Anti-large deformation steel for X80 pipeline and production method hereof

Abstract

The invention discloses anti-large deformation steel for an X80 pipeline which consists of the following components in percentage by weight: 0.050-0.085% of C, 0.20-0.45% of Si, 1.75-1.90% of Mn, less than or equal to 0.012% of P, less than or equal to 0.0015% of S, 0.15-0.35% of Mo, 0.25-0.50% of Cr, less than or equal to 0.03% of Cu, 0.045-0.080% of Nb, less than or equal to 0.01% of V, 0.005-0.030% of Ti, 0.02-0.05% of Al, less than or equal to 0.010% of N and 0.0010-0.0050% of Ca. The production steps of the anti-large deformation steel comprises smelting and continuous casting into blank, cast blank heating, rough rolling, finish rolling, two-section cooling and air cooling to room temperature and straightening. According to the invention, the uniform elongation A, the stress ratio and the deformability of steel are obviously improved through accurate duplex structure control; and by adopting low-temperature heating and two-section cooling, relaxation after rolling is canceled, the rolling holding time is shortened, the low-temperature toughness and structure of the pipeline steel are improved, and the performance is stable.

Description

Technical field [0001] The invention relates to pipeline steel and a production method thereof, and specifically belongs to a large-deformation resistant X80 pipeline steel and a production method thereof. It is precisely to meet the requirements of major long-distance pipeline projects at home and abroad in earthquakes, landslides, and polar frozen soil zones. The demand for high-grade large-deformation pipeline steel in harsh areas provides a strain-based X80 pipeline steel and its manufacturing method. Background technique [0002] With the gradual depletion of terrestrial oil and gas resources, the exploitation of new resources extends to areas with harsh geological conditions such as earthquakes, landslide zones, seabeds, and polar tundra. Long-distance pipelines passing through such areas are affected by the environment of use and need to withstand large strains induced by ground displacements such as earthquakes, landslides, frozen soil thawing, etc. The pipelines laid in ...

AI Technical Summary

Problems solved by technology

[0004] The Chinese patent application number is 200910187466.6, which discloses "a hot-rolled X80 pipeline steel coil and its manufacturing method"; and the Chinese patent number is 200410025584.4, which discloses a "high-strength and high-toughness X80 pipeline Steel and its hot-rolled plate manufacturing method", the above-mentioned documents have high yield ratio, low uniform elongation, insufficient denaturation ability, and cannot bear the large strain induced by ground displacement in harsh environments such as earthquakes, landslides, and polar tundra

The disadvantage is that the thickness of the steel plate is strictly limited, and the relaxation after rolling is not conducive to stable, efficient and smooth production.

The Chinese patent application number is 201010266539.3, which discloses "a large deformation resistant pipeline steel prepared by a heat treatment method and its manufacturing method", which is produced by a two-phase zone quenching + tempering heat treatment process, which requires complex and time-consuming quenching and tempering heat treatment process, the production cost will increase significantly

Images