CN108754114A - The heat treatment method of steel rail weld joint - Google Patents
The heat treatment method of steel rail weld joint Download PDFInfo
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- CN108754114A CN108754114A CN201810720765.0A CN201810720765A CN108754114A CN 108754114 A CN108754114 A CN 108754114A CN 201810720765 A CN201810720765 A CN 201810720765A CN 108754114 A CN108754114 A CN 108754114A
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- rail
- weld joint
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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
- C21D9/505—Cooling thereof
Abstract
The invention discloses a kind of heat treatment methods of steel rail weld joint, belong to rail welding technique field.The present invention is in order to solve rail steel rail weld joint " saddle " abrasion and technical problems such as connector early fatigue fracture caused by welding region lower hardness or Microstructure of Joint exception during circuit military service, provide a kind of heat treatment method of steel rail weld joint, steel rail weld joint is subjected to the first cooling stage successively, second cooling stage and third cooling stage, and control the cooling velocity and temperature in each stage, martensitic structure content can effectively be controlled, improve rail steel rail weld joint " saddle " abrasion and early fatigue fracture caused by welding region lower hardness or Microstructure of Joint exception during circuit military service, ensure railway operation safety.
Description
Technical field
The invention belongs to rail welding technique fields, and in particular to a kind of heat treatment method of steel rail weld joint.
Background technology
Currently, heavy haul railway circuit mostly uses eutectoid pearlite steel rail both at home and abroad, the phosphorus content of such rail usually exists
Within the scope of 0.72-0.82 weight %, metallographic structure is pearlite, has obdurability matching good, comprehensive mechanical property index is suitable
The features such as middle.With the fast development of railway, big axis weight heavy-haul line proposes requirements at the higher level to rail military service performance, and due to
The comprehensive mechanical property of conventional pearlitic rail has almost developed to the limit with welding performance.In this case, strength grade is more
Height, the hypereutectoid rail for taking into account the comprehensive performances such as good abrasion resistance properties and contact fatigue come into being, such rail it is carbon containing
For amount usually within the scope of 0.90-1.10 weight %, metallographic structure is pearlite+a small amount of secondary cementite.At this stage, rail moves
Flash welding has become the online welding technique of mainstream rail at domestic and international construction of railways scene.For strength grade and material not phase
With two kinds of rail, the difference between base material performance brings huge challenge to its welding.After rail is acted on by Thermal Cycle, weldering
The quench-hardened case for connecing region disappears and the soft area larger in weld seam both sides formation width, leads to the hardness of weld dimensions
Less than rail base material.Rail easily preferentially forms " saddle " abrasion, no during circuit is on active service in the rail head tread of welding point
Wheel-rail impact is increased only, also seriously affects rail service life, or even jeopardize traffic safety.Thus, how to restore rail because
The mechanical property welded and reduced just is able to the premise applied at rail.
Currently, report and document about hypereutectoid steel rail and eutectoid steel rail welding and post weld heat treatment technical study
Data is also relatively fewer.CN201610909362.1 discloses a kind of hypereutectoid rail and PG4 heat treatment eutectoid pearlite steel rails
The post weld heat treatment method of welding point, this method include that will weld obtained steel rail weld joint to be cooled to carry out first cold
But to 400 DEG C hereinafter, the first steel rail weld joint after cooling is then heated to 860-930 DEG C, then progress second cools down
Wheel tread temperature to steel rail weld joint is 410-450 DEG C.The xenogenesis steel rail weld joint obtained using this method can meet state
Interior existing railroad industry standard TB/T1632.2-2014《Rail welding part 2：Flash Butt Welding》In for fatigue, stretch, punching
It hits and the test request of quiet curved experiment；But rail postwelding normalizing heat treatment has been arrived involved in foregoing invention, has needed to use rail
PWHT equipment carries out local heating, operation and implementation process complexity, high expensive to steel rail weld joint.
Invention content
The present invention is in order to solve rail during circuit is on active service because welding region lower hardness or Microstructure of Joint are different
Steel rail weld joint " saddle " abrasion and the technical issues of early fatigue fracture caused by often provide a kind of rail welding and connect
The heat treatment method of head comprising following steps：The steel rail weld joint to be cooled that welding is obtained is in the first cooling velocity
Lower progress first stage cooling then makes rail weld so that the rail head skin temperature of steel rail weld joint is down to 650~720 DEG C
Connector carries out second stage cooling under the second cooling velocity, so that the rail head skin temperature of steel rail weld joint is down to 220
~280 DEG C, steel rail weld joint is finally made to carry out phase III cooling under third cooling velocity, so that steel rail weld joint
Rail head skin temperature is down to 10~30 DEG C.
Wherein, in the heat treatment method of steel rail weld joint described above, the steel rail weld joint is same by having
The xenogenesis steel rail weld joint that the hypereutectoid rail and eutectoid rail of kind rail type are welded.
