X 60 pipeline steel with thickness of 16-25 mm and production method of pipeline steel

Abstract

The invention discloses X 60 pipeline steel with the thickness of 16-25 mm and a production method of the pipeline steel. The pipeline steel comprises chemical components as follows: 0.06 wt%-0.09 wt% of C, 0.25 wt%-0.35 wt% of Si, 1.55 wt%-1.69 wt% of Mn, 0.20 wt%-0.29 wt% of (Nb+Ti+V+Mo+Ni), no more than 0.010 wt% of P and no more than 0.003 wt% of S. The production method mainly comprises LF+VD, continuous casting and controlled rolling and controlled cooling. Obtained X 60 microstructure contains 42 %-46 % of lath-shaped ferrites, 32 %-38 % of acicular ferrites, 13 %-15 % of bainite, a small amount of M-A islands and fine dispersion precipitated phases; the phase interface bonding performance is good, the yield ratio is 0.66-0.76, and the grain size reaches 11.5-12.5 grades; and the welding performance is good, and the Bauschinger effect is low.

Description

technical field [0001] The invention belongs to the technical field of pipeline steel production, and in particular relates to a 16-25mm thick X60 pipeline steel and a production method thereof. Background technique [0002] In recent years, with the further development of energy sources such as oil and natural gas, the development and production of pipeline steel have been rapidly developed. In order to improve transmission efficiency and reduce energy consumption, pipeline steel has been continuously developing into high-grade pipelines with high strength, high toughness and excellent welding performance. Steel development, and at the present stage, X60 grade pipeline steel occupies a huge market share. [0003] High-strength pipeline steel obtains properties such as high yield strength and high toughness through composition design, ultra-fine purification, controlled rolling and controlled cooling and other modern metallurgical and rolling technologies. The composition de...

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Problems solved by technology

In this study, "low temperature, high reduction" rolling was adopted. Due to the influence of chemical composition design and controlled rolling and controlled cooling process, the microstructure was only ferrite plus a small amount of pearlite. Ferritic pearlite steel is difficult To achieve high-level strength and meet the impact toughness requirements at low temperature, the yield ratio is 0.82 to 0.85, which is close to the maximum value of 0.85 generally required, which fails to effectively reduce the yield ratio of pipeline steel, resulting in the general deformation ability of the material and the plastic range Small; the impurities P, S, alumina, and silicate inclusions in the composition are quite high, which affects the purity of the steel; the ADCO cooling equipment used in this process has a large cooling capacity and uniform cooling, but the equipment is tall and noisy. It is difficult to overhaul, and there are not many adopters of this system

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