Super-thick pipeline steel plate with excellent low-temperature toughness and production 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 low-alloy high-strength pipeline steel manufacturing, 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 gas energy is increasing. Therefore, in order to improve the transmission efficiency, the pipeline transportation pressure and pipe diameter have been increasing. At the same time, in order to improve the safety of pipeline transportation, the designer has increased the wall thickness of the energy transmission pipeline. At present, the market demand for pipeline steel ≥35mm thick is showing a clear upward trend, especially with the start of the Sinopec’s new Guangdong-Zhejiang pipeline project and the Sino-Russian East Route pipeline project. In order to improve the efficiency of gas transmission and the safety performance ...

AI Technical Summary

Problems solved by technology

[0007] 3) The patent with the publication number CN102941226A relates to a controlled rolling and controlled cooling process for extra-thick plates with guaranteed performance, in order to solve the problem that in the past, thick steel plates could only meet the product performance through heat treatment process or increasing the content of alloy elements

[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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