Preferably, in the post weld heat treatment method of hypereutectoid steel rail described above and eutectoid steel steel rail weld joint,
The rail type of the hypereutectoid rail is 60~75kg/m, and the rail type of the eutectoid rail is 60~75kg/m.
Wherein, in the heat treatment method of steel rail weld joint described above, the initial temperature of the steel rail weld joint
It is 1000~1400 DEG C.
Wherein, in the heat treatment method of steel rail weld joint described above, the mode of first stage cooling be
Natural cooling in air.
Wherein, in the heat treatment method of steel rail weld joint described above, first cooling velocity is 5.0~9.0
℃/s。
Wherein, in the heat treatment method of steel rail weld joint described above, the second stage cooling uses rail rail
Imitative type cooling device, using compressed air or water mist gaseous mixture as cooling medium to the rail head tread and rail of steel rail weld joint
Rostral face is cooled down, and cooling device is 20~50mm apart from rail head of rail tread；The compressed air that cooling device is ejected
Or the gas pressure of water mist gaseous mixture is 0.40~0.80MPa.
Wherein, in the heat treatment method of steel rail weld joint described above, second cooling velocity is 1.5~2.5
℃/s。
Wherein, in the heat treatment method of steel rail weld joint described above, the phase III cooling uses rail rail
Imitative type cooling device, using compressed air or water mist gaseous mixture as cooling medium to the rail head tread and rail of steel rail weld joint
Rostral face is cooled down, and cooling device is 20~50mm apart from rail head of rail tread；The compressed air that cooling device is ejected
Or the gas pressure of water mist gaseous mixture is 0.05~0.25MPa.
Wherein, in the heat treatment method of steel rail weld joint described above, the third cooling velocity be 0.05~
0.50℃/s。
Wherein, in the heat treatment method of steel rail weld joint described above, the steel rail weld joint is moved using rail
Dynamic flash welder is welded.
The beneficial effects of the invention are as follows：
The method of the present invention can improve rail rail caused by welding region lower hardness during circuit military service
Connector " saddle " is worn away, it is ensured that corresponding to meeting respectively away from the rail joint longitudinal direction hardness in the regions Weld pipe mill ± 10mm
Eutectoid pearlite steel rail and the ± 30HV ranges of hypereutectoid rail base material average hardness (do not include the axis of a weld of decarburization：
Influenced by rail welding high temperature, Weld pipe mill decarburization simultaneously generates melting loss of elements, leads to lower hardness), and joint welding both sides
Softening sector width is below 15mm；Meanwhile, it is capable to which the martensitic structure percentage being likely to occur in rail joint metallographic structure is contained
Amount control helps to ensure that railway operation safety in≤1% range.
Description of the drawings
Fig. 1 is that the hypereutectoid rail under the conditions of the post weld heat treatment obtained using the method in embodiment 1 analyses pearly-lustre together
Longitudinal stiffening effect figure of the positions 3-5mm below the rail head tread of body steel rail weld joint.
Fig. 2 is to analyse pearl together using the hypereutectoid rail under the conditions of the obtained post weld heat treatment of method in embodiment 2
Longitudinal stiffening effect figure of the positions 3-5mm below the rail head tread of body of light steel rail weld joint.
Fig. 3 is to analyse pearly-lustre together using hypereutectoid rail of the obtained postwelding of method in comparative example 1 under the conditions of air-cooled
Longitudinal stiffening effect figure of the positions 3-5mm below the rail head tread of body steel rail weld joint.
Fig. 4 is to analyse pearl together using the hypereutectoid rail under the conditions of the obtained post weld heat treatment of method in comparative example 2
Longitudinal stiffening effect figure of the positions 3-5mm below the rail head tread of body of light steel rail weld joint.
Fig. 5 is to analyse pearl together using the hypereutectoid rail under the conditions of the obtained post weld heat treatment of method in comparative example 3
Longitudinal stiffening effect figure of the positions 3-5mm below the rail head tread of body of light steel rail weld joint.
Fig. 6 is longitudinal hardness determination schematic diagram of the rail head tread of the steel rail weld joint of the present invention or less the positions 3-5mm.
Fig. 7 is the rail head tread metallographic specimen sample position schematic diagram of the rail joint of the present invention.
Specific implementation mode
The heat treatment method of steel rail weld joint, includes the following steps：The rail welding to be cooled that welding obtains is connect
Head carries out first stage cooling under the first cooling velocity, so that the rail head skin temperature of steel rail weld joint is down to 650~720
DEG C, so that steel rail weld joint is carried out second stage cooling under the second cooling velocity, so that the rail head of steel rail weld joint
Skin temperature is down to 220~280 DEG C, and steel rail weld joint is finally made to carry out phase III cooling under third cooling velocity, with
The rail head skin temperature of steel rail weld joint is set to be down to 10~30 DEG C.
