant steel plates often rely on forging, electroslag remelting or imports from abroad, which seriously restricts the pressure of my country's hydropower st...

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Problems solved by technology

[0004] CN201310203415.4 discloses a steel for offshore platforms with a thickness of 150 mm and its production method. This invention proposes a method for producing steel for marine engineering with a maximum finished product thickness of only 150 mm by using continuous casting slabs, and the invention discloses The steel only achieves the strength index of 36kg steel plate, and does not mention the achievable index of its low-temperature toughness, which cannot meet the needs of modern marine engineering steel for low-temperature resistant and large-thickness steel plates

[0005] CN201110135930.X discloses a large-thickness offshore platform steel and its production method. The patent uses electroslag remelting billets as raw materials. The maximum thickness of the product is 300mm, but the strength level is only 32kg. Not only the process cost is high, but also cannot Meet the steel index requirements for higher-level offshore platforms

[0006] CN201510120477.8 discloses S355G10+N steel plates for large-thickness offshore platforms and their production methods. This patent proposes a rolling method for steel for marine engineering with S355 grade and a maximum thickness of 100-150 mm, which cannot meet the requirements of steel for marine engineering. The need for larger thickness dimensions above

[0007] CN101987330A discloses a method for manufacturing an ultra-thick lamellar tear-resistant steel plate, whose low-temperature toughness evaluation only reaches 0°C, which cannot meet the toughness requirements of materials in low-temperature service environments

[0009] CN1044357755A and CN102747285A respectively disclose a large-thickness, high-strength steel plate suitable for use at low temperature and a kind of extra-thick steel plate for ships and offshore platforms and their production methods. Process production can not meet the technical requirements of large thickness component materials

[0010] In the above existing patents, the maximum thickness of the invented steel is mostly less than 150mm, and for steel plates with a thickness greater than 150mm, the production process is mostly steel ingot + forging, or electroslag remelting billet + rolling production, which improves the The production cost of the steel plate, and it is impossible to guarantee that the performance of 1 / 2 and 1 / 4 of the steel plate will remain at the same level

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