Search

CN-122012900-A - Rail for turnout with evenly distributed hardness of central section of rail web and production method thereof

CN122012900ACN 122012900 ACN122012900 ACN 122012900ACN-122012900-A

Abstract

The invention relates to the technical field of steel rail production, and particularly discloses a turnout steel rail with uniformly distributed rail web center section hardness and a production method thereof. The production method comprises the steps of carrying out on-line heat treatment on the rolled steel rail, wherein the on-line heat treatment comprises an accelerated cooling stage, an air cooling stage and a cooling stage, wherein the accelerated cooling stage is used for carrying out accelerated cooling on the long leg side rail web and the short leg side rail web of the rolled steel rail to 490-570 ℃ when the temperature of the rail top surface of the steel rail to be rolled is 700-800 ℃, the accelerated cooling speed of the short leg side rail web is higher than the accelerated cooling speed of the long leg side rail web, and the air cooling stage is used for carrying out air cooling on the steel rail cooled in the accelerated cooling stage to room temperature. The production method of the invention can produce the turnout steel rail with evenly distributed hardness of the central section of the rail web, and improve the stability of the turnout steel rail in the service process.

Inventors

  • LI RUOXI
  • CHEN CHONGMU
  • WU WEI
  • HUANG YUHANG

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 evenly distributed hardness of the central section of a rail web is characterized by comprising the step of carrying out on-line heat treatment 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 web and the short leg side rail web of the rolled steel rail to 490-570 ℃ when the temperature of the rail top surface of the steel rail to be rolled is 700-800 ℃, wherein the accelerated cooling speed of the short leg side rail web is higher than that of the long leg side rail web; 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 waist and the accelerated cooling rate of the long leg side rail waist is 0.1 to 0.5 ℃.
  3. 3. The production method according to claim 1, wherein the accelerated cooling rate of the long leg side rail web is 1.0 to 2.0 ℃ per second, and the accelerated cooling rate of the short leg side rail web is 1.0 to 2.5 ℃ per second.
  4. 4. 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 700-800 ℃, the rail top surface and the two sides of the rail head of the rail after rolling are accelerated and cooled to 490-570 ℃, wherein the accelerated cooling speed of the rail top surface is 1.5-2.0 ℃ per second, and the accelerated cooling speed of the two sides of the rail head is 2.0-2.5 ℃ per second.
  5. 5. The method according to claim 1, wherein the cooling medium used in the accelerated cooling stage is compressed air and/or water mist.
  6. 6. The method according to claim 1, wherein the air cooling stage is performed by placing the rail on a cooling bed.
  7. 7. The production method according to claim 1, wherein the production method further comprises the steps of converter smelting, LF furnace refining, RH vacuum treatment, continuous casting and rolling in sequence before the on-line heat treatment, and the production method further comprises the steps of straightening and processing after the on-line heat treatment.
  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 turnout rail with a uniform distribution of web center section hardness, obtained by the production method of any one of claims 1-8.
  10. 10. The turnout steel rail according to claim 9, wherein the hardness of the central section of the rail web of the turnout steel rail is in the range of 29-33 HRC, the maximum and minimum difference of the hardness is less than or equal to 1.0HRC, 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 whole section microstructure of the steel rail is pearlite.

Description

Rail for turnout with evenly distributed hardness of central section of rail web and production method thereof Technical Field The invention relates to the technical field of steel rail production, in particular to a turnout steel rail with evenly distributed hardness of a rail web center section 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 of the switch rail has been the focus of the railway field, the performance requirement range of the switch rail is gradually improved, and the problem of the reduction of the service life of the switch rail caused by the insufficient hardness of the central section of the rail web of the switch rail for processing the switch rail is also the focus of switch processing enterprises. In recent years, in order to improve the performance of the turnout rail, rail production enterprises at home and abroad mainly adopt a way of carrying out on-line heat treatment on the turnout rail, so as to refine the interlayer spacing of pearlite sheets of the turnout rail, optimize the distribution of pearlite pellets and improve the strong hardness of the turnout rail, thereby improving the safety, stability and service life of the turnout rail in the service process. The related patent technology related to optimizing the structure and the performance of the turnout steel rail by an on-line heat treatment mode is as follows: Patent CN 20121059.0752.9, a heat treatment method of a turnout rail and the turnout rail, disclose a heat treatment method of the turnout rail, the method includes that the turnout rail with the tread temperature of the rail head to be treated being 650-900 ℃ is subjected to accelerated cooling to obtain the turnout rail with full pearlitic structure, wherein the accelerated cooling speed of the working side of the rail head of the turnout rail is higher than the accelerated cooling speed of the non-working side of the rail head of the turnout rail, and the turnout rail manufactured by the method has the hardness of the working side of the rail head being 1-3 HRC higher than the hardness of the non-working side of the turnout rail and the tensile strength of the rail head being 20-50 MPa higher. However, the technical means adopted by the invention for avoiding the risk of the abnormal microstructure of the steel rail when the cooling rates of the two sides of the rail head are consistent can only obtain the turnout steel rail with inconsistent hardness and strength of the two sides of the rail head, so that the requirements of the present turnout manufacturing on the full section high-strength hardness of the steel rail are difficult to meet, and the invention cannot be popularized and applied in large scale in the actual turnout steel rail manufacturing. Patent CN 201811378013.7, on-line heat treatment method of turnout rail web and restraining device thereof, discloses an on-line heat treatment method of turnout rail web and restraining device thereof, the method comprises controlling the temperature of the rail at 700-800 ℃ and the carbon mass percentage content between 0.7-0.90%, then sending the rail into the restraining device, applying accelerated cooling medium to the tread center of the rail head, the two sides of the rail head and the center of the rail bottom by using the restraining device, the cooling speed is between 1-5 ℃ per second, and finally sending the rail out of the restraining device when the temperature of the rail is reduced to 450-500 ℃, the invention can reduce the residual stress of the turnout rail web and improve the comprehensive performance of the rail web. However, the patent does not specify a detailed heat treatment process of the steel rail, the hardness of the central section of the web of the obtained turnout steel rail cannot be ensured, and the additional heat treatment can cause the increase of the product cost and the reduction of the production efficiency. Patent CN 202411097828.3, a subeutectoid turnout rail in a high and cold region and a heat treatment production method, disclose a subeutectoid turnout rail in a high and cold region and a heat treatment production method, wherein the patent adopts a billet with the C content of 0.5-0.7%, the Cr+V content of 0.25-0.50