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Bainite steel rail welding joint, and post-weld heat treatment method for controlling 'white block' structure of bainite steel rail welding joint

A technology of post-weld heat treatment and welded joints, applied in heat treatment furnaces, heat treatment equipment, manufacturing tools, etc., can solve problems such as shortening the service life of rails, achieve the effects of controlling abnormal tissue content, avoiding crack expansion, and improving mechanical properties

Active Publication Date: 2019-03-12
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

[0004] More importantly, using the existing bainitic rail welding technology, the number of "white blocks" in the microstructure of the welded joint formed by welding is large, and the size is large, while the damaged bainite rail welded joint The main reason is that these "white blocks" are prone to micro-cracks, and the cracks expand along the direction of the joint band structure, forming rail head nuclear damage, and rail head nuclear damage is the main cause of rail fracture, thereby shortening the use of rails. life

Method used

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  • Bainite steel rail welding joint, and post-weld heat treatment method for controlling 'white block' structure of bainite steel rail welding joint
  • Bainite steel rail welding joint, and post-weld heat treatment method for controlling 'white block' structure of bainite steel rail welding joint
  • Bainite steel rail welding joint, and post-weld heat treatment method for controlling 'white block' structure of bainite steel rail welding joint

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preparation example Construction

[0068] In principle, the present invention has no special limitation on the preparation form of the welded joint, and the preparation form of the bainite rail welded joint well known to those skilled in the art can be used. Those skilled in the art can select according to the actual application situation, product requirements and quality requirements. For selection and adjustment, the welding described in the present invention preferably includes flash welding and / or air pressure welding, more preferably flash welding or air pressure welding. In order to better reduce the mechanical properties of joints reduced by welding of bainitic rails, the present invention can control the quantity and size of "white block" structures in microscopic regions under different conditions. Bainitic rail welded joints are obtained after heat treatment. The heat treatment of the present invention preferably includes three cooling steps. Wherein the heat treatment specifically preferably include...

Embodiment 1

[0100] Air-cool the welded joints of bainite rails with high residual temperature obtained by flash welding. When the welded joints are cooled from 1530°C to 180°C, use medium-frequency induction imitation electric heating coils to heat the entire section of the welded joints of the rails . Stop heating when the tread temperature of the rail reaches 950°C, and then immediately air-cool the obtained rail welded joint to 230°C, at this time, the temperature of the bainite rail welded joint at a lower temperature will rise to a certain extent, wait for the temperature When returning to the highest temperature, add a heat preservation cover, and then slowly cool the welded joint to room temperature (about 23° C.), so as to obtain the welded joint of bainite rail of the present invention through post-weld heat treatment.

[0101] The bainite rail welded joint obtained in Example 1 was characterized.

[0102] The bainite rail welded joint obtained in this embodiment is machined int...

Embodiment 2

[0107] Air-cool the welded joints of bainite rails with high residual temperature obtained by flash welding. When the welded joints are cooled from 1550°C to 200°C, use an oxy-acetylene flame profiling heater to conduct a full-section inspection of the welded joints of the rails. heating. Stop heating when the tread temperature of the rail reaches 940°C, and then air-cool the welded joint of the rail to 240°C. At this time, the temperature of the welded joint of the bainite rail at a lower temperature will rise to a certain extent, and wait for the temperature to rise to the highest. temperature, add a heat preservation cover, and finally slowly cool the welded joint to room temperature (about 23° C.), thereby obtaining the welded joint of bainite rail of the present invention through post-weld heat treatment.

[0108] The bainite rail welded joint obtained in Example 2 was characterized.

[0109] The bainite rail welded joint obtained in this example is machined into a metal...

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Abstract

The invention provides a bainite steel rail welding joint. From microscopic metallography, the welding joint comprises a welding seam structure and white block structures distributed on a welding seamand the periphery of the welding seam, wherein the size of each white block structure is smaller than or equal to 2000mum. The invention adopts a specific post-weld heat treatment method for the bainite steel rail welding joint, so that through a three-level cooling manner of the specific process, the bainite steel rail welding joint with a small white block defect size and less content is obtained. According to the bainite steel rail welding joint and the post-weld heat treatment method for the bainite steel rail welding joint provided by the invention, through the specific post-weld heat treatment process, the number of 'white block' defects in a microscopic structure of the welding joint can be remarkably reduced, the occurrence of the phenomenon of crack propagation of the welding joint caused by the defects of the welding area is avoided, the mechanical property of the bainite steel rail welding joint is favorably improved, the 'saddle' wear and the wheel rail impact caused by low hardness of a steel rail welding area during the railway line running process are further improved, the service life of a steel rail is prolonged, and the railway running safety is ensured.

Description

technical field [0001] The invention belongs to the technical field of bainite rail welding, and relates to a bainite rail welding joint and a post-weld heat treatment method for the bainite rail welding joint, in particular to a bainite rail welding joint and control bainite rail welding Post-weld heat treatment method for "white block" structure of joints. Background technique [0002] When the austenite is supercooled to the temperature range between the transformation temperature below the pearlite transformation temperature and the temperature above the martensite transformation temperature, a transformation combined with shear phase transformation and short-range diffusion will occur, and the transformation product is called bainite or Bein body. Bainite in steel is a mixed structure of ferrite and carbide. [0003] In recent decades, bainitic steel rails have become a research hotspot around the world. Because of their high toughness, wear resistance and long servic...

Claims

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Application Information

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IPC IPC(8): C21D9/04C21D9/50
CPCC21D9/04C21D9/50C21D2211/002
Inventor 徐飞翔李大东王若愚邓建
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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