Pipe made of high-strength and high-tenacity X90 thick wall seamless pipeline steel and manufacturing method thereof

Abstract

The invention provides a pipe made of high-strength and high-tenacity X90 thick wall seamless pipeline steel tube and a manufacturing method thereof, and the steel type comprises the following elements in percentages by weight: 0.08-0.12% of C, 0.20-0.32% of Si, 1.25-1.35% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.016-0.042% of Al, 0.03-0.05% of Nb, 0.05-0.07% of V and 0.12-0.18% of Cu, wherein the contents of Cr, Mo and Ni elements in the steel are determined according to the wall thickness value of a steel pipe, the balance of are ferrum, and a trace amount of impurity elements. The invention also provides a production method of the rolling and heat processing of the seamless pipeline steel. The invention has the beneficial effects that a micro-alloying technique is adopted; the seamless pipeline steel is suitable for the production of a thick wall pipeline of the wall thickness below 50mm; a pipe body integrative structure is a uniform tempering bainite structure; the carbon equivalent is low; the welding properties are good; the low-temperature impact properties are excellent; the requirements for the thick wall pipeline of deep sea or other cold weathers are achieved; the hardenability of the steel is enhanced in the process of water cooling; and the mechanical properties of a pipeline are enhanced.

Description

technical field [0001] The invention belongs to the manufacturing technology of seamless steel pipes in the metallurgical industry, and relates to a X90 thick-walled seamless pipeline steel pipe with high strength and high toughness and a manufacturing method thereof. Background technique [0002] With the continuous development of offshore and deep-sea oil fields, the demand for high-grade, large-diameter and thick-walled pipelines is gradually increasing. The strength of steel grades has developed from the earlier X52, X56, and X60 to the more commonly used X65 and X70 steel grades, and the higher steel grades X80 and X90 steel grades have begun mass production and supply. The continuous improvement of the demand for the strength of pipeline steel grades is inseparable from the progress of offshore oil extraction technology and the continuous harshness of the mining environment. Most of the initially developed oil fields are shallow sea oil and gas resources close to the ...

AI Technical Summary

Problems solved by technology

[0007] The key point of high-strength and high-toughness thick-walled seamless pipeline steel is that due to the low carbon equivalent, the hardenability of thick-walled pipelines is difficult to be guaranteed, and it is easy to cause the core structure to be inconsistent with the outer surface, resulting in poor performance. Qualified, poor impact performance and poor welding performance, etc.

Images