CN116287656A - Heat treatment method for online heat treatment of aluminum thermal welding head of pearlitic steel rail and bainite steel rail - Google Patents
Heat treatment method for online heat treatment of aluminum thermal welding head of pearlitic steel rail and bainite steel rail Download PDFInfo
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- CN116287656A CN116287656A CN202310076012.1A CN202310076012A CN116287656A CN 116287656 A CN116287656 A CN 116287656A CN 202310076012 A CN202310076012 A CN 202310076012A CN 116287656 A CN116287656 A CN 116287656A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 115
- 239000010959 steel Substances 0.000 title claims abstract description 115
- 238000003466 welding Methods 0.000 title claims abstract description 93
- 238000010438 heat treatment Methods 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 35
- 229910001563 bainite Inorganic materials 0.000 title claims abstract description 22
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 17
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 17
- 239000003832 thermite Substances 0.000 claims abstract description 19
- 238000005096 rolling process Methods 0.000 claims abstract description 12
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 11
- 238000005498 polishing Methods 0.000 claims abstract description 7
- 238000001816 cooling Methods 0.000 claims description 35
- 238000004321 preservation Methods 0.000 claims description 13
- 238000005496 tempering Methods 0.000 claims description 13
- 238000010583 slow cooling Methods 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 230000008569 process Effects 0.000 abstract description 20
- 239000000463 material Substances 0.000 abstract description 11
- 206010016256 fatigue Diseases 0.000 description 11
- 229910045601 alloy Inorganic materials 0.000 description 8
- 239000000956 alloy Substances 0.000 description 8
- 229910052799 carbon Inorganic materials 0.000 description 6
- 230000002159 abnormal effect Effects 0.000 description 4
- 238000005299 abrasion Methods 0.000 description 4
- 230000009466 transformation Effects 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 1
- 208000013201 Stress fracture Diseases 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/50—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for welded joints
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/04—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rails
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
The invention discloses a heat treatment method for an online heat treatment pearlite steel rail and bainite steel rail aluminum heat welding head, which comprises the following steps: and respectively polishing and derusting the end faces of the U75VH pearlitic steel rail and the U20Mn bainitic steel rail with the same rolling section, wherein the rolling section of the steel rail is 60kg/m or 75kg/m, and performing joint heat treatment after thermite welding and hybrid welding of the two steel rails. The invention aims to provide an online heat treatment method for an aluminum heat welding joint of a pearlitic steel rail and a bainitic steel rail, which can ensure that the mechanical properties of the hybrid welding joint of a U75VH pearlitic steel rail and a U20Mn bainitic steel rail meet the standard and the line service requirement after the joint heat treatment process is used, and the obtained mechanical properties of the hybrid welding joint of the heterogeneous steel rail can be well matched with two different steel base materials, so that the service performance of the hybrid welding joint and the smoothness of a seamless line are effectively improved.
Description
Technical Field
The invention relates to the technical field of steel rail welding, in particular to a heat treatment method for an online heat treatment pearlitic steel rail and bainite steel rail aluminum heat welding head.
Background
Along with the progress of railway heavy load transportation technology, the heavy load transportation capability of the railway in China is continuously improved, the axle weight of heavy load trucks is gradually improved, and the heavy load railway has the characteristics of large axle weight, large transportation capacity, high departure density and the like, for example, the large Qin line traffic of the Taiyuan in 2021 reaches 5 hundred million tons/year. The rapid development of the steel rail for the heavy haul railway brings more severe requirements on the toughness, the wear resistance and the fatigue resistance of the steel rail material of a steel mill. The strength and toughness of the pearlitic steel rail commonly used at present are basically limited due to the characteristics of components and tissue structures, and the pearlitic steel rail is low in impact toughness and fracture toughness, so that the service requirements of heavy haul railways cannot be completely met. The bainite steel rail has good strength, plasticity, impact toughness, wear resistance and rolling contact fatigue resistance, and is very suitable for heavy haul railway application. However, compared with a pearlitic steel rail, the bainite steel rail has higher cost, restricts the wide application of the bainite steel rail, combines the characteristics of low cost of the pearlitic steel rail, realizes equal-service-life matching by matching with different steel rails at different positions, different curve radiuses and different service requirements of straight lines, curves and the like on a railway line, can lay wear-resistant steel rails on the curves, and lays common steel rails on the straight lines, so that reasonable steel rail matching can effectively improve the service performance and the application cost performance of the railway steel rail, and reduce the replacement and maintenance cost of the steel rail.
