Method for reducing the width of heat-affected zone of hypereutectoid rail flash welding joint

Abstract

The present invention discloses a method for reducing the width of the heat-affected zone of a flash welded hypereutectoid rail. The method comprises: flash welding the rail; quenching the joint of the welded rail by using a quenching device; wherein the flash welding process comprises the following stages: a flash flattening stage, a preheating stage, an accelerated sintering stage, an upsetting stage, a forging stage, and a post-heat holding stage; in the flash flattening stage, the displacement limit is 4.0 mm to 6.0 mm, and the maximum flash speed is 2.0 mm / s to 5.0 mm / s; in the upsetting stage, the upsetting time limit is 0.1 s to 0.5 s, and the upsetting current setting value is 30.0 kA to 32.0 kA. The present invention can reduce the width of the visible heat-affected zone of the flash welded hypereutectoid rail and improve the service performance of the joint.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a method for reducing the width of a heat-affected zone of a hypereutectoid rail flash welding joint. Background Art

[0002] In order to meet the requirements of heavy-duty rails for wear resistance, peeling resistance and fatigue resistance, the performance of the pearlite rails currently in widespread use is mainly optimized by adding alloy elements and using online heat treatment processes to optimize their microstructures, such as controlling the size of pearlite clusters and reducing the spacing between pearlite lamellae. This allows the eutectoid pearlite rails to obtain the ultimate mechanical properties of a hardness of 370HB and a tensile strength of 1280MPa. Although this mechanical property meets the requirements of most heavy-duty lines, it cannot meet the requirements of current lines with large loads, high traffic density and small radius. To further improve the mechanical properties of the rails, it is necessary to reduce the isothermal temperature and increase the cooling rate, which is likely to cause the formation of a structure such as martensite and bainite. Although the hardness of the rails is improved, the brittleness is greatly increased, and it is very easy to break, which seriously endangers driving safety. After years of research, technicians have adopted the method of increasing the thickness and density of cementite lamellae in the matrix to improve the hardness and wear resistance of the rails, that is, increasing the carbon content to obtain higher hardness. Generally speaking, steel with a carbon content of more than 0.77% and a cementite content of more than 12% in the matrix structure is called hypereutectoid steel. However, in the field of rail production, rails with a carbon content of more than 0.90% are usually called hypereutectoid rails.

[0003] During the service of rail welded joints, the bonding strength of the rail joints determines whether the rail joints are prone to fatigue or brittle fracture; the longitudinal section hardness of the rail joints determines the smoothness of different micro-regions of the joints. In the field of rail welding, different countries and regions have detailed regulations on the performance evaluation methods of rail joints. The mainstream international standards for rail flash welding mainly include China Railway Industry Standard Series Standard TB / T 1632.2 "Rail Welding Part 2: Flash Welding", American Railway Engineering Association Manual AMERICAN RARILWAY ENGINEERING AND MAINTENANCE-OF-WAY ASOCIATION (AREMA), European Standard BS EN14587-3:2012, Rail way applications-Track-Flashbutt welding of rails. Part 3: Welding in association with crossing construction and Australian Standard AS1085.20-2012, Railway track material Part 20: Welding of steel rail. All current standards and enterprise technical conditions applicable to pearlite and hypereutectoid rail flash welding have detailed provisions on the items, methods and requirements for quality assessment of rail flash welded joints. The inspection items specified in China Railway Standard TB / T 1632 include flaw detection, drop hammer, static bending, fatigue, hardness, macro-low magnification, microstructure, impact and tensile properties, etc. Foreign standards and enterprise technical conditions have little difference in the types of inspection items for joints, and only differ in inspection methods and technical requirements. However, compared with domestic standards, there is no drop hammer, impact and tensile properties.

[0004] At present, the mainstream welding method for rails is flash welding. Rail flash welding is a resistance welding method that uses the resistance of the small contact points on the contact surface of the rail end and the heat generated by the arc to heat the end of the rail to be welded, and applies pressure to the joint after an appropriate time, so that the entire area of ​​the rail butt surface is firmly combined at the same time. It has a high degree of automation and stable welding quality. It is the main method for on-site construction welding of seamless lines at home and abroad. According to its production method, it is mainly divided into fixed flash welding and mobile flash welding. Fixed flash welding usually fixes the welding equipment in the factory, so it is also commonly called factory welding or base welding. Fixed flash welding is usually achieved by directly short-circuiting the rail and heating the rail by resistance heat. The heating process is not (or only a small amount of) accompanied by flash.

[0005] The width of the visible heat-affected zone of the rail flash weld joint (often also referred to as the heat-affected zone width) refers to the area in the rail weld joint where the organization changes due to the welding heat cycle. This indicator is mainly measured by the macroscopic low-power project of the longitudinal section of the joint. After being corroded by the acidic medium, there is a large difference in color between the fusion line and the parent material that is not affected by the heat. It is generally believed in the industry that the width of the heat-affected zone needs to be controlled within a certain range. A heat-affected zone that is too wide or too narrow is not conducive to the service performance of the joint. Generally speaking, the heat-affected zone should be controlled within a smaller range, which is conducive to the service performance of the joint. Because normalizing treatment is generally not required for joints after welding abroad, necessary restrictions are imposed on the width of the heat-affected zone of the rail joint. The European standard EN standard requires that the width of the heat-affected zone of the joint be 20mm~45mm, and the difference between the widest area and the narrowest area of ​​the heat-affected zone on the longitudinal section of the joint be less than 20mm; the width of the heat-affected zone required in the Australian standard AS standard is 30mm~50mm, and it is perpendicular to the bottom surface of the rail, and the inclination of the visible heat-affected zone is <5°.

[0006] How to control the width of the heat affected zone of the rail joint through welding process and improve the service performance of the joint is a problem that must be faced in the field of rail welding technology. Summary of the invention

[0007] The main purpose of the present invention is to provide a method for reducing the width of the heat-affected zone of a hypereutectoid rail flash weld joint, so as to ensure that the width of the heat-affected zone of the rail flash weld joint meets the standard requirements.

[0008] According to one aspect of the present invention, a method for reducing the width of the heat affected zone of a flash welded hypereutectoid rail is proposed, comprising: flash welding the rail; quenching the joint of the rail after welding using a quenching device; wherein the flash welding process comprises the following stages: a flash flattening stage, a preheating stage, an accelerated burning stage, an upsetting stage, a forging stage, and a post-heat holding stage; in the flash flattening stage, the displacement limit is 4.0 mm to 6.0 mm, and the maximum flash speed is 2.0 mm / s to 5.0 mm / s; in the upsetting stage, the upsetting time limit is 0.1 s to 0.5 s, and the upsetting current setting value is 30.0 kA to 32.0 kA.