The critical cooling rate about 0.7-1.5 of martensite transfor mation during eutectoid pearlite steel rail steel continuous cooling transformation
DEG C/s, and the about 1.8-3.0 DEG C/s of critical cooling rate of the martensite transfor mation during hypereutectoid steel rail steel continuous cooling transformation.
About 250 DEG C of eutectoid pearlite steel rail Ms temperature (start temperature that martensitic structure is formed), and hypereutectoid rail Ms temperature about 190
℃.To avoid steel rail weld joint from the abnormal structures such as martensite occur, when the welding to hypereutectoid steel rail and eutectoid steel rail
When connector carries out post weld heat treatment, the final cooling temperature during need to being quickly cooled down post weld heat treatment is controlled in eutectoid pearlite steel
It is more than rail Ms temperature.Meanwhile the cooling velocity in PWHT procedures must be with the relatively low eutectoid pearlite of Critical cooling speed
Rail steel is limited, and otherwise steel rail weld joint will cause premature fatigue to be broken due to the martensitic structure largely hardened.Cause
This, provides in rail welding standard such as Australia rail welding standard AS1085.20-2012：For certain high grades, Gao Han
The rail of carbon amounts and high alloy content, under the observation multiplying power of metallographic microscope 100x, for martensite in steel rail weld joint
The most serious region of appearance, the percentage composition of martensitic structure must not be higher than 5%, and otherwise connector will be due to the horse largely hardened
Family name's body tissue and cause premature fatigue to be broken, seriously affect railway operation safety.Therefore, strictly in control rail welding tissue
Martensite content is most important for the stable operation of rail track.In addition, in hypereutectoid rail base material, there is also a small amount of
Secondary cementite, be in netted Intergranular precipitation during rail welding to avoid secondary cementite, therefore must be in austenite to pearl
Butt joint implementation is quickly cooled down before body of light transformation starts.Based on above-mentioned discovery, inventor completes the present invention.
The present invention realizes the PWHT procedures of rail using the welding waste heat of rail.For the obtained residual temperature of welding compared with
The rail joint of high (1000~1400 DEG C) implements postwelding and accelerates cooling, to reduce connector rail head from austenite to perlitic transformation
Phase transition temperature, to improve the hardness in austenite recrystallization area.Based on Principles of Metallography, rail joint is quick in postwelding high temperature
There are certain dynamic degree of supercooling under cooling condition, cause under nonequilibrium condition austenite under the phase transition temperature of perlitic transformation
It moves, and with the increase of degree of supercooling, phase transition temperature continuously decreases.Thus, even if opening the relatively low second stage of cold temperature
Cooling, connector rail head remains to occur the structural transformation from austenite to pearlite.
In the present invention, the first cold stage is but the natural cooling (can carry out at room temperature) carried out in air, cold
But speed is 5.0~9.0 DEG C/s, can be realized to the first stage (as used central air-conditioner temperature control) by adjusting test ambient temperature
The control of cooling velocity, and can be by adjusting the end that welding machine is arranged or manual operation cools down the steel rail weld joint first stage
Cold temperature control is at 650~720 DEG C；The cold temperature of opening of the second stage cooling is 650~720 DEG C, it is notable that this
In invention, the final cooling temperature of the second stage cooling turns higher than the martensite of hypereutectoid steel rail steel and eutectoid pearlite steel rail steel
Become start temperature (Ms temperature), the present invention in the second cooling stage final cooling temperature be 220~280 DEG C, cooling velocity be 1.5~
2.5℃/s；When carrying out phase III cooling to rail joint, for the martensitic structure for avoiding connector from occurring hardening, the present invention
Selection is with real less than 0.05~0.50 DEG C/s of the cooling velocity butt joints of eutectoid pearlite steel rail steel martensite transfor mation Critical cooling speed
It applies and cools down at a slow speed, and be cooled to room temperature (10~30 DEG C)；The type of cooling that the present invention is cooled down by using three steps, limitation are different cold
But the cooling velocity and cooling temperature in stage can reach and promote steel rail weld joint hardness, ensure in steel rail weld joint metallographic
The purpose of abnormal structures≤1% such as martensite, bainite.
In the method for the present invention, the second stage cooling and phase III cooling imitate type cooling device using rail head of rail,
The rail head tread of steel rail weld joint and rail head side are cooled down as cooling medium using compressed air or water mist gaseous mixture,
Cooling device is 20~50mm apart from rail head of rail tread；The compressed air or water that the second stage cooling device is ejected
The gas pressure of mist gaseous mixture is 0.40~0.80MPa, the compressed air or water that the phase III cooling device is ejected
The gas pressure of mist gaseous mixture is 0.05~0.25MPa.
In the present invention, hypereutectoid rail and eutectoid rail for welding are specification of the same race, specially 60~75kg/m
Specification, the steel rail weld joint is using same welding procedure by the dissimilar welding that is welded of rail movement flash welder
Connector.
