阅读说明：本技术 一种控制r260钢轨闪光焊接头马氏体组织的方法 (A method of control R260 WELDING JOINT martensitic structure ) 是由 李大东 陆鑫 王若愚 白威 于 2019-07-31 设计创作，主要内容包括：本发明涉及一种控制R260钢轨闪光焊接头马氏体组织的方法,属于铁路钢轨焊接技术领域。本发明解决的技术问题是R260钢轨闪光焊接头焊后空冷容易出现马氏体组织。本发明的技术方案是一种控制R260钢轨闪光焊接头马氏体组织的方法,包括R260钢轨母材化学成分控制,热轧工艺控制,焊接工艺控制,焊后冷却控制,其中控制R260钢轨母材以重量百分数计Mn含量为0.90％～1.0％、C含量处于中下限、Si≤0.30％、0.03％～0.05％Cr。本发明可避免在轨头中心面和轨底脚规定的检查位置出现马氏体组织,保证了接头各项力学性能指标,满足EN 14587-2:2009标准的技术要求,具有良好的推广应用前景。(The present invention relates to a kind of methods for controlling R260 WELDING JOINT martensitic structure, belong to railway track welding technology field.Present invention solves the technical problem that being that R260 WELDING JOINT postwelding is air-cooled is easy to appear martensitic structure.The technical scheme is that a kind of method for controlling R260 WELDING JOINT martensitic structure, including R260 rail base material chemical Composition Control, hot rolling technology control, welding procedure control, the cooling control of postwelding, wherein Mn content is that 0.90%~1.0%, C content is in lower limit, Si≤0.30%, 0.03%~0.05%Cr to control R260 rail base material by weight percentage.The present invention can avoid the inspection position as defined in rail head median plane and rail bottom foot and martensitic structure occurs, ensure that connector items mechanical performance index, meets the technical requirements of EN 14587-2:2009 standard, has good popularization and application foreground.)

1. a kind of method for controlling R260 WELDING JOINT martensitic structure, it is characterised in that the following steps are included: R260 Rail base material chemical Composition Control, hot rolling technology control, welding procedure control, the cooling control of postweld heat preservation, wherein controlling R260 Mn content is that 0.90%~1.0%, C content is in lower limit, Si≤0.30% to rail base material by weight percentage, is made steel 0.03%~0.05%Cr is added in journey in molten steel.

2. a kind of method for controlling R260 WELDING JOINT martensitic structure according to claim 1, feature exist Make to roll mechanics property of rail in: hot rolling technology control and meets Rm >=880MPa, tyre tread hardness >=260HB.

3. a kind of method for controlling R260 WELDING JOINT martensitic structure according to claim 1 or 2, feature Be: the welding procedure control welding upset amount is maintained at 14.0~15.0mm.

4. a kind of described in any item methods for controlling R260 WELDING JOINT martensitic structure according to claim 1~3, It is characterized by: it is cold to carry out postweld heat preservation when the welding procedure control is air-cooled to 550~520 DEG C after the completion of connector pushes away tumor But it controls.

5. a kind of method for controlling R260 WELDING JOINT martensitic structure according to any one of claims 1 to 4, It is characterized by: the cooling control postwelding connector temperature heat preservation of the postweld heat preservation is cooled to 300 DEG C hereinafter, air-cooled to room temperature again.

6. a kind of described in any item methods for controlling R260 WELDING JOINT martensitic structure according to claim 1~5, It is characterized by: the cooling control of the postwelding is that butt welding rear joint carries out heat preservation cooling, control joint is in austenite to pearlite The cooling velocity of the phase transition temperature interval of transformation is in 0.6~0.3 DEG C/s.

7. a kind of described in any item methods for controlling R260 WELDING JOINT martensitic structure according to claim 1~6, It is characterized by: the cooling control of the postwelding is that butt welding rear joint carries out heat preservation cooling, control joint is in 620~500 DEG C of sections Cooling velocity in 0.6~0.3 DEG C/s.

8. a kind of described in any item methods for controlling R260 WELDING JOINT martensitic structure according to claim 1~7, It is characterized by: the cooling control of the postwelding carries out heat preservation cooling using attemperator, attemperator is using in hinge type structure The rail head attemperator or tunneling boring rail attemperator of embedding aluminosilicate fiber cotton.

9. a kind of method for controlling R260 WELDING JOINT martensitic structure according to claim 7, feature exist In: the attemperator length 190mm~220mm；Aluminosilicate fiber cotton is with a thickness of 35mm.

10. a kind of method for controlling R260 WELDING JOINT martensitic structure according to claim 1, feature exist In: the welding procedure is using the high heat-input amount pulsation of 8.5~9.5MJ or preheating flash butt welding.

Technical field

The invention belongs to railway track welding technology fields, and in particular to a kind of control R260 WELDING JOINT geneva The method of body tissue.

