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Seamless steel pipe of high-strength hollow spring

A seamless steel pipe, high-strength technology, applied in the direction of pipes, rigid pipes, pipes/pipe joints/fittings, etc., can solve problems such as poor productivity, surface scars, difficulty in manufacturing strong steel pipes, and achieve excellent durability.

Inactive Publication Date: 2012-10-17
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This technology stipulates the heating temperature conditions and intermediate heat treatment conditions before Mannesmann piercing, and improves workability while ensuring a certain quality. However, in terms of poor productivity, it is based on the above-mentioned raw material that can be pierced, so it is manufactured. There are problems with steel pipes, and there are also problems such as surface scratches on the inner peripheral surface of steel pipes.

Method used

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  • Seamless steel pipe of high-strength hollow spring
  • Seamless steel pipe of high-strength hollow spring
  • Seamless steel pipe of high-strength hollow spring

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Embodiment Construction

[0021] The inventors of the present invention focused on the limitation in the strength improvement of seamless steel pipes obtained by the techniques disclosed in Patent Documents 3 and 4 described in the background art, and conducted intensive research on this problem. As a result, it was found that these existing The factor hindering the technical high strength is the coarse carbide existing in the metal structure of the steel pipe.

[0022] That is, in the prior art of Patent Documents 3 and 4, in order to ensure the workability of the seamless steel pipe, the heat treatment of heating and softening the raw material at 650 to 750° C. is repeated (refer to Patent Document 3 Publications [0060] and [0063] of Patent Document 4 and the heating steps (D) and (H)) described in publications [0031] and [0039] of Patent Document 4 are so-called spheroidizing annealing. Therefore, the manufactured steel pipe has a structure containing coarsened carbides. Then, although the quenchin...

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Abstract

Disclosed is a seamless steel pipe for a high-strength hollow spring, which comprises 0.20 to 0.70 mass% of C, 0.5 to 3.0 mass% of Si, 0.1 to 3.0 mass% of Mn, 0.030 mass% or less (including 0%) of P, 0.030 mass% or less (including 0%) of S, 0.02 mass% or less (including 0%) of N, and the remainder made up by Fe and unavoidable impurities, and which is characterized in that a carbide has an equivalent circle diameter of 1.00 [mu]m or less. The seamless steel pipe enables the production of a hollow spring having high strength and excellent durability.

Description

technical field [0001] The present invention relates to a high-strength seamless steel pipe for hollow springs, and particularly to a high-quality seamless steel pipe suitable for manufacturing hollow-shaped suspension springs and the like used in automobiles. Background technique [0002] In general, a coil spring is formed by winding a solid single wire, but in order to reduce the weight, it is known that the idea of ​​using a hollow single wire, that is, a tubular single wire has been proposed in Patent Document 1, etc., but its manufacture is difficult. In addition, the market demand in the past was not so strong, so it has not yet reached the practical situation. [0003] On the other hand, in recent years, the demand for weight reduction of various vehicles centered on automobiles has been further increased. Not only gasoline vehicles subject to exhaust gas restrictions, but also electric vehicles expected in the future, from the perspective of reducing energy consumpt...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/04C22C38/58C21D9/08
CPCC21D9/02C22C38/02C22C38/34C21D1/32C21D7/13C22C38/04C21D2211/001C21D2211/003C22C38/06C21D1/18B21C23/002C21D9/08F16L9/02C22C38/58
Inventor 高知琢哉畑野等丰武孝太郎
Owner KOBE STEEL LTD
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