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Method for post-weld heat processing of rail welded joint

A technology of post-weld heat treatment and welded joints, which is applied in the field of rail welding, can solve the problems of non-eutectoid rails and PG4 heat-treated rails, and achieve the effects of good matching of joint strength and toughness, good stability, and stable welding quality

Active Publication Date: 2017-03-29
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

[0003] At present, there are no reports and documents about the welding and post-weld heat treatment of hypereutectoid rails and PG4 heat-treated rails.

Method used

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  • Method for post-weld heat processing of rail welded joint
  • Method for post-weld heat processing of rail welded joint

Examples

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Embodiment 1

[0044] This embodiment is used to illustrate the method for the post-weld heat treatment of the rail welded joint provided by the present invention

[0045] The 75kg / m PG5 hypereutectoid rail and PG4 heat-treated rail are welded by a mobile rail flash welding machine. The welding heat input in the flash flat stage is 2.5MJ, the displacement is 2.1mm, and the duration is 29s; the welding in the pulsating stage The heat input is 8.4MJ, the displacement is 10.2mm, and the duration is 81.2s; the welding heat input in the accelerated firing stage is 0.4MJ, the displacement is 11.6mm, and the duration is 26.1s; the welding heat input in the upsetting stage The displacement is 0.1MJ, the displacement is 16.9mm, and the live upsetting time is 0.4s; the holding pressure in the holding stage is 28.6t, and the duration is 15.5s. The total heat input of welding is 11.4MJ, the duration is 152.2s, the burning displacement of the rail is 40.8mm, and the welding upset is 16.9mm. The welding ...

Embodiment 2

[0057] This embodiment is used to illustrate the method for the post-weld heat treatment of the rail welded joint provided by the present invention

[0058] The 75kg / m PG5 hypereutectoid rail and PG4 heat-treated rail were welded by a mobile rail flash welding machine. The welding heat input in the flash flat stage was 2.6MJ, the displacement was 2mm, and the duration was 29s; the welding heat in the pulsating stage The input is 8.1MJ, the displacement is 10mm, and the duration is 80s; the welding heat input in the accelerated sintering stage is 0.3MJ, the displacement is 12mm, and the duration is 27s; the welding heat input in the upsetting stage is 0.08MJ, The displacement is 17.5mm, and the live upsetting time is 0.45s; the holding pressure in the holding stage is 30t, and the duration is 15s. The total heat input of welding is 11.08MJ, the duration is 151.45s, the burning displacement of the rail is 41.5mm, and the welding upsetting amount is 17.5mm. The short circuit imp...

Embodiment 3

[0063] This embodiment is used to illustrate the method for the post-weld heat treatment of the rail welded joint provided by the present invention

[0064] The 75kg / m PG5 hypereutectoid rail and PG4 heat-treated rail are welded by a mobile rail flash welding machine. The welding heat input in the flash flat stage is 2.7MJ, the displacement is 2.5mm, and the duration is 30s; the welding in the pulsating stage The heat input is 8.6MJ, the displacement is 10.5mm, and the duration is 82s; the welding heat input in the accelerated firing stage is 0.5MJ, the displacement is 10mm, and the duration is 25s; the welding heat input in the upsetting stage is 0.07 MJ, the displacement is 16.5mm, and the live upsetting time is 0.5s; the holding pressure in the holding stage is 28t, and the duration is 16s. The total heat input of welding is 11.87MJ, the duration is 153.5s, the burning displacement of the rail is 39.5mm, and the welding upsetting amount is 16.5mm. The short circuit impedan...

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Abstract

The invention relates to the field of rail welding and discloses a method for post-weld heat processing of a rail welded joint. The method comprises the steps that first cooling is conducted to the to-be-cooled rail welded joint obtained through welding till the temperature is lower than 400 DEG C; then, the rail welded joint obtained after the first cooling is heated to a temperature between 860 DEG C and 930 DEG C; and second cooling is then conducted to the rail welded joint till a tread face temperature of the joint is between 410 DEG C and 450 DEG C, wherein the rail welded joint is a welded joint of a 75kg / m hypereutectoid steel rail and a pearlite steel rail. The method disclosed by the invention is used for the post-weld heat processing of the welded joint of the hypereutectoid steel rail and the PG4 heat-processing steel rail; and the heterogeneous rail joint has fewer internal defects and stable welding quality, and can satisfy requirements for passing tests such as a fatigue test, a stretching and impact test and a static bending test.

Description

technical field [0001] The invention relates to the field of rail welding, in particular to a method for performing post-weld heat treatment on rail welded joints. Background technique [0002] Hypereutectoid steel rail is a new type of steel rail developed in recent years. The carbon content of hypereutectoid steel rail is generally in the range of 0.90-1.0% by weight, and its microstructure is intergranular secondary cementite + pearlite. The mixed structure is the top steel rail with the highest strength (1350MPa) and hardness (400HB-420HB) in the world. The structure of pearlitic steel rail is pearlite, and the representative pearlitic steel rail is PG4 heat-treated steel rail. PG4 heat-treated steel rail (also known as U78CrV, referred to as PG4 steel rail) has a carbon content in the range of 0.72-0.82% by weight, a microstructure of pearlite structure, a strength equivalent to that of a hypereutectoid steel rail, and a slightly lower hardness of 20HB. The structures...

Claims

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Application Information

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IPC IPC(8): E01B31/02C21D9/50
CPCC21D9/505E01B31/02
Inventor 李大东王若愚白威邓健陆鑫徐飞翔
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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