[0009] According to one embodiment of the present invention, in the preheating stage, the preheating pressure setting value is 100.0 kN to 120.0 kN, the separation distance is 2.0 mm to 3.2 mm, the deformation limit is 0.6 mm to 1.0 mm, and the number of preheating cycles is 7 to 10 times.

[0010] According to an embodiment of the present invention, in the accelerated burning stage, the displacement limit is 7.0 mm to 15.0 mm, and the maximum flash speed is 0.4 mm / s to 2.6 mm / s.

[0011] According to one embodiment of the present invention, during the forging stage, the displacement limit is 5.0 mm to 10.0 mm, the forging time limit is 1.0 s to 2.5 s, and the average forging speed is 0.50 mm / s to 2.0 mm / s.

[0012] According to one embodiment of the present invention, in the post-heat holding stage, the heating time is 0.3s to 1.0s, and the displacement limit is 30.0mm to 38.0mm.

[0013] According to one embodiment of the present invention, the welded rail moves along the longitudinal direction of the rail on the production line, the quenching device includes a guide rail and a main unit that can move along the guide rail, the extension direction of the guide rail is the same as the moving direction of the rail, and the quenching of the joint of the welded rail by using the quenching device includes: allowing the main unit to move with the rail, and blowing gas to the top surface, side surface and lower jaw of the rail head at the rail joint during the movement of the rail to cool it; or the welded rail moves along the longitudinal direction of the rail on the production line, the quenching device includes a plurality of quenching units arranged along the moving direction of the rail, and the quenching of the joint of the welded rail by using the quenching device includes: during the movement of the rail, allowing the rail joint to pass through the plurality of quenching units in sequence, and allowing the plurality of quenching units to blow gas to the top surface, side surface and lower jaw of the rail head at the rail joint to cool it.

[0014] According to one embodiment of the present invention, when the quenching device includes the guide rail and the main unit, the moving speed of the rail is 0.08m / s~1.0m / s, and the total effective air jet length of the quenching device is 10m~40m; when the quenching device includes a plurality of the quenching units, the moving speed of the rail is 0.2m / s~2.5m / s, and the total effective air jet length of the quenching device is 10m~40m.

[0015] According to one embodiment of the present invention, the distance between the air outlet of the main unit or the quenching unit and the corresponding rail head top surface, rail head side surface or rail head lower jaw surface is 20mm-40mm; and / or the gas is compressed air, and the pressure value of the compressed air before entering the quenching device is 100kPa-300kPa.

[0016] According to one embodiment of the present invention, the main unit and the quenching unit both include: a first air supply section, a second air supply section and a third air supply section, the length directions of the first air supply section, the second air supply section and the third air supply section are the same as the moving direction of the rail, and the first air supply section, the second air supply section and the third air supply section are provided with a plurality of air outlets arranged along their respective length directions; the first air supply section, the second air supply section and the third air supply section are respectively arranged on the outer side of the top surface of the rail head, the outer side of the rail head and the outer side of the lower jaw of the rail head.

[0017] According to one embodiment of the present invention, the lengths of the first air supply part, the second air supply part and the third air supply part are all greater than or equal to 150 mm; and / or the first air supply part is box-shaped, and the width of the first air supply part of the main unit is greater than or equal to 70 mm, or the width of the first air supply part of the quenching unit is greater than or equal to 75 mm; and / or the second air supply part and the third air supply part are tubular, and the inner diameters of the second air supply part and the third air supply part are 25 mm to 30 mm; and / or the diameter of the air outlet is 1 mm to 3 mm, and the distance between adjacent air outlets is 5 mm to 15 mm.

[0018] In the method for reducing the width of the heat affected zone of a hypereutectoid rail flash weld joint according to an embodiment of the present invention, by improving the parameters of the flash welding process, especially the parameters of the flash flattening stage and the upsetting stage, the welding heat input can be reasonably controlled, which is beneficial to reducing the width of the heat affected zone of the weld joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A flow chart showing a method for reducing the width of a heat-affected zone of a hypereutectoid rail flash weld joint according to an embodiment of the present invention;

[0021] Figure 2 A flow chart showing a method for reducing the width of a heat-affected zone of a hypereutectoid rail flash weld joint according to another embodiment of the present invention;

[0022] Figure 3 A schematic diagram showing a quenching device used in a method for reducing the width of a heat-affected zone of a hypereutectoid rail flash weld joint according to an embodiment of the present invention;

[0023] Figure 4 Show Figure 3Another schematic diagram of a quenching device;

[0024] Figure 5 A schematic diagram showing a visible heat-affected zone of a rail flash weld joint obtained by using the method for reducing the width of the heat-affected zone of a hypereutectoid rail flash weld joint according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0026] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0027] The inventors of the present application realized that the width of the heat-affected zone is related to the amount of heat input for welding. The greater the welding heat input, the wider the heat-affected zone of the joint, and the smaller the welding input, the narrower the heat-affected zone of the joint. In addition to the heat input, the width of the heat-affected zone of the joint is related to the length of time the rail metal stays in the high-temperature area. The longer the rail joint stays in the high-temperature area, the more heat is conducted along the longitudinal direction of the rail to the parent material, and the easier it is to widen the width of the heat-affected zone. On this basis, the present invention proposes the method to be described below to reduce the width of the heat-affected zone of a hypereutectoid rail flash weld joint, and the method can be implemented using a rail-fixed flash welder.

[0028] The method for reducing the width of the heat affected zone of a hypereutectoid rail flash weld according to an embodiment of the present invention comprises:

[0029] Flash welding of rails;

[0030] Using a quenching device to quench the joints of the welded rails;

[0031] Among them, the flash welding process includes the following stages: flash flattening stage, preheating stage, accelerated burning stage, upsetting stage, forging stage and post-heat holding stage;

[0032] In the flash flat stage, the displacement limit is 4.0 mm to 6.0 mm, and the maximum flash speed is 2.0 mm / s to 5.0 mm / s;

[0033] In the upset forging stage, the upset forging time limit is 0.1s to 0.5s, and the upset forging current setting value is 30.0kA to 32.0kA.

[0034] During the flash welding process, the rail is heated by the resistance heat generated by the short circuit of the rail to be welded, and forging is performed after the top forging is completed. In order to reduce the width of the visible heat-affected zone of the hypereutectoid rail flash weld joint, it is necessary to strictly control the heat and heat conduction time from the end face of the rail to be welded along the longitudinal direction of the rail to the unheated side, as well as the cooling rate of the joint cooling process.

