阅读说明：本技术 一种无缝钢轨的铝热焊方法 (Thermite welding method for seamless steel rail ) 是由 张绵胜 张绵栋 陈良旗 张志强 于 2019-11-26 设计创作，主要内容包括：本发明涉及一种无缝钢轨的铝热焊方法,焊剂的成分为C、Si、Mn、Cr、Ni、Mo、V、铝粉和氧化以及铁粉；流程为：钢轨打磨除锈、去湿；对轨、组装；钢轨预热至轨头颜色发红；铝热焊剂点火预热、反应浇注；浇注后两边在距砂模框架外500mm内将钢轨加热到250-300℃；推瘤,并且同时两边在砂模距框架外500m内钢轨保持温度250-300℃；焊口降温到500℃,热打磨,热打磨后焊肉部分降温,期间两边在距砂模框架外500m内钢轨保持温度250-300℃,至焊肉部分达到250-300℃,焊口覆盖保温20分钟；去除覆盖,自然冷却到室温。这种方法保证了焊接质量。(The invention relates to a thermit welding method of a seamless steel rail, wherein the welding flux comprises C, Si, Mn, Cr, Ni, Mo, V, aluminum powder, oxide and iron powder; the process is as follows: polishing, derusting and dehumidifying the steel rail; aligning and assembling; preheating the steel rail until the rail head turns red; igniting thermite flux, preheating, reacting and pouring; heating the steel rail to 250-300 ℃ within 500mm from the sand mold frame at two sides after casting; pushing the edge, and simultaneously keeping the temperature of the steel rail at 250-300 ℃ in the sand mold distance frame of 500m at two sides; cooling the welded junction to 500 ℃, performing hot grinding, cooling the welded part after the hot grinding, keeping the temperature of the steel rail at the inner part 500m away from the sand mold frame at 250-300 ℃ on both sides, and covering and insulating the welded junction for 20 minutes until the welded part reaches 300 ℃ at 250-300 ℃; removing the cover, and naturally cooling to room temperature. The method ensures the welding quality.)

1. A thermite welding method for seamless steel rail features that the flux contains C, Si, Mn, Cr, Ni, Mo, V, aluminium powder, iron powder and oxide;

the welding process comprises the following steps:

(1) polishing, derusting and dehumidifying the steel rail, wherein the dehumidifying and heating temperature is 300-350 ℃;

(2) aligning and assembling the rails, and wiping the welded junctions again after assembling;

(3) preheating the steel rail for more than 5 minutes until the rail head turns red;

(4) igniting thermite flux, preheating, reacting and pouring;

(5) heating the steel rail to 250-300 ℃ within 500mm from the sand mold frame at two sides after casting;

(6) pushing the edge, and simultaneously keeping the temperature of the steel rail at 250-300 ℃ in the sand mold distance frame of 500m at two sides;

(7) cooling the welded junction to 490-510 ℃, and performing hot grinding, wherein the steel rails at the two sides within 500m away from the sand mold frame are kept at 250-300 ℃ during the hot grinding;

(8) cooling the welding meat part after hot polishing, keeping the temperature of the steel rail at the two sides within 500m away from the sand mold frame at 250-300 ℃ until the temperature of the welding meat part reaches 250-300 ℃, and covering and insulating the welding opening for 10-20 minutes;

(9) removing the cover, and naturally cooling to room temperature.

2. The method of claim 1, wherein: and (4) when the temperature is lower than 15 ℃, performing heat preservation for 10 minutes by using a heat preservation cover after the tumor is pushed in the step (6), and performing heat polishing.

3. The method of claim 1, wherein: when the temperature is lower than 15 ℃, heating the two sides of the steel rail to be within the range of 1000mm to 37 ℃ respectively before preheating in the step (3).

4. The method of claim 1, wherein: after the hot polishing in the step (8), cooling the welding meat to 250-300 ℃ by wind.

5. The method of claim 1, wherein the meat is cooled to 500 ℃ in step (7) by air cooling.

6. The method of claim 1, wherein in step (1), the craters are not heated for de-wetting and are wiped or ground clean after heating.

7. The method of claim 1, wherein the rail gap width is 27-30mm when assembling the rails in step (2).

8. A method according to claim 1, characterised in that the mould removal is started 4.5 minutes after the end of the casting, and cannot be performed prematurely.

9. The method according to claim 1, wherein the knob work should be performed 7 minutes and 40 seconds after the end of the casting without being advanced.

Technical Field

The invention relates to a thermite welding method of a seamless steel rail.

Background

The jointless track is a long steel rail track formed by welding steel rails with standard lengths, and is also called a welding long steel rail track. The rail gap is eliminated, so that the impact of wheels on the rail head is eliminated, the train runs stably, and the service lives of the line equipment and the locomotive are prolonged.

Thermite welding is a rail welding technique used for jointless tracks, and is a method of completing welding by melting a metal base material and filling a joint using heat generated by an oxidation-reduction reaction between a metal oxide and aluminum. The welding difficulty is the welding between heterogeneous steel rails, for example, the welding between a bainite steel rail and a pearlite steel rail, which is mainly reflected in that white spots and stress micro-crack sources are easily generated in a heat affected zone.

Through years of research and tests, BTF bainite steel and steel rails are developed by Beijing Temetallurgical industry and trade Co Ltd, and thermite welding flux related to CN105921881A is developed, so that the BTF bainite steel and steel rails can be used for welding homogeneous and heterogeneous steel rails, good hardness transition at welding seams is realized, and the welding seam performance completely meets the TBT1632.3-2005 and TBT1632.1-2005 standards. The hardness difference of the welding seam relative to the base metal is small, and good transitivity is realized.

However, thermite welding of jointless tracks is carried out in railway laying sites, and with the development of railway industry, railways span different areas, and the change of climate, particularly temperature and humidity, in different areas has a great influence on welding quality, which shows that welding defects such as cracks, bubbles and the like are generated in a welding seam transition area. In addition, due to the difference of alloy components of different welding fluxes, each welding flux needs to develop a corresponding welding process, and the existing process is difficult to apply, which also causes certain difficulty for construction. Therefore, it is necessary to develop a new thermite welding process for seamless rails to ensure the welding quality. In view of the above, on the basis of the development of the thermite welding agent, through a great amount of investigation and tests, the new thermite welding process for the seamless steel rail is developed and perfected by Beijing Temetallurgical industry and trade company Limited.

Disclosure of Invention

The invention aims to provide a thermite welding method of a seamless steel rail, which is based on CN105921881A thermite developed by special metallurgy and is suitable for welding steel rails in different environments.

A thermite welding method for seamless steel rail features that the flux contains C, Si, Mn, Cr, Ni, Mo, V, aluminium powder, iron powder and oxide;

the welding process comprises the following steps:

(1) polishing, derusting and dehumidifying the steel rail, wherein the dehumidifying and heating temperature is 300-350 ℃;

(2) aligning and assembling the rails, and wiping the welded junctions again after assembling;

(3) preheating the steel rail for more than 5 minutes until the rail head turns red;

(4) igniting thermite flux, preheating, reacting and pouring;

(5) heating the steel rail to 250-300 ℃ within 500mm from the sand mold frame at two sides after casting;

(6) pushing the knurls, keeping the temperature of the steel rails at 250-300 ℃ in the position of 500m away from the outside of the sand pot mold frame on two sides;

(7) cooling the welded junction to 500 ℃, and performing hot grinding while keeping two sides outside the sand mold frame

Keeping the temperature of the steel rail within 500m at 250-300 ℃;

(8) cooling the welding meat part after hot polishing, keeping the temperature of the steel rail at the two sides within 500m away from the sand mold frame at 250-300 ℃ until the temperature of the welding meat part reaches 250-300 ℃, and covering and insulating the welding opening for 10-20 minutes;

(9) removing the cover, and naturally cooling to room temperature. Further, the meat welding part is blown in step (8).

And further, when the temperature is lower than 15 ℃, a heat-insulating cover is used for heat insulation for 10 minutes after the burl is pushed in the step (6), so that the phenomenon that the temperature is too fast reduced to refine the crystal grains can be avoided, and the hot grinding can be carried out.

When the temperature is lower than 15 ℃, before preheating in the step (3), heating the two sides of the steel rail within the range of 1000mm to 37 ℃.

Further, after the hot polishing in the step (8), the welding meat can be cooled to 250-300 ℃ by wind, so that the tissue transformation is facilitated, the field work efficiency is improved, and the maintenance time is reduced.

Similarly, air cooling may be used to cool the solder meat to 500 ℃ in step (7).

In the step (1), the weld craters are not heated during dehumidification, so that carbon deposition and oxide scale are generated, and the weld craters are wiped or polished clean after heating.

When the rails are assembled in the step (2), the width of the rail gap is preferably 27-30mm, and the difference between the widest and narrowest parts is not large.

And the mold stripping is started 4.5 minutes after the pouring is finished, and the mold stripping cannot be carried out in advance.

The push button should be performed 7 minutes and 40 seconds after the end of the casting, and not ahead of time. .

The thermite welding process of the invention is to perform dehumidification and heating before assembling the rail, so as to avoid the defect of air holes generated by the moisture on the surface of the rail, and to prevent the transition zone from being cooled too fast by heating and heat preservation at 250-.

Drawings

FIG. 1 is a surface photograph of a weld zone of example 1;

fig. 2 is a surface photograph of a land of example 2.

Detailed Description

The present invention will be further described with reference to specific examples to assist understanding of the invention.