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Heat treatment method of steel rail welding joint

A heat treatment method and technology for welding joints, applied in heat treatment furnaces, heat treatment equipment, furnaces, etc., can solve problems such as low longitudinal hardness of rail head treads, achieve high fatigue life, ensure railway operation safety, and improve the effect of joint toughness

Inactive Publication Date: 2019-10-22
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

[0005] The purpose of the present invention is to provide a heat treatment method for rail welded joints in order to make up for the low longitudinal hardness of the rail head tread that still exists after post-weld air cooling or post-weld heat treatment in the existing rail post-weld heat treatment technology. Control the metallographic structure and longitudinal hardness of the rail welded joints within a reasonable range, thereby helping to improve the "saddle-shaped" wear caused by the low hardness of the welded area during the service of the rail, ensuring wear resistance and toughness, and extending the rail Service life and ensuring the safety of railway operation

Method used

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  • Heat treatment method of steel rail welding joint
  • Heat treatment method of steel rail welding joint
  • Heat treatment method of steel rail welding joint

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Effect test

Embodiment 1

[0039] After the rail with a specification of 68kg / m has completed the upsetting and push-out during the mobile flash welding process, the welded joint is subjected to post-weld heat treatment. Firstly, the rail joint with residual temperature of 1100 °C after welding is cooled in the first stage at the first cooling rate of 7.0 °C / s to reduce the surface temperature of the rail head of the rail joint to 740 °C, and then the rail joint is cooled at 3.0 °C The second cooling rate of / s is used for second-stage cooling to reduce the surface temperature of the rail head of the rail joint to 300°C, and finally the third cooling rate of 0.7°C / s is used for the third-stage cooling of the rail joint to reduce the temperature of the rail joint The temperature of the surface layer of the rail head is lowered to the room temperature of 25° C., thereby obtaining the welded joint of the rail with post-weld heat treatment of the present invention.

[0040] In the post-weld heat treatment p...

Embodiment 2

[0047] After the rails with a specification of 60kg / m have completed upsetting and push-out during the mobile flash welding process, the welded joints are subjected to post-weld heat treatment. Firstly, the rail joint with residual temperature of 1000 °C obtained by welding is cooled in the first stage at the first cooling rate of 8 °C / s to reduce the surface temperature of the rail head of the rail joint to 680 °C, and then the rail joint is cooled at 3.2 °C The second cooling rate of / s is used for the second-stage cooling to reduce the surface temperature of the rail head of the rail joint to 320°C, and finally the rail joint is subjected to the third-stage cooling at a third cooling rate of 0.70°C / s to reduce the temperature of the rail joint The temperature of the surface layer of the rail head is lowered to room temperature of 25° C., thereby obtaining the post-weld heat-treated rail welded joint of dissimilar materials of the present invention.

[0048] In the post-weld...

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Abstract

The invention discloses a heat treatment method of a steel rail welding joint, and belongs to the technical field of steel rail welding. The heat treatment method of the steel rail flash welding jointaims at solving the technical problems of saddle-shaped abrasion and early fatigue fracture of the steel rail welding joint of a steel rail caused by low hardness of a welding area or abnormal microstructure of the joint in the line service process. According to the method, the steel rail welding joint is sequentially subjected to a first cooling stage, a second cooling stage and a third coolingstage, the cooling speed and temperature of each stage are controlled, so that no martensite structure exists in the metallographic structure of the steel rail welding joint, saddle-shaped abrasion and early fatigue fracture of the steel rail welding joint of the steel rail caused by low hardness of the welding area or abnormal microstructure of the joint in the line service process are avoided, and it is ensured that the fatigue life of the steel rail welding joint reaches 3 million times or more.

Description

technical field [0001] The invention belongs to the technical field of rail welding, and in particular relates to a heat treatment method for rail welding joints. 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 to 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. Since the comprehensive mechanical properties and welding performance of traditional pearlitic steel rails have almost reached the limit, in this case, the hypereutectoid steel rail with higher strength level and good wear resistance and contact fatigue has emerged as the times require. The ca...

Claims

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Application Information

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IPC IPC(8): C21D9/50
CPCC21D9/505C21D2211/009
Inventor 白威李大东邓健陆鑫
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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