Low-yield-ratio economical thin-gauge L450M pipeline steel plate and manufacturing method thereof

Through specific chemical composition and process optimization, the problem of low production efficiency of L450M pipeline steel plates with low cost, high strength and toughness and low yield strength ratio in the existing technology has been solved, and thin-gauge steel plates with high strength, low yield strength ratio and high straightness have been realized, which are suitable for oil pipelines.

CN120843970AActive Publication Date: 2025-10-28ANGANG STEEL CO LTD
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Patent Information

Application Number
CN202511359106.5
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-09-23
Publication Date
2025-10-28
Estimated Expiration
2045-09-23

AI Technical Summary

Technical Problem

Existing technologies are insufficient for the efficient production of low-cost, thin-gauge, high-strength, and low-yield-strength-ratio L450M pipeline steel plates. Furthermore, production efficiency is low, rolling is difficult, and plate shape control is challenging.

Method used

By employing a specific chemical composition design and a two-stage controlled rolling process, combined with KR hot metal pretreatment, converter double slag dephosphorization, RH vacuum degassing, slow cooling treatment, heating control, and high cooling rate, the billet heating and rolling process is optimized to control the steel plate microstructure to be mainly granular bainite and polygonal ferrite.

Benefits of technology

The L450M pipeline steel plate, characterized by low cost, high strength and toughness, low yield strength ratio and high straightness, is suitable for oil pipelines with diameters of Φ914mm and below, ensuring the safe operation of the pipeline.

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Abstract

The invention relates to the technical field of low-carbon microalloyed steel production, in particular to a low-yield-ratio economical thin L450M pipeline steel plate and a manufacturing method thereof.The low-yield-ratio economical thin L450M pipeline steel plate comprises, by weight, 0.05%-0.07% of C, 0.10%-0.25% of Si, 1.50%-1.65% of Mn, smaller than or equal to 0.020% of P, smaller than or equal to 0.015% of S, 0.02%-0.04% of Nb, 0.008%-0.020% of Ti, 0.015%-0.04% of Al, 0.25%-0.30% of Cr, 0.003%-0.006% of N, 0.36%-0.40% of CEIIW = C + Mn / 6 + (Cr + V + Mo) / 5 + (Cu + Ni) / 15 and the balance Fe and The production process comprises the steps of molten steel smelting, external refining and degassing, continuous casting, casting blank heating, controlled rolling, relaxation, controlled cooling and air cooling to the room temperature. The method is used for manufacturing the high-strength L450M hot-rolled steel plate for the low-yield-ratio economical oil pipeline with the thickness specification of 9-17.5 mm and the pipe diameter phi of 914 mm or below, the problems that the rolling efficiency of the steel plate is low, the rolling resistance is large, the plate shape is not easy to control and the like are solved, and the steel plate is low in cost, high in strength and toughness, low in yield ratio and high in straightness.
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