In the present invention, in the absence of explanation to the contrary, " steel rail weld joint " be it is welded obtain include
Length including weld seam and/or heat affected area is the region of 70~100mm ranges, and the center in the region is the weld seam of rail.
In the present invention, the temperature signal of rail head of rail tread is acquired using infrared radiation thermometer, the rail head of rail tread is
The contact portion of wheel and rail；The hardness number corresponding to softened zone width measurement line in the hardness curve of rail joint longitudinal direction is
Rail base material average hardness subtracts the hardness after 25HV；Softening sector width in hardness curve is hardness curve and softening sector width
Measure the intercept of line.
Below by embodiment, invention is further described in detail, but does not therefore limit the scope of the present invention
Among the embodiment described range.
When the embodiment of the present invention and comparative example carry out steel rail weld joint Hardness Surveillance, welding point vertical section hardness specimens
Sample position sees that Fig. 6, weld seam are located at specimen length center, tests the hardness number of steel rail weld joint vertical section, measuring point is with weld seam
Centered on to the left and right both sides be symmetrically arranged, measuring point spacing 2mm；Welding point vertical section detects Vickers hardness, and test method presses GB/
T4340.1-2009 regulations carry out, experiment force value 294.2N；Recrystallization zone is apart from the region of Weld pipe mill ± 10mm；Hardness is examined
Survey should cover welding point whole region, including base material, heat affected area, weld seam, extend to welding point per side rail base material
The region of 20mm.
Embodiment 1
After the rail that specification is 68kg/m completes the upset during mobile Flash Butt Welding and pushes away tumor, connect to what welding obtained
Head carries out post weld heat treatment.First, residual temperature welding obtained is fast with the first cooling of 7.0 DEG C/s in 1100 DEG C of rail joint
Degree carries out first stage cooling so that the rail head skin temperature of rail joint is down to 670 DEG C, then makes rail joint with 2.0 DEG C/s
The second cooling velocity carry out second stage cool down the rail head skin temperature of rail joint is down to 280 DEG C, finally make rail
Connector carries out phase III cooling so that the rail head skin temperature of rail joint is down to 25 DEG C with the third cooling velocity of 0.4 DEG C/s
Room temperature, to obtain the present invention the steel rail weld joint through post weld heat treatment.
In PWHT procedures, first is cooled to the natural cooling carried out in air, the second cooling and third cooling
Rail head of rail is used to imitate type cooling device using compressed air or water mist gaseous mixture as cooling medium to rail joint in the process
Rail head tread and rail head side are cooled down, and cooling device is apart from rail head of rail tread 40mm；In second cooling procedure, cooling dress
The gas pressure of the compressed air or water mist gaseous mixture of setting injection is 0.60MPa；In third cooling procedure, cooling device injection
The gas pressure of compressed air or water mist gaseous mixture is 0.20MPa.Rail head of rail wheel tread temperature is monitored using infrared radiation thermometer.
The rail joint through post weld heat treatment that the present embodiment obtains is machined to longitudinal hardness specimens.It is hard using cloth dimension
Degree meter positions 4mm below rail head of rail tread (Laizhou, Shandong city testing machine head factory, model HBV-30A), using 2mm between measuring point
Away from longitudinal Vickers hardness detection is carried out to hardness specimens, both sides are symmetrically arranged measuring point to the left and right centered on weld seam.Vickers hardness
The method of inspection is with reference to GB/T 4340.1-2009《Vickers Hardness Test part 1：Test method》It carries out, is marked using HV
Ruler.Hardness Surveillance data are shown in Table 1, and the distributed effect of connector longitudinal direction hardness is as shown in Figure 1.
1 embodiment of table, 1 steel rail weld joint Hardness Surveillance data
By table 1 and Fig. 1 it is found that for steel rail weld joint processed by the invention, away from the regions Weld pipe mill ± 10mm
Interior rail joint longitudinal direction hardness meets corresponding eutectoid pearlite steel rail and hypereutectoid rail base material average hardness respectively
± 30HV ranges (do not include the axis of a weld of decarburization：It is influenced by rail welding high temperature, Weld pipe mill decarburization simultaneously generates first biscuiting
Damage, leads to lower hardness).The softening sector width of joint welding eutectoid pearlite steel rail side is 9mm, hypereutectoid rail side
Softening sector width is 7mm, and the softening sector width of joint welding both sides is below 15mm.
GB/T13298-2015 is pressed with reference to sampling method shown in Fig. 7《The metal microstructure method of inspection》To rail joint
Metallographic specimen carries out microstructure examination, carries out etch to rail joint metallographic specimen using 3% nital, using moral
State comes card MeF3 light microscopes and observes rail joint metallographic structure.The result shows that connector metallographic martensite-free, bayesian
Ti Deng abnormal structures.