[0035] The present invention controls the heat conduction amount, heat conduction time and cooling rate of the quenching process in the welding process by designing the parameters of the flash flattening stage and the upset forging stage as described above, the parameters of other stages of the welding process to be described below, and the relevant technical means and parameters of the quenching process, thereby reducing the width of the visible heat affected zone of the hypereutectoid rail flash welding joint.

[0036] The flashing stage mainly loads a certain current on the rail and uses the lintel blasting to transform the solid metal into molten metal so that the end surface to be welded tends to be infinitely flat, providing conditions for the subsequent uniform short-circuit heating of the entire section of the rail. Parameters such as the displacement limit and the maximum flash speed in this stage are the main factors affecting the total heat conduction and the heat conduction time. As described above, the present invention sets a reasonable numerical range for the displacement limit and the maximum flash speed in the flashing stage.

[0037] The upsetting stage mainly applies inward loads to both ends of the steel rail to be welded, and most of the molten metal and the high-temperature solid metal with low plasticity are squeezed out of the joint and the rails are welded. The upsetting time limit and the upsetting current setting value in this stage are the main factors affecting the total heat conduction and the heat conduction time. As mentioned above, the present invention sets a reasonable numerical range of the upsetting time limit and the upsetting current setting value in the upsetting stage.

[0038] In addition, the preheating stage mainly heats the rails by the resistance heat generated by the continuous short circuit at both ends of the rails and forms the required temperature gradient in the longitudinal direction of the rails. In this stage, parameters such as the preheating pressure setting value, separation distance, deformation limit and number of preheating cycles are the main factors affecting the total heat conduction and heat conduction time. In an embodiment of the present invention, in the preheating stage, the preheating pressure setting value is 100.0kN~120.0kN, the separation distance is 2.0mm~3.2mm, the deformation limit is 0.6mm~1.0mm, and the number of preheating cycles is 7~10 times.

[0039] The accelerated burning stage mainly forms a protective atmosphere to prevent end face oxidation in the entire welding area through continuous and rapid flash explosions, providing end face protection for welding upsetting. The displacement limit and maximum flash speed in this stage are the main factors affecting the total heat conduction and heat conduction time. In the embodiment of the present invention, in the accelerated burning stage, the displacement limit is 7.0mm-15.0mm, and the maximum flash speed is 0.4mm / s-2.6mm / s.

[0040] The main function of the forging stage is to continuously apply load to the rail joint during the crystallization process of the joint metal after the rail top forging and to further squeeze the plastic metal in the relatively low temperature area of ​​the joint out of the joint. Parameters such as displacement limit, forging time limit and average forging speed in this stage are the main factors affecting the heat conduction time. In an embodiment of the present invention, in the forging stage, the displacement limit is 5.0mm~10.0mm, the forging time limit is 1.0s~2.5s, and the average forging speed is 0.50mm / s~2.0mm / s.

[0041] The post-heat holding stage is mainly to further improve the joint performance by continuing to apply load after the rail is forged. The heating time and displacement limit in this stage are the main factors affecting the total heat conduction and heat conduction time. In an embodiment of the present invention, in the post-heat holding stage, the heating time is 0.3s to 1.0s, and the displacement limit is 30.0mm to 38.0mm.

[0042] In the embodiment of the present invention, the main chemical components of the hypereutectoid rail include carbon mass fraction of 0.90% to 1.20%, silicon mass fraction of 0.10% to 1.00%, manganese mass fraction of 0.60% to 1.50%, phosphorus and sulfur mass fractions not exceeding 0.020%, chromium mass fraction not exceeding 0.3%, and vanadium mass fraction not exceeding 0.01%. The minimum tensile strength of the rail is 1200MPa, and the minimum hardness of the rail head is 400HB.

[0043] Figure 1 A flow chart showing a method for reducing the width of the heat affected zone of a hypereutectoid rail flash weld joint according to an embodiment of the present invention is shown. Figure 1 As shown, the welded rail moves along the longitudinal direction of the rail on the production line, the quenching device includes a guide rail and a main unit 10 that can move along the guide rail, the extension direction of the guide rail is the same as the moving direction of the rail, and the quenching device is used to quench the joint of the welded rail, including:

[0044] The main unit 10 moves along with the rails, and during the movement of the rails, gas is blown to the top surface, side surface and lower jaw of the rail head at the rail joint to cool them.

[0045] The rail can move along the roller of the production line, and in the process of movement, it passes through the front-end process, welding process, quenching process and back-end process in sequence. By using the main unit 10 to follow the movement of the joint to cool the rail during its movement, it can be ensured that the entire welding and subsequent processing process of the rail is carried out continuously to avoid affecting the production efficiency. By quenching the rail, on the one hand, it is beneficial to adjust the width of the visible heat-affected zone of the hypereutectoid rail flash weld head, and on the other hand, it can also adjust the hardness of the rail weld head, which is beneficial to comprehensively improve the performance of the rail. The top surface of the rail head, the side surface of the rail head and the lower jaw of the rail head are the main parts for carrying out rail performance testing. The present invention focuses on cooling these parts, which can save energy and cost on the basis of ensuring that the performance of the rail is qualified.

[0046] The first end of the guide rail is arranged close to the welding machine, and the second end is arranged far from the welding machine. The main unit 10 moves from the first end to the second end of the guide rail, and then returns to the first end after moving to the second end. During the movement, the running direction and speed of the main unit 10 are consistent with the rail, and its center position coincides with the center of the flash welding head of the rail.

[0047] Figure 2 A flow chart showing a method for reducing the width of the heat affected zone of a hypereutectoid rail flash weld joint according to another embodiment of the present invention is shown. Figure 2 As shown, the welded rail moves along the longitudinal direction of the rail on the production line, and the quenching device includes a plurality of quenching units 20 arranged along the moving direction of the rail. The quenching of the joint of the welded rail by the quenching device includes:

[0048] During the movement of the rail, the rail joint passes through a plurality of quenching units 20 in sequence, and the plurality of quenching units 20 blow gas to the rail head top surface, rail head side surface and rail head lower jaw at the rail joint to cool them.

[0049] In some embodiments, a certain gap may be left between adjacent quenching units 20, and multiple quenching units 20 are evenly arranged at equal intervals. In a more preferred embodiment, adjacent quenching units 20 are closely connected to ensure a continuous and good cooling effect. By setting a plurality of quenching units 20 arranged in sequence, the independence of the plurality of quenching units 20 can be ensured compared to setting a whole integrated quenching unit 20, and the gas pressure of each quenching unit 20 can be individually regulated, which is convenient for individual maintenance and replacement, while also ensuring good technical feasibility and reducing the difficulty of production and manufacturing.

