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Extremely thick quenched and tempered rack steel plate for 785 MPa level ocean platform and preparation method

An offshore platform, quenched and tempered steel plate technology, applied in the field of extra thick quenched and tempered rack steel plate and its preparation, can solve the problems of poor quenching cooling rate and uniformity, difficult penetration of rolling deformation, uneven structure and performance, etc., to achieve high structure Performance uniformity, improvement of low temperature impact toughness, and strong precipitation strengthening effect

Active Publication Date: 2020-09-04
NORTHEASTERN UNIV LIAONING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to defects such as porosity, shrinkage cavity, and segregation in the core of the steel ingot or billet, the difficulty of rolling deformation to penetrate into the core, and poor quenching and cooling rate and uniformity, the microstructure and properties of the current 690MPa level rack steel for offshore platforms are seriously uneven in the thickness direction. , especially the core with low strength and poor toughness

Method used

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  • Extremely thick quenched and tempered rack steel plate for 785 MPa level ocean platform and preparation method
  • Extremely thick quenched and tempered rack steel plate for 785 MPa level ocean platform and preparation method
  • Extremely thick quenched and tempered rack steel plate for 785 MPa level ocean platform and preparation method

Examples

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Effect test

Embodiment 1

[0033] To prepare extra-thick rack steel plates for offshore platforms with a thickness of 100mm, the process steps are as follows:

[0034] The steel billet with a thickness of 170mm after forging is heated to 1200°C with the furnace and held for 3 hours. Its chemical composition is as follows: C: 0.13%, Mn: 1.2%, Si: 0.27%, S: 0.0021%, P: 0.005 %, Ni: 3.7%, Cr: 0.66%, Mo: 0.6%, Cu: 0.20%, V: 0.04%, Al: 0.048%, B: 0.0010%, the balance is Fe and other unavoidable impurities; 5 passes of hot rolling into 100mm thick hot rolled steel plate. The starting and finishing temperatures of the rough rolling stage are 1100°C and 1020°C respectively, the rough rolling is carried out in 3 passes to 120mm, and the pass reduction rate is 10-12%; the starting and finishing temperatures of the finish rolling stage are respectively At 850°C and 845°C, finish rolling to 100mm in 2 passes, and the reduction rate of each pass is 7-8%. Air-cool to room temperature after hot rolling. Then conduc...

Embodiment 2

[0037] To prepare extra-thick rack steel plates for offshore platforms with a thickness of 90mm, the process steps are as follows:

[0038] The forged billet with a thickness of 162mm was heated to 1200°C with the furnace and held for 3 hours. Its chemical composition was as follows: C: 0.13%, Mn: 1.1%, Si: 0.26%, S: 0.0026%, P: 0.005 %, Ni: 3.0%, Cr: 0.65%, Mo: 0.6%, Cu: 0.20%, V: 0.04%, Al: 0.024%, B: 0.0010%, the balance is Fe and other unavoidable impurities; 6-pass hot-rolled into 90mm thick hot-rolled steel plate. The starting and finishing temperatures of the rough rolling stage were 1065°C and 1000°C, respectively, and the rough rolling was carried out in 3 passes to 115mm, with a reduction rate of 10-12%. At 850°C and 848°C, finish rolling to 90mm in 3 passes, and the reduction rate of each pass is 7-9%. Air-cool to room temperature after hot rolling. Then off-line quenching and tempering heat treatment: put the steel plate cooled to room temperature after hot roll...

Embodiment 3

[0041] To prepare extra-thick rack steel plates for offshore platforms with a thickness of 80 mm, the process steps are as follows:

[0042] The steel billet with a thickness of 160mm after forging is heated to 1200°C with the furnace and held for 3 hours. Its chemical composition is as follows: C: 0.123%, Mn: 1.1%, Si: 0.26%, S: 0.0015%, P: 0.004 %, Ni: 2.9%, Cr: 0.60%, Mo: 0.5%, Cu: 0.21%, Nb: 0.03, V: 0.04%, Ti: 0.010, Al: 0.024%, B: 0.0010%, the balance is Fe and Other unavoidable impurities; followed by 6 passes of hot rolling into a 90mm thick hot rolled steel plate. The starting and finishing temperatures of the rough rolling stage were 1085°C and 1010°C respectively, and the rough rolling was carried out in 3 passes to 110mm, and the pass reduction rate was 11-13%. The starting and finishing temperatures of the finish rolling stage were respectively At 858°C and 850°C, finish rolling to 80mm in 3 passes, and the reduction rate of each pass is 9-11%. Air-cool to room ...

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Abstract

The invention discloses an extremely thick quenched and tempered rack steel plate for a 785 MPa level ocean platform and a preparation method. The steel plate comprises the chemical components in percent by weight: 0.08-0.15% of C, 0.60-1.55 of Mn, 0.10-0.50% of Si, 0.002-0.005% of S, 0.005-0.015% of P, 2.7-4.0% of Ni, 0.40-1.00% of Cr, 0.30-0.70% of Mo, 0.10-0.40% of Cu, 0-0.080% of Nb, 0-0.10% of V, 0-0.08% of Ti, 0.02-0.08% of Al, 0.0008-0.0015% of B and the balance Fe and other inevitable impurities. By adopting a low C and high Ni-Cr-Mo alloyed and Nb, V and Ti microalloyed component system, the yield strength is greater than or equal to 795 MPa, the tensile strength is greater than or equal to 865 MPa, the -60 DEG C Charpy V-shaped notch impact energy is greater than or equal to 140J, Z is greater than or equal to 35%, and the maximum thickness is 100 mm, and the extremely thick quenched and tempered rack steel plate can be used for manufacturing a rack for the ocean platform. The extremely thick quenched and tempered rack steel plate for the 785 MPa level ocean platform with high hardenability and high toughness further has a characteristic of low yield ratio, and is widerin application range, higher in structural safety and suitable for a working environment in an extremely low-temperature sea area.

Description

technical field [0001] The invention belongs to the field of thick plate and extra thick plate production, and in particular relates to a 785MPa grade high hardenability, high strength and toughness extra thick quenched and tempered rack steel plate for offshore platforms and a preparation method thereof. Background technique [0002] The increasingly prominent energy crisis has promoted the over-exploitation of land-based high-quality oil resources, and at the same time accelerated the exploration and exploitation of offshore oil and gas in countries all over the world. Offshore oil and gas development has gradually extended from land to offshore and deep sea, which has become a development trend in the world's energy field. The oil and gas resources in my country's waters are very rich, especially in the South China Sea. In order to develop and utilize marine resources, our country continues to develop and upgrade the technical level of marine equipment. At present, steel...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/42C22C38/44C22C38/46C22C38/48C22C38/50C22C38/54C21D8/02C21D1/25
CPCC22C38/04C22C38/02C22C38/002C22C38/44C22C38/42C22C38/48C22C38/46C22C38/50C22C38/54C22C38/06C21D8/0226C21D1/25C21D2211/008
Inventor 叶其斌王庆海田勇王昭东
Owner NORTHEASTERN UNIV LIAONING
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