Method for eliminating abnormal structure of gas pressure welded joint of medium-carbon low-alloy corrosion-resistant rail

Abstract

The present application relates to the technical field of steel rail welding, in particular to a method for eliminating abnormal structure of a medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint. The method comprises: S1, using compressed air to cool the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint after welding, so that the joint is cooled to a set temperature and the cooling is stopped; S2, normalizing the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint after cooling to the set temperature. The present application adopts post-weld cooling and normalizing process, the joint hardness HJ / HP is greater than or equal to 0.94, the joint softening zone width is less than or equal to 14 mm, and the abnormal structure such as martensite and bainite of the gas pressure welded joint is completely eliminated, so that the joint has good service performance. The present application can eliminate the abnormal structure of the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint, avoiding the improper post-weld cooling process of the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint, the formation of abnormal structure such as martensite and bainite after the joint is cooled, and the inheritance of the abnormal structure which still remains abnormal structure such as martensite and bainite after the joint is normally normalized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rail welding, in particular to a method for eliminating abnormal structure of gas pressure welded joint of medium-carbon low-alloy corrosion-resistant rail. BACKGROUND

[0002] In order to meet the needs of railway transportation development, higher requirements are put forward for the toughness, fracture resistance, wear resistance and corrosion resistance of the rail. The medium-carbon low-alloy corrosion-resistant rail is delivered in a heat-treated state, with a tensile strength of ≥1080MPa, an average surface hardness of 340HB, and chemical components meeting the following requirements: C mass fraction of 0.50% to 0.65%, Si mass fraction of 0.48% to 0.55%, Mn mass fraction of 0.75% to 0.88%, Cr mass fraction of 0.30% to 0.45%, Cu mass fraction of 0.30% to 0.40%, Ni mass fraction of 0.10% to 0.20%, P mass fraction of ≤0.020%, S mass fraction of ≤0.020%, V mass fraction of ≤0.050%, and at least one of Mo, Nb and Ti, wherein Mo: 0.03-0.15%, Nb: 0.01-0.08%, Ti: 0.01-0.05%, and the rest is Fe and inevitable impurities. The rail has low carbon and alloy elements, good toughness and fracture resistance, and the alloy elements Cr, Cu and Ni are added to improve the corrosion resistance of the rail. The full-length heat treatment of the rail can improve the wear resistance, compression resistance and impact resistance of the rail, and prolong the service life of the rail. It is the most effective and economic method to improve the quality of the line.

[0003] Currently, the main rail welding methods include flash welding, aluminothermic welding and gas pressure welding. In the gas pressure welding process, the rail does not melt, so there is no decarburization layer in the weld, which is an advantage of gas pressure welding over flash welding. The gas pressure welded joint is a forged structure, which is an advantage of gas pressure welding over aluminothermic welding. In theory, the strength of the gas pressure welded joint is not lower than that of the flash welded joint and is superior to that of the aluminothermic welded joint.

[0004] If the post-weld air cooling process of the gas pressure welded joint of the medium-carbon low-alloy corrosion-resistant rail is improper, the same air jet pressure as normalizing is used for air jet cooling, and a large amount of abnormal structures such as martensite and bainite will be formed in the joint after cooling. Moreover, the abnormal structures are easy to be "inherited", and the abnormal structures such as martensite and bainite will still remain in the joint after normalizing according to the normal normalizing process. SUMMARY

[0005] In order to solve the above technical problems in the prior art, the present application provides a method for eliminating abnormal structure of gas pressure welded joint of medium-carbon low-alloy corrosion-resistant rail.

[0006] To achieve the above-mentioned purpose, the embodiments of the present application provide the following technical solutions:

[0007] In a first aspect, in one embodiment of the present application, a method for eliminating abnormal structure of a medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint is provided, and the method comprises the following steps:

[0008] S1, using compressed air to cool the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint after welding, so that the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint is cooled to a set temperature and then stopped air cooling;

[0009] S2, normalizing the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint cooled to the set temperature.

[0010] As a further scheme of the present application, the air cooling pressure after welding is 0.12MPa-0.2MPa, and the air cooling time is 150s-200s.

[0011] The set temperature is 280℃-350℃.

