CN116833539A - Mobile gas pressure welding and joint heat treatment process for Nb and RE containing pearlitic steel rail - Google Patents
Mobile gas pressure welding and joint heat treatment process for Nb and RE containing pearlitic steel rail Download PDFInfo
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- CN116833539A CN116833539A CN202310726732.8A CN202310726732A CN116833539A CN 116833539 A CN116833539 A CN 116833539A CN 202310726732 A CN202310726732 A CN 202310726732A CN 116833539 A CN116833539 A CN 116833539A
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- 238000003466 welding Methods 0.000 title claims abstract description 79
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 58
- 239000010959 steel Substances 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 53
- 230000008569 process Effects 0.000 title claims abstract description 51
- 238000010438 heat treatment Methods 0.000 title claims abstract description 28
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 14
- 229910052799 carbon Inorganic materials 0.000 claims description 9
- 229910045601 alloy Inorganic materials 0.000 claims description 6
- 239000000956 alloy Substances 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 238000005498 polishing Methods 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 4
- 239000002932 luster Substances 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 2
- 229910000734 martensite Inorganic materials 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 230000002159 abnormal effect Effects 0.000 description 4
- 229910001563 bainite Inorganic materials 0.000 description 4
- 239000010953 base metal Substances 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 238000005299 abrasion Methods 0.000 description 3
- 239000011651 chromium Substances 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 208000010392 Bone Fractures Diseases 0.000 description 2
- 206010017076 Fracture Diseases 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 239000011572 manganese Substances 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- QFGIVKNKFPCKAW-UHFFFAOYSA-N [Mn].[C] Chemical compound [Mn].[C] QFGIVKNKFPCKAW-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229940037003 alum Drugs 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 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
- 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
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
- B23K20/02—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating by means of a press ; Diffusion bonding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
- B23K20/26—Auxiliary equipment
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
-
- 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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Butt Welding And Welding Of Specific Article (AREA)
- Heat Treatment Of Articles (AREA)
- Pressure Welding/Diffusion-Bonding (AREA)
Abstract
The invention discloses a movable gas pressure welding and joint heat treatment process of a pearlite steel rail containing Nb and RE, which comprises the following steps: adopting a GPW1200 type movable air pressure welder to weld steel rails; 3) The mobile air pressure welding process comprises the following steps: the joint quantity of the steel rail welding seam is controlled between 10 and 12mm, the arching quantity is controlled between 0.35 and 0.55mm, the welding preheating time is controlled between 11 and 13 times, the preheating current is controlled between 410 and 600A, the welding upsetting quantity is controlled between 11.7mm, and the advancing speed is controlled between 0.3 and 2.5 mm/s; the initial temperature of the rail joint is 400-500 ℃ and the final temperature is 850-900 ℃. The invention solves the problems of low hardness, inadequacy of drop hammer performance and low collapse of the joint of the high-strength and high-hardness steel rail joint, and improves the comprehensive mechanical property and contact fatigue property of the joint, thereby effectively improving the service performance of the joint.
Description
Technical Field
The invention relates to the technical field of steel rail welding, in particular to a movable gas pressure welding and joint heat treatment process for a pearlite steel rail containing Nb and RE.
Background
Mobile gas pressure welding is widely used in line welding as one of important connection modes of rail lines. The welding performance of the steel is mainly affected by the chemical components of the steel, the research and development of the pearlitic steel rail in China all belong to the category of high carbon, low silicon and medium manganese, and alloy strengthening elements such as chromium, alum and the like are added according to different strength and hardness requirements. Because the high-strength and high-hardness pearlite steel rail for the heavy haul railway has high carbon content, the welding performance is poor, and the welding performance is mainly expressed as follows: (1) the defects of the welding overheat area are more, and the overheat area of the movable pneumatic welding has carbon-manganese component segregation along the austenite grain boundary, so that the joint has abnormal microstructures such as bainite or martensite in a supercooled state, and the brittleness of the joint is increased. (2) Because of the burning loss of carbon and alloy in the welding process, the mechanical property of the joint is obviously reduced, particularly the hardness of the joint is obviously reduced, the joint is poorer in performance matching with a base metal, the characteristics of high strength and high hardness of the steel rail for a heavy-duty line cannot be reflected, saddle-shaped abrasion and joint stripping and blocking phenomena can occur in the line service process, and the smoothness of a seamless line is seriously influenced.
