An ultra-thick specification pipeline steel plate with excellent low-temperature toughness and its manufacturing method

Abstract

The invention relates to a super-thick pipeline steel plate with excellent low-temperature toughness and a production method. The technical scheme is as follows: P is less than or equal to 0.006%, S is less than or equal to 0.002%, N is less than or equal to 0.0040%, H is less than or equal to 0.00015%, O is less than or equal to 0.0020%, the sum of N,O,H,S and P is less than or equal to 100 ppm, the trace element Sn is less than or equal to 0.015%, the trace element Pb is less than or equal to 0.005%, the trace element Sb is less than or equal to 0.010%, the trace element Bi is less than or equal to 0.005%, the radioactive element intensity is lower than 100 Bq / gram, fineness of various non-metallic inclusions is smaller than or equal to 1.5 grade, and the sum is smaller than or equal to 4.0. Crystal grains are refined, the inherent structure texture of the steel plate is eliminated, the performance uniformity of the super-thick steel plate is guaranteed, technological difficulties that toughness is difficult to match and the thickness direction performance is non-uniform during production of super-thick pipeline steel are broken through, the tiny and uniform acicular ferrite structure is obtained, and the steel plate is good in strength, excellent in series low-temperature toughness and high in uniformity.

Description

technical field [0001] The invention belongs to the technical field of manufacturing low-alloy high-strength pipeline steel, and relates to a thick-gauge pipeline steel plate with excellent low-temperature toughness and a manufacturing method thereof. Background technique [0002] With the rapid development of China's economy, the country's demand for oil and natural gas energy is increasing. Therefore, in order to improve the transmission efficiency, the pressure and pipe diameter of the pipeline are continuously increased. At the same time, in order to improve the safety of the pipeline, the designer increases the wall thickness of the energy transmission pipeline. At present, the market demand for pipeline steel with a thickness of ≥35mm is showing an obvious upward trend, especially with the successive start of the Sinopec Xinyue-Zhejiang pipeline project and the China-Russia east pipeline project, in order to improve the efficiency of gas transmission and the safety of ...

AI Technical Summary

Problems solved by technology

[0007] 3) The patent of publication number CN 102941226 A relates to a controlled rolling and controlled cooling process for extra-thick plates with guaranteed performance, in order to solve the problem that thick steel plates can only satisfy product performance through heat treatment process or increasing the content of alloy elements in the past

[0011] The above patent 2 is the closest to the prior art, and this patent is mainly based on the defects existing on the basis of patent 2. The above patent only considers increasing the reduction rate and reduction amount of the rough rolling and finishing rolling passes, and the It does not take into account that large reduction and reduction rate can easily cause steel plate texture, but it is more likely to cause uneven properties of the steel plate. The present invention just takes into account the anisotropy of the steel plate that may be formed by rough rolling, and innovatively applies double converters in smelting. Dephosphorization by dephosphorization method, double desulfurization method, and cross electromagnetic stirring technology ensure the uniformity of molten steel, and strictly control the content of each key element to obtain "fine material"

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