A kind of 250mm extra-thick EH36 steel plate for offshore platform and its preparation method

An offshore platform, EH36 technology, applied in the field of iron and steel metallurgy, to achieve the effects of stable production process, high impact toughness, and easy mass production

Active Publication Date: 2019-06-25
JIANGYIN XINGCHENG SPECIAL STEEL WORKS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The production of continuous casting composite billets is not accepted. The maximum thickness of domestic continuous casting bill...

Method used

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  • A kind of 250mm extra-thick EH36 steel plate for offshore platform and its preparation method
  • A kind of 250mm extra-thick EH36 steel plate for offshore platform and its preparation method
  • A kind of 250mm extra-thick EH36 steel plate for offshore platform and its preparation method

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preparation example Construction

[0048] Preparation method of extra thick EH36 steel:

[0049] (1) Select high-quality scrap steel as the raw material for smelting, use high-quality raw and auxiliary materials for steelmaking, and smelt 2 furnaces, each furnace is 50 tons. The molten steel is smelted in an electric furnace, LF refined, and VD vacuum degassed in sequence, and then cast into 2 steel ingots in a steady state, each 45 tons. The section of steel ingot is greater than 900mm to ensure that the compression ratio of the final product is greater than 3. Control harmful residual elements in molten steel: S≤0.0030%, P≤0.0070%, O≤12ppm. Considering the requirement of fully floating inclusions and controlling the porosity and segregation inside the steel ingot to the degree of superheat, it is cast under the condition of superheat of 25-40 ℃, and the casting is protected by argon gas throughout the casting, and the flat steel ingot with a thickness of ≥900mm is cast. After the steel ingot is uncapped, it...

Embodiment 1

[0055] Examples 1 and 2 are extra-thick EH36 plates of 250mm, and the total level of inclusions A, B, C, and D is controlled at 2.0. As far as extra-thick plates are concerned, the uniformity of the steel plate in the thickness direction is directly related to the performance of the steel, and the uniform structure is the safety guarantee for the normal use and service of the steel plate. There is no obvious gradient structure in the thickness direction of the steel plate of the present invention, and the quenching structure is composed of pearlite ferrite structure. The accompanying drawing shows the structure at 1 / 4 thickness and 1 / 2 thickness of the steel plate in Example 1, the difference is not obvious, there is no obvious structure gradient in the thickness direction, the pearlite is evenly distributed, and it is diffusely distributed around the ferrite. Segregation forms flakes. The average grain size of ferrite is between 6 and 12 mm.

[0056] Table 2 shows the tensi...

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Abstract

The invention relates to a 250 mm extremely-thick EH36 steel plate for an ocean platform. According to chemical ingredients of the steel plate, hardenability elements such as C, Mn, Cr, Ni and Cu are added according to the upper limit of the tolerance range specified by the classification society, no Ti element is added, and the content of O in the steel plate is effectively controlled through the relatively-high content of Nb and an appropriate number of V refined grains. A manufacturing method comprises the steps of electric furnace smelting, LF refining, VD vacuum degassing, die casting, steel ingot heating, cogging rolling, intermediate billet dehydrogenizing, steel billet rolling, quenching and tempering and the like which are carried out in sequence. The quenched steel plate has no obvious gradient structure in the thickness direction, is composed of mixed structures of ferrite and pearlite and is small and uniform in structure, the average grain size is 6-12 micrometers, and the single steel plate weight is larger than or equal to 33 t. According to the transverse stretching properties, the yield strength is 355-400 MPa, the tensile strength is 520-550 MPa, the ductility is larger than or equal to 21%, the minus 40 DEG C longitudinal impact toughness value at the near surface position, 1/4 thickness position and 1/2 thickness position of the steel plate is larger than or equal to 99 J, and the comprehensive mechanical property is excellent.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, and in particular relates to a 250mm EH36 extra-thick steel plate for offshore platforms and a preparation method thereof. Background technique [0002] Recently, my country's marine engineering and shipbuilding industry has made great progress, achieved a historic leap, the scale of the industry has expanded rapidly, the comprehensive strength has been significantly enhanced, and the international status has been greatly improved, which has driven the unprecedented development of my country's shipbuilding and marine engineering steel. . At present, my country's steel supply can basically meet the needs of the domestic marine engineering and ship market. However, some high-grade special steels such as large thickness, high heat input welding, corrosion resistance, and high crack arrest performance still rely on imports. Especially for high-strength extra-thick plates, marine engineering o...

Claims

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Application Information

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IPC IPC(8): C22C38/42C22C38/46C22C38/48C22C38/58C22C38/02C22C38/04C22C38/06C22C33/04B21C37/02C21D8/02
CPCB21C37/02C21D8/0205C21D8/0221C21D8/0247C22C33/04C22C38/02C22C38/04C22C38/06C22C38/42C22C38/46C22C38/48C22C38/58
Inventor 刘朝霞许晓红李经涛赵孚刘俊芦莎
Owner JIANGYIN XINGCHENG SPECIAL STEEL WORKS CO LTD
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