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A method of controlling the martensitic structure of r260 rail flash welded joints

A head martensite and rail technology, which is applied in the field of controlling the martensite structure of R260 rail flash welded joints, can solve the problems of failing to pass the welding type inspection, appearing point-like martensite structure, and shifting to the right, and achieves good promotion and application prospects. Control the effect of simple craftsmanship

Active Publication Date: 2021-05-25
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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  • A method of controlling the martensitic structure of r260 rail flash welded joints
  • A method of controlling the martensitic structure of r260 rail flash welded joints
  • A method of controlling the martensitic structure of r260 rail flash welded joints

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Effect test

Embodiment 1

[0036]Control the Mn content in the base metal composition of R260 rails to 1.10% 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 normally produced and rolled by the universal line meet Rm≥880MPa, and the tread hardness ≥260HB, using the rail mobile flash welder or fixed flash welder, after pulsating or preheating flash welding with a large heat input of 8.5MJ, the actual welding upsetting amount is kept at 14.0mm, and when the joint pushing is completed, it is air-cooled to 570 When the temperature is below 250°C, use the rail head heat preservation device with a hinged structure embedded in 40mm thick aluminosilicate fiber cotton or the full-section rail heat preservation device for slow cooling. The length of the heat preservation and slow cooling device is 230 mm. With the device, allow the joint to air cool to room temperature.

[0037] After testing, according to EN145...

Embodiment 2

[0039] Control the Mn content in the base metal composition of R260 rail to 1.15% 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 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 580 When the temperature is below 250°C, use the rail head heat preservation device with a hinged structure embedded in 40mm thick aluminosilicate fiber cotton or the full-section rail heat preservation device for slow cooling. The length of the heat preservation and slow cooling device is 240 mm. With the device, allow the joint to air cool to room temperature.

[0040] After testing, according to EN14587-2:2009 stan...

Embodiment 3

[0042] Control the R260 rail parent material composition when the Mn content is 1.20% Mn, the C content of other chemical components is at the middle and lower limits, and the Si is kept 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 surface Hardness ≥ 260HB, using the rail mobile flash welder or fixed flash welder, after pulsating or preheating flash welding with a large heat input of 9.0MJ, the actual welding upsetting amount is kept at 14.5mm, and when the joint pushing is completed, it is air cooled to When the temperature is 580°C, the rail head heat preservation device or the full-section rail heat preservation device with a hinged structure embedded with 40mm thick aluminosilicate fiber cotton is used for slow cooling. Insulation device, allow joint to air cool to room temperature.

[0043] After testing, according to the requirements of EN14587-2:2009 standard, the position i...

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Abstract

The invention relates to a method for controlling the martensitic structure of R260 rail flash welding joints, belonging to the technical field of railway rail welding. The technical problem solved by the invention is that the martensitic structure is easy to appear in the R260 rail flash welding joint after welding in air cooling. The technical solution of the present invention is a method for controlling the martensitic structure of R260 rail flash welded joints, including the control of the chemical composition of the R260 rail base material, the control of the hot rolling process, the control of the welding process, and the post-weld cooling control, wherein the control of the R260 rail base material is controlled by In terms of weight percentage, the Mn content is 1.10%-1.25%, the C content is in the middle and lower limit, and the Si≤0.30%. The invention can avoid martensitic structure at the specified inspection positions of the center surface of the rail head and the rail foot, ensures various mechanical performance indexes of the joint, meets the technical requirements of the EN14587‑2:2009 standard, and has good prospects for popularization and application.

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 the mechanical properties of the R260 rail, the tensile strength Rm≥880MPa, the elongation after fracture A≥10%, and the tread...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04B21B37/00B23K11/04
CPCB21B37/00B21B2201/06B23K11/04C22C38/02C22C38/04
Inventor 李大东陆鑫王若愚白威
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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