[0050] When the quenching device includes the guide rail and the main unit 10, the moving speed of the rail is 0.08m / s to 1.0m / s, and the total effective air jet length of the quenching device is 10m to 40m. When the quenching device includes a plurality of quenching units 20, the moving speed of the rail is 0.2m / s to 2.5m / s, and the total effective air jet length of the quenching device is 10m to 40m.

[0051] The effective total air jet length can be determined by the air jet length of the main unit 10 itself and its moving distance, or by the comprehensive determination of the air jet lengths of multiple quenching units 20. In combination with the above-defined speed value and the effective total air jet length value, a reasonable cooling time can be defined. When the quenching device is a mobile device (i.e., including a guide rail and a main unit 10), the operation and implementation of the quenching device is more difficult than when the quenching device is a stationary device (i.e., including multiple quenching units 20). Accordingly, in the embodiment using a mobile quenching device, the moving speed of the rail is smaller.

[0052] In some embodiments, the distance between the air outlet of the main unit 10 or the quenching unit 20 and the corresponding rail head top surface, rail head side surface or rail head lower jaw surface is 20mm-40mm (for example, a1 in the figure can be 20mm-40mm, a2 can be 30mm); and / or the gas is compressed air, and the pressure value of the compressed air before entering the quenching device is 100kPa-300kPa. This ensures a suitable gas blowing intensity, and further ensures a suitable cooling rate.

[0053] Figure 3 A schematic diagram showing a quenching device used in a method for reducing the width of a heat-affected zone of a hypereutectoid rail flash weld joint according to an embodiment of the present invention, Figure 4 Show Figure 3 Another schematic diagram of the quenching device, Figure 3 Can be a cross-sectional view, Figure 4 It may be a top view of the first air supply unit 30 and the second air supply unit 40 . Figure 3 The steel rail 1 and the rail head 2 are shown in FIG. 1 . In addition to the rail head 2 , the steel rail 1 also includes a rail waist and a rail bottom.

[0054] Combination Figure 3 and Figure 4 The main unit 10 and the quenching unit 20 both include: a first air supply part 30, a second air supply part 40 and a third air supply part 50, the length direction of the first air supply part 30, the second air supply part 40 and the third air supply part 50 is the same as the moving direction of the rail, and the first air supply part 30, the second air supply part 40 and the third air supply part 50 are provided with a plurality of air outlet holes 60 arranged along their respective length directions; the first air supply part 30, the second air supply part 40 and the third air supply part 50 are respectively arranged on the outer side of the top surface of the rail head, the outer side of the rail head and the outer side of the lower jaw of the rail head.

[0055] In some embodiments, the lengths a3 of the first air supply part 30, the second air supply part 40 and the third air supply part 50 are all greater than or equal to 150 mm; and / or the first air supply part 30 is box-shaped, and the width a4 of the first air supply part 30 of the main unit 10 is greater than or equal to 70 mm, or the width a4 of the first air supply part 30 of the quenching unit 20 is greater than or equal to 75 mm; and / or the second air supply part 40 and the third air supply part 50 are tubular, and the inner diameters of the second air supply part 40 and the third air supply part 50 are 25 mm to 30 mm; and / or the diameter of the air outlet 60 is 1 mm to 3 mm, and the distance a5 between adjacent air outlets 60 is 5 mm to 15 mm. By designing these structural parameters of the main unit 10 and the quenching unit 20, a suitable cooling effect can be ensured.

[0056] Figure 5 A schematic diagram showing the visible heat-affected zone of a rail flash weld obtained by the method of the present invention is shown in FIG. Figure 5 As shown, by adopting the above method of the present invention, it is possible to achieve that the width of the macroscopically visible heat-affected zone of the high-strength pearlite rail joint for heavy-duty railway is in a relatively small range of 20 mm to 32 mm, the heat-affected zones on both sides of the fusion line are parallel to each other and symmetrical about the fusion line, and the difference between the maximum value and the minimum value is only 0.4 mm to 1.2 mm, which greatly meets the technical index requirements specified in the standard.

[0057] The following is an explanation based on specific embodiments and comparative examples.

[0058] Example 1

[0059] In the test rail material of this embodiment, the mass fraction of carbon is 0.93%, the mass fraction of silicon is 0.67%, the mass fraction of manganese is 1.23%, the tensile strength of the rail is 1280MPa-1400MPa, and the hardness of the rail head is 405HB-415HB. The displacement limit of the flash flat stage of fixed flash welding is 6.0mm, and the maximum flash speed is 5.0mm / s; the preheating pressure setting value of the preheating stage is 100.0kN, the separation distance is 3.2mm, the deformation limit is 0.6mm, and the number of preheating cycles is 7 times; the displacement limit of the accelerated burning stage is 15.0mm, and the maximum flash speed is 2.6mm / s; the upsetting time limit of the upsetting stage is 0.5s, and the upsetting current setting value is 32.0kA; the displacement limit of the forging stage is 10.0mm, the forging time limit is 2.5s, and the average forging speed is 2.0mm / s; the heating time of the post-heat holding stage is 0.3s, and the displacement limit is 38.0mm. After welding, the rail passes through a special quenching device along the longitudinal direction of the rail at a speed of 0.08m / s; the residual heat quenching device is tightly connected to the outlet end of the welding machine, and its total effective air jet length is 40m; the main unit of the quenching device runs from the side of the residual heat quenching device close to the welding machine to the far end, and after running to the end of the entire device, it returns to the starting end of the residual heat quenching device; during operation, the running direction and speed of the main unit of the quenching device are consistent with the rail. The length of the wind box and air duct of the main unit of the quenching device is 150mm, the width of the wind box on the top of the rail is 75mm, the internal diameter of the air duct is Φ30mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 20mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ3mm, and the distance between the air outlets is 5mm; the pressure value of the compressed air before entering the quenching device is 300kPa. After inspection, the maximum macroscopically visible heat-affected zone width of the rail joint in this embodiment is 22 mm, the heat-affected zones on both sides of the fusion line are parallel to each other and symmetrical about the fusion line, and the difference between the maximum and minimum values ​​is only 0.4 mm, and the technical indicators meet the standard requirements. The rest of the joint performance meets the standard technical requirements.

