Rare earth containing low-cost seamless steel pipe for L415N pipeline and production method thereof

Abstract

The invention relates to a rare earth containing low-cost seamless steel pipe for the L415N pipeline and a production method thereof, and belongs to the technical field of metallurgy and moulding. The raw material is composed of the following components in percentage by weight: 90 wt% of blast furnace molten iron and 10 wt% of high-quality waste steel. The pipe blank comprises the following chemical components in percentage by weight: 0.06 to 0.13 wt5% of C, 0.15 to 0.35 wt% of Si, 1.30 to 1.60 wt% of Mn, not more than 0.020 wt% of P, not more than 0.010 wt% of S, 0.20 to 0.40 wt% of Cr, 0.05 to 0.10 wt% of V, 0.01 to 0.03 wt% of Ti, 0.01 to 0.04 wt% of Al, 0.0005 to 0.010 wt% of rare earth (RE), less than 0.10 wt% of Cu, and the balance being substrate Fe and undetectable trace impurity elements. The technology process orderly comprises the following steps: molten iron pre-treating, smelting in a top-bottom combined blowing converter, refining in a LE furnace, VD vacuum processing, round continuous casting, cutting, heating the pipe blank, perforating, continuous rolling, sizing (stretch reducing), cooling, sawing, flaw detecting, and chamfering. The mechanical properties of the product are as follows: the yield strength is 420 to 460 MPa, the tensile strength is 560 to 620 MPa, the impact value is more than or equal to 80 J / cm<2>, the grain size is more than or equal to 8.5 grade, and the shear ratio is more than or equal to 80%. The product has the advantages of high toughness matching degree, small crystal grain, and low production cost in the condition of low carbon equivalence.

Description

Technical field: [0001] The invention belongs to the field of ferrous metal smelting and metal pressure processing, and relates to a rare earth-containing low-cost seamless steel pipe for L415N pipeline 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 used. In order to reduce pipeline laying costs and steel usage, high-grade steel-grade thin-walled pipes are used. , In order to ensure the welding performance of the line pipe, low carbon equivalent design components are adopted, and low carbon equivalent and high strength are contradictory. L415N is a commonly used steel grade for pipeline branch lines. L415Q steel grade line pipes have been developed at home and abroad. The heat treatment process of quenching + high temperature tempering is adopted,...

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Problems solved by technology

[0003] After searching, the Chinese invention patent "X60 pipeline steel and its preparation method" (patent application number: CN 101928882A) belongs to the field of pipeline steel, and the manufacturing method of seamless pipe has not been reported

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