The welding of steel rails is a key and precondition for the wide-range application of a seamless line, the welding of steel rails with different types of steel belongs to the difficulty in the industry, and the welding among different materials is influenced by various aspects such as components, performances, organizations, standard requirements, service requirements and the like. The U20Mn bainite steel rail belongs to a low-carbon and high-alloy component system, the U75VH steel rail belongs to a high-carbon and low-alloy component system, the alloy content of the bainite steel rail is obviously higher than that of a pearlite steel rail, and the carbon content of the pearlite steel rail is obviously higher than that of the bainite steel rail. The bainite steel rail has high alloy content, and alloy components along austenite grain boundaries are segregated in a welding overheat zone, so that a microstructure is uneven, and liquefaction cracks can be generated. And the bainite steel rail flash welding head has high welding residual stress, uneven distribution and easy surface crack generation when the welding line is in service. The pearlitic steel rail has the defects of gray specks, microcracks and the like easily generated by joints due to higher carbon equivalent and poorer welding performance, and the joints have poorer toughness, strength and hardness which reach the limit and have higher breaking rate in the service process of the joints.
Thermite welding has the characteristics of simple equipment, low cost, short flow, high efficiency, stable quality and the like, is suitable for on-site flowing operation, broken rail online repair and turnout welding, has been widely applied to seamless rail welding, but the thermite welding is the weakest welding method in all rail welding methods, has the worst joint performance and service performance, has more difficult thermite welding and joint heat treatment processes of heterogeneous rails, and has very difficult control of joint mechanical properties and metallographic structures. The heat treatment process and the heat treatment mode of the welding line are main reasons for influencing the quality of the flash welding joint, and the different heating temperature and cooling modes of the welding line directly influence the performance indexes such as strength, hardness, toughness and the like of the joint and can also lead to uneven abrasion or abnormal structure of the joint. Each performance of the heterogeneous steel rail aluminothermic welding joint needs to be matched with two base materials, and meets the requirements of section 3 of TB/T1632.3-2019 steel rail welding: thermite welding.
Publication number CN105364299a provides a welding material and welding process for thermite welding of bainitic steel, which mainly provides a composition range and an alloy system of the thermite welding material, and discloses for the heat treatment process part: the weld head is again heated to 900-1000 ℃ and then cooled to room temperature at a rate of less than 5 ℃. The process has the advantages that the cooling speed of the joint is not controlled after normalizing, tempering treatment is not adopted, the hardness of the joint is 344HB, the indexes of joint strength, toughness and fatigue performance are not mentioned, and the welding of steel rails made of the same material is different from the core invention content of the patent.
The publication No. CN112662861A provides a post-thermite welding heat treatment process for bainitic steel rails, after normalizing the joints at 950-1000 ℃, the joints are subjected to heat preservation and slow cooling treatment at a cooling speed of 0.2-0.4 ℃/s, and further the joints are subjected to tempering treatment at 350 ℃, the tensile strength of the joints obtained by combining the processes is 941MPa, the tread hardness is 339HBW, the joint toughness and fatigue performance indexes are not mentioned, and the patent is the welding of the steel rails made of the same material. The invention provides a joint toughness index, the extension of the joint can reach more than 6.5%, and the core invention content of the patent is a heat treatment process of a heterogeneous steel rail aluminum-thermal-mixed welding joint, which is relatively higher than the welding difficulty of steel rails made of the same material.