Embodiment 2
After the rail that specification is 60kg/m completes the upset during mobile Flash Butt Welding and pushes away tumor, connect to what welding obtained
Head carries out post weld heat treatment.First, residual temperature welding obtained is fast with the first cooling of 6.5 DEG C/s in 1000 DEG C of rail joint
Degree carries out first stage cooling so that the rail head skin temperature of rail joint is down to 680 DEG C, then makes rail joint with 2.3 DEG C/s
The second cooling velocity carry out second stage cool down the rail head skin temperature of rail joint is down to 230 DEG C, finally make rail
Connector carries out phase III cooling so that the rail head skin temperature of rail joint is down to 25 with the third cooling velocity of 0.10 DEG C/s
DEG C room temperature, to obtain the present invention the heterogeneous material steel rail weld joint through post weld heat treatment.
In PWHT procedures, first is cooled to the natural cooling carried out in air；Second cooling and third cooling
In the process, use rail head of rail imitate type cooling device using water mist gaseous mixture as cooling medium to the rail head tread of rail joint and
Rail head side is cooled down, and cooling device is apart from rail head of rail tread 40mm；In second cooling procedure, the water of cooling device injection
The gas pressure of mist gaseous mixture is 0.66MPa；In third cooling procedure, the gas pressure of the water mist gaseous mixture of cooling device injection
For 0.09MPa.Rail head of rail wheel tread temperature is monitored using infrared radiation thermometer.
The rail joint through post weld heat treatment that the present embodiment obtains is machined to longitudinal hardness specimens.It is hard using cloth dimension
Degree meter positions 4mm below rail head of rail tread (Laizhou, Shandong city testing machine head factory, model HBV-30A), using 2mm between measuring point
Away from longitudinal Vickers hardness detection is carried out to hardness specimens, both sides are symmetrically arranged measuring point to the left and right centered on weld seam.Vickers hardness
The method of inspection is with reference to GB/T 4340.1-2009《Vickers Hardness Test part 1：Test method》It carries out, is marked using HV
Ruler.Hardness Surveillance data are shown in Table 2, and the distributed effect of connector longitudinal direction hardness is as shown in Figure 2.
2 embodiment of table, 2 steel rail weld joint Hardness Surveillance data
By table 2 and Fig. 2 it is found that for steel rail weld joint processed by the invention, away from the regions Weld pipe mill ± 10mm
Interior rail joint longitudinal direction hardness meets corresponding eutectoid pearlite steel rail and hypereutectoid rail base material average hardness respectively
± 30HV ranges (do not include the axis of a weld of decarburization：It is influenced by rail welding high temperature, Weld pipe mill decarburization simultaneously generates first biscuiting
Damage, leads to lower hardness).The softening sector width of joint welding eutectoid pearlite steel rail side is 8mm, hypereutectoid rail side
Softening sector width is 7mm, and the softening sector width of joint welding both sides is below 15mm.
GB/T 13298-2015 are pressed with reference to sampling method shown in Fig. 7《The metal microstructure method of inspection》Rail is connect
Head metallographic specimen carries out microstructure examination, carries out etch to rail joint metallographic specimen using 3% nital, uses
Leca MeF3 light microscopes observe rail joint metallographic structure.The result shows that welding point eutectoid rail one
Occurs a small amount of martensite in the heat affected area of side, under the 100x observation multiplying powers of metallographic microscope, for martensitic structure
The percentage composition in the most serious region of appearance, martensitic structure is only 0.5%.
Comparative example 1
After the rail that specification is 68kg/m completes the upset during mobile Flash Butt Welding and pushes away tumor, by residual temperature at 1100 DEG C
Rail joint Direct Air-Cooled to room temperature (about 25 DEG C), to obtain the steel rail weld joint under the conditions of air-cooled (natural cooling).
Rail joint under the conditions of taking the postwelding that this comparative example obtains air-cooled is processed into longitudinal hardness specimens.It is hard using cloth dimension
Degree meter positions 5mm below rail head of rail tread (Laizhou, Shandong city testing machine head factory, model HBV-30A), using 2mm between measuring point
Away from longitudinal Vickers hardness detection is carried out to hardness specimens, both sides are symmetrically arranged measuring point to the left and right centered on weld seam.Vickers hardness
The method of inspection is with reference to GB/T 4340.1-2009《Vickers Hardness Test part 1：Test method》It carries out, is marked using HV
Ruler.Hardness Surveillance data are shown in Table 3, and the distributed effect of connector longitudinal direction hardness is as shown in Figure 3.
