Seamless steel tube for rare-earth-containing L625Q pipeline and production method of seamless steel tube

Abstract

The invention relates to a seamless steel tube for a rare-earth-containing L625Q submerged pipeline and a production method of the seamless steel tube. The production method comprises the following steps: carrying out pretreatment on blast furnace molten iron so that the S content of the blast furnace molten iron is reduced to below 0.010% in percentage by mass; adding the treated blast furnace molten iron and steel scrap to a top-bottom combined blowing converter for smelting, adopting deoxidation alloy in the steel tapping process for deoxidation alloying, carrying out final deoxidation by adopting an aluminum deoxidation technology, carrying out slag blocking or deslagging in the steel tapping process, adding lime blocks after adding the alloy in the steel tapping process, then adding the smelted molten iron to an LF (Ladle Furnace) for refining, blowing argon during refining, and heating for warming in a manner of gradually increasing the warming speed; then carrying out slag making, desulfurization, composition adjustment and warming operations; adopting the operation of white slag making, and adding ferrovanadium alloy and ferrotitanium alloy; finally continuously blowing argon gas softly at the bottom, adding rare earth wires, and then carrying out VD (Vacuum Distillation) vacuum treatment, round billet continuous casting, tube blank heating, perforating, continuous rolling, sizing, cooling, saw cutting, heat treatment, straightening, flaw detection and chamfering.

Description

technical field [0001] The invention relates to the technical field of ferrous metal smelting and metal pressure processing, in particular to a rare earth-containing high-strength and high-toughness L625Q seamless steel pipe and a production method thereof. Background technique [0002] Pipeline transportation is widely used because of its cost-effective, uninterrupted and pollution-free characteristics. In order to realize long-distance transportation of pipelines, high-pressure transportation is required; in order to reduce the cost of laying pipelines and the use of steel materials, high-pressure Steel-grade thin-walled pipe; in order to ensure the welding performance of line pipe, it is necessary to adopt a low carbon equivalent design composition, although there is a contradiction between low carbon equivalent and high strength. L625Q is an ultra-high steel grade for pipeline branches that meets the above requirements. [0003] After searching, there is no record in th...

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Problems solved by technology

[0003] After searching, there is no record in the patent literature, nor is there any public report in books and magazines about the steel grade seamless steel pipe and its manufacturing method.

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