Background technique

EN R260 rail is to climb steel one of steel grade most to the countries in Southeast Asia such as Malaysia, Thailand export volume every year, Ten thousand tons of 2-4 or so are about exported every year.EN13674-1:2011"Railway applications-Track-RailPart 1: Vignole railway rails 46kg/mand above " standard requirements production R260 finished product rail chemical component Are as follows: 0.60%~0.82%C, 0.65%~1.25%Mn, 0.13%~0.60%Si, P, S≤0.030% ,≤0,15% Cr ,≤0,030%V, remaining Mo, Ni, Cu, Sn, Pb etc. are control element, the control of general content requirement 0.02%~ 0.15%.Meanwhile EN standard requirements R260 mechanics property of rail tensile strength Rm >=880MPa, elongation after fracture A >=10%, 260~300HB of tyre tread hardness.

Rail Production quotient meets standard requirements for the intensity and tyre tread hardness that guarantee R260 rail, and most economical method is Mn content is promoted to middle upper range, to guarantee after normal rolling that rail meets EN standard under the conditions of air-cooled: Rm >= 880MPa, the technical requirements of 260~300HB of tyre tread hardness.However, C, Mn be segregation element, when in rail Mn content improve to After middle upper range, the rail base material of high Mn ingredient certainly will cause Mn microcell to be segregated, and the chemical component of line of segragation high-content makes CCT Curve seriously moves to right, and is particularly easy to cause dotted martensitic structure occur in postwelding connector process air cooler, can not pass through EN standard Solder type inspection.

Summary of the invention

Present invention solves the technical problem that being that R260 WELDING JOINT postwelding is easy to appear martensitic structure.

The technical solution that the present invention solves above-mentioned technical problem is to provide a kind of control R260 WELDING JOINT geneva The method of body tissue, step include: R260 rail base material chemical Composition Control, hot rolling technology control, welding procedure control, postwelding Cooling control, wherein Mn content is during 0.90%~1.0%, C content is in control R260 rail base material by weight percentage 0.03%~0.05%Cr is added in steelmaking process in molten steel for lower limit, Si≤0.30%.

Wherein, hot rolling technology control, which makes to roll mechanics property of rail, meets Rm >=880MPa, tyre tread hardness >=260HB.

Further, hot rolling technology carries out hot rolling using universal rolling production line.

Wherein, welding procedure control welding upset amount is maintained at 14.0~15.0mm.

Further, welding procedure is using the high heat-input amount pulsation of 8.5~9.5MJ or preheating flash butt welding.

Wherein, when welding procedure control is air-cooled to 550~520 DEG C after the completion of connector pushes away tumor, the cooling control of postwelding is carried out.

Wherein, the cooling control of postwelding is cooled to 300 DEG C hereinafter, air-cooled to room temperature again when connector temperature is kept the temperature.

Wherein, the cooling control of postwelding is that butt welding rear joint keep the temperature cooling (slow cooling), and control joint is in austenite to pearl The cooling velocity of the phase transition temperature interval of body of light transformation is in 0.6~0.3 DEG C/s.

Specifically, control joint 620~500 DEG C of sections cooling rate in 0.6~0.3 DEG C/s.

Wherein, the cooling control of postwelding carries out slow cooling using attemperator, and attemperator embeds sial using hinge type structure The rail head attemperator or tunneling boring rail attemperator of silicate fiber cotton.

Further, attemperator length 190mm~220mm；Aluminate fiber cotton thickness 35mm.

The beneficial effects of the present invention are:

The present invention is made by the comprehensively control cooling to R260 rail chemical component, hot rolling technology, welding procedure, postwelding R260 rail ingredient Mn content in the case where 0.90%~1.0%, flash welding connector can avoid in rail head median plane and Check that martensitic structure occurs in position, ensure that connector items mechanical performance index, meets EN 14587-2 as defined in rail bottom foot: The technical requirements of 2009 standards；The present invention is kept the temperature using easy rail head attemperator or tunneling boring rail attemperator Cooling control, by the setting to attemperator length and thickness, preferably controls postwelding cooling velocity；The present invention controls work Skill is simple, mating can solve the problems, such as the great welding technique on EN R260 rail promotion and application road, has good popularization Application prospect.

Detailed description of the invention

Fig. 1 is microscopic structure check position schematic diagram as defined in EN 14587-2:2009 standard, wherein 1,2 is micro- group Knit check position；

Fig. 2 is that rail head attemperator of the present invention keeps the temperature schematic diagram, and wherein a is attemperator length；

Fig. 3 is that tunneling boring attemperator of the present invention keeps the temperature schematic diagram；

Fig. 4 is 1 connector metallographic structure figure of the embodiment of the present invention.