3 comparative example of table, 1 steel rail weld joint Hardness Surveillance data
By table 3 and Fig. 3 it is found that for not connect using the rail welding of post weld heat treatment method provided by the invention processing
Head, compared with the rail base material hardness of weld seam both sides, entire welding region is rendered as soft state.Away from Weld pipe mill ± 10mm
It is average with hypereutectoid rail base material that rail joint longitudinal direction hardness in region cannot meet corresponding eutectoid pearlite steel rail
± 30HV the ranges of hardness (do not include the axis of a weld of decarburization：It is influenced by rail welding high temperature, Weld pipe mill decarburization simultaneously generates
Melting loss of elements leads to lower hardness).The softening sector width of joint welding eutectoid pearlite steel rail side is 17mm, hypereutectoid steel
The softening sector width of rail side is 18mm.The welding point obtained by the comparative example is easily preferentially connecing during circuit is on active service
The softened zone of head weld seam hypereutectoid rail side forms that rail head of rail tread is low to collapse, and influences Track regularity and traffic safety.
GB/T13298-2015 is pressed with reference to sampling method shown in Fig. 7《The metal microstructure method of inspection》To rail joint
Metallographic specimen carries out microstructure examination, carries out etch to rail joint metallographic specimen using 3% nital, using moral
State comes card MeF3 light microscopes and observes rail joint metallographic structure.The result shows that connector metallographic structure is normal, no horse
The abnormal structures such as family name's body, bainite.
Comparative example 2
After the rail that specification is 75kg/m completes the upset during mobile Flash Butt Welding and pushes away tumor, connect to what welding obtained
Head carries out post weld heat treatment.First, residual temperature welding obtained is fast with the first cooling of 6.0 DEG C/s in 1050 DEG C of rail joint
Degree carries out first stage cooling so that the rail head skin temperature of rail joint is down to 680 DEG C, then makes rail joint with 2.8 DEG C/s
The second cooling velocity carry out second stage cool down the rail head skin temperature of rail joint is down to 180 DEG C, finally make rail
Connector carries out phase III cooling so that the rail head skin temperature of rail joint is down to 25 with the third cooling velocity of 0.10 DEG C/s
DEG C room temperature, to obtain the heterogeneous material steel rail weld joint through post weld heat treatment of this comparative example.
In PWHT procedures, first is cooled to the natural cooling carried out in air；Second cooling and third cooling
In the process, rail head of rail is used to imitate rail head tread and rail of the type cooling device using compressed air as cooling medium to rail joint
Rostral face is cooled down, and cooling device is apart from rail head of rail tread 45mm；In second cooling procedure, the compression of cooling device injection
The gas pressure of air is 0.90MPa；In third cooling procedure, the gas pressure of the compressed air of cooling device injection is
0.13MPa.Rail head of rail wheel tread temperature is monitored using infrared radiation thermometer.
Rail joint under the conditions of taking the postwelding that this comparative example obtains air-cooled is processed into longitudinal hardness specimens.It is hard using cloth dimension
Degree meter positions 4mm below rail head of rail tread (Laizhou, Shandong city testing machine head factory, model HBV-30A), using 2mm between measuring point
Away from longitudinal Vickers hardness detection is carried out to hardness specimens, both sides are symmetrically arranged measuring point to the left and right centered on weld seam.Vickers hardness
The method of inspection is with reference to GB/T 4340.1-2009《Vickers Hardness Test part 1：Test method》It carries out, is marked using HV
Ruler.Hardness Surveillance data are shown in Table 4, and the distributed effect of connector longitudinal direction hardness is as shown in Figure 4.
4 comparative example of table, 2 steel rail weld joint Hardness Surveillance data
By table 4 and Fig. 4 it is found that for not connect using the rail welding of post weld heat treatment method provided by the invention processing
The softening sector width of head, obtained connector eutectoid rail side is 10mm, and the softening sector width of hypereutectoid rail side is
9mm.Joint welding eutectoid pearlite steel rail side hardness is higher, and the hardness away from the positions Weld pipe mill 2mm reaches 476HV, exceeds
Eutectoid pearlite steel rail base material average hardness 36HV.Such connector is during circuit is on active service, due to joint welding hypereutectoid steel
Rail side hardness is relatively low, easily preferentially forms that rail head of rail tread is low collapses in the side softened zone, and connector " saddle " is caused to wear away,
Influence Track regularity.
GB/T 13298-2015 are pressed with reference to sampling method shown in Fig. 7《The metal microstructure method of inspection》Rail is connect
Head metallographic specimen carries out microstructure examination, carries out etch to rail joint metallographic specimen using 3% nital, uses
Leca MeF3 light microscopes observe rail joint metallographic structure.The result shows that connector hypereutectoid rail and altogether
It analyses in the welding heat affected zone of pearlite steel rail and martensite occurs, under the 100x observation multiplying powers of metallographic microscope, for
The most serious region that martensitic structure occurs in connector, the percentage composition of the martensitic structure of both sides has been more than 6%, is unfavorable for
Railway operation safety.
