Post-weld heat treatment method for steel rail

A post-weld heat treatment and rail technology, applied in heat treatment furnaces, heat treatment equipment, furnace types, etc., can solve problems such as high cost, complicated operation and implementation process, and achieve the effect of improving wear and ensuring the safety of railway operation

Inactive Publication Date: 2018-12-18
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

This method is mainly aimed at the post-weld heat treatment process for welded joints of bainitic rails. However, bainitic rails have a different composition system from hypoeutectoid rails, and their metallographic structure and mechanical properties are also completely different. In addition, the above invention also It involves the post-weld normalizing heat treatment process of the rail, which requires the use of rail post-weld heat treatment equipment to locally heat and cool the welded joints of the rail. Not only is the operation and implementation process complicated, but the cost is also high

Method used

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  • Post-weld heat treatment method for steel rail
  • Post-weld heat treatment method for steel rail
  • Post-weld heat treatment method for steel rail

Examples

Experimental program
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Effect test

Embodiment 1

[0042] 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.

[0043] 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 750 °C, and then the rail joint is cooled at 2.0 °C The second cooling rate of / s is used for the second stage of cooling, and the surface temperature of the rail head of the rail joint is reduced to 350°C. Finally, the rail joint is cooled at the third cooling rate of 0.30°C / s for the third stage, and the rail joint is cooled. 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.

[0044] In the post-weld heat treatment ...

Embodiment 2

[0049] 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.

[0050] Firstly, the rail joint with residual temperature of 1200 °C obtained by welding is cooled in the first stage at the first cooling rate of 6.5 °C / s to reduce the surface temperature of the rail head of the rail joint to 730 °C, and then the rail joint is cooled at 2.5 °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 0.20°C / s 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.

[0051] In the post...

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Abstract

The invention relates to a post-weld heat treatment method for a steel rail and belongs to the technical field of railway steel rail welding. According to the post-weld heat treatment method for the steel rail, a technical problem to be solved is that the hardness of a hypoeutectoid steel rail welding area is lower. According to the technical scheme of the post-weld heat treatment method for the steel rail, a welded hypoeutectoid steel rail welding joint to be cooled is cooled to 730-820 degrees centigrade in a first stage, and then is cooled to 280-360 degrees centigrade in a second stage andis finally cooled to a room temperature of 10-40 degrees centigrade in a third stage. According to the post-weld heat treatment method for the steel rail, the longitudinal stiffness of the steel railwelding joint within an area with a distance of +/- 10 mm from the center of a welding seam can be guaranteed to fall within a range of +/-30 HV of the corresponding hypoeutectoid steel rail base metal average hardness; the widths of softening areas on the two sides of the welding seam of the joint are not larger than 10 mm; and meanwhile, abnormal structures, such as martensite and bainite, in ametallographic structure of the welding joint are not available.

Description

technical field [0001] The invention belongs to the technical field of railway rail welding, and in particular relates to a post-weld heat treatment method for rails. Background technique [0002] At this stage, the global railway system mainly covers three types: heavy-haul railway, high-speed railway and mixed passenger and freight railway. The heavy-duty railway train has a heavy axle (axle load 25t-40t), the carbon content of the rail used is usually greater than 0.75%, the tensile strength is above 1200MPa, has a full pearlite structure or is mainly pearlite, and contains a small amount of secondary carburization Body, with high strength, high hardness while ensuring wear resistance. Since the passenger-freight mixed railway has to undertake both passenger transport and cargo transport, it is required that the rails not only have a certain wear resistance, but also have good fatigue resistance. Therefore, the carbon content of rails used in mixed passenger and freight...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/50C21D9/04C21D1/84C22C38/02C22C38/04C22C38/06C22C38/12C22C38/14C22C38/18C22C38/24C22C38/28
CPCC21D9/505C21D1/84C21D9/0062C21D9/04C22C38/002C22C38/005C22C38/02C22C38/04C22C38/06C22C38/12C22C38/14C22C38/18C22C38/24C22C38/28
Inventor 白威李大东陆鑫徐飞翔
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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