Construction method for heat treatment of welded joints of dissimilar rails

A construction method and technology for welding joints, applied in heat treatment furnaces, heat treatment equipment, heat treatment process control, etc., to achieve the effects of ensuring railway operation safety, improving wear and tear, and good joint toughness

Active Publication Date: 2022-03-22
PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] CN201810581145.3 discloses a post-weld heat treatment method for welded joints of hypereutectoid steel rails and eutectoid steel rails, CN201810720765.0 discloses a heat treatment method for welded joints of rails, and CN201810710040.3 discloses a welded joint for rails made of different materials The three introduced the post-weld heat treatment method of the welded joints of hypereutectoid steel rail and eutectoid steel rail. The principle of post-heat treatment is to use compressed air or water mist mixture as the cooling medium, through rapid cooling of the rail joints at the austenitizing temperature, to refine the pearlite lamellar spacing, to improve the thermoplasticity of the rail welding area, and Not suitable for joints formed by welding bainitic steel rails and eutectoid pearlitic steel rails

Method used

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  • Construction method for heat treatment of welded joints of dissimilar rails
  • Construction method for heat treatment of welded joints of dissimilar rails
  • Construction method for heat treatment of welded joints of dissimilar rails

Examples

Experimental program
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Effect test

Embodiment 1

[0056] After the dissimilar rails with a specification of 75kg / m are upset and pushed during the mobile flash welding process, the welded joints are subjected to post-weld heat treatment. Firstly, the dissimilar rail joints obtained by welding with a residual temperature of 1200 °C are placed in the air to cool naturally to reduce the surface temperature of the rail head of the rail joints to 200 °C; Heating the entire cross-section, and stop heating when the temperature of the rail tread reaches 950°C; then use compressed air as the cooling medium, and perform rapid cooling at a cooling rate of 3.0°C / s, and the final cooling temperature at this stage is 430°C; The third cooling rate of ℃ / s is used for the third-stage cooling to reduce the surface temperature of the rail head of the rail joint to 170 °C; then, use a split-type electric heating and tempering device to heat the welded joint of the rail with a surface temperature of 170 °C Tempering heat treatment at 350°C with a...

Embodiment 2

[0064] After the dissimilar rails with a specification of 68kg / m are upset and pushed during the mobile flash welding process, post-weld heat treatment is performed on the welded joints. Firstly, the dissimilar rail joints obtained by welding with a residual temperature of 1250 °C are placed in the air for natural cooling to reduce the surface temperature of the rail joint rail head to 150 °C; Heating the entire cross-section, and stop heating when the temperature of the rail tread reaches 930°C; then use compressed air as the cooling medium, and perform rapid cooling at a cooling rate of 2.5°C / s, and the final cooling temperature at this stage is 400°C; then, use 0.6°C The third cooling rate of ℃ / s is used for the third-stage cooling to reduce the surface temperature of the rail head of the rail joint to 160 °C; then, use a split-type electric heating and tempering device to heat the welded joint of the rail with a surface temperature of 170 °C Tempering heat treatment at 320...

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Abstract

The invention discloses a construction method for heat treatment of post-weld joints of dissimilar rails, and belongs to the technical field of post-weld heat treatment of rails. The invention provides a construction method for heat treatment of dissimilar rail welded joints with low cost and good mechanical properties of welded joints after heat treatment, comprising: first cooling the welded joints to 100-200°C; then normalizing and heating to 920°C ~980°C; followed by the second cooling to 380~450°C; then the third cooling to 100~180°C; then heating and tempering to 280~350°C and keeping it warm; finally, natural cooling to room temperature. The method of the invention can improve the "saddle" wear of the rail welding joint caused by the low hardness of the welding area during the service of the rail, the heat affected zone of the rail welding has no obvious signs of large-size martensite, and the joint has good toughness, which contributes to Ensure the safety of railway operation.

Description

technical field [0001] The invention belongs to the technical field of post-weld heat treatment of rails, and in particular relates to a construction method for post-weld joint heat treatment of dissimilar rails. Background technique [0002] At present, eutectoid pearlitic steel rails are mostly used in domestic and foreign heavy-duty railway lines. The carbon content of such steel rails is usually in the range of 0.72-0.82% by weight. The metallographic structure is pearlite, which has good strength and toughness matching, and comprehensive mechanical properties. Moderate features. With the rapid development of railways, heavy-duty lines with large axle loads put forward higher requirements for the service performance of rails. Because the comprehensive mechanical properties and welding properties of traditional pearlitic steel rails have almost reached the limit, in this case, the strength level is higher, and the bainitic steel rails with good wear resistance and contac...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D9/50C21D1/28C21D1/18C21D1/84C21D11/00C21D6/00C22C38/02C22C38/04C22C38/22C22C38/24C22C38/34C22C38/38
CPCC21D9/50C21D9/505C21D1/28C21D1/18C21D1/84C21D11/005C21D6/002C21D6/005C21D6/008C22C38/02C22C38/04C22C38/22C22C38/24C22C38/34C22C38/38C21D2211/002C21D2211/009
Inventor 白威李大东陆鑫徐飞翔
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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