Disclosure of Invention
The invention aims to provide an online heat treatment method for an aluminum heat welding joint of a pearlitic steel rail and a bainitic steel rail, which can ensure that the mechanical properties of the hybrid welding joint of a U75VH pearlitic steel rail and a U20Mn bainitic steel rail meet the standard and the line service requirement after the joint heat treatment process is used, and the obtained mechanical properties of the hybrid welding joint of the heterogeneous steel rail can be well matched with two different steel base materials, so that the service performance of the hybrid welding joint and the smoothness of a seamless line are effectively improved.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention discloses a heat treatment method for an online heat treatment pearlitic steel rail and bainite steel rail aluminum heat welding head, which comprises the following steps: polishing and derusting the end faces of a U75VH pearlitic steel rail and a U20Mn bainitic steel rail with the same rolling section respectively, wherein the rolling section of the steel rail is 60kg/m or 75kg/m, and performing joint heat treatment according to the following steps after thermite welding and hybrid welding of the two steel rails:
1) Air cooling the heterogeneous aluminum thermal mixed welding head in a high-temperature welding state to below 200 ℃, ensuring that each position of the joint is completely phase-changed, properly carrying out accelerated cooling when the temperature of the joint is less than or equal to 250 ℃, and polishing all welding ribs of the joint to be flat;
2) Normalizing the heterogeneous steel rail aluminum thermal mixed welding head by using a heating device, controlling the normalizing temperature to be between 900 and 950 ℃, keeping the temperature at the rail bottom angle to be not lower than 900 ℃, and keeping the temperature at 3 to 5min to enable the temperature within the range of 30mm below the tread of the mixed welding head to be heated to the target temperature;
3) Cooling the high-temperature hybrid joint to 370-430 ℃ at a cooling rate of 2.0-5.0 ℃/s;
4) After the hybrid joint is cooled to 370-430 ℃, the whole section of the joint is slowly cooled by using a heat preservation device, the slow cooling speed of the joint is less than or equal to 0.2 ℃/s, and the joint can be finely adjusted according to the practical production condition;
5) When the temperature of the mixed welding head is below 200 ℃, naturally cooling to room temperature;
6) Tempering the heterogeneous steel rail aluminum-thermal mixed welding head by using a heating device, wherein the tempering temperature is controlled to be 300-400 ℃, and the heat preservation is carried out for 3-5min, so that the temperature of the joint steel rail tread within the range of 30mm can be heated to the target temperature;
7) After tempering, heating and heat preservation of the hybrid joint, slowly cooling the whole section of the joint by using a heat preservation device, controlling the cooling speed of the joint to be less than or equal to 0.2 ℃/s, and carrying out fine adjustment according to the practical conditions of production;
8) And when the temperature of the mixed welding head is below 200 ℃ after slow cooling treatment, naturally cooling to room temperature.
Further, the measuring point of the normalizing temperature is on the top surface of the steel rail.
Further, the measuring point of the rail bottom angle heating temperature is positioned on the upper surface of the rail bottom of the welding rib at the position 0-10mm away from the outer edge of the rail bottom angle.
Further, the cooling control method in 3) uses air-jet cooling treatment.
Compared with the prior art, the invention has the beneficial technical effects that:
the invention combines the transformation characteristics of pearlite steel rail and bainite steel rail structures, and aims at the process invention which is carried out by combining each key temperature point in the CCT curves of the two steel rails, and the pearlite structure is obtained on the pearlite side and the bainite structure is obtained on the bainite side of the heat affected zone of the thermit welding head by controlling the transformation temperature and the transformation time of the pearlite and the bainite structure. And normalizing and cooling control are combined for the mixed welding joint, so that the joint structure and grain size are refined, and the segregation of the banded structure is improved, thereby improving the joint strength and toughness. The tempering and the controlled cooling of the joint are added, the joint structure can be stabilized, the joint residual stress is reduced, the joint banded structure segregation is improved, and the joint strength and toughness are further improved, so that the hybrid joint has higher strength, hardness and toughness, the saddle-shaped abrasion and early fatigue fracture of the steel rail welding joint caused by overlarge hardness difference of a welding area or abnormal microstructure of the joint in the service process of the heterogeneous thermite welding joint are improved, and the running safety of a railway is ensured.
Based on the present disclosure, a heterogeneous thermite welded joint: tensile strength R of joint m More than or equal to 919MPa, joint elongation A more than or equal to 6.5%, weld hardness more than or equal to 341HBW, and joint physical fatigue 2×10 6 The mechanical property of the welded joint can be well matched with two different steel base materials without breaking for ten thousands times, thereby effectively improving the service stability and safety of heterogeneous steel rail aluminum-thermal welded joint lines.
Detailed Description
The thermite welded pearlitic steel rail provided by the embodiment of the invention takes C, mn, si, V as a main alloy element, and comprises the following chemical components in percentage by weight: 0.75-0.79%, si:0.60-0.70%, mn:0.85-1.05%, V:0.05-0.12%, P is less than or equal to 0.030%, S is less than or equal to 0.025%, al: less than or equal to 0.010 percent, and the balance of Fe and unavoidable impurities; the bainite steel rail takes C, mn, si, cr, ni, mo as a main alloy element, and the weight percentage of the chemical components of the steel rail is C:0.15-0.35%, si:0.60-1.50%, mn:1.50-3.0%, cr:0.45-1.30%, N i:0.20-0.80%, mo 0.20-0.60%, P less than or equal to 0.022%, S less than or equal to 0.015%, al: less than or equal to 0.010 percent, and the balance of Fe and unavoidable impurities. The two steel rails are produced by smelting, continuous casting, slow cooling of steel billets, rolling, heat treatment and the like; the rolling compression ratio of the steel rail is not less than 9:1, the final rolling temperature is not higher than 950 ℃, so that the grain size of the prior austenite of the steel rail is ensured.