Comparative example 3
After the rail that specification is 68kg/m completes the upset during mobile Flash Butt Welding and pushes away tumor, connect to what welding obtained
Head carries out post weld heat treatment.First, residual temperature welding obtained is fast with the first cooling of 7.0 DEG C/s in 1050 DEG C of rail joint
Degree carries out first stage cooling so that the rail head skin temperature of rail joint is down to 660 DEG C, then makes rail joint with 2.4 DEG C/s
The second cooling velocity carry out second stage cool down the rail head skin temperature of rail joint is down to 260 DEG C, finally make rail
Connector carries out phase III cooling so that the rail head skin temperature of rail joint is down to 25 DEG C with the third cooling velocity of 2.5 DEG C/s
Room temperature, to obtain the heterogeneous material steel rail weld joint through post weld heat treatment of this comparative example.
In PWHT procedures, first is cooled to the natural cooling carried out in air；Second cooling and third cooling
In the process, rail head of rail is used to imitate rail head tread and rail of the type cooling device using compressed air as cooling medium to rail joint
Rostral face is cooled down, and cooling device is apart from rail head of rail tread 40mm；In second cooling procedure, the compression of cooling device injection
The gas pressure of air is 0.68MPa；In third cooling procedure, the gas pressure of the compressed air of cooling device injection is
0.80MPa.Rail head of rail wheel tread temperature is monitored using infrared radiation thermometer.
Rail joint under the conditions of taking the postwelding that this comparative example obtains air-cooled is processed into longitudinal hardness specimens.It is hard using cloth dimension
Degree meter positions 4mm below rail head of rail tread (Laizhou, Shandong city testing machine head factory, model HBV-30A), using 2mm between measuring point
Away from longitudinal Vickers hardness detection is carried out to hardness specimens, both sides are symmetrically arranged measuring point to the left and right centered on weld seam.Vickers hardness
The method of inspection is with reference to GB/T4340.1-2009《Vickers Hardness Test part 1：Test method》It carries out, using HV scales.
Hardness Surveillance data are shown in Table 5, and the distributed effect of connector longitudinal direction hardness is as shown in Figure 5.
5 comparative example of table, 3 steel rail weld joint Hardness Surveillance data
By table 5 and Fig. 5 it is found that for not connect using the rail welding of post weld heat treatment method provided by the invention processing
The softening sector width of head, obtained connector eutectoid rail side is 10mm, and the softening sector width of hypereutectoid rail side is
10mm.Joint welding eutectoid pearlite steel rail side hardness is higher, exceeds eutectoid pearl away from the hardness at Weld pipe mill ± 10mm
Body of light rail and hypereutectoid rail base material average hardness 30HV.Such connector is during circuit is on active service, due to joint welding mistake
Eutectoid rail side hardness is relatively low, easily preferentially forms that rail head of rail tread is low collapses in the side softened zone, causes connector " saddle
Type " is worn away, and influences Track regularity.
GB/T 13298-2015 are pressed with reference to sampling method shown in Fig. 7《The metal microstructure method of inspection》Rail is connect
Head metallographic specimen carries out microstructure examination, carries out etch to rail joint metallographic specimen using 3% nital, uses
Leca MeF3 light microscopes observe rail joint metallographic structure.The result shows that connector hypereutectoid rail and altogether
It analyses in the welding heat affected zone of pearlite steel rail and martensite occurs, under the 100x observation multiplying powers of metallographic microscope, for
The most serious region that martensitic structure occurs in connector, the percentage composition of martensitic structure has been more than 10%, is unfavorable for railway
Operational safety.
It can be seen that by welding point rail head tread longitudinal direction hardness in comparison diagram 1 to Fig. 5 and welding joint softened sector width：
Pearlite steel rail welding point is analysed for hypereutectoid rail using post weld heat treatment method provided by the invention together and implements postwelding
Heat treatment can make meeting corresponding eutectoid pearly-lustre respectively away from the rail joint longitudinal direction hardness in the regions Weld pipe mill ± 10mm
Body rail and the ± 30HV ranges of hypereutectoid rail base material average hardness (do not include the axis of a weld of decarburization：By rail welding
High temperature influences, and Weld pipe mill decarburization simultaneously generates melting loss of elements, leads to lower hardness), and the softened zone of joint welding both sides is wide
Degree is below 15mm.Meanwhile, it is capable to which the martensitic structure percentage composition being likely to occur in rail joint metallographic structure control is existed
In≤1% range, railway operation safety is advantageously ensured that.
The preferred embodiment of the present invention has been described above in detail, although being described according to this hair with reference to specific embodiment
Bright Post-Welding Heattreatment of Rail method, it will be recognized to those skilled in the art that in the thought and range for not departing from the present invention
In the case of, herein various modifications and combinations can be made to the present invention.