Specific embodiment

The rail welding method and test stone of the standard requirements such as external EN, AREMA are different from Chinese T B/T1632- The standard of 2014 rail weldings series.The maximum difference of welding method is that postwelding does not use the air-cooled technique of postwelding normalizing to carry out Connector post weld heat treatment, and generally use postwelding air-cooled or air quenching technique.It is generally adopted before R260 rail in foreign countries It is welded and is checked and accepted with AS standard, but require to check and accept in strict accordance with EN 14587-2:2009 standard in recent years.Especially EN 14587-2:2009《Rail way applications-Track-Flash butt welding of rails.Part 2: New R220R260R260Mn and R350HT grade rails by mobile welding machines at sites Other than a fixed plant " standard regulation check the air-cooled connector tyre tread of R260 flash welding in rail under 0mm~20mm hang down The microscopic structure of straight median plane position is as shown in Figure 1.Rail vertical central plane is the center crystal plane of continuous casting steel billet, is C, Mn etc. Element segregation is enriched with region the most serious.

The present invention provides a kind of method for controlling R260 WELDING JOINT martensitic structure, and step includes: R260 steel Rail base material chemical Composition Control, hot rolling technology control, welding procedure control, the cooling control of postwelding, wherein control R260 rail is female Mn content is that 0.90%~1.0%, C content is in lower limit, Si≤0.30% to material by weight percentage, in steelmaking process 0.03%~0.05%Cr is added in molten steel.C content is in lower limit general control between 0.70~0.75%.

Wherein, hot rolling technology control, which makes to roll mechanics property of rail, meets Rm >=880MPa, tyre tread hardness >=260HB.This hair Conventional hot rolling technique can be used in the bright hot rolling technology carried out to rail base material, make after hot rolling mechanics property of rail meet Rm >= 880MPa, tyre tread hardness >=260HB.Preferably, hot rolling technology carries out hot rolling using universal rolling production line.

Wherein, welding procedure control makes welding upset amount be maintained at 14.0~15.0mm.The present invention terminates laggard in hot rolling Enter the welding procedure control stage, wherein having carried out special control to upset amount, because upset amount is too small, weld seam, which exists, not to be extracted only Oxide, reduce joint performance；Excessive upset amount leads to cold junction, and performance equally reduces.It needs to pass through in practice operation A large amount of quiet curved or stretching experiments confirm optimal upset amount.

Specifically, the present invention is using the mobile flash welder of rail or fixes flash welder, using the big heat of 8.5~9.5MJ Input quantity pulsation or preheating flash butt welding connect.Heat input is bigger, and connector postwelding cooling velocity is slower, is conducive to mitigation and geneva occurs The area percentage content of body tissue.

Further, when welding procedure is air-cooled to 550~520 DEG C after the completion of connector pushes away tumor, the cooling control of postwelding is carried out.

The cooling control of postwelding is even more important, and the present invention carries out cooling control in such a way that heat preservation is cooling, and connector is worked as in control Temperature is cooled to 300 DEG C hereinafter, air-cooled to room temperature again.

The present invention reduces cooling velocity by way of keeping the temperature cooling (slow cooling), so that martensitic structure be avoided to occur.Tool Body, control joint phase transition temperature interval from austenite to perlitic transformation cooling velocity in 0.6~0.3 DEG C/s.Pass through A large number of experiments verifying, postwelding control joint 620~500 DEG C of sections cooling velocity in 0.6~0.3 DEG C/s, can avoid be more than Critical martensite transfor mation speed.

Specifically, the cooling control of postwelding carries out slow cooling using attemperator, attemperator embeds silicon using hinge type structure The rail head attemperator (Fig. 2) or tunneling boring rail attemperator (Fig. 3) of aluminate fiber cotton.

Wherein, the length of attemperator and thickness are very big to the cooling influence of heat preservation, in order to preferably control cooling velocity, Preferably, setting attemperator length 190mm~220mm, aluminate fiber cotton thickness 35mm.

The present invention is further illustrated by the following examples.

In the present invention, it is described welding " connector " be obtain after weld formation include weld seam including length be 70~110mm The region of range, the center in the region are steel rail welding line.The present invention relates to connector temperature be welding point rail head surface layer Temperature namely rail head wheel tread temperature are acquired temperature signal using infrared radiation thermometer, and the rail head of rail tyre tread is wheel With the contact portion of rail.Length including tunneling boring refers to comprising weld seam is about that rail welding within the scope of 70~110mm connects Head whole cross section, including rail head, the web of the rail, rail bottom.

Metallographic structure is carried out to rail joint metallographic specimen by GB/T13298-2015 " the metal microstructure method of inspection " It examines, etch is carried out to rail joint metallographic specimen using 3% nital, using Leca MeF3 optical microscopy Rail joint metallographic structure is observed.