High-toughness and low-yield-ratio hot-rolled thick plate for cold-resistant pipeline and production method of high-toughness and low-yield-ratio hot-rolled thick plate

Abstract

The invention provides a high-toughness and low-yield-ratio hot-rolled thick plate for a cold-resistant pipeline and a production method of the high-toughness and low-yield-ratio hot-rolled thick plate. The steel plate comprises the following components in percentage by weight: 0.045%-0.070% of C, 0.26%-0.39% of Si, 1.35%-1.55% of Mn, 0.01%-0.03% of Nb, 0.011%-0.019% of Ti, 0.18%-0.28% of Cr, 0-0.10% of Ni, 0-0.14% of Cu, 0.25%-0.44% of (Cr+Ni+Cu), 0.020%-0.045% of Als, 0.0020%-0.0045% of N, less than or equal to 0.010% of P, less than or equal to 0.001% of S, less than or equal to 0.00015% of H, less than or equal to 0.0020% of O, 3.42-5.71 of Ti / N and the balance of Fe and unavoidable impurities; and W is controlled at 0.355%-0.385%, and CEPcm is controlled at 0.155%-0.175%. The production method comprises molten iron pretreatment, converter smelting, external refining, casting blank reheating, continuous casting, rolling, relaxation and cooling. The invention provides a raw material suitable for manufacturing a large-thickness-wall steel pipe of a cold-resistant pipeline in a low-temperature area, and the raw material is excellent in comprehensive performance.

Description

technical field [0001] The invention belongs to the field of low-carbon low-alloy steel, and in particular relates to a high-toughness and low-yield-ratio hot-rolled thick plate for oil and gas transportation with a thickness ≥ 28 mm and a yield strength level of 440 MPa and a production method thereof. Background technique [0002] With the continuous deterioration of the service environment of oil and gas transmission pipelines and the increase of transmission pressure, the requirements for the performance and quality of pipelines are constantly increasing. In recent years, oil and gas pipeline projects have continued to develop in areas with harsh environments such as alpine zones, tundra zones, and earthquake zones, such as Russia, Canada, and Alaska. The service temperature of pipelines in these areas is low, and plastic deformation is easy to occur, so pipelines are required to have good low-temperature toughness and plastic deformation resistance. [0003] The techni...

AI Technical Summary

Problems solved by technology

[0011] To sum up, the current research on hot-rolled thick plates with high toughness and low yield ratio for cold-resistant pipelines is still insufficient.

Images