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CN-122012899-A - Railroad switch rail with low rail bottom center residual stress and method of producing the same

CN122012899ACN 122012899 ACN122012899 ACN 122012899ACN-122012899-A

Abstract

The invention relates to the technical field of steel rail production, and particularly discloses a turnout steel rail with low rail bottom center residual stress and a production method thereof. The production method comprises the steps of carrying out online heat treatment on rolled steel rails, wherein the online heat treatment comprises an accelerated cooling stage, and an air cooling stage, wherein the accelerated cooling stage is used for carrying out accelerated cooling on long leg side rail bottoms and short leg side rail bottoms of the rolled steel rails to 450-550 ℃ when the temperature of the rail top surface of the rolled steel rails is 740-880 ℃, the accelerated cooling speed of the long leg side rail bottoms is 1.5-2.0 ℃ per second, the accelerated cooling speed of the short leg side rail bottoms is 1.8-2.5 ℃ per second, and the accelerated cooling speed of the short leg side rail bottoms is higher than the accelerated cooling speed of the long leg side rail bottoms, and the air cooling stage is used for carrying out air cooling on the steel rails cooled in the accelerated cooling stage to room temperature. Besides the lower corrected residual stress detection value, the turnout steel rail produced by the method has more uniform distribution of residual stress, reduces the concentration degree of rail bottom stress, is beneficial to prolonging the service life of the steel rail, and improves the safety of the turnout steel rail in service.

Inventors

  • LI RUOXI
  • WANG YUAN
  • CHEN DONG
  • PENG HUI

Assignees

  • 攀钢集团攀枝花钢铁研究院有限公司

Dates

Publication Date
20260512
Application Date
20260227

Claims (10)

  1. 1. A production method of a turnout steel rail with low rail bottom center residual stress is characterized by comprising the steps of sequentially carrying out on-line heat treatment and straightening on the rolled steel rail, wherein the on-line heat treatment comprises the following steps: The accelerated cooling stage is to accelerate cooling of the long leg side rail bottom and the short leg side rail bottom of the rolled steel rail to 450-550 ℃ per second when the temperature of the rail top surface of the steel rail to be rolled is 740-880 ℃, wherein the accelerated cooling speed of the long leg side rail bottom is 1.5-2.0 ℃ per second, the accelerated cooling speed of the short leg side rail bottom is 1.8-2.5 ℃ per second, and the accelerated cooling speed of the short leg side rail bottom is higher than that of the long leg side rail bottom; And an air cooling stage, namely air cooling the steel rail cooled in the accelerated cooling stage to room temperature.
  2. 2. The production method according to claim 1, wherein a difference between the accelerated cooling rate of the short leg side rail bottom and the accelerated cooling rate of the long leg side rail bottom is 0.3 to 0.5 ℃.
  3. 3. The production method according to claim 1, wherein in the accelerated cooling stage, when the temperature of the rail top surface of the rail to be rolled is 740-880 ℃, the rail top surface of the rail after rolling and the two sides of the rail head are accelerated and cooled to 450-550 ℃ per second, wherein the accelerated cooling speed of the rail top surface is 1.5-2.5 ℃ per second, and the accelerated cooling speed of the two sides of the rail head is 2.0-3.0 ℃ per second.
  4. 4. The method according to claim 1, wherein the cooling medium used in the accelerated cooling stage is compressed air and/or water mist.
  5. 5. The method according to claim 1, wherein the air cooling stage is performed by placing the rail on a cooling bed.
  6. 6. The production method according to claim 1, further comprising, before the on-line heat treatment, sequentially performing converter smelting, LF refining, RH vacuum treatment, continuous casting, and rolling.
  7. 7. The method according to claim 1, wherein straightening is performed by using a flat-vertical composite straightener.
  8. 8. The method of claim 1, wherein the railroad switch rail has a chemical composition of ：C：0.70~0.90%、Si：0.15~0.80%、Mn：0.75~1.20%、Cr：0.01~0.20%、V：0.001~0.030%、P：0.005~0.015%、S：0.005~0.015%,% by weight, the balance being Fe and unavoidable impurities.
  9. 9. A railroad switch rail having low rail bottom center residual stress obtained by the method of any one of claims 1-8.
  10. 10. The turnout steel rail according to claim 9, wherein the residual stress at the center of the rail bottom after the turnout steel rail is straightened is 120-150 MPa, the residual stress at the bottom of the long leg side rail is 90-130 MPa, the residual stress at the bottom of the short leg side rail is 80-120 MPa, the tensile strength of the turnout steel rail is more than or equal to 1200MPa, the elongation after break is more than or equal to 10%, the surface hardness is more than or equal to 340HB, and the full-section microscopic structures of the steel rail are all pearlite.

