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Rail

A rail and quality technology, applied in the direction of rails, rails, furnaces, etc., can solve problems such as cost increase and control difficulties, and achieve the effect of improving delayed fracture resistance and service life

Inactive Publication Date: 2014-12-03
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, in the technology disclosed in Patent Document 7, the control for obtaining sufficient Mg oxide, Mg-Al oxide, or Mg sulfide is difficult, and there is a problem of increased cost.

Method used

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Embodiment

[0145] Next, examples of the present invention will be described.

[0146] Table 1-1 to Table 1-4 show the chemical composition and various properties of the rails of the present invention. Table 1-1 to Table 1-2 show the chemical composition values, and Table 1-3 to Table 1-4 show the microstructure of the head surface, the hardness of the head surface, and the particle size of the Al-based oxide as the core1 The number of MnS-based sulfides of ~10 μm. In addition, Table 1-3 to Table 1-4 also describe the Figure 6A Results of delayed fracture tests (critical stress values) performed by the method indicated. The microstructures of the head surfaces in Tables 1-3 to 1-4 also include traces of proeutectoid ferrite, proeutectoid cementite and / or martensite mixed with an area ratio of 5% or less Case.

[0147] Table 2-1 and Table 2-2 show the chemical composition and various properties of the comparative rails. Table 2-1 shows the chemical composition values, and Table 2-2 s...

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Abstract

In this rail, at least 95% of the structure of a head corner part and a head surface part, which constitutes a range up to a depth of 20 mm using the surface of a head top part as a starting point, is a pearlite or bainite structure. The structure in a lateral cross section of the rail contains 20 to 200 MnS sulfides per square millimeter of detected area, the MnS-based sulfides having Al oxides as nuclei and measuring 1 to 10 µm in grain size.

Description

technical field [0001] This invention relates to high strength steel rails for use in freight railroads having improved delayed fracture resistance. [0002] This application claims priority based on Patent Application No. 2012-097584 for which it applied in Japan on April 23, 2012, The content is used here. Background technique [0003] Along with economic development, new development of natural resources such as coal is progressing. Specifically, mining is progressing in regions with harsh natural environments that have not been developed so far. Accompanied by this, the track environment has become significantly harsher in the freight railways that transport resources. Therefore, for rails, higher wear resistance than conventional ones is required. From such a background, the development of a rail having higher wear resistance than the currently used high-strength rail has been demanded. [0004] In order to improve the wear resistance and surface damage resistance of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/06C22C38/58C21C7/06C21D9/04
CPCC22C38/22C21D9/04C22C38/12C21C7/06C22C38/06C22C38/04C22C38/58C22C38/002C22C38/18C22C38/02C21D2211/002C21D2211/004C21D2211/009C22C38/00C22C38/001C22C38/005C22C38/08C22C38/10C22C38/16E01B5/02
Inventor 上田正治宫崎照久山本刚士诸星隆
Owner NIPPON STEEL CORP
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