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On-line heat treatment process of a u75v rail

A rail and process technology, applied in the field of on-line heat treatment of U75V rail, can solve the problems of large thickness of pearlite structure, low strength and toughness parameters, and achieve the effects of improved impact toughness, uniform distribution and increased elongation

Active Publication Date: 2018-12-25
WUHU CRSIC JIFU RAIL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the thickness of the pearlite structure of the steel rail produced by this heat treatment process is still relatively large, as is the interlayer spacing, and the strength and toughness parameters are not high.

Method used

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  • On-line heat treatment process of a u75v rail
  • On-line heat treatment process of a u75v rail

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] An on-line heat treatment process for U75V steel rails, comprising the following process steps:

[0021] (1) Heat the surface of the U75V rail to 1120°C by medium frequency induction and keep it warm for 12 minutes. The current frequency of medium frequency induction heating is 1.5kHz;

[0022] (2) When the heated rail in step (1) is cooled to 850°C, send it to the online heat treatment device, use the air cooling device to cool the top surface and two sides of the rail, and quench to 635°C , the cooling rate is controlled to be 3°C / s, the distance between the nozzle and the rail is 18mm, the initial velocity of the air ejected from the nozzle is 4.8m / s, and the nozzle pressure is 0.27MPa;

[0023] (3) After the temperature of the quenched steel rail in step (2) is lowered to 455° C., it is naturally cooled to room temperature.

[0024] In this embodiment, the two ends of the rail in the step (2) are fixed by a rail clamping device, the rail clamping device includes tw...

Embodiment 2

[0026] An on-line heat treatment process for U75V steel rails, comprising the following process steps:

[0027] (1) Heat the surface of the U75V rail to 1132°C by medium frequency induction and keep it warm for 11 minutes. The current frequency of medium frequency induction heating is 1.8kHz;

[0028] (2) When the heated rail in step (1) is cooled to 862°C, send it to the online heat treatment device, use the air cooling device to cool the top surface and two sides of the rail, and quench to 640°C , the cooling rate is controlled to be 3.5°C / s, the distance between the nozzle and the rail is 18mm, the initial velocity of the air ejected from the nozzle is 4.7m / s, and the nozzle pressure is 0.27MPa;

[0029] (3) After the temperature of the quenched rail in step (2) is lowered to 458°C, it is naturally cooled to room temperature.

[0030] In this embodiment, the two ends of the rail in the step (2) are fixed by a rail clamping device, the rail clamping device includes two symm...

Embodiment 3

[0032] An on-line heat treatment process for U75V steel rails, comprising the following process steps:

[0033] (1) Heat the surface of the U75V rail to 1150°C by medium frequency induction and keep it warm for 10 minutes. The current frequency of medium frequency induction heating is 2.0kHz;

[0034] (2) When the heated rail in step (1) is cooled to 870°C, send it to the online heat treatment device, use the air cooling device to cool the top surface and two sides of the rail, and quench to 645°C , the cooling rate is controlled to be 3°C / s, the distance between the nozzle and the rail is 16mm, the initial velocity of the air ejected from the nozzle is 4.5m / s, and the nozzle pressure is 0.25MPa;

[0035] (3) After the temperature of the quenched steel rail in step (2) is lowered to 460° C., it is naturally cooled to room temperature.

[0036] In this embodiment, the two ends of the rail in the step (2) are fixed by a rail clamping device, the rail clamping device includes tw...

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Abstract

The invention discloses an online thermal treatment process for a U75V steel rail, and relates to the technical field of steel rail thermal treatment. The online thermal treatment process comprises the following steps of: firstly performing medium-frequency induction heating to 1120-1150 DEG C, and preserving the heat for 10-12 minutes; while cooling to a quenching temperature of 850-870 DEG C, utilizing an air-cooling device to perform jet-air cooling quenching on the top surface and the two side surfaces of the steel rail, and controlling cooling speed to 3-4 DEG C per second; and naturallycooling to the room temperature when the temperature of the steel rail is reduced to 455-460 DEG C. Through the process, hardness of the surface of the steel rail is improved, and tensile strength andelongation are greatly improved.

Description

technical field [0001] The invention relates to the technical field of rail heat treatment, in particular to an online heat treatment process for U75V rails. Background technique [0002] With the development of my country's railway transportation industry, the gradual increase of train traction weight, running speed, transportation density and annual throughput has greatly increased the load on the rails and increased the damage of the rails, especially the curved rails. In order to improve the service life of the rail, higher requirements are put forward for the strength, hardness and fatigue resistance of the rail. The practice of railways in various countries in the world has shown that heat treatment of rails is the most effective and economical measure to improve the strength and toughness of rail materials. my country also requires the selection of heat-treated rails of different strength levels according to different line conditions. However, there are still defici...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D9/04C21D1/10
CPCY02P10/25
Inventor 闫忠杰王力红吴志有夏仕敏
Owner WUHU CRSIC JIFU RAIL CO LTD