Pearlite rail having superior abrasion resistance and excellent toughness

Abstract

This pearlite rail consists of a steel including: in terms of percent by mass, C: 0.65 to 1.20%; Si: 0.05 to 2.00%; Mn: 0.05 to 2.00%; P‰¤ 0.0150%; S‰¤ 0.0100%; Ca: 0.0005 to 0.0200%, and Fe and inevitable impurities as the balance, wherein a head surface portion which ranges from surfaces of head corner portions and a head top portion to a depth of 10 mm has a pearlite structure, a hardness Hv of the pearlite structure is in a range of 320 to 500, and Mn sulfide-based inclusions having major lengths in a range of 10 to 100 µm are present at an amount per unit area in a range of 10 to 200 / mm 2 in a cross-section taken along a lengthwise direction in the pearlite structure.

Description

technical field [0001] The present invention relates to a pearlite system steel rail for the purpose of simultaneously improving the wear resistance and toughness of the head among the steel rails used in overseas freight railways. [0002] This application claims priority based on Japanese Patent Application No. 2008-281847 for which it applied in Japan on October 31, 2008, and uses the content here. Background technique [0003] With the development of the economy, new development of natural resources such as coal has been carried out. Specifically, extraction of previously unexplored areas of harsh natural environments has been ongoing. Subsequently, the track environment is very harsh in overseas freight railways that transport resources. For rails, in addition to the above wear resistance, toughness in cold regions has been required. From such a background, it is required to develop a steel rail having wear resistance and high toughness higher than the high-strength ...

AI Technical Summary

Problems solved by technology

As a result, large unevenness occurs in the suppression of grain growth, and grain coarsening occurs partially, and there is a problem that the damage resistance and toughness of the rail cannot be stably improved only by the carbonitride of the alloy.

[0021] In addition, the technology disclosed in Patent Document 7 only realizes the miniaturization of the austenite structure

There is no effect on damage from Mn sulfide-based inclusions extending in the longitudinal direction during rolling, and there is a problem that the damage resistance and toughness of the rail cannot be improved stably.

[0022] In addition, in the disclosed technologies of Patent Documents 4 to 7, there is a problem that structural embrittlement occurs due to changes in steel components, especially changes in components mixed as impurities, and only by adding alloys or reducing oxygen to control inclusions , and the use of precipitates to refine the austenite structure cannot stably improve the damage resistance and toughness of the rail

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