X70 large deformation resisting pipeline steel and manufacturing method

Abstract

The invention discloses an X70 large deformation resisting pipeline steel and a manufacturing method. The steel comprises chemical components including, by mass percent, 0.04%-0.09% of C, 0.15%-0.55% of Si, 1.45%-1.75% of Mn, 0.04%-0.10% of Nb, 0.02%-0.08% of V, 0.01%-0.03% of Ti, 0%-0.20% of Cu, 0.15%-0.55% of Ni, 0%-0.15% of Mo, 0.15%-0.45% of Cr, 0.025%-0.045% of Al, 0.0002%-0.011% of N, smaller than or equal to 0.015% of P, smaller than or equal to 0.005% of S, and the balance Fe and other inevitable impurity elements. Production of the X70 large deformation resisting pipeline steel comprises the following process routes of material preparing, converter or electric furnace smelting, furnace exterior refining, casting, slab reheating, controlled rolling and controlled cooling, and after two-phase region quenching, tempering is conducted or the tempering technology is not adopted. Compared with the prior art, the X70 large deformation resisting pipeline steel and the manufacturing method have the beneficial effects that the yield ratio is lower, the uniform ductility is higher, tenacity matching is better, the steel plate and copper plate performance difference is small, the structure uniformity in the thickness direction is high, and the strip-shaped level is low.

Description

technical field [0001] The invention belongs to the technical field of steel for pipelines, and relates to an X70 large-deformation-resistant pipeline steel and a manufacturing method thereof, in particular to an X70 large-deformation-resistant wide-thick plate for pipelines prepared by a two-phase region quenching method and a preparation method thereof. The wide and thick plates for pipelines prepared by applying the invention can be applied to manufacture large-diameter longitudinal submerged arc welded pipes for regions designed based on strain. Background technique [0002] With the increasing demand for oil and gas resources, the investment and construction of new oil and gas fields are gradually increasing. Since the production and consumption of oil and gas often need to pass through areas with harsh geological conditions such as permafrost zones and seismic zones, long-distance oil and gas pipelines are required to meet the requirements of strain-based design: the t...

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Problems solved by technology

[0007] The object of the present invention is to provide a kind of X70 anti-large deformation pipeline steel and its preparation method, in order to solve the deficiencies such as large difference in performance between the same plate and high level of banded structure existing in the process of producing large deformation resistant pipeline steel by the current TMCP process, At the same time, we will further produce wider and thicker plates for strain-based design areas with higher thickness specifications to meet the requirements of wider and thicker plates for large-deformation-resistant pipeline steels of X70 and above

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