The steel rail moving gas pressure welding process and the joint heat treatment process directly influence the joint organization performance and the service state. The defects of over-burning, unwelded joint, excessive gray spots, liquefied cracks and the like of the joint can be caused by improper welding process, the metallographic grain size of the joint is coarser and only about 1-2 grades in the welding state, and the joint performance is poor. The weld joint is subjected to normalizing heat treatment, the microstructure of the weld joint is obviously refined, the grain size is increased from level 1 to more than level 8, the toughness of the movable pneumatic welding joint is well improved, but the weld joint heat treatment process is improper, such as the characteristics of high and low heating temperature, high and low heating speed, nonuniform temperature residence time, nonuniform temperature distribution, continuous cooling under air cooling conditions and the like, the joint, especially a heat affected zone, is easy to have coarse structure, even easy to form martensite and other harmful structures, the joint is easy to have hardening, embrittlement and other phenomena, and the joint is extremely easy to break under the action of wheel rail stress in the line service process, thus becoming a weak link of line operation.
Aiming at the high-strength and high-hardness pearlite rail moving air pressure welding and joint heat treatment process containing Nb, cr and RE for heavy haul railways, the invention can ensure that the joints are all normal pearlite structures and have no abnormal structures such as bainite, martensite and the like. Solves the problems of low hardness, poor drop hammer performance and low collapse of the joint of the high-strength high-hardness pearlitic steel rail joint containing Nb, cr and RE, and obtains an excellent joint matched with the base material performance, so that the joint performance meets the following requirements of welding part 4 of TB/T1632.2-2014 steel rail: and the pneumatic welding is required for checking the mechanical property and drop weight of the joint.
Disclosure of Invention
The invention aims to provide a movable air pressure welding and joint heat treatment process for a pearlite steel rail containing Nb, RE, which can ensure that the pearlite steel rail joint containing Nb, cr and RE is of a normal pearlite structure without abnormal structures such as bainite, martensite and the like after the movable air pressure welding head process and the joint heat treatment process are used; the invention solves the problems of low hardness, inadequacy of drop hammer performance and low collapse of the joint of the high-strength and high-hardness steel rail joint, can effectively improve the performance matching of the steel rail joint and the base metal, and improves the comprehensive mechanical property and contact fatigue property of the joint, thereby effectively improving the service performance of the joint.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention relates to a movable air pressure welding and joint heat treatment process of an Nb and RE containing pearlitic steel rail, which comprises the following steps:
1) Polishing and derusting end surfaces of two steel rails with the same section of 60kg/m and the same material, and derusting and polishing clamping ends of electrodes;
2) Adopting a GPW1200 type movable air pressure welder to weld steel rails;
3) The mobile air pressure welding process comprises the following steps: the joint quantity of the steel rail welding seam is controlled between 10 and 12mm, the arching quantity is controlled between 0.35 and 0.55mm, the welding preheating time is controlled between 11 and 13 times, the preheating current is controlled between 410 and 600A, the welding upsetting quantity is controlled between 11.5 and 11.9mm, preferably 11.7mm, and the advancing speed is controlled between 0.3 and 2.5 mm/s;
4) And (3) a joint normalizing process: the initial temperature of the rail joint is 400-500 ℃ and the final temperature is 850-900 ℃.
2. The Nb, RE-containing pearlitic rail mobile gas pressure welding and joint heat treatment process according to claim 1, wherein: before welding, the end of the steel rail is treated, the perpendicularity of the air pressure welding end face is within 0.6mm, and the steel rail is polished to metallic luster.
Further, the pressure welding process increases the air spraying process to improve the hardness of the joint.
Further, the same heater is used for heating and normalizing.
Further, the welded pearlitic steel rail containing Cr, nb and RE takes C, S i and Mn, cr, nb, RE as main alloy elements, and the weight percentage of the chemical components is C: 0.73-0.83%, S i:0.50 to 0.80 percent, mn:0.80 to 1.10 percent, cr:0.30 to 0.60 percent, nb:0.01 to 0.05 percent, RE:0.0005 to 0.0020 percent, P is less than or equal to 0.010 percent, S is less than or equal to 0.005 percent, al: less than or equal to 0.004 percent, and the balance of Fe and unavoidable impurities.
Compared with the prior art, the invention has the beneficial technical effects that:
the tensile strength Rm of the joint is more than or equal to 1044MPa, the extension A of the joint is more than or equal to 9.4%, the fatigue load cycle of the joint is 2 multiplied by 106 times, HJ/HP is more than or equal to 0.9, HJ1/HP is more than or equal to 0.8, the softening area W is less than or equal to 20mm, 15 joints are not broken, the welding seam and the heat affected zone are typical pearlite structures, no martensite or bainite harmful structures exist, and all performances meet the standard requirements.