[0060] Example 2

[0061] In the test rail material of this embodiment, the mass fraction of carbon is 0.93%, the mass fraction of silicon is 0.67%, the mass fraction of manganese is 1.23%, the tensile strength of the rail is 1280MPa-1400MPa, and the hardness of the rail head is 405HB-415HB. The displacement limit of the flash flat stage of fixed flash welding is 6.0mm, and the maximum flash speed is 5.0mm / s; the preheating pressure setting value of the preheating stage is 100.0kN, the separation distance is 3.2mm, the deformation limit is 0.6mm, and the number of preheating cycles is 7 times; the displacement limit of the accelerated burning stage is 15.0mm, and the maximum flash speed is 2.6mm / s; the upsetting time limit of the upsetting stage is 0.5s, and the upsetting current setting value is 32.0kA; the displacement limit of the forging stage is 10.0mm, the forging time limit is 2.5s, and the average forging speed is 2.0mm / s; the heating time of the post-heat holding stage is 0.3s, and the displacement limit is 38.0mm. After welding, the rail passes through a special quenching device along the longitudinal direction of the rail at a speed of 1.0m / s; the residual heat quenching device is tightly connected to the outlet end of the welding machine, and its total effective air jet length is 10m; the main unit of the quenching device runs from the side of the residual heat quenching device close to the welding machine to the far end, and after running to the end of the entire device, it returns to the starting end of the residual heat quenching device; during operation, the running direction and speed of the main unit of the quenching device are consistent with the rail. The length of the wind box and air duct of the main unit of the quenching device is 150mm, the width of the wind box on the top of the rail is 70mm, the internal diameter of the air duct is Φ25mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 40mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ1mm, and the distance between the air outlets is 15mm; the pressure value of the compressed air before entering the quenching device is 100kPa. After inspection, the maximum macroscopically visible heat-affected zone width of the rail joint in this embodiment is 22 mm, the heat-affected zones on both sides of the fusion line are parallel to each other and symmetrical about the fusion line, and the difference between the maximum and minimum values ​​is only 0.8 mm, and the technical indicators meet the standard requirements. The rest of the joint performance meets the standard technical requirements.

[0062] Example 3

[0063] In the test rail material of this embodiment, the mass fraction of carbon is 1.17%, the mass fraction of silicon is less than 0.31%, the mass fraction of manganese is 0.62%, the tensile strength of the rail is 1420MPa-1480MPa, and the hardness of the rail head is 420HB-435HB. The displacement limit of the flash flat stage of fixed flash welding is 4.0mm, and the maximum flash speed is 2.0mm / s; the preheating pressure setting value of the preheating stage is 120.0kN, the separation distance is 2.0mm, the deformation limit is 1.0mm, and the number of preheating cycles is 10 times; the displacement limit of the accelerated burning stage is 7.0mm, and the maximum flash speed is 0.4mm / s; the upsetting time limit of the upsetting stage is 0.1s, and the upsetting current setting value is 30.0kA; the displacement limit of the forging stage is 5.0mm, the forging time limit is 1.0s, and the average forging speed is 0.50mm / s; the heating time of the post-heat holding stage is 1.0s, and the displacement limit is 30.0mm. After welding, the rail passes through a special quenching device along the longitudinal direction of the rail at a speed of 0.08m / s; the residual heat quenching device is tightly connected to the outlet end of the welding machine, and its total effective air jet length is 40m; the main unit of the quenching device runs from the side of the residual heat quenching device close to the welding machine to the far end, and after running to the end of the entire device, it returns to the starting end of the residual heat quenching device; during operation, the running direction and speed of the main unit of the quenching device are consistent with the rail. The length of the wind box and air duct of the main unit of the quenching device is 150mm, the width of the wind box on the top of the rail is 75mm, the internal diameter of the air duct is Φ30mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 20mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ3mm, and the distance between the air outlets is 5mm; the pressure value of the compressed air before entering the quenching device is 300kPa. After inspection, the maximum macroscopically visible heat-affected zone width of the rail joint in this embodiment is 32 mm, the heat-affected zones on both sides of the fusion line are parallel to each other and symmetrical about the fusion line, and the difference between the maximum and minimum values ​​is only 1.2 mm, and the technical indicators meet the standard requirements. The rest of the joint performance meets the standard technical requirements.

[0064] Example 4

[0065] In the test rail material of this embodiment, the mass fraction of carbon is 1.17%, the mass fraction of silicon is less than 0.31%, the mass fraction of manganese is 0.62%, the tensile strength of the rail is 1420MPa-1480MPa, and the hardness of the rail head is 420HB-435HB. The displacement limit of the flash flat stage of fixed flash welding is 4.0mm, and the maximum flash speed is 2.0mm / s; the preheating pressure setting value of the preheating stage is 120.0kN, the separation distance is 2.0mm, the deformation limit is 1.0mm, and the number of preheating cycles is 10 times; the displacement limit of the accelerated burning stage is 7.0mm, and the maximum flash speed is 0.4mm / s; the upsetting time limit of the upsetting stage is 0.1s, and the upsetting current setting value is 30.0kA; the displacement limit of the forging stage is 5.0mm, the forging time limit is 1.0s, and the average forging speed is 0.50mm / s; the heating time of the post-heat holding stage is 1.0s, and the displacement limit is 30.0mm. After welding, the rail passes through a special quenching device along the longitudinal direction of the rail at a speed of 1.0m / s; the residual heat quenching device is tightly connected to the outlet end of the welding machine, and its total effective air jet length is 10m; the main unit of the quenching device runs from the side of the residual heat quenching device close to the welding machine to the far end, and after running to the end of the entire device, it returns to the starting end of the residual heat quenching device; during operation, the running direction and speed of the main unit of the quenching device are consistent with the rail. The length of the wind box and air duct of the main unit of the quenching device is 150mm, the width of the wind box on the top of the rail is 70mm, the internal diameter of the air duct is Φ25mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 40mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ1mm, and the distance between the air outlets is 15mm; the pressure value of the compressed air before entering the quenching device is 100kPa. After inspection, the maximum macroscopically visible heat-affected zone width of the rail joint in this embodiment is 31 mm, the heat-affected zones on both sides of the fusion line are parallel to each other and symmetrical about the fusion line, and the difference between the maximum and minimum values ​​is only 1.0 mm, and the technical indicators meet the standard requirements. The rest of the joint performance meets the standard technical requirements.