An online heat treatment method for an aluminum heat welding head for heat-treating a pearlitic steel rail and a bainitic steel rail comprises the following steps:
polishing and derusting the end faces of a U75VH pearlitic steel rail and a U20Mn bainitic steel rail with the same rolling section respectively, wherein the rolling section of the steel rail can be 60kg/m or 75kg/m, and performing joint heat treatment after thermite welding and hybrid welding of the two steel rails according to the following steps:
1) Air cooling the heterogeneous aluminum thermal mixed welding head in a high-temperature welding state to below 200 ℃, ensuring that each position of the joint is completely phase-changed, properly carrying out accelerated cooling when the temperature of the joint is less than or equal to 250 ℃, and polishing all welding ribs of the joint to be flat;
2) Normalizing the heterogeneous steel rail aluminum thermal mixed welding head by using a heating device, controlling the normalizing temperature to be 900-950 ℃ (the measuring point is on the top surface of the steel rail), heating the rail bottom angle to be not lower than 900 ℃ (the measuring point is on the upper surface of the rail bottom of the welding rib at the position 0-10mm away from the outer edge of the rail bottom angle), and preserving the heat for 3-5min to enable the temperature of the mixed welding head tread to be heated to the target temperature within the range of 30 mm;
3) Cooling the high-temperature hybrid joint to 370-430 ℃ at a cooling speed of 2.0-5.0 ℃/s, wherein the cooling mode can be controlled by using air-jet cooling;
4) After the hybrid joint is cooled to 370-430 ℃, the whole section of the joint is slowly cooled by using a heat preservation device, the slow cooling speed of the joint is less than or equal to 0.2 ℃/s, and the joint can be finely adjusted according to the practical production condition;
5) When the temperature of the mixed welding head is below 200 ℃, naturally cooling to room temperature;
6) Tempering the heterogeneous steel rail aluminum-thermal mixed welding head by using a heating device, wherein the tempering temperature is controlled to be 300-400 ℃, and the heat preservation is carried out for 3-5min, so that the temperature of the joint steel rail tread within the range of 30mm can be heated to the target temperature;
7) After tempering, heating and heat preservation of the hybrid joint, slowly cooling the whole section of the joint by using a heat preservation device, controlling the cooling speed of the joint to be less than or equal to 0.2 ℃/s, and carrying out fine adjustment according to the practical conditions of production;
8) And when the temperature of the mixed welding head is below 200 ℃ after slow cooling treatment, naturally cooling to room temperature.
Process comparison during the examples:
table 1 comparison of different heat treatment processes during the examples
Example 1-example 4 are respectively production process improvements performed during the development process of thermite welding process of pearlite steel rail and bainite steel rail, and the mechanical properties of the welded joint are compared according to the heat treatment process of examples at different stages.
Comparative analysis of joint mechanical properties was performed for examples 1-4, see section 3 of TB/T1632.3-2019 rail weld: thermite welding, and performing tensile strength, hardness and physical fatigue comparison analysis on the joint. The overall performance results are shown in table 2.
TABLE 2 comparison of joint Performance at different tempering temperatures
As can be seen from Table 2, the joint strength of example 1 meets the standard requirements, but the weld hardness does not meet the standard requirements, and the joint hardness is too low, so that the "saddle type" abrasion occurs in the joint, the irregularity of the seamless line is affected, and the physical fatigue of the joint is 1.3X10 6 Breaking occurs for ten thousands times, and the service and standard requirements of the circuit are not met.
In the embodiment 2, the joint strength and fatigue meet the standard requirements, but the weld hardness does not meet the standard requirements, so that the joint is worn in a saddle shape due to the fact that the joint is too low in hardness, and the irregularity of a seamless line is affected.
Example 3 joint Strength and hardness meet the Standard requirements but the joint physical fatigue is 1.6X10 6 Breaking occurs for ten thousands times, and the requirements of the safety service and standard of the circuit are not met. And the joint elongation is lower, so that the risk of joint rail breakage in the line service process is increased.