The invention can effectively improve various mechanical properties of the movable pneumatic welding joint of the pearlite steel rail containing Nb, cr and RE, and improve the strength, hardness and toughness of the joint so as to match the properties of the base metal. The welded joint can meet the requirement of the joint drop hammer 15, improve the risk of fracture caused by saddle abrasion or joint micro abnormal structure due to overlarge hardness difference of a welding area in the service process of the steel rail, fully exert the characteristics of high strength, high hardness and high toughness of the pearlite steel rail containing Nb, cr and RE and the joint, and ensure that the steel rail and the joint meet the service requirement of a heavy-duty railway and the running safety of the line.
Drawings
The invention is further described with reference to the following description of the drawings.
Fig. 1 is a graph of CCT for a Nb-containing RE pearlitic rail.
Detailed Description
A movable gas pressure welding and joint heat treatment process for a pearlite steel rail containing Nb and RE comprises the following steps:
1) The welded pearlitic steel rail containing Cr, nb and RE takes C, S i and Mn, cr, nb, RE as main alloy elements, and the weight percentage of the chemical components of the steel rail is C: 0.73-0.83%, S i:0.50 to 0.80 percent, mn:0.80 to 1.10 percent, cr:0.30 to 0.60 percent, nb:0.01 to 0.05 percent, RE:0.0005 to 0.0020 percent, P is less than or equal to 0.010 percent, S is less than or equal to 0.005 percent, A l: less than or equal to 0.004 percent.
2) The components are subjected to steel rail production by smelting, continuous casting, slow cooling of steel billets, rolling, heat treatment and the like, wherein the rolling compression ratio of the steel rail is more than or equal to 11, the final rolling temperature is less than or equal to 950 ℃, and the final cooling temperature is less than or equal to 510 ℃, so that the grain size, the tensile strength and the hardness of the steel rail are ensured.
3) And (5) adopting a GPW1200 type mobile pneumatic welding machine to weld the steel rails.
The end parts of the steel rail are required to be treated before welding by the two welding methods, particularly the perpendicularity of the end surfaces of the steel rail to be welded by flash welding is required to be within 0.2mm, the steel rail is required to be cleaned by carbon tetrachloride solution, the treatment process is more strict, the perpendicularity of the end surfaces of the air pressure welding is required to be within 0.6mm, and the steel rail is required to be polished to the metallic luster; the flash welding heating area is narrow and steep, and the air pressure welding heating area is wide and slow, so the air pressure welding technology increases the air spraying process to improve the hardness of the joint; the automatic normalizing cannot be realized at present by the field flash welding, and the pneumatic welding can be heated and normalized by the same pair of heaters.
4) The mobile air pressure welding process comprises the following steps: the joint quantity of the steel rail welding seam is controlled between 10 and 12mm, the arching quantity is controlled between 0.35 and 0.55mm, the welding preheating times are controlled between 11 and 13 times, the preheating current is controlled between 410 and 600A, the welding upsetting quantity is controlled to be about 11.7mm, and the advancing speed is controlled to be between 0.3 and 2.5 mm/s. The welding process has the advantages of good flatness of the joint, and no welding defects such as overburning, unwelding, excessive gray spots, liquefied cracks and the like.
5) And (3) a joint normalizing process: the initial temperature of the rail joint is 400-500 ℃ and the final temperature is 850-900 ℃.
The implementation process comprises the following steps:
the content of carbon and alloy in the pearlite steel rail containing Nb, cr and RE is higher, and element segregation such as C, mn and microstructure defects are easy to generate in a superheating area in the air pressure welding process, therefore, in the welding process parameter adjustment link, key parameters such as preheating times, top end quantity, tail burning rate and the like are adjusted, and the comparison analysis of joint mechanical properties, drop hammer results and the like are combined, so that the steel rail moving air pressure welding process is determined, and the main adjustment parameters of the welding process, the corresponding joint hardness and drop hammer test results in the implementation process are shown in Table 1.
Table 1 results of welding Process and performance comparisons during the implementation
According to the rail moving air pressure welding process, the drop hammers are not broken, and the hardness of the joint meets the requirements.
The metallographic grain size of the Nb-RE-containing pearlitic steel rail joint in the welded state is coarser and is only about 1-2 grade, the mechanical properties of the joint are poor, and the weld joint is subjected to normalizing heat treatment, so that the microstructure of the weld joint can be thinned, and the comprehensive mechanical properties of the movable pneumatic welding joint can be effectively improved. The steel rail CCT curve is an important basis for making a steel heat treatment process, and the steel rail CCT curve shows that the austenitizing can be achieved by the heating temperature of the steel rail joint reaching 679 ℃, as shown in fig. 1. The normalizing process in the implementation process is shown in table 2.
The normalized air pressure welded joint of the embodiment is welded according to the section 4 of TB/T1632.2-2014 rail: air pressure welding, and the Rockwell hardness of the longitudinal section of the rail head is analyzed, and the results are shown in Table 3.
