CN105414797A - Bainitic steel and pearlitic steel thermit welding material and welding technology - Google Patents
Bainitic steel and pearlitic steel thermit welding material and welding technology Download PDFInfo
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- CN105414797A CN105414797A CN201510933486.9A CN201510933486A CN105414797A CN 105414797 A CN105414797 A CN 105414797A CN 201510933486 A CN201510933486 A CN 201510933486A CN 105414797 A CN105414797 A CN 105414797A
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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
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
- B23K35/3053—Fe as the principal constituent
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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
- B23K23/00—Alumino-thermic welding
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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
- B23K2101/00—Articles made by soldering, welding or cutting
- B23K2101/26—Railway- or like rails
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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
- B23K2103/00—Materials to be soldered, welded or cut
- B23K2103/02—Iron or ferrous alloys
- B23K2103/04—Steel or steel alloys
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Abstract
The invention provides a bainitic steel and pearlitic steel thermit welding material and application of the bainitic steel and pearlitic steel thermit welding material to bainitic steel and pearlitic steel welding. The bainitic steel and pearlitic steel thermit welding material comprises, by weight percentage, 18%-19% of aluminum powder, 68%-69% of iron oxide, 2.7%-2.8% of ferromanganese, 0.6%-0.7% of ferrochromium, 1.1%-1.2% of ferrosilicon, 0.4%-0.6% of ferromolybdenum and the balance iron powder. The invention further provides a steel rail thermite welding technology characterized by utilization of the bainitic steel and pearlitic steel thermit welding material. When a pearlitic steel rail and a bainitic steel rail are welded by the use of the bainitic steel and pearlitic steel thermit welding material and the welding technology, the chemical composition of weld metal is similar to the chemical composition of bainitic steel, the microstructure of the weld metal is carbide-free bainite, no cracks or abnormal structures exist, a welded joint has good mechanical properties, and the hardness, the static bending performance and other performance meet the existing industrial standards.
Description
Technical field
The invention belongs to metal welding techniques field, be specifically related to a kind of exothermic welding welding material welded with pearlitic steel for bainitic steel, and use this exothermic welding welding material to carry out the technique of welding.
Background technology
Heavy haul railway transport to be subject to the extensive attention of countries in the world railway because its capacity is large, efficiency is high, cost of transportation is low, particularly the bulk supply tariff freight volume such as, aboundresources, coal and ore vast in territory at some occupies the country of larger specific gravity.Heavy-haul transport technology by the world generally acknowledge be railway freight development direction, become one of important trend of world's railway development.In order to adapt to heavy haul transport needs, China railways improves constantly vehicle load.China's load-carrying in 2006 60 tons and about 450,000, above vehicle, account for 85.7% of vehicle fleet, the vehicle that its axis weighs 23 tons (load-carryings 70 tons) has reached more than 20,000, axle weighs existing more than 8400 of the vehicle of 25 tons of load-carryings 80 tons, this will to improving