Method for improving hardness uniformity of cross section of heat-treated steel rail head

A technology with uniform hardness and cross-section, which is applied in heat treatment equipment, manufacturing tools, quenching agents, etc., can solve the problems of uneven distribution of Rockwell hardness in cross-section and does not involve the uniformity control of Rockwell hardness distribution in cross-section, and achieves easy Popularization and application, strong operability, and the effect of improving the uniformity of distribution

Active Publication Date: 2020-11-20
WUHAN UNIV OF SCI & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] In summary, the defect of the prior art is that it focuses on the improvement of the hardness of the heat-treated rail tread, the depth of the hardened layer of the rail head, and the strength, and does not involve the uniformity control of the cross-sectional Rockwell hardness distribution. The cross-sectional Rockwell hardness existing in the heat-treated rail The problem of uneven distribution of hardness from the surface to the core

Method used

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  • Method for improving hardness uniformity of cross section of heat-treated steel rail head
  • Method for improving hardness uniformity of cross section of heat-treated steel rail head
  • Method for improving hardness uniformity of cross section of heat-treated steel rail head

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Embodiment 1

[0040] A method for improving the hardness uniformity of the cross-section of the rail head of a heat-treated steel rail. The method described in this embodiment is:

[0041] Step 1. The chemical composition of the heat-treated steel rail is: C is 0.72wt%, Si is 0.68wt%, Mn is 1.05wt%, V is 0.05wt%, Cr is 0.2wt%, P is 0.014wt%, S is 0.005wt% %, the rest is Fe and inevitable impurities.

[0042] According to the chemical composition of the heat-treated rail, it is carried out according to the conventional rail production method: molten iron desulfurization, converter smelting, LF refining, vacuum treatment, continuous casting, billet heating, hot rolling.

[0043] Step 2. Perform dynamic staged accelerated cooling on the hot rolled rail head, and the starting cooling temperature is 760°C. The accelerated cooling process of the heat-treated rail head is divided into 5 stages: the cooling rate of the first stage is 8.5°C / s , the cooling time of the first stage is 11s; the cooli...

Embodiment 2

[0046] A method for improving the hardness uniformity of the cross-section of the rail head of a heat-treated steel rail. The method described in this embodiment is:

[0047] Step 1. The chemical composition of the heat-treated steel rail is: C is 0.83wt%, Si is 0.57wt%, Mn is 0.93wt%, V is 0.08wt%, Cr is 0.15wt%, P is 0.012wt%, S is 0.006wt% %, the rest is Fe and inevitable impurities.

[0048] According to the chemical composition of the heat-treated rail, it is carried out according to the conventional rail production method: molten iron desulfurization, converter smelting, LF refining, vacuum treatment, continuous casting, billet heating, hot rolling.

[0049] Step 2. Perform dynamic staged accelerated cooling on the hot rolled steel rail head. The starting cooling temperature is 780°C. The accelerated cooling process of the heat treated rail head is divided into 5 stages: the cooling rate of the first stage is 8.0°C / s , the cooling time of the first stage is 8s; the coo...

Embodiment 3

[0052] A method for improving the hardness uniformity of the cross-section of the rail head of a heat-treated steel rail. The method described in this embodiment is:

[0053] Step 1. The chemical composition of the heat-treated steel rail is: C is 0.76wt%, Si is 0.60wt%, Mn is 0.85wt%, V is 0.07wt%, Cr is 0.18wt%, P is 0.013wt%, S is 0.007wt% %, the rest is Fe and inevitable impurities.

[0054] According to the chemical composition of the heat-treated rail, it is carried out according to the conventional rail production method: molten iron desulfurization, converter smelting, LF refining, vacuum treatment, continuous casting, billet heating, hot rolling.

[0055] Step 2. Perform dynamic staged accelerated cooling on the hot-rolled steel rail. The initial cooling temperature is 800 °C. The accelerated cooling process of the heat-treated steel rail head is divided into 5 stages: the cooling speed of the first stage is 6.5 °C / s, and the cooling speed of the first stage is 6.5 °...

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Abstract

The invention relates to a method for improving hardness uniformity of a cross section of a heat-treated steel rail head. The method comprises the following steps that the starting cooling temperatureof the heat-treated steel rail head is 740-820 DEG C, a dynamic staged accelerated cooling process is adopted, and the cooling speed and the cooling time of five cooling stages of the heat-treated steel rail head are sequentially as follows that the cooling speed is less than or equal to 9 DEG C/s, and cooling time is 8-12s; the cooling speed is less than or equal to 3 DEG C/s, and the cooling time is 3s; the cooling speed is less than or equal to 6 DEG C/s, and the cooling time is 30-40s; the cooling speed is less than or equal to 2 DEG C/s, and the cooling is carried out to 300-380 DEG C; and the natural cooling is carried out to room temperature. In the cooling stage, the cooling speed difference between adjacent stages is less than and equal to 6 DEG C/s. The cooling stage and the initial time of the heat-treated rail bottom are the same as those of the heat-treated rail head, and the cooling speed of each stage of the heat-treated rail bottom is 60-70% of that of the corresponding stage of the heat-treated rail head. The method is simple and high in operability, and the Rockwell hardness distribution uniformity of the cross section of the heat-treated steel rail head is remarkably improved.

Description

technical field [0001] The invention belongs to the technical field of hardness uniformity of heat-treated steel rails. Specifically, it relates to a method for improving the hardness uniformity of the cross-section of a heat-treated steel rail head. Background technique [0002] At present, railway construction is in the stage of rapid development, and the train running speed, axle load, and transportation volume have increased significantly, followed by a significant increase in the problem of rail damage, which has seriously affected the service life of the rail and the safety of running vehicles. Practice has proved that heat-treated steel rails can effectively improve the wear resistance and fatigue resistance of steel rails. At present, domestic and foreign steel rail manufacturers basically adopt the online heat treatment process to produce heat-treated steel rails. [0003] Rail on-line heat treatment mainly uses the residual temperature of the rail after rolling to...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/19C21D1/613C21D1/84
CPCC21D1/19C21D1/613C21D1/84C21D2211/009
Inventor 费俊杰吴润周桂峰宋述鹏柯德庆吴腾
Owner WUHAN UNIV OF SCI & TECH
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