[0066] Example 5

[0067] In the test rail material of this embodiment, the mass fraction of carbon is 0.93%, the mass fraction of silicon is 0.51%, the mass fraction of manganese is 0.96%, the tensile strength of the rail is 1380MPa-1420MPa, and the hardness of the rail head is 410HB-425HB. The displacement limit of the flash flat stage of fixed flash welding is 5.0mm, and the maximum flash speed is 3.0mm / s; the preheating pressure setting value of the preheating stage is 110.0kN, the separation distance is 2.5mm, the deformation limit is 0.8mm, and the number of preheating cycles is 8 times; the displacement limit of the accelerated burning stage is 10.0mm, and the maximum flash speed is 2.0mm / s; the upsetting time limit of the upsetting stage is 0.3s, and the upsetting current setting value is 31.0kA; the displacement limit of the forging stage is 8.0mm, the forging time limit is 2.0s, and the average forging speed is 1.5mm / s; the heating time of the post-heat holding stage is 0.8s, and the displacement limit is 35.0mm. After welding, the rail passes through a special quenching device along the longitudinal direction of the rail at a speed of 0.4m / s; the residual heat quenching device is tightly connected to the outlet end of the welding machine, and its total effective air jet length is 35m; the main unit of the quenching device runs from the side of the residual heat quenching device close to the welding machine to the far end, and after running to the end of the entire device, it returns to the starting end of the residual heat quenching device; during operation, the running direction and speed of the main unit of the quenching device are consistent with the rail. The length of the wind box and air duct of the main unit of the quenching device is 150mm, the width of the wind box on the top of the rail is 70mm, the internal diameter of the air duct is Φ30mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 35mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ2mm, and the distance between the air outlets is 12mm; the pressure value of the compressed air before entering the quenching device is 250kPa. After inspection, the maximum macroscopically visible heat-affected zone width of the rail joint in this embodiment is 30 mm, the heat-affected zones on both sides of the fusion line are parallel to each other and symmetrical about the fusion line, and the difference between the maximum and minimum values ​​is only 1.0 mm, and the technical indicators meet the standard requirements. The rest of the joint performance meets the standard technical requirements.

[0068] Example 6

[0069] The rail material composition and welding process of this embodiment are the same as those of embodiment 1. In this embodiment, after welding is completed, the rail passes through a special quenching device along the longitudinal direction of the rail at a certain running speed. Under the action of compressed air with a specific pressure, the rail welded joint with residual heat from welding is accelerated to cool. The running speed of the rail is 2.5m / s; the total effective quenching length of the residual heat quenching device is 40m; the length of the wind box and the air duct of the independent quenching unit of the residual heat quenching device is 150mm, the width of the wind box on the top of the rail is 75mm, the internal diameter of the air duct is Φ30mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 20mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ3mm, and the distance between the air outlets is 5mm; the pressure value of the compressed air before entering the quenching device is 300kPa. After inspection, the maximum visible heat-affected zone width of the rail joint in this embodiment is 20mm, the heat-affected zones on both sides of the fusion line are parallel to each other and symmetrical about the fusion line, and the difference between the maximum and minimum values ​​is only 0.4mm, and the technical indicators meet the standard requirements. The rest of the joint performance meets the standard technical requirements.

[0070] Example 7 (low heat input, low cooling rate)

[0071] The rail material composition and welding process of this embodiment are the same as those of Example 2. In this embodiment, after welding is completed, the rail passes through a special quenching device along the longitudinal direction of the rail at a certain running speed. Under the action of compressed air with a specific pressure, the rail welded joint with residual heat from welding is accelerated to cool. The running speed of the rail is 2.5m / s; the total effective quenching length of the residual heat quenching device is 40m; the length of the wind box and the air duct of the independent quenching unit of the residual heat quenching device is 150mm, the width of the wind box on the top of the rail is 75mm, the internal diameter of the air duct is Φ30mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 20mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ3mm, and the distance between the air outlets is 5mm; the pressure value of the compressed air before entering the quenching device is 300kPa. After inspection, the maximum visible heat-affected zone width of the rail joint in this embodiment is 22mm, the heat-affected zones on both sides of the fusion line are parallel to each other and symmetrical about the fusion line, and the difference between the maximum and minimum values ​​is only 0.8mm, and the technical indicators meet the standard requirements. The rest of the joint performance meets the standard technical requirements.

[0072] Example 8

[0073] The rail material composition and welding process of this embodiment are the same as those of embodiment 3. In this embodiment, after welding is completed, the rail passes through a special quenching device along the longitudinal direction of the rail at a certain running speed. Under the action of compressed air with a specific pressure, the rail welded joint with residual heat from welding is accelerated to cool. The running speed of the rail is 2.5m / s; the total effective quenching length of the residual heat quenching device is 40m; the length of the wind box and the air duct of the independent quenching unit of the residual heat quenching device is 150mm, the width of the wind box on the top of the rail is 75mm, the internal diameter of the air duct is Φ30mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 20mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ3mm, and the distance between the air outlets is 5mm; the pressure value of the compressed air before entering the quenching device is 300kPa. After inspection, the maximum visible heat-affected zone width of the rail joint in this embodiment is 32mm, the heat-affected zones on both sides of the fusion line are parallel to each other and symmetrical about the fusion line, and the difference between the maximum and minimum values ​​is only 1.2mm, and the technical indicators meet the standard requirements. The rest of the joint performance meets the standard technical requirements.

[0074] Example 9

[0075] The rail material composition and welding process of this embodiment are the same as those of embodiment 4. In this embodiment, after welding is completed, the rail passes through a special quenching device along the longitudinal direction of the rail at a certain running speed. Under the action of compressed air with a specific pressure, the rail welded joint with residual heat from welding is accelerated to cool. The running speed of the rail is 2.5m / s; the total effective quenching length of the residual heat quenching device is 40m; the length of the wind box and the air duct of the independent quenching unit of the residual heat quenching device is 150mm, the width of the wind box on the top of the rail is 75mm, the internal diameter of the air duct is Φ30mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 20mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ3mm, and the distance between the air outlets is 5mm; the pressure value of the compressed air before entering the quenching device is 300kPa. After inspection, the maximum visible heat-affected zone width of the rail joint in this embodiment is 31mm, the heat-affected zones on both sides of the fusion line are parallel to each other and symmetrical about the fusion line, and the difference between the maximum and minimum values ​​is only 1.0mm, and the technical indicators meet the standard requirements. The rest of the joint performance meets the standard technical requirements.

[0076] Example 10

[0077] The rail material composition and welding process of this embodiment are the same as those of embodiment 5. In this embodiment, after welding is completed, the rail passes through a special quenching device along the longitudinal direction of the rail at a certain running speed. Under the action of compressed air with a specific pressure, the rail welded joint with residual heat from welding is accelerated to cool. The running speed of the rail is 1.0m / s; the total effective quenching length of the residual heat quenching device is 35m; the length of the wind box and the air duct of the independent quenching unit of the residual heat quenching device is 150mm, the width of the wind box on the top of the rail is 75mm, the internal diameter of the air duct is Φ25mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 30mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ2mm, and the distance between the air outlets is 10mm; the pressure value of the compressed air before entering the quenching device is 200kPa. After inspection, the maximum visible heat-affected zone width of the rail joint in this embodiment is 30mm, the heat-affected zones on both sides of the fusion line are parallel to each other and symmetrical about the fusion line, and the difference between the maximum and minimum values ​​is only 1.0mm, and the technical indicators meet the standard requirements. The rest of the joint performance meets the standard technical requirements.