TABLE 2 results of the test on the vertical section (test line 1) of the connector of the example
According to section 1 of TB/T1632.2-2014 rail welding: general technical conditions sampling method the moving pneumatic welding head of the example was subjected to joint stretching and joint impact performance test, and specific results are shown in tables 3 and 4.
Table 3 example pneumatic weld joint tensile properties
Table 4 example pneumatic weld joint impact properties
As can be seen from tables 3 and 4, the tensile property and impact property of the mobile pneumatic welding head of the examples meet the standard requirements, and the joint has a large performance margin.
As known from process optimization in the implementation process, the tensile strength Rm of the joint is larger than or equal to 1007MPa, the joint extension A is larger than or equal to 11.10%, and the joint impact KU 2 =21.9j, average hardness of joint H J Average value H of hardness of base material P The ratio of (2) is as follows: h J /H P Not less than 0.91, average hardness H of joint soft point J1 Average value H of hardness of base material P Ratio of (3): h J1 /H P And the softening area W is more than or equal to 0.84, less than or equal to 20mm, 15 joints are not broken, and all performances meet the standard requirements. The joint strength, hardness and toughness obtained by the embodiment are matched with the performance of the base metal, so that the requirements of heavy haul railways on the smoothness of the rail joints can be met, the risk of fracture caused by saddle abrasion or joint microstructure caused by overlarge hardness difference of welding areas in the rail service process is improved, the characteristics of high strength, high hardness and high toughness of the Nb and RE containing pearlitic rails and joints are fully brought into play, and the service requirements and the line operation safety of the heavy haul railways are 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 (5)
1. A movable gas pressure welding and joint heat treatment process for a pearlite steel rail containing Nb and RE is characterized in that: comprising the following steps:
1) Polishing and derusting end surfaces of two steel rails with the same section of 60kg/m and the same material, and derusting and polishing clamping ends of electrodes;
2) Adopting a GPW1200 type movable air pressure welder to weld steel rails;
3) The mobile air pressure welding process comprises the following steps: the joint quantity of the steel rail welding seams is controlled to be between 10 and 12mm, the arching quantity is controlled to be between 0.35 and 0.55mm, the welding preheating times are controlled to be between 11 and 13 times, the preheating current is controlled to be between 410 and 600A, the welding upsetting quantity is controlled to be between 11.5 and 11.9mm, and the advancing speed is controlled to be between 0.3 and 2.5 mm/s;
4) And (3) a joint normalizing process: the initial temperature of the rail joint is 400-500 ℃ and the final temperature is 850-900 ℃.
2. The Nb, RE-containing pearlitic rail mobile gas pressure welding and joint heat treatment process according to claim 1, wherein: before welding, the end of the steel rail is treated, the perpendicularity of the air pressure welding end face is within 0.6mm, and the steel rail is polished to metallic luster.
3. The Nb, RE-containing pearlitic rail mobile gas pressure welding and joint heat treatment process according to claim 1, wherein: the air-jet process is added in the air-pressure welding process to improve the hardness of the joint.
4. The Nb, RE-containing pearlitic rail mobile gas pressure welding and joint heat treatment process according to claim 1, wherein: the same pair of heaters is adopted for heating and normalizing.
5. The Nb, RE-containing pearlitic rail mobile gas pressure welding and joint heat treatment process according to claim 1, wherein: the welded pearlitic steel rail containing Cr, nb and RE takes C, si, mn, cr, nb, RE as a main alloy element, and comprises the following chemical components in percentage by weight: 0.73 to 0.83 percent, si:0.50 to 0.80 percent, mn:0.80 to 1.10 percent, cr:0.30 to 0.60 percent, nb:0.01 to 0.05 percent, RE:0.0005 to 0.0020 percent, P is less than or equal to 0.010 percent, S is less than or equal to 0.005 percent, al: less than or equal to 0.004 percent, and the balance of Fe and unavoidable impurities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310726732.8A CN116833539A (en) | 2023-06-19 | 2023-06-19 | Mobile gas pressure welding and joint heat treatment process for Nb and RE containing pearlitic steel rail |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310726732.8A CN116833539A (en) | 2023-06-19 | 2023-06-19 | Mobile gas pressure welding and joint heat treatment process for Nb and RE containing pearlitic steel rail |
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| Publication Number | Publication Date |
|---|---|
| CN116833539A true CN116833539A (en) | 2023-10-03 |
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| CN202310726732.8A Pending CN116833539A (en) | 2023-06-19 | 2023-06-19 | Mobile gas pressure welding and joint heat treatment process for Nb and RE containing pearlitic steel rail |
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| CN (1) | CN116833539A (en) |
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2023
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