A low-compression ratio low-temperature structural steel plate and its manufacturing method

Abstract

The invention relates to a low-compression-ratio super-thick low-temperature structural steel plate. The thickness of the steel plate is 180-220 mm, the compression ratio from a billet to a finished product in the production process is less than or equal to 3, and the low-compression-ratio super-thick low-temperature structural steel plate is prepared from the components in percentage by weight: 0.06-0.12 % of C, 0.3-0.4% of Si, 1.5-1.9% of Mn, less than or equal to 0.15% of Nb+Ti+V, 0.06-0.08% of Al, less than or equal to 0.012% of P, less than or equal to 0.003% of S, 0.003-0.005% of N, andthe balance of Fe and unavoidable impurities. A production procedure comprises the steps of molten steel melting, continuous casting, continuous casting billet heating, high-pressure water descaling,controlled rolling and controlled cooling, straightening, steel plate normalizing treatment, and accelerated cooling after normalizing. The impact energy at the temperature of -60 DEG C can be greaterthan or equal to 100 J, the yield strength is greater than or equal to 350 MPa, the tensile strength is greater than or equal to 490 MPa, and the good lamellar tearing resisting performance is achieved.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and relates to a low-compression bit-thick low-temperature structural steel plate and a manufacturing method thereof. Background technique [0002] With the continuous development of large-scale equipment manufacturing projects, the demand for extra-thick structural steel plates is increasing, and the performance requirements for steel plates are also getting higher and higher. In addition to conventional tensile impact, depending on the use environment, part of the ultra-low temperature environment is added. Under the low temperature impact requirements of the use. For extra-thick plates, there are two main difficulties. One is that due to the increase in the thickness of the finished steel plate, the overall compression ratio is reduced, and the grain is coarse, so the performance is difficult to guarantee; the other is that even if the compression ratio is increased by means of steel ingots...

AI Technical Summary

Problems solved by technology

For extra-thick plates, there are two main difficulties. One is that due to the increase in the thickness of the finished steel plate, the overall compression ratio is reduced, and the grain is coarse, so the performance is difficult to guarantee; the other is that even if the compression ratio is increased by means of steel ingots and composite billets, but Due to the quality of the billet and the coarse grains, it is difficult to guarantee the impact energy, especially at low temperature at ~60°C

Therefore, at present, low-compression bit-thick low-temperature structural steel plates with a thickness of 180-220 mm have not yet appeared.

[0003] Patent announcement number CN104451375A announced "a 160mm thick Q235C low-compression bit thick steel plate and its preparation method", which adopts one-stage rolling and water cooling process to produce extra-thick Q235C grade structural steel, but in the application of specific microalloying elements and the selection of heating temperature , and rolling process control are difficult to mass-produce, which cannot be used in production and application, and the final product cannot be used at a low temperature of ~60°C

[0004] Patent announcement number CN104561772B announced "A 130mm-150mm thick ultra-low temperature steel plate and its production method", which adopts ingot production, two-stage rolling, and normalizing process production. Although it can be used under low temperature conditions, the manufacturing method has a long production cycle. , the compression ratio is clearly required to be ≥ 4, high energy consumption, high production costs, and poor market competitiveness

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