[0012] As a further scheme of the present application, the air cooling after welding adopts full-section air cooling or rail head air cooling.

[0013] As a further scheme of the present application, the air cooling pressure of the full-section air cooling is 0.12MPa-0.15MPa, the air cooling time is 150s-180s, and the set temperature is 300℃-330℃.

[0014] As a further scheme of the present application, the air cooling pressure of the rail head air cooling is 0.15MPa-0.20MPa, the air cooling time is 170s-200s, the rail top surface final cooling temperature is 280℃-300℃, and the temperature of the rail waist and rail bottom is less than 350℃.

[0015] As a further scheme of the present application, the heating area of the normalizing treatment is 30-35mm on both sides of the weld, and the heating time is 180s-230s.

[0016] As a further scheme of the present application, the normalizing treatment further comprises normalizing air cooling of the rail top surface and both sides of the rail head after stopping heating.

[0017] As a further scheme of the present application, the normalizing air cooling is air cooling by spraying, and the air cooling pressure is 0.5MPa-0.65MPa, the air cooling time is 90s-110s, and then air cooling to room temperature.

[0018] As a further scheme of the present application, the normalizing air cooling is air cooling by using an air cooling device.

[0019] As a further scheme of the present application, the air cooling device automatically swings, and the swing range is 40-50mm on both sides of the weld.

[0020] The technical scheme provided by the present application has the following beneficial effects:

[0021] The application provides a method for eliminating abnormal structure of a medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint, which comprises the following steps: S1, using compressed air to cool the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint after welding, and stopping air cooling when the temperature reaches a set temperature; and S2, normalizing the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint after cooling to the set temperature. The application adopts post-weld air cooling and normalizing process, the hardness of the joint is HJ / HP≥0.94, the width of the joint softening zone is ≤14 mm, the abnormal structure such as martensite and bainite of the gas pressure welded joint is completely eliminated, and the joint has good service performance. The application avoids the improper post-weld air cooling process of the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint, the abnormal structure such as martensite and bainite is formed after the joint is cooled, the abnormal structure is "inherited" to cause the abnormal structure such as martensite and bainite to still remain after the joint is normally normalized, and the application can completely eliminate the abnormal structure of the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint.

[0022] These and other aspects of the present application will become more apparent with the following description of the embodiments. It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other embodiments can be obtained by those skilled in the art without creative effort based on these drawings.

[0024] Figure 1 Pearlite + ferrite structure diagram of the gas pressure welded joint of Example 1.

[0025] Figure 2 Pearlite + ferrite structure diagram of the gas pressure welded joint of Example 2.

[0026] Figure 3 Abnormal structure of the gas pressure welded joint of Comparative Example 1 Figure 1 .

[0027] Figure 4 Abnormal structure of the gas pressure welded joint of Comparative Example 1 Figure 2 .

[0028] Figure 5 Abnormal structure of the gas pressure welded joint of Comparative Example 2 Figure 1 .

[0029] Figure 6 Abnormal structure of the gas pressure welded joint of Comparative Example 2 Figure 2 . DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0031] The flowchart shown in the drawings is only an example and does not necessarily include all the contents and operations / steps, nor does it have to be executed in the order described. For example, some operations / steps can be further decomposed, combined or partially merged, so the actual execution order can be changed according to the actual situation.

[0032] The chemical composition of the medium-carbon low-alloy corrosion-resistant rail base material meets the following requirements: the mass fraction of C is 0.50% to 0.65%, the mass fraction of Si is 0.48% to 0.55%, the mass fraction of Mn is 0.75% to 0.88%, the mass fraction of Cr is 0.30% to 0.45%, the mass fraction of Cu is 0.30% to 0.40%, the mass fraction of Ni is 0.10% to 0.20%, the mass fraction of P is ≤0.020%, the mass fraction of S is ≤0.020%, the mass fraction of V is ≤0.050%, and at least one of Mo, Nb and Ti is further included, wherein Mo is 0.03-0.15%, Nb is 0.01-0.08%, and Ti is 0.01-0.05%, and the rest is Fe and unavoidable impurities. The addition of alloying elements such as Cr, Ni and Cu in the rail increases the stability of the supercooled austenite, moves the CCT curve to the right, and causes the formation of harmful structures such as martensite and bainite during the post-weld air cooling and normalizing air blowing of the joint. Due to the limitations of steelmaking process and steel homogeneity, local segregation of the rail is inevitable. Due to the segregation, the chemical composition of each micro area is different, resulting in different Ms points, causing the martensite transformation to appear at different times. These segregations will cause the formation of martensite in the local part of the rail under the action of the welding thermal cycle. Even if the final cooling temperature during the post-weld air cooling and heat treatment of the rail is higher than the Ms (martensite transformation start temperature) temperature of the rail, the CCT curve is moved to the right due to local segregation, causing the formation of abnormal structures such as martensite and bainite. In order to solve this technical problem, the present application provides a method for eliminating abnormal structures of a medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint, which comprises the following steps:

[0033] S1, using compressed air to cool the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint after welding, so that it is cooled to a set temperature and the air cooling is stopped;

[0034] The air blowing pressure for post-weld cooling is 0.12 MPa to 0.2 MPa, and the air blowing time is 150 s to 200 s.

[0035] The setting temperature is 280-350 DEG C.

[0036] The post-weld cooling can adopt full-face air jet cooling or rail head air jet cooling.

[0037] In the full-face air jet cooling, the air jet pressure is 0.12-0.15 MPa, the air jet time is 150-180 s, and the setting temperature is 300-330 DEG C.

[0038] In the rail head air jet cooling, the air jet pressure is 0.15-0.20 MPa, the air jet time is 170-200 s, the final cooling temperature of the rail top surface is 280-300 DEG C, and the temperature of the rail waist and rail bottom is less than 350 DEG C.

[0039] The post-weld cooling process can eliminate abnormal structures such as martensite and bainite generated in the post-weld cooling process of the gas pressure welded joint.

[0040] S2, normalizing the gas pressure welded joint of the medium-carbon low-alloy corrosion-resistant rail cooled to the setting temperature.

[0041] The heating area of the normalizing treatment is 30-35 mm on both sides of the weld, the heating time is 180-230 s, and the temperature of the rail top surface reaches 920-960 DEG C to stop heating.

[0042] The normalizing treatment further comprises normalizing air cooling of the rail top surface and both sides of the rail head after stopping heating.

[0043] The normalizing air cooling is air jet cooling, the air jet pressure is 0.5-0.65 MPa, the air jet time is 90-110 s, the area within 0-15 mm below the rail top surface is rapidly cooled to the final cooling temperature of 400-440 DEG C to stop air jet cooling, and then air cooling to room temperature.

[0044] The normalizing air cooling utilizes an air jet device for air cooling, the air jet device automatically swings, and the swing range is 40-50 mm on both sides of the weld.

[0045] The post-weld air cooling and normalizing process can make the joint hardness HJ / HP be greater than or equal to 0.94, the joint softening zone width be less than or equal to 14 mm, and completely eliminate abnormal structures such as martensite and bainite of the gas pressure welded joint, and has good service performance. The improper post-weld air cooling process of the gas pressure welded joint of the medium-carbon low-alloy corrosion-resistant rail can form abnormal structures such as martensite and bainite after cooling, the abnormal structures are "inherited" to cause the abnormal structures such as martensite and bainite to still remain after normalizing of the joint, and the present application can completely eliminate the abnormal structures of the gas pressure welded joint of the medium-carbon low-alloy corrosion-resistant rail.

[0046] In the present application, the "rail joint, gas pressure welded joint" is a region with a length of 80-100 mm after welding, including a weld and a heat-affected zone, the center of which is the weld. During the forced cooling process by air blowing after gas pressure welding, the "rail top surface temperature, final cooling temperature" referred to in the present application is the temperature at the fusion line of the rail top surface, and the temperature signal is collected by using an infrared temperature measuring instrument. The rail top surface of the rail is the contact part of the wheel and the rail.

[0047] Example 1

[0048] A method for eliminating abnormal microstructure of a medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint, comprising the following steps:

[0049] S1, using compressed air to cool the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint after welding to a set temperature and stopping the air cooling;

[0050] The post-weld cooling can be carried out by blowing air on the rail head, i.e. blowing air on the rail top surface and both sides of the rail head.

