Manufacturing method of X70M pipeline steel plate used under low-cost and ultralow-temperature conditions

Abstract

The invention relates to a manufacturing method of an X70M pipeline steel plate used under low-cost and ultralow-temperature conditions. The X70M pipeline steel plate used under the low-cost and ultralow-temperature conditions is manufactured through the process steps of KR molten iron pretreatment, BOF smelting, RH vacuum degassing, LF refining, RH vacuum degassing, continuous casting of a continuous casting billet with the thickness of 150mm, checking and cleaning of the continuous casting billet, hot charging and hot conveying at the temperature of 350-680 DEG C, casting billet heating, high-pressure water descaling, rolling, ACC cooling, straightening, steel plate shearing and inspection and warehousing in sequence. The pipeline steel plate produced by adopting a hot charging and hot conveying process, an ultralow C and microalloy composite adding process and a controlled rolling and controlled cooling process can meet the use requirements under the ultralow-temperature conditionsthat the Charpy impact work at -80 DEG C is greater than or equal to 120J and the drop hammer shearing area at -20 DEG C is greater than or equal to 85%.

Description

technical field [0001] The invention relates to a manufacturing method of X70M pipeline steel plate. Background technique [0002] For X70M pipeline steel plate, M means deformation heat treatment, which means that the delivery state of the material is heat treatment state. Oil and natural gas are important energy sources for the development of industrialization, the blood of economic development, and provide a driving force for social progress. Oil and natural gas are still the core of the entire energy. For this core energy, the most economical transportation method is pipeline transportation. From the initial development of industrial pipelines to the present, the construction of oil and gas pipelines has experienced more than two centuries of development. The early transmission pipelines were relatively close to the central city, and the geographical environment and social support conditions were superior. Most of the newly discovered oil fields are in remote areas, e...

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Problems solved by technology

At present, there are few reports on X70M pipeline steel products that can be used under low temperature conditions and are produced by hot charging and hot delivery. On the one hand, they are limited by the design of steelmaking and rolling workshops; High, especially the requirements for internal segregation and H content of the billet are high, so the use of hot charging and hot delivery technology for production will bring greater production difficulties to enterprises, and there are relatively few related researches

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