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Spiral steel pipe having ribs formed on inner surface thereof, and process for production thereof

A technology of spiral steel pipe and inner surface, applied in the direction of manufacturing tools, sheet pile walls, furnace types, etc., can solve the problems of limited strength and plate thickness, and achieve the effect of improving safety

Inactive Publication Date: 2014-01-01
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the spiral steel pipes used for large-diameter steel pipe piles have limited strength and plate thickness due to processing reasons.

Method used

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  • Spiral steel pipe having ribs formed on inner surface thereof, and process for production thereof
  • Spiral steel pipe having ribs formed on inner surface thereof, and process for production thereof
  • Spiral steel pipe having ribs formed on inner surface thereof, and process for production thereof

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Embodiment

[0090] Hereinafter, examples of the present invention will be described. Helical steel pipes before tempering with an outer diameter of 1400 mm were produced by spiral forming and welding from hot-rolled coils (base materials) with protrusions having various components. Then, heating, water cooling, and tempering were performed on the spiral steel pipe before tempering, and various properties were investigated. Regarding low-temperature toughness, a Charpy impact test was performed, and evaluation was performed by absorbed energy at 0°C. The weldability of the steel pipe was evaluated by whether or not low-temperature cracks occurred when welding accessories to the steel pipe.

[0091] The compositions and yield strengths of Steel Nos. 1 to 14, 35, and 36 related to the present invention and Steel Nos. 15 to 34 for comparison are shown in Tables 1 to 4, respectively. In addition, the heating, cooling, tempering conditions and various properties of the spiral steel pipes obta...

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Abstract

A spiral steel pipe having ribs formed on the inner surface thereof, comprising C, Si, Mn, P, S, Nb, Ti, Al, N and O, and having a CE value of 0.40 to 0.55, a ferrite fraction of less than 20%, a total fraction of bainite and martensite of 80% or more, and an yield strength of 450 to 650 MPa inclusive.

Description

technical field [0001] The present invention relates to a spiral steel pipe with protrusions on the inner surface and its manufacturing method. The spiral steel pipe with protrusions on the inner surface has a yield strength of not less than 450 MPa and not more than 650 MPa, and can be used as a concrete-filled steel pipe used in basic structures such as buildings, bridges, and iron towers. [0002] this application claims priority based on Japanese Patent Application No. 2009-188280 for which it applied to Japan on August 17, 2009, and uses the content here. Background technique [0003] Generally, buildings, bridges, iron towers, etc. employ a foundation structure in which the pile heads of steel pipe piles support the footings. Axial force, shear force, and bending moment act on the pile head due to the self-weight of a building or the like or horizontal force generated during an earthquake. Recently, against the background of the rationalization of foundation structur...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/00C21D9/08C21D9/50C22C38/14C22C38/38E02D5/30
CPCE02D27/42C22C38/14C21D9/08C22C38/06C22C38/02C22C38/12C22C38/04C22C38/001
Inventor 寺田好男辻井正人松井延行坂本俊彦上田宗一波多野浩司森宪治坂井孝行
Owner NIPPON STEEL CORP