Postweld heat treatment method for bainite steel rail welded joint

A technology of post-weld heat treatment and welded joints, applied in heat treatment furnaces, heat treatment equipment, welding/welding/cutting items, etc., can solve problems such as fracture and fatigue performance degradation of welded joints, and achieve the goal of ensuring service performance and railway operation safety Effect

Active Publication Date: 2017-11-24
PANGANG GROUP RESEARCH INSTITUTE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, it is inappropriate to evaluate the mechanical properties of bainitic rail welded joints in full compliance with the current domestic rail welding technical standards, and the longitudinal hardness of the rail head tread of the welded joint is too high (higher than 90% of the average hardness of the rail base metal) It will lead to a decrease in the fatigue performance of the welded joint and early fracture

Method used

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

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Air-cool the welded joints of the bainite rails obtained by flash welding at a temperature of 1500-1600 °C. When the welded joints are cooled from 1550 °C to 200 °C, use a medium-frequency induction profiling electric heating coil to completely heat the area of ​​the welded joints of the rails. section heating. Stop heating when the tread temperature of the rail reaches 950°C, then immediately air-cool the obtained rail welded joint to 220°C, and finally air-cool the welded joint to room temperature (about 23°C), thereby obtaining the post-weld heat treatment of the present invention welded joints of bainitic rails.

[0037] The bainite rail welded joint obtained in this embodiment is machined into a longitudinal hardness sample, and the longitudinal Rockwell hardness test is carried out on the welded joint at a position 5 mm below the tread, and the measuring points are arranged symmetrically to the left and right sides with the weld seam as the center. The measuring ...

Embodiment 2

[0042] Air-cool the welded joints of bainite rails obtained by gas pressure welding at a temperature of 1500-1600°C. When the welded joints are cooled from 1530°C to 180°C, use an oxygen-acetylene flame profiling heater to heat the welded joints of the rails. Heated throughout. Stop heating when the tread temperature of the rail reaches 940°C, then air-cool the welded joints of the rails to 210°C, and finally air-cool the welded joints to room temperature (about 23°C), thereby obtaining the post-weld heat-treated Belleville of the present invention Body rail welded joints.

[0043] Take the longitudinal hardness sample of the bainite rail welded joint obtained in this embodiment and carry out the longitudinal Rockwell hardness test at the position 5mm below the rail head tread. 5mm. The Rockwell hardness test method is carried out according to the provisions of GB / T 230.1-2009, and the HRC scale is used. The hardness distribution effect is the same as that of figure 1 The e...

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Abstract

The invention discloses a postweld heat treatment method for a bainite steel rail welded joint and relates to the technical field of railway steel rail manufacturing. Through the provided postweld heat treatment method for the bainite steel rail welded joint, the tread longitudinal hardness of the bainite steel rail welded joint can be controlled in a reasonable range. The method sequentially comprises the following steps that A, the welded joint, obtained through welding, with the temperature being 1500-1600 DEG C is primarily cooled to 150-250 DEG C, and natural cooling in the air is adopted as the mode of primary cooling; B, the welded joint is heated to 880-960 DEG C through a medium frequency induction profiling electric heating coil and / or an oxygen-acetylene flame profiling heater; and C, the welded joint is subjected to secondary cooling, secondary cooling is stopped when the welded joint is cooled to 180-250 DEG C, then the welded joint is subjected to tertiary cooling instantly and cooled to the room temperature of 5-40 DEG C, secondary cooling is conducted in the form of rapid cooling by applying coolants, the starting cooling temperature of secondary cooling is 800 DEG C or above, and natural cooling in the air is adopted as the mode of tertiary cooling.

Description

technical field [0001] The invention relates to the technical field of railway rail manufacturing, in particular to a post-weld heat treatment method for welded joints of 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 oc...

Claims

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Application Information

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IPC IPC(8): C21D9/50C21D9/04
CPCC21D9/04C21D9/50C21D2211/002C21D9/505C21D1/42C21D1/52C21D1/613B23K2101/26B23K2103/04B23K31/02B23K11/002B23K11/16B23K11/02B23K11/04Y02P10/25
Inventor 白威李大东王若愚邓健陆鑫徐飞翔
Owner PANGANG GROUP RESEARCH INSTITUTE CO LTD
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