[0078] Comparative Example 1

[0079] In this comparative example, the mass fraction of carbon in the test rail material is 0.93%, the mass fraction of silicon is 0.51%, the mass fraction of manganese is 0.96%, the tensile strength of the rail is 1380MPa-1420MPa, and the hardness of the rail head is 410HB-425HB. The displacement limit of the flash flat stage of fixed flash welding is 3.0mm, and the maximum flash speed is 1.0mm / s; the preheating pressure setting value of the preheating stage is 200.0kN, the separation distance is 1.0mm, the deformation limit is 0.4mm, and the number of preheating cycles is 13 times; the displacement limit of the accelerated burning stage is 5.0mm, and the maximum flash speed is 0.3mm / s; the upsetting time limit of the upsetting stage is 0.1s, and the upsetting current setting value is 20.0kA; the displacement limit of the forging stage is 4.0mm, the forging time limit is 1.0s, and the average forging speed is 0.40mm / s; the heating time of the post-heat holding stage is 3.0s, and the displacement limit is 20.0mm. After welding, the rail passes through a special quenching device along the longitudinal direction of the rail at a speed of 0.4m / s; the residual heat quenching device is tightly connected to the outlet end of the welding machine, and its total effective air jet length is 35m; the main unit of the quenching device runs from the side of the residual heat quenching device close to the welding machine to the far end, and after running to the end of the entire device, it returns to the starting end of the residual heat quenching device; during operation, the running direction and speed of the main unit of the quenching device are consistent with the rail. The length of the wind box and air duct of the main unit of the quenching device is 150mm, the width of the wind box on the top of the rail is 70mm, the internal diameter of the air duct is Φ30mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 35mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ2mm, and the distance between the air outlets is 12mm; the pressure value of the compressed air before entering the quenching device is 250kPa. After inspection, the maximum macroscopic visible heat affected zone width of the rail joint in this embodiment is 55mm, and the heat affected zone on both sides of the fusion line has obvious bending, and the visible heat affected zone width on both sides of the fusion line is obviously asymmetric, and the difference between the maximum and minimum values ​​of the visible heat affected zone width of the full section is 10mm, which does not meet the technical index requirements specified in the standard. The main difference between this comparative example and Example 5 lies in the control of the welding process. In all stages of the flash blasting process in the welding process, the flash speed is slow, the displacement limit is small, the metal with high heat is consumed less, and the welding heat accumulates more; the greater the top pressure in the preheating stage, the smaller the separation distance, the more cycles, and the more welding heat accumulates; the smaller the pressure and the displacement limit value in the top forging and forging stages of the welding process, the less high-temperature metal is consumed, and the more heat is retained in the welding process. The accumulation of heat in each stage ultimately leads to the visible heat affected zone of the rail joint being too wide. That is, under the same conditions of the rail material and the post-weld quenching process, the use of this comparative method cannot achieve the expected effect.

[0080] Comparative Example 2

[0081] In this comparative example, the mass fraction of carbon in the test rail material is 0.93%, the mass fraction of silicon is 0.51%, the mass fraction of manganese is 0.96%, the tensile strength of the rail is 1380MPa-1420MPa, and the hardness of the rail head is 410HB-425HB. The displacement limit of the flash flat stage of fixed flash welding is 7.0mm, and the maximum flash speed is 6.0mm / s; the preheating pressure setting value of the preheating stage is 80.0kN, the separation distance is 3.5mm, the deformation limit is 1.2mm, and the number of preheating cycles is 5 times; the displacement limit of the accelerated burning stage is 16.0mm, and the maximum flash speed is 3.0mm / s; the upsetting time limit of the upsetting stage is 0.1s, and the upsetting current setting value is 20.0kA; the displacement limit of the forging stage is 12.0mm, the forging time limit is 3.0s, and the average forging speed is 2.5mm / s; the heating time of the post-heat holding stage is 0.2ss, and the displacement limit is 25.0mm. After welding, the rail passes through a special quenching device along the longitudinal direction of the rail at a running speed of 0.4m / s; the residual heat quenching device is tightly connected to the outlet end of the welding machine, and its total effective air jet length is 35m; the main unit of the quenching device runs from the side of the residual heat quenching device close to the welding machine to the far end, and after running to the end of the entire device, it returns to the starting end of the residual heat quenching device; during operation, the running direction and speed of the main unit of the quenching device are consistent with the rail. The length of the wind box and the air duct of the main unit of the quenching device is 150mm, the width of the wind box on the top of the rail is 70mm, the internal diameter of the air duct is Φ30mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 35mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ2mm, and the spacing between the air outlets is 12mm; the pressure value before the compressed air enters the quenching device is 250kPa. After inspection, the maximum macroscopic visible heat affected zone width of the rail joint in this embodiment is 18mm, which does not meet the technical index requirements specified in the standard. At the same time, the maximum load of the static bending test of the joint welded by this method only breaks when it is 900kN, and the static bending fracture is flush. The main difference between this comparative example and Example 5 lies in the control of the welding process. In all stages of the flash blasting process during the welding process, the flash speed is fast, the displacement limit is large, the metal with higher heat is consumed more, and the welding heat accumulation is small; the smaller the top pressure in the preheating stage, the larger the separation distance, the fewer the number of cycles, and the less welding heat accumulation; the greater the pressure and the displacement limit value in the top forging and forging stages of the welding process, the more high-temperature metal is consumed, and the less heat is retained in the welding process. The accumulation of heat in each stage ultimately leads to a narrower visible heat-affected zone of the rail joint. That is, under the condition that the rail material and the post-weld quenching process are the same, the use of this comparative example method cannot achieve the expected effect. At the same time, because the heat of the joint is too small, a cold joint has been formed, which eventually leads to a sharp decrease in the static bending performance of the joint.

[0082] Comparative Example 3

[0083] The rail material composition and welding process of this comparative example are the same as those of comparative example 1. In this comparative example, after welding is completed, the rail passes through a special quenching device along the longitudinal direction of the rail at a certain running speed. Under the action of compressed air with a specific pressure, the rail welded joint with residual heat from welding is accelerated to cool. The running speed of the rail is 1.0m / s; the total effective quenching length of the residual heat quenching device is 35m; the length of the wind box and the air duct of the independent quenching unit of the residual heat quenching device is 150mm, the width of the wind box on the top of the rail is 75mm, the internal diameter of the air duct is Φ25mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 30mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ2mm, and the distance between the air outlets is 10mm; the pressure value of the compressed air before entering the quenching device is 200kPa. After inspection, the maximum visible heat affected zone width of the rail joint in this embodiment is 55mm, and the heat affected zone on both sides of the fusion line is obviously bent, and the visible heat affected zone width on both sides of the fusion line is obviously asymmetric. The difference between the maximum and minimum widths of the visible heat affected zone of the full section is 10mm, which does not meet the technical index requirements specified in the standard. The main difference between this comparative example and Example 5 lies in the control of the welding process. In all stages of the flash blasting process in the welding process, the flash speed is slow, the displacement limit is small, the metal with high heat is consumed less, and the welding heat accumulates more; the greater the top pressure in the preheating stage, the smaller the separation distance, the more cycles, and the more welding heat accumulates; the smaller the pressure and the displacement limit value in the top forging and forging stages of the welding process, the less high-temperature metal is consumed, the more heat is retained in the welding process, and the accumulation of heat in each stage ultimately leads to a larger visible heat affected zone of the rail joint. That is, under the same rail material and post-weld quenching process, the use of this comparative method cannot achieve the expected effect.

