A post-weld heat treatment method for 1100mpa low-alloy heat-treated rails

A post-weld heat treatment and low-alloy technology, applied in heat treatment furnaces, heat treatment equipment, furnaces, etc., can solve the problems of low heat treatment cost, poor mechanical properties of welded joints, complicated operation process, etc., to simplify the heat treatment process, improve wear, and ensure safe effect

Active Publication Date: 2022-07-19
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

[0009] The purpose of the present invention is to overcome the problems of complicated operation process and high cost of heat treatment method for rail welded joints in the prior art, poor mechanical properties of welded joints after heat treatment, and short physical fatigue life of rail joints, and to provide a A post-weld heat treatment method for 1100MPa low-alloy heat-treated rails. This method heat-treats welded joints of 1100MPa-level low-alloy heat-treated rails. The cost of heat treatment is low, and the mechanical properties of welded joints after heat treatment are good.

Method used

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  • A post-weld heat treatment method for 1100mpa low-alloy heat-treated rails
  • A post-weld heat treatment method for 1100mpa low-alloy heat-treated rails
  • A post-weld heat treatment method for 1100mpa low-alloy heat-treated rails

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Embodiment 1

[0084] 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. First, the rail joint obtained by welding with a residual temperature of 1250 °C was subjected to the first stage cooling at a first cooling rate of 7.5 °C / s to reduce the surface temperature of the rail head of the rail joint to 640 °C, and then the rail joint was cooled at 2.5 °C. At the second cooling rate of 0.40°C / s, the second-stage cooling was performed to reduce the surface temperature of the rail head of the rail joint to 450°C, and finally the rail joint was subjected to the third-stage cooling at the third cooling rate of 0.40°C / s to reduce the temperature of the rail joint to 450°C. The surface temperature of the rail head is lowered to a room temperature of 25° C., thereby obtaining a rail welded joint that has undergone post-weld heat treatment. In the post-weld heat treat...

Embodiment 2

[0091] After the upsetting and push-out during the mobile flash welding process of the 60kg / m rail, the welded joints are subjected to post-weld heat treatment. First, the rail joint obtained by welding with a residual temperature of 1200°C was subjected to first-stage cooling at a first cooling rate of 7°C / s to reduce the surface temperature of the rail head of the rail joint to 600°C, and then the rail joint was cooled to 2°C. At the second cooling rate of 0.2°C / s, the second-stage cooling was performed to reduce the surface temperature of the rail head of the rail joint to 430°C, and finally the rail joint was subjected to the third-stage cooling at the third cooling rate of 0.2°C / s to reduce the temperature of the rail joint to 430°C. The surface temperature of the rail head is lowered to a room temperature of 20° C., thereby obtaining a rail welded joint that has undergone post-weld heat treatment. In the post-weld heat treatment process, the first stage cooling is natura...

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Abstract

The invention relates to the technical field of railway steel rail manufacturing, and discloses a post-weld heat treatment method for a 1100 MPa grade low-alloy heat-treated steel rail. The method includes the following steps: (1) first-stage cooling of the rail welded joint formed by welding with a residual temperature of 1150-1300°C, so that the surface temperature of the rail welded joint is reduced to 580-640°C; (2) welding the rail The joints are cooled in the second stage to reduce the surface temperature of the rail welded joints to 410‑470℃; (3) The third stage cooling of the rail welded joints is carried out to reduce the surface temperature of the rail welded joints to 10‑30℃. The invention utilizes the residual heat of welding for heat treatment without reheating, thus simplifying the heat treatment process and reducing the cost; the percentage content of the martensite structure that may appear in the metallographic structure of the rail welded joint can be controlled within the range of ≤3% , At the same time, the physical fatigue life of rail joints can reach 2.5 million times.

Description

technical field [0001] The invention relates to the technical field of railway steel rail manufacturing, in particular to a post-weld heat treatment method for a 1100 MPa low-alloy heat-treated steel rail. Background technique [0002] With the continuous improvement of my country's high-speed railway network, the existing passenger and freight trunk lines will gradually undergo heavy-duty transformation. Large capacity, large axle load, and high density are the future development directions of heavy-duty railways. The rapid development of railways has put forward higher requirements for the service performance of steel rails, and ordinary carbon steel rails have been unable to meet the needs of railway speed-up and heavy-duty transportation. [0003] There are usually two ways to strengthen rails: heat treatment and alloying. Heat treatment is the most economical and effective way to improve the performance of rails. The advantage of alloying is that the production proces...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D9/50C21D9/04C22C38/02C22C38/04C22C38/18C22C38/24
CPCC21D9/505C21D9/04C22C38/02C22C38/04C22C38/18C22C38/24Y02P10/20
Inventor 白威李大东王若愚邓健
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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