Description

Railroad switch rail with low rail bottom center residual stress and method of producing the same Technical Field The invention relates to the technical field of steel rail production, in particular to a turnout steel rail with low rail bottom center residual stress and a production method thereof. Background Along with the high-speed development of economy of various countries in the world, railway construction enters a new peak period, the speed and the carrying capacity of a train, the carrying capacity of a line and the train number are greatly improved, the operation condition of a railway track is more severe, and higher requirements are also put forward on the quality of an important component of the railway track, namely a steel rail. The quality of the turnout rail, which is an important part of a railway track, namely a core material of the turnout, directly influences the safety and stability of train operation, and meanwhile, the turnout rail can be used on a railway after being assembled by a special production enterprise. Therefore, the performance and the service performance of the turnout rail are all focus in the railway field, the performance requirement of the turnout rail is gradually improved, the performance focus range is gradually enlarged, for example, the residual stress of the rail bottom center is influenced on the service life of the rail, and the turnout rail is a new focus for improving the performance of the turnout rail of rail manufacturing enterprises at home and abroad. In recent years, in order to reduce the residual stress of the rail bottom center of a rail in rail production enterprises at home and abroad, mainly adopting modes of straightening, constraint heat treatment and the like, and controlling the residual stress of the rail bottom center of a rail final product by applying an external force in the production process, so that a lower detection result of the residual stress of the rail bottom center is obtained in finished product detection. The related patent technology related to the control of the residual stress of the steel rail is as follows: Patent CN201610479176.9, a method for reducing the residual stress of a steel rail, the obtained steel rail and an application thereof, discloses a method for reducing the residual stress of the steel rail, which sequentially carries out accelerated cooling, slow cooling and air cooling on the center of a rail head tread, two sides of a rail head and the center part of a rail bottom of the rolled steel rail, wherein the opening cooling temperature of the accelerated cooling is 650-950 ℃, the cooling speed is 2-8 ℃ per second, the final cooling temperature is 400-600 ℃, the cooling speed of the slow cooling is 0.1-1.5 ℃ per second, the final cooling temperature is 180-300 ℃, the whole-process guide straightening is carried out in the heat treatment process to control the flatness and torsion of the steel rail, and the residual stress of the steel rail obtained by the patent is effectively reduced compared with the comparative example and is suitable for high-speed railways. However, the method for producing the steel rail is only suitable for the steel rail with symmetrical section, and the method for controlling the flatness of the steel rail by adopting the constraint heat treatment and straightening mode can only control the residual stress detection value of the final product, but can lead to uneven distribution of residual stress in the areas except the center of the rail bottom of the steel rail, such as the rail bottom angle and the like, and easily cause stress concentration in the service process of the steel rail, and can lead to the reduction of the service life of the steel rail. Meanwhile, the constraint heat treatment method has high requirements on equipment and personnel operation, is easy to cause surface defects such as scratches on the surface of the steel rail, and is difficult to popularize on a large scale. Patent CN202310397360.9, the preparation method of the low residual stress corrosion-resistant steel rail at the rail bottom, discloses a preparation method of the low residual stress corrosion-resistant steel rail at the rail bottom, which comprises the steps of cooling, straightening, heating and straightening the rolled steel rail, and the method can ensure that the longitudinal residual stress at the center of the rail bottom of the steel rail is less than or equal to 150MPa, the fluctuation range of the residual stress is less than or equal to 30MPa, and meanwhile, the corrosion resistance of the steel rail is improved. However, the method is complex and difficult to put into practical operation, and on the basis, the mechanical properties of the base metal of the steel rail are easy to change unpredictably through repeated heating, cooling and straightening, so that the method cannot be applied to the turnout steel rail with a severe service environment. Patent CN 20121059.0752.9, a heat