[0051] The air blowing pressure of the rail head air blowing cooling is 0.15 MPa, and the air blowing time is 200 s, at which time the rail top surface final cooling temperature is 285℃, and the temperature of the rail waist and rail bottom is 350℃.

[0052] The post-weld cooling process adopted in the present application can eliminate abnormal microstructure such as martensite and bainite generated during the cooling process of the gas pressure welded joint.

[0053] S2, normalizing the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint cooled to the set temperature.

[0054] The heating area of the normalizing treatment is 30 mm on both sides of the weld, the heating time is 180 s, and at this time the rail top surface temperature reaches 925℃ to stop heating.

[0055] The normalizing treatment also includes normalizing air cooling on the rail top surface and both sides of the rail head after stopping heating.

[0056] The normalizing air cooling is air blowing cooling, and the air blowing pressure is 0.5 MPa, the air blowing time is 110 s, and the area within 0-15 mm below the rail top surface is rapidly cooled to the final cooling temperature of 412℃ to stop air blowing cooling, and then air cooled to room temperature.

[0057] The normalizing air cooling is carried out by using an air blowing device, and the air blowing device automatically swings with a swing amplitude of 40-50 mm on both sides of the weld.

[0058] The microstructure of the weld in Example 1 is pearlite + ferrite, as shown in Figure 1As shown in the figure, the joint hardness HJ / HP is greater than or equal to 0.94, the joint softening zone width is less than or equal to 14mm, and the joint has good service performance.

[0059] Example 2

[0060] A method for eliminating abnormal microstructure of a medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint, S1, using compressed air to cool the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint after welding to stop air cooling when the temperature reaches a set temperature;

[0061] The post-weld cooling can be rail head air cooling, that is, air is sprayed on the rail top surface and both sides of the rail head.

[0062] The air pressure for the rail head air cooling is 0.20MPa, and the air spraying time is 200s, at which time the final cooling temperature of the rail top surface is 300℃, and the temperature of the rail waist and rail bottom is 320℃.

[0063] The post-weld cooling process can eliminate abnormal microstructure such as martensite and bainite generated during the cooling process of the gas pressure welded joint.

[0064] S2, normalizing the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint cooled to the set temperature.

[0065] The heating area of the normalizing treatment is 35mm on both sides of the weld, the heating time is 230s, and at this time the temperature of the rail top surface reaches 960℃ to stop heating.

[0066] The normalizing treatment also includes normalizing air cooling of the rail top surface and both sides of the rail head after stopping heating.

[0067] The normalizing air cooling is air cooling, and the air pressure is 0.65MPa, the air spraying time is 90s, and the area within 0mm-15mm below the rail top surface is rapidly cooled to the final cooling temperature of 440℃ to stop air cooling, and then air cooled to room temperature.

[0068] The normalizing air cooling is air cooling, and the air pressure is 0.65MPa, the air spraying time is 90s, and the area within 0mm-15mm below the rail top surface is rapidly cooled to the final cooling temperature of 440℃ to stop air cooling, and then air cooled to room temperature.

[0069] The normalizing air cooling is air cooling, and the air pressure is 0.65MPa, the air spraying time is 90s, and the area within 0mm-15mm below the rail top surface is rapidly cooled to the final cooling temperature of 440℃ to stop air cooling, and then air cooled to room temperature. Figure 2 As shown in the figure, the joint hardness HJ / HP is greater than or equal to 0.94, the joint softening zone width is less than or equal to 14mm, and the joint has good service performance.

[0070] Example 3

[0071] A method for eliminating abnormal microstructure of a medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint, S1, using compressed air to cool the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint after welding to stop air cooling when the temperature reaches a set temperature;

[0072] Post-welding cooling can be achieved by full-section air jet cooling.

[0073] The full-section air-cooling system has an air pressure of 0.12 MPa, an air-cooling time of 180 s, and a set temperature of 300℃~330℃.

[0074] Specifically, at this time, the temperature of the top surface of the rail is 320℃, the temperature of the web of the rail is 315℃, and the temperature of the triangular area at the bottom of the rail is 318℃.