Example 4 Joint tensile Strength Rm is greater than or equal to 919MPa, joint elongation A is greater than or equal to 6.5%, weld hardness is greater than or equal to 341HBW, and joint physical fatigue is 2×10 6 The mechanical properties of the hybrid welding head meet the standard requirements without breaking for ten thousands of times. The mechanical properties of the welded joint obtained in the embodiment 4 can be well matched with two different steel parent metals, so that the service stability and safety of the heterogeneous steel rail thermite welded joint can be effectively improved, the abnormal abrasion drop-off and early fatigue damage condition of the steel rail welded joint caused by overlarge hardness difference of a welding area or abnormal microstructure of the joint in the service process of a heterogeneous thermite welded joint line can be effectively improved, and the running safety of a railway can be ensured.
The above embodiments are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention without departing from the design spirit of the present invention.
Claims (4)
1. An online heat treatment method for an aluminum heat welding joint of a pearlitic steel rail and a bainitic steel rail is characterized by comprising the following steps of: comprising the following steps: polishing and derusting the end faces of a U75VH pearlitic steel rail and a U20Mn bainitic steel rail with the same rolling section respectively, wherein the rolling section of the steel rail is 60kg/m or 75kg/m, and performing joint heat treatment according to the following steps after thermite welding and hybrid welding of the two steel rails:
1) Air cooling the heterogeneous aluminum thermal mixed welding head in a high-temperature welding state to below 200 ℃, ensuring that each position of the joint is completely phase-changed, properly carrying out accelerated cooling when the temperature of the joint is less than or equal to 250 ℃, and polishing all welding ribs of the joint to be flat;
2) Normalizing the heterogeneous steel rail thermite welding head by using a heating device, wherein the normalizing temperature is controlled to be 900-950 ℃, the heating temperature of the rail bottom angle is not lower than 900 ℃, and the temperature is kept for 3-5min, so that the temperature of the welding head tread within the range of 30mm can be heated to the target temperature;
3) Cooling the high-temperature hybrid joint to 370-430 ℃ at a cooling rate of 2.0-5.0 ℃/s;
4) After the hybrid joint is cooled to 370-430 ℃, the whole section of the joint is slowly cooled by using a heat preservation device, the slow cooling speed of the joint is less than or equal to 0.2 ℃/s, and the joint can be finely adjusted according to the practical production condition;
5) When the temperature of the mixed welding head is below 200 ℃, naturally cooling to room temperature;
6) Tempering the heterogeneous steel rail aluminum-thermal mixed welding head by using a heating device, wherein the tempering temperature is controlled to be 300-400 ℃, and the heat preservation is carried out for 3-5min, so that the temperature of the joint steel rail tread within the range of 30mm can be heated to the target temperature;
7) After tempering, heating and heat preservation of the hybrid joint, slowly cooling the whole section of the joint by using a heat preservation device, controlling the cooling speed of the joint to be less than or equal to 0.2 ℃/s, and carrying out fine adjustment according to the practical conditions of production;
8) And when the temperature of the mixed welding head is below 200 ℃ after slow cooling treatment, naturally cooling to room temperature.
2. The on-line heat treatment method for the aluminum heat welding head of the pearlite steel rail and the bainite steel rail according to claim 1, characterized in that: the measuring point of the normalizing temperature is on the top surface of the steel rail.
3. The on-line heat treatment method for the aluminum heat welding head of the pearlite steel rail and the bainite steel rail according to claim 1, characterized in that: the measuring point of the rail bottom angle heating temperature is arranged on the upper surface of the rail bottom of the welding rib at a position 0-10mm away from the outer edge of the rail bottom angle.
4. The on-line heat treatment method for the aluminum heat welding head of the pearlite steel rail and the bainite steel rail according to claim 1, characterized in that: the control cooling mode in the 3) uses air-jet cooling treatment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310076012.1A CN116287656A (en) | 2023-02-07 | 2023-02-07 | Heat treatment method for online heat treatment of aluminum thermal welding head of pearlitic steel rail and bainite steel rail |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310076012.1A CN116287656A (en) | 2023-02-07 | 2023-02-07 | Heat treatment method for online heat treatment of aluminum thermal welding head of pearlitic steel rail and bainite steel rail |
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| CN116287656A true CN116287656A (en) | 2023-06-23 |
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| CN202310076012.1A Pending CN116287656A (en) | 2023-02-07 | 2023-02-07 | Heat treatment method for online heat treatment of aluminum thermal welding head of pearlitic steel rail and bainite steel rail |
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- 2023-02-07 CN CN202310076012.1A patent/CN116287656A/en active Pending
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