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Post-welding heat treatment method for bainite steel rails

A post-weld heat treatment and bainite technology, used in heat treatment furnaces, heat treatment equipment, furnace types, etc., can solve problems such as insufficient fatigue life and low longitudinal hardness, and achieve extended fatigue life, improved toughness, and improved wear and resistance. The effect of grinding performance

Inactive Publication Date: 2019-10-15
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

[0012] The purpose of the present invention is to provide a bainite rail welding method to make up for the problems of low longitudinal hardness and insufficient fatigue life of the rail head tread surface of the rail joint after post-weld air cooling or post-weld heat treatment in the existing rail post-weld heat treatment technology. Post-heat treatment method, which can control the metallographic structure and longitudinal hardness of bainite rail joints within a reasonable range, thereby helping to improve the "saddle" wear and tear caused by the low hardness of the welding area during the service process of the rail. Guarantee wear resistance, prolong the service life of rails and ensure the safety of railway operation

Method used

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  • Post-welding heat treatment method for bainite steel rails

Examples

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Effect test

Embodiment 1

[0046] The bainitic rail welded joint obtained by flash welding at a temperature of 1200°C is subjected to the first-stage cooling, and the first-stage cooling is performed at a first cooling rate of 6.0°C / s to cool the rail head surface temperature of the rail joint to at 300°C. Then, the medium-frequency induction profiling electric heating coil is used to heat the entire cross-section of the welded joint area of ​​the rail. When the tread temperature of the rail reaches 870 °C, the heating is stopped, and then the second stage of cooling is carried out at a second cooling rate of 3.0 °C / s. The rail joint is cooled to 380°C, and finally the third stage of cooling is carried out at a third cooling rate of 0.6°C / s to reduce the surface temperature of the rail head of the rail joint to room temperature (25°C), thereby obtaining the post-weld heat-treated Bainitic rail welded joints.

[0047] In the post-weld heat treatment process, the first cooling is natural cooling in the a...

Embodiment 2

[0054]The bainite rail welded joint obtained by gas pressure welding at a temperature of 1250°C is subjected to the first-stage cooling, and the first-stage cooling is performed at a first cooling rate of 7.0°C / s to cool the surface temperature of the rail head of the rail joint to 330°C. Then, an oxy-acetylene flame profiling heater is used to heat the entire section of the rail welded joint area. When the tread temperature of the rail reaches 850 °C, the heating is stopped, and then the water mist mixture is used to cool the rail joint to 400 °C at the second cooling rate of 3.5 °C / s, and finally the second cooling rate is 0.40 °C / s. The third stage of cooling is carried out at three cooling speeds to reduce the surface temperature of the rail head of the rail joint to room temperature (25° C.), thereby obtaining the bainite rail welded joint of the present invention after post-weld heat treatment.

[0055] In the post-weld heat treatment process, the first cooling is natur...

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Abstract

The invention discloses a post-welding heat treatment method for bainite steel rails, and belongs to the technical field of steel rail welding. The invention aims to make up the defects of the existing post-welding heat treatment technology for steel rails and provides the post-welding heat treatment method for bainite steel rails. The method comprises the following steps of carrying out first cooling on a bainite steel rail welding joint at the temperature of 1100-1300 DED C to 260-350 DED C, then heating the welding joint obtained by the first cooling to 780-870 DED C, then, performing secondary cooling to 360-420 DED C, and then, performing a third cooling to the room temperature of 10-40 DED C. According to the method, the post-welding heat treatment process of the bainite steel rail is reasonably established, so that the martensite structure content is less than or equal to 3%, the average hardness in a region of + / -70 mm from the center of a welding seam is 80-85% of a steel railbase material, and the fatigue life of a bainite steel rail joint reaches more than 3.5 million times.

Description

technical field [0001] The invention belongs to the technical field of rail welding, and in particular relates to a post-weld heat treatment method for bainitic rails. Background technique [0002] Bainitic steel rails have been a research hotspot in countries around the world in recent decades. Due to their high strength, toughness, wear resistance and long service life, they are expected to replace traditional pearlite steel rails. They are widely used in railway turnout components and small radius of heavy-duty lines. curve segment. At this stage, rail seamlessness has become an inevitable trend. As an important process in the seamless link of rails, the quality of rail welding is directly related to the service life of railway lines and even the safety of traffic. During the service process of rails, due to the influence of welding quality and the complexity of the actual operating conditions of the line, most of the fractures of welded long rails occur on the welded j...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/50C21D9/04C21D1/19
CPCC21D1/19C21D9/04C21D9/505C21D2211/002
Inventor 白威李大东邓健陆鑫
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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