Claims (10)
1. the heat treatment method of steel rail weld joint, it is characterised in that：Include the following steps：The steel to be cooled that welding is obtained
Rail welding point carries out first stage cooling under the first cooling velocity, so that the rail head skin temperature of steel rail weld joint is down to
650~720 DEG C, steel rail weld joint is then set to carry out second stage cooling under the second cooling velocity, so that rail welding connects
The rail head skin temperature of head is down to 220~280 DEG C, and steel rail weld joint is finally made to carry out the phase III under third cooling velocity
It is cooling, so that the rail head skin temperature of steel rail weld joint is down to 10~30 DEG C.
2. the heat treatment method of steel rail weld joint according to claim 1, it is characterised in that：The steel rail weld joint
For by hypereutectoid rail and the xenogenesis steel rail weld joint that is welded of eutectoid rail with rail type of the same race.
3. the heat treatment method of steel rail weld joint according to claim 1, it is characterised in that：The steel rail weld joint
Initial temperature be 1000~1400 DEG C.
4. the heat treatment method of steel rail weld joint according to claim 1, it is characterised in that：The first stage cooling
Mode be natural cooling in air.
5. the heat treatment method of steel rail weld joint according to claim 1, it is characterised in that：First cooling velocity
For 5.0~9.0 DEG C/s.
6. the heat treatment method of steel rail weld joint according to claim 1, it is characterised in that：The second stage cooling
Type cooling device is imitated using rail head of rail, using compressed air or water mist gaseous mixture as cooling medium to the rail of steel rail weld joint
Head tread and rail head side are cooled down, and cooling device is 20~50mm apart from rail head of rail tread；Cooling device is ejected
Compressed air or water mist gaseous mixture gas pressure be 0.40~0.80MPa.
7. the heat treatment method of steel rail weld joint according to claim 6, it is characterised in that：Second cooling velocity
For 1.5~2.5 DEG C/s.
8. the heat treatment method of steel rail weld joint according to claim 1, it is characterised in that：The phase III cooling
Type cooling device is imitated using rail head of rail, using compressed air or water mist gaseous mixture as cooling medium to the rail of steel rail weld joint
Head tread and rail head side are cooled down, and cooling device is 20~50mm apart from rail head of rail tread；Cooling device is ejected
Compressed air or water mist gaseous mixture gas pressure be 0.05~0.25MPa.
9. the heat treatment method of steel rail weld joint according to claim 8, it is characterised in that：The third cooling velocity
For 0.05~0.50 DEG C/s.
10. according to the heat treatment method of claim 1~9 any one of them steel rail weld joint, it is characterised in that：The steel
Rail welding point is welded using rail movement flash welder.
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| CN110016546A (en) * | 2019-05-28 | 2019-07-16 | 攀钢集团攀枝花钢铁研究院有限公司 | Construction method for the heat treatment of bainite rail postwelding connector |
| CN110358906A (en) * | 2019-08-23 | 2019-10-22 | 攀钢集团攀枝花钢铁研究院有限公司 | The heat treatment method of steel rail weld joint |
| CN110358905A (en) * | 2019-08-23 | 2019-10-22 | 攀钢集团攀枝花钢铁研究院有限公司 | The heat treatment method of steel rail weld joint |
| CN110512148A (en) * | 2019-07-31 | 2019-11-29 | 攀钢集团攀枝花钢铁研究院有限公司 | A method of control R260 WELDING JOINT martensitic structure |
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| CN112251587A (en) * | 2020-10-23 | 2021-01-22 | 攀钢集团攀枝花钢铁研究院有限公司 | Heat treatment method for welded joint of bainite steel rail and eutectoid pearlite steel rail |
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| CN112280965A (en) * | 2020-10-21 | 2021-01-29 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for inhibiting harmful microstructure of steel rail welding joint |
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| CN112280966A (en) * | 2020-10-21 | 2021-01-29 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for regulating and controlling microstructure of steel rail welding joint |
| CN112280965A (en) * | 2020-10-21 | 2021-01-29 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for inhibiting harmful microstructure of steel rail welding joint |
| CN112359195A (en) * | 2020-10-21 | 2021-02-12 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for optimizing steel rail welded joint microstructure |
| CN112251592A (en) * | 2020-10-23 | 2021-01-22 | 攀钢集团攀枝花钢铁研究院有限公司 | Construction method for heat treatment of dissimilar steel rail flash welded joint |
| CN112251587A (en) * | 2020-10-23 | 2021-01-22 | 攀钢集团攀枝花钢铁研究院有限公司 | Heat treatment method for welded joint of bainite steel rail and eutectoid pearlite steel rail |
| CN112251592B (en) * | 2020-10-23 | 2022-03-22 | 攀钢集团攀枝花钢铁研究院有限公司 | Construction method for heat treatment of dissimilar steel rail flash welded joint |
| CN112251587B (en) * | 2020-10-23 | 2022-03-22 | 攀钢集团攀枝花钢铁研究院有限公司 | Heat treatment method for welded joint of bainite steel rail and eutectoid pearlite steel rail |
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