[0084] Comparative Example 4

[0085] The rail material composition and welding process of this comparative example are the same as those of comparative example 2. In this comparative example, after welding is completed, the rail passes through a special quenching device along the longitudinal direction of the rail at a certain running speed. Under the action of compressed air with a specific pressure, the rail welded joint with residual heat from welding is accelerated to cool. The running speed of the rail is 1.0m / s; the total effective quenching length of the residual heat quenching device is 35m; the length of the wind box and the air duct of the independent quenching unit of the residual heat quenching device is 150mm, the width of the wind box on the top of the rail is 75mm, the internal diameter of the air duct is Φ25mm, the distance between the wind box and the air duct on the side adjacent to the rail surface is 30mm, and a number of air outlets are evenly distributed, the diameter of the air outlet is Φ2mm, and the spacing between the air outlets is 10mm; the pressure value before the compressed air enters the quenching device is 200kPa. After inspection, the maximum visible heat-affected zone width of the rail joint in this embodiment is 18mm, which does not meet the technical index requirements specified in the standard. At the same time, the maximum load of the static bending test of the joint welded by this method only breaks when it is 900kN, and the static bending fracture is flush. The main difference between this comparative example and Example 5 lies in the control of the welding process. In all stages of the flash blasting process during the welding process, the flash speed is fast, the displacement limit is large, the metal with higher heat is consumed more, and the welding heat accumulation is small; the smaller the top pressure in the preheating stage, the larger the separation distance, the fewer the number of cycles, and the less welding heat accumulation; the greater the pressure and the displacement limit value in the top forging and forging stages of the welding process, the more high-temperature metal is consumed, the less heat is retained in the welding process, and the accumulation of heat in each stage ultimately leads to a smaller visible heat-affected zone of the rail joint. That is, under the condition that the rail material and the post-weld quenching process are the same, the use of this comparative example method cannot achieve the expected effect. At the same time, because the heat of the joint is too small, a cold joint has been formed, which eventually leads to a sharp decrease in the static bending performance of the joint.

[0086] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for reducing the width of the heat affected zone of a hypereutectoid rail flash weld joint, characterized in that: include: Flash welding of rails; Using a quenching device to quench the joints of the welded rails; Among them, the flash welding process includes the following stages: flash flattening stage, preheating stage, accelerated burning stage, upsetting stage, forging stage and post-heat holding stage; In the flash flat stage, the displacement limit is 4.0 mm to 6.0 mm, and the maximum flash speed is 2.0 mm / s to 5.0 mm / s; In the upset forging stage, the upset forging time limit is 0.1s to 0.5s, and the upset forging current setting value is 30.0kA to 32.0kA; In the preheating stage, the preheating pressure setting value is 100.0 kN to 120.0 kN, the separation distance is 2.0 mm to 3.2 mm, the deformation limit is 0.6 mm to 1.0 mm, and the number of preheating cycles is 7 to 10 times; In the accelerated burning stage, the displacement limit is 7.0 mm to 15.0 mm, and the maximum flash speed is 0.4 mm / s to 2.6 mm / s; In the forging stage, the displacement limit is 5.0 mm to 10.0 mm, the forging time limit is 1.0 s to 2.5 s, and the average forging speed is 0.50 mm / s to 2.0 mm / s; In the post-heat holding stage, the heating time is 0.3s to 1.0s, and the displacement limit is 30.0mm to 38.0mm; The welded rail moves along the longitudinal direction of the rail on the production line. The quenching device includes a guide rail and a main unit that can move along the guide rail. The extension direction of the guide rail is the same as the moving direction of the rail. The quenching device is used to quench the joint of the welded rail, including: The main unit moves with the rails, and during the movement of the rails, gas is blown to the top surface, side surface and lower jaw of the rail head at the rail joint to cool them; or The welded rail moves along the longitudinal direction of the rail on the production line. The quenching device includes a plurality of quenching units arranged along the moving direction of the rail. The quenching of the joint of the welded rail by the quenching device includes: During the movement of the rail, the rail joint passes through a plurality of the quenching units in sequence, and the plurality of the quenching units blow gas to the top surface, the side surface and the lower jaw of the rail head at the rail joint to cool the rail; When the quenching device includes the guide rail and the main unit, the moving speed of the rail is 0.08m / s to 1.0m / s, and the total effective air jet length of the quenching device is 10m to 40m; When the quenching device includes a plurality of quenching units, the moving speed of the rail is 0.2 m / s to 2.5 m / s, and the total effective air jet length of the quenching device is 10 m to 40 m; The distance between the air outlet of the main unit or the quenching unit and the corresponding rail head top surface, rail head side surface or rail head lower jaw surface is 20 mm to 40 mm; The gas is compressed air, and the pressure of the compressed air before entering the quenching device is 100 kPa to 300 kPa.

2. The method according to claim 1, characterized in that The main unit and the quenching unit both include: a first air supply section, a second air supply section and a third air supply section, the length directions of the first air supply section, the second air supply section and the third air supply section are the same as the moving direction of the rail, and the first air supply section, the second air supply section and the third air supply section are provided with a plurality of air outlets arranged along their respective length directions; the first air supply section, the second air supply section and the third air supply section are respectively arranged on the outer side of the top surface of the rail head, the outer side of the rail head and the outer side of the lower jaw of the rail head.

3. The method according to claim 2, characterized in that The lengths of the first air supply part, the second air supply part and the third air supply part are all greater than or equal to 150 mm; and / or The first air supply part is box-shaped, and the width of the first air supply part of the main unit is greater than or equal to 70 mm, or the width of the first air supply part of the quenching unit is greater than or equal to 75 mm; and / or The second air supply part and the third air supply part are tubular, and the inner diameters of the second air supply part and the third air supply part are 25 mm to 30 mm; and / or The diameter of the air outlet holes is 1 mm to 3 mm, and the distance between adjacent air outlet holes is 5 mm to 15 mm.

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