Postweld heat treatment method of welded joint of bainite steel rail

A post-weld heat treatment and welded joint technology, applied in heat treatment furnaces, heat treatment equipment, furnaces, etc., can solve problems such as reduction of toughness and plasticity, and achieve the effect of improving impact toughness, uniform distribution of martensite structure, and reduction of area percentage.

Active Publication Date: 2014-07-02
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

As for the bainite rail with higher alloy content, it is air-cooled to room temperature under the same post-weld heat treatment process conditions, and the high Mn segregation zone will be in the rail head and rail waist in the normal post-weld air-cooling and post-weld normal

Method used

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  • Postweld heat treatment method of welded joint of bainite steel rail
  • Postweld heat treatment method of welded joint of bainite steel rail
  • Postweld heat treatment method of welded joint of bainite steel rail

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] Air-cool the welded joints of the bainite rails to be cooled after the bainite rails are welded by flash welding. When the welded joints are cooled from 1350 °C to 350 °C, the intermediate frequency induction image heater is used to weld the joints of the rails again. The area is fully heated, and the temperature difference between the rail head and the rail foot is kept at 35°C. When the tread temperature of the rail reaches 500°C, the heating is stopped, and then the obtained rail welded joint is air-cooled to room temperature (about 25°C) again, thereby obtaining a bainite rail welded joint subjected to the post-weld heat treatment of the present invention.

[0040] Take an appropriate amount of the welded joint area of ​​the bainite rail obtained in this embodiment. ) samples were observed under an optical metallographic microscope, the effect of the distribution of martensitic structure in the rail head is as follows figure 1 (The light-colored area in the figure ...

Embodiment 2

[0044] Air-cool the welded joint of the bainite rail to be cooled after the bainite rail is welded by flash welding. Full-surface heating is implemented in the welding joint area, and the temperature difference between the rail head and the rail foot is kept at 30 °C. Heating is stopped when the tread temperature of the rail reaches 480°C, and then the obtained rail welded joint is air-cooled to room temperature (about 25°C) again, thereby obtaining a bainite rail welded joint subjected to the post-weld heat treatment of the present invention.

[0045] Take an appropriate amount of samples of the rail head and rail bottom in the welded joint region of the bainite rail obtained in this embodiment and observe under an optical metallographic microscope, the effect of the martensitic structure distribution in the rail head is similar to that of figure 1 Similar to the effect shown, the effect of martensitic structure distribution in the rail bottom is similar to that of figure 2...

Embodiment 3

[0047] The welded joint of the bainitic steel rail to be cooled obtained after the bainitic steel rail is welded by air pressure welding is pre-cooled (air-cooled). When the welded joint is cooled from 1350 ° C to 400 ° C, the welded joint is subjected to normalizing heat treatment to 900°C, then air-cooled to 340°C, and then use the medium-frequency induction image-shaped electric heater to heat the entire section of the rail welded joint area, keeping the temperature difference between the rail head and the rail foot at 40°C. When the tread temperature of the rail reaches 490°C, the heating is stopped, and then the obtained rail welded joint is air-cooled to room temperature (about 25°C) again, thereby obtaining a bainite rail welded joint subjected to the post-weld heat treatment of the present invention.

[0048] Take an appropriate amount of samples of the rail head and rail bottom in the welded joint region of the bainite rail obtained in this embodiment and observe under...

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Abstract

The invention discloses a postweld heat treatment method of a welded joint of a bainite steel rail. The postweld heat treatment method comprises the following steps: carrying out primary cooling on the welded joint of the bainite steel rail to be cooled obtained by welding to a first temperature, then heating the welded joint subjected to primary cooling to a second temperature, and carrying out secondary cooling, wherein the first temperature is not higher than 450 DEG C, and the second temperature is higher than the first temperature and is not higher than 510 DEG C. The postweld heat treatment method of the welded joint of the bainite steel rail, which is disclosed by the invention, is simple to operate and capable of obviously improving the impact toughness of the welded joint of the bainite steel rail and reducing the content of a martensitic structure in the welded joint of the bainite steel rail, thus the safe operation of railways is ensured.

Description

technical field [0001] The invention relates to the technical field of railway rail welding, in particular to a post-weld heat treatment method for welded joints of bainitic rails. Background technique [0002] Bainite rail is a new variety developed in recent years. It is mainly used in the production of rails and turnouts used by railway users. Because of its advantages of high tensile strength, high hardness, good fatigue resistance and excellent wear resistance, it is increasingly popular in manufacturing The concern of manufacturers and railway users. Rails generally need to be welded (whether it is flash welding at the base of the welded rail, or aluminothermic welding at the railway site, or gas pressure welding) to form a seamless line, as well as to improve the smoothness of the railway and ensure the smooth operation of the train. Years of data statistics show that the probability of damage to rail welded joints is much greater than that of the rail parent materia...

Claims

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Application Information

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IPC IPC(8): C21D9/50C21D9/04
Inventor 李大东邓健余腾义刘锦燕韩振宇邹明袁俊郭华王春建贾济海
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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