[0075] The present invention employs this post-weld cooling process, which can eliminate abnormal structures such as martensite and bainite generated during the cooling process of gas pressure welded joints.

[0076] S2. Normalize the gas pressure welded joint of medium carbon low alloy corrosion-resistant steel rail after it has cooled to the set temperature.

[0077] The heating area for the normalizing treatment is 35mm on both sides of the weld, the heating time is 230s, and the heating stops when the temperature of the rail top surface reaches 940℃.

[0078] The normalizing process also includes normalizing and air cooling of the rail top surface and both sides of the rail head after heating is stopped.

[0079] The normalizing air cooling is a jet cooling, with a jet pressure of 0.60 MPa and a jet time of 100 s. During this time, the area within 0 mm to 15 mm below the rail top surface is rapidly cooled to the final cooling temperature of 430°C, and then the jet cooling is stopped. Then, it is air cooled to room temperature.

[0080] Normalizing air cooling is achieved using an air jet device, which automatically oscillates with an amplitude of 40-50 mm on both sides of the weld.

[0081] In this embodiment, the microstructure of the weld is pearlite + ferrite, the joint hardness HJ / HP≥0.94, and the width of the softened zone of the joint ≤14mm, which has good service performance.

[0082] Example 4

[0083] A method for eliminating abnormal microstructure of gas pressure welded joints of medium carbon low alloy corrosion resistant steel rails, S1: using compressed air to cool the gas pressure welded joints of medium carbon low alloy corrosion resistant steel rails after welding, cooling them to a set temperature and then stopping the air cooling.

[0084] Post-welding cooling can be achieved by full-section air jet cooling.

[0085] The full-section air-cooling system has a spray pressure of 0.12 MPa, a spray time of 180 s, and a set temperature of 320 ℃.

[0086] The present invention employs this post-weld cooling process, which can eliminate abnormal structures such as martensite and bainite generated during the cooling process of gas pressure welded joints.

[0087] S2, normalizing the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint cooled to a set temperature.

[0088] The heating area of the normalizing treatment is 30 mm on both sides of the weld, the heating time is 220 s, and the rail top surface temperature reaches 930 ℃ at this time to stop heating.

[0089] The normalizing treatment also includes normalizing air cooling of the rail top surface and both sides of the rail head after stopping heating.

[0090] The normalizing air cooling is air jet cooling, the air jet pressure is 0.58 MPa, the air jet time is 110 s, the area within 0 mm to 15 mm below the rail top surface is rapidly cooled to the final cooling temperature 415 ℃ to stop air jet cooling, and then air cooled to room temperature.

[0091] The normalizing air cooling utilizes an air jet device for air cooling, the air jet device automatically swings, and the swing amplitude is 40-50 mm on both sides of the weld.

[0092] The microstructure of the weld in Example 4 is pearlite + ferrite, the joint hardness HJ / HP is greater than or equal to 0.94, the joint softening zone width is less than or equal to 14 mm, and the joint has good service performance.

[0093] Comparative Example 1

[0094] After the medium-carbon low-alloy corrosion-resistant rail gas pressure welded joint is pushed, air jet is performed on the rail top surface and both sides of the rail head to accelerate joint cooling and shorten joint cooling time, the same air jet pressure 0.55 MPa as the normalizing is used for air jet, the air jet time is 170 s, the rail top surface temperature is 230 ℃ at this time, the rail waist temperature is 301 ℃, and the rail bottom triangular area temperature is 320 ℃. Start heating normalizing, the heating area is 35 mm on both sides of the weld, the heating time is 200 s, the rail top surface temperature is 920 ℃ to stop heating, a special air jet device is used for air jet forced cooling of the rail top surface and both sides of the rail head, the air jet pressure is 0.55 MPa, the air jet time is 100 s, the final cooling temperature is 440 ℃ to stop air jet cooling, and air cooled to room temperature. Using this post-weld air cooling and normalizing process, the rail head of the gas pressure welded joint has martensite and bainite abnormal structures. As shown in Figure 3 、 4 , it does not meet the standard requirements.

[0095] Comparative Example 2

[0096] After the bulge of the gas pressure welded joint of the medium carbon low alloy corrosion resistant rail is pushed, the whole section of the joint is blasted to accelerate the cooling of the joint and shorten the cooling time of the joint. The same blast pressure 0.60 MPa as normalizing is used for blast, and the blast time is 150 s. At this time, the temperature of the rail top surface is 245 ℃, the temperature of the rail waist is 240 ℃, and the temperature of the rail bottom triangular area is 248 ℃. The heating of normalizing is started, the heating area is 30 mm on both sides of the weld, the heating time is 220 s, the temperature of the rail top surface is 950 ℃, and the heating is stopped. A special blast device is used to blast and forcibly cool the rail top surface and both sides of the rail head, the blast pressure is 0.60 MPa, the blast time is 100 s, and the blast cooling is stopped immediately after the final cooling temperature drops to 420 ℃. The air cooling is performed to room temperature. By using the blast cooling after welding and the normalizing process, the martensite and bainite abnormal structure in the weld position is not satisfied with the standard requirements, as shown in Figs. Figure 5 、 6 .

[0097] The above describes the preferred embodiments of the present application in detail, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A method for eliminating abnormal microstructure of a gas pressure welded joint of a medium-carbon low-alloy corrosion-resistant rail, characterized in that, The method comprises the following steps: S1, using compressed air to cool the middle carbon low alloy corrosion-resistant rail gas pressure welded joint after welding, so that it is cooled to a set temperature and stopped air cooling; the air cooling pressure of the post-weld cooling is 0.12-0.2 MPa, the air cooling time is 150-200 s, and the set temperature is 280-350 DEG C; S2, normalizing the middle carbon low alloy corrosion-resistant rail gas pressure welded joint cooled to the set temperature; the normalizing treatment comprises stopping heating and then air cooling the rail top surface and both sides of the rail head; the normalizing air cooling is air cooling by spraying, the spraying pressure is 0.5-0.65 MPa, the spraying time is 90-110 s, and then air cooling to room temperature; The chemical composition of the middle carbon low alloy corrosion-resistant rail meets the following requirements: the mass fraction of C is 0.50-0.65%, the mass fraction of Si is 0.48-0.55%, the mass fraction of Mn is 0.75-0.88%, the mass fraction of Cr is 0.30-0.45%, the mass fraction of Cu is 0.30-0.40%, the mass fraction of Ni is 0.10-0.20%, the mass fraction of P is ≤0.020%, the mass fraction of S is ≤0.020%, the mass fraction of V is ≤0.050%, and at least one of Mo, Nb and Ti is further included, wherein Mo: 0.03-0.15%, Nb: 0.01-0.08%, Ti: 0.01-0.05%, and the rest is Fe and inevitable impurities.

2. The method for eliminating abnormal structure of gas pressure welded joints of medium-carbon low alloy corrosion resistant steel rails according to claim 1, characterized in that, The post-weld cooling adopts full-section air cooling or rail head air cooling.

3. The method for eliminating abnormal structure of gas pressure welded joints of medium-carbon low alloy corrosion resistant steel rails according to claim 2, characterized in that, The air cooling pressure of the full-section air cooling is 0.12-0.15 MPa, the air cooling time is 150-180 s, and the set temperature is 300-330 DEG C.

4. The method for eliminating abnormal structure of gas pressure welded joints of medium-carbon low alloy corrosion resistant steel rails according to claim 2, characterized in that, The air cooling pressure of the rail head air cooling is 0.15-0.20 MPa, the air cooling time is 170-200 s, and the final cooling temperature of the rail top surface is 280-300 DEG C.

5. The method for eliminating abnormal structure of gas pressure welded joints of medium-carbon low alloy corrosion resistant steel rails according to claim 1, characterized in that, The heating area of the normalizing treatment is 30-35 mm on both sides of the weld, and the heating time is 180-230 s.

6. The method for eliminating abnormal structure of gas pressure welded joints of medium-carbon low alloy corrosion resistant steel rails according to claim 1, characterized in that, The normalizing air cooling is air cooling by using an air spraying device.

7. The method for eliminating abnormal structure of gas pressure welded joints of medium-carbon low alloy corrosion resistant steel rails according to claim 6, characterized in that, The air spraying device is automatically swung, and the swing range is 40-50 mm on both sides of the weld.

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