Rare earth-containing high-strength atmospheric corrosion-resistant seamless steel pipe and production method thereof

Abstract

The invention relates to a rare earth-containing high-strength atmospheric corrosion-resistant seamless steel pipe and a production method thereof, and belongs to the technical fields of metallurgy and molding. According to the rare earth-containing high-strength atmospheric corrosion-resistant seamless steel pipe, the raw materials comprise 90 wt% of blast furnace molten iron and 10 wt% of high-quality waste steel; the pipe billet comprises the following chemical components: 0.05 to 0.10 wt% of C, 0.10 to 0.30 wt% of Si, 1.00 to 1.30 wt% of Mn, less than or equal to 0.020 wt% of P, less than or equal to 0.005 wt% of S, 0.70 to 1.00 wt% of Cr, 0.10 to 0.30 wt% of Mo, 0.20 to 0.40 wt% of Ni, 0.30 to 0.50 wt% of Cu, 0.01 to 0.03 wt% of Ti, 0.01 to 0.04 wt% of Al, 0.0005 to 0.0100 wt% of RE and the balance of Fe and trace elements which cannot be detected. The process flow comprises pretreatment of the molten iron, top and bottom combined blowing converter smelting, ladle furnace (LF) refining, vacuum distillation (VD) vacuum treatment, round billet continuous casting, cutting, pipe billet heating, perforation, tandem rolling, reheating, sizing, cooling, saw cutting, heat treatment, straightening and flaw detection. The rare earth-containing high-strength atmospheric corrosion-resistant seamless steel pipe comprises the following mechanical properties: the yield strength is 620-670 MPa; the tensile strength is 730-820 MPa; the yield ratio is less than or equal to 0.86; the extension ratio is more than or equal to 23 percent; the transverse impact value is more than or equal to 100 J / cm<2> (-40 DEG C); the shear ratio is 100 percent; the grain size is more than or equal to 8.5 level; the hardness is less than or equal to 22.0 HRC; and the residual stress is less than or equal to 30 MPa. The seamless steel pipe has the characteristics of high strength, good toughness, small grain size and good atmospheric corrosion resistance.

Description

1. Technical field: [0001] The invention belongs to the field of ferrous metal smelting and metal pressure processing, and relates to a rare earth-containing high-strength atmospheric corrosion-resistant seamless steel pipe and a production method thereof. 2. Background technology: [0002] my country's climate is complex and changing, and a lot of steel is scrapped due to atmospheric corrosion every year. For this reason, seamless steel pipes for atmospheric corrosion resistance are specially developed, which are mainly used for transportation pipelines, oil derricks and construction machinery, etc., to meet the requirements of atmospheric corrosion resistance. At the same time, the pipe body should have the characteristics of high strength and good toughness. However, resistance to atmospheric corrosion and high steel grades are contradictory. For this reason, wet atmospheric corrosion resistant steels have been developed successively at home and abroad. The application of...

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Problems solved by technology

[0004] 1. The range of chemical composition is too wide, resulting in large fluctuations in mechanical properties and poor operability;

[0005] 2. The controlled rolling and controlled cooling process is suitable for plate production, but the reference significance for seamless steel pipe production is not strong

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