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Method for controlling martensite structure of R260 steel rail flash welding head

A head martensite and rail technology, which is used in the field of controlling the martensite structure of R260 rail flash welded joints, can solve the problems of point-like martensite structure, failure to pass the welding type inspection, right shift, etc., and achieve a simple and good control process. The effect of promoting application prospects

Active Publication Date: 2019-11-08
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

However, C and Mn are segregation elements. When the Mn content in the rail increases to the upper-middle range, the rail base metal with high Mn content will inevitably lead to Mn micro-segregation. The high content of chemical components in the segregation zone will seriously shift the CCT curve to the right. It is easy to cause spot martensitic structure in the air cooling process of the welded joint, which cannot pass the welding type inspection of the EN standard.

Method used

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  • Method for controlling martensite structure of R260 steel rail flash welding head
  • Method for controlling martensite structure of R260 steel rail flash welding head
  • Method for controlling martensite structure of R260 steel rail flash welding head

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036]Control the Mn content in the base metal composition of R260 rails to 1.1% Mn, the C content of other chemical components to the middle and lower limits, and keep Si at ≤0.30%. The mechanical properties of the hot-rolled rails that are normally produced and rolled by the universal line meet Rm≥880MPa, and the tread hardness ≥260HB, use rail mobile flash welder or fixed flash welder, adopt 8.5MJ large heat input after pulsating or preheating flash welding, the actual welding upsetting amount is kept at 14.0mm, when the joint pushing is completed, it is air-cooled to 550 When the temperature is lower than ℃, the rail head insulation device with a thickness of 35mm embedded in aluminosilicate fiber cotton in the hinged structure or the full-section rail insulation device is used for slow cooling. The length of the insulation and slow cooling device is 210mm. With the device, allow the joint to air cool to room temperature.

[0037] After testing, the joints are inspected ac...

Embodiment 2

[0039] Control the Mn content in the base metal composition of R260 rail to 1.03% Mn, the C content in other chemical components to the middle and lower limits, and keep Si at ≤0.30%. The mechanical properties of the hot-rolled rails that are normally produced and rolled by the universal line meet Rm≥880MPa, and the tread hardness ≥260HB, use rail mobile flash welding machine or fixed flash welding machine, adopt 8.5MJ large heat input after pulsating or preheating flash welding, the actual welding upsetting amount is kept at 14.00mm, when the joint pushing is completed, it is air-cooled to 560 When the temperature is below 280°C, use the rail head heat preservation device with a hinged structure embedded in 35mm thick aluminosilicate fiber cotton or the full-section rail heat preservation device for slow cooling. With the device, allow the joint to air cool to room temperature.

[0040] After testing, the joints are inspected according to the specified position of the rail he...

Embodiment 3

[0042] Control the content of Mn in the parent material of R260 rail to 1.07%, the content of C in other chemical components to the middle and lower limits, and keep Si at ≤0.30%. The mechanical properties of the hot-rolled rails normally produced and rolled by the universal line meet Rm≥880MPa, and the tread hardness≥ 260HB; use rail mobile flash welding machine or fixed flash welding machine, adopt 9.0MJ large heat input after pulsating or preheating flash welding, the actual welding upsetting amount is kept at 14.5mm, and when the joint pushing is completed, it is air-cooled to 560°C When using a hinged structure with 35mm-thick aluminosilicate fiber cotton embedded in the rail head insulation device or a full-section rail insulation device for slow cooling, the length of the insulation and slow cooling device is 220mm. When the slow cooling temperature is below 280°C, remove the insulation device , and allow the connector to air cool to room temperature.

[0043] After tes...

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Abstract

The invention relates to a method for controlling martensite structure of a R260 steel rail flash welding head, and belongs to the technical field of railway steel rail welding. The invention providesthe method for solving the technical problem that martensite structure is easily caused by air cooling after R260 steel rail flash welding head welding. According to the technical scheme, the methodfor controlling the martensite structure of the R260 steel rail flash welding head comprises the steps that the chemical component of the R260 steel rail base metal is controlled, the hot rolling process is controlled, the cooling control is carried out after welding, wherein the R260 steel rail base metal is controlled, the content of Mn in percentage by weight is 1.0%-1.10%, the C content is atthe middle lower limit, and the content of Si is less than or equal to 0.30%. According to the method, the martensite structure can be prevented from appearing at the inspection position specified bythe center surface of a rail head and rail bottom studs, so that various mechanical performance indexes of the welding head are ensured, the technical requirements of EN 14587-2 : 009 standard are met, and the method has good popularization and application prospect.

Description

technical field [0001] The invention belongs to the technical field of railway rail welding, and in particular relates to a method for controlling the martensitic structure of R260 rail flash welding joints. Background technique [0002] EN R260 steel rail is one of the steel grades that Panzhihua Steel exports to Malaysia, Thailand and other Southeast Asian countries every year, with an annual export volume of about 20,000 to 40,000 tons. EN13674-1:2011 "Railway applications-Track-RailPart 1: Vignole railway rails 46kg / mand above" standard requires the chemical composition of R260 finished rails to be: 0.60%~0.82%C, 0.65%~1.25%Mn, 0.13 %~0.60% Si, P, S≤0.030%, Cr≤0.15%, V≤0.030%, and the rest Mo, Ni, Cu, Sn, Pb, etc. are control elements, and the general content is required to be controlled at 0.02%~0.15%. At the same time, the EN standard requires R260 rail mechanical properties, tensile strength Rm ≥ 880MPa, elongation after fracture A ≥ 10%, and tread hardness 260-300HB...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C22C38/42C22C38/44C22C38/46C22C38/60B21B37/00B23K11/04
CPCC22C38/02C22C38/04C22C38/002C22C38/46C22C38/44C22C38/42C22C38/008C22C38/60B21B37/00B23K11/04B21B2201/06
Inventor 李大东陆鑫邓健徐飞翔
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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