Extremely-thick high-strength high-toughness seabed pipeline steel for ultra-deep sea and manufacturing method of extremely-thick high-strength high-toughness seabed pipeline steel

Abstract

The invention discloses extremely-thick high-strength high-toughness seabed pipeline steel for ultra-deep sea. The extremely-thick high-strength high-toughness seabed pipeline steel for ultra-deep sea is prepared from the following components: 0.020-0.050% of C, not greater than 0.10% of Si, 1.00-1.50% of Mn, not greater than 0.010% of P, not greater than 0.0010% of S, 0.10-0.30% of Cu, 0.10-0.25% of Cr, 0.31-0.50% of Ni, not greater than 0.15% of Mo, 0.030-0.065% of Nb, 0.015-0.040% of V, 0.010-0.025% of Ti, 0.010-0.050% of Al, not greater than 0.008% of N, and the balance of Fe. The invention further discloses a manufacturing method of the extremely-thick high-strength high-toughness seabed pipeline steel for ultra-deep sea. The manufacturing method comprises the following steps: 1) casting blank; 2) roughly rolling; 3) finely rolling; 4) cooling; and 5) relaxing. The extremely-thick high-strength high-toughness seabed pipeline steel for ultra-deep sea disclosed by the invention has characteristics of high strength and excellent low-temperature toughness, and can be widely applied to the microalloyed steel manufacturing field.

Description

technical field [0001] The invention relates to the field of micro-alloyed steel manufacturing, in particular to an extra-thick, high-strength, high-toughness submarine pipeline steel for ultra-deep seas and a manufacturing method thereof. Background technique [0002] With the gradual depletion of land oil and gas resources, new resource exploitation extends to areas with harsh geological conditions such as oceans and polar regions. At present, it has been proven that the world's offshore oil resources account for 34% of the world's total oil resources, and the annual production of offshore natural gas has reached 32% of the world's total annual natural gas production. More than 100 countries around the world are conducting offshore oil exploration, of which More than half of the deep-sea and ultra-deep sea areas have been explored for oil. Therefore, the importance of the development and application of submarine pipeline steel, especially deep-sea and ultra-deep sea submar...

AI Technical Summary

Problems solved by technology

[0004] Before the patent of the present invention, the Chinese invention patent with the patent application number of 201110350933.X "A deep-sea pipeline steel based on the production of a steckel mill and its manufacturing method" described a method of using low C, high Mn, and adding Nb and Cr in an appropriate amount. Composition design of alloy elements such as , Cu, Ni, Mo, etc., combined with the TMCP process to manufacture X65 grade submarine pipeline steel. This method is produced by a steckel rolling mill, and the thickness of the slab and the thickness of the intermediate billet are limited, which cannot meet the needs of ultra-deep sea submarine pipelines. Requirements for extra thick steel (≥35mm), high strength, high and low temperature toughness, and uniformity of structure and properties

[0005] The Chinese invention patent "Pipeline steel plate with a thickness of ≥25mm for deep sea and its production method" with the patent application number 201110232809.3 describes a composition that uses low C, high Mn, and adds appropriate amounts of alloying elements such as Mo, Nb, Ni, Cr, and Mo. Design, combined with the TMCP process of controlled rolling + relaxation + controlled cooling to produce thick-gauge submarine pipeline steel. This method is designed with low Mo, low Ni, and Cu-free composition. It is difficult to realize ultra-thick and high-strength pipelines for ultra-deep sea High strength and high and low temperature toughness of steel

[0006] Chinese invention patent with patent application number 200810151232.1 "High-strength and high-toughness X70 thick-walled seamless pipeline steel and its manufacturing method" and Chinese invention patent with patent application number 200710113424.9 "A microalloyed oil and gas transmission seamless pipeline steel and its manufacturing Method” describes the method of using seamless steel pipes to transport land or seabed oil and gas, but large-scale seamless steel pipes have large dimensional deviations, few resources and high prices, and are not suitable for the selection of steel for ultra-deep sea pipelines

[0007] Patent application number 200710052601.7 of the Chinese invention patent "a steel plate for making submarine pipelines and its manufacturing method" and the article "Development and Application of Steel for Submarine Pipelines" (Welded Pipe. 2006, 29(5): 36-39) A method for producing steel plates for submarine pipelines using hot continuous rolling flat plates is proposed. The production method of hot continuous rolling flat plates can only produce steel plates for shallow sea submarine pipelines with a thickness of ≤20 mm, and cannot be used to produce extra-thick specifications (≥ 35mm) for ultra-deep sea submarine pipeline steel, and after continuous hot rolling, it needs to be flattened and cut, the production process is long and the efficiency is low

[0008] Articles "Summary of High-strength Pipeline Steel Production in Japan" (Welded Pipe. 32(3): 64-69), "Recent steel technology of high-grade line pipe for critical application" (2010 China International Pipeline Forum Proceedings: 52-63) , "Development status of high-grade pipeline steel" (Iron and Steel. 41(10): 1-10) introduced the R&D and application of Sumitomo Metal Corporation in the field of steel for large-wall submarine pipelines, but did not disclose its specific composition and the production process, and the mechanical properties do not list the low-temperature drop-weight tearing properties necessary for steel used in ultra-deep sea pipelines, so it is impossible to determine whether it can meet the strict technical requirements of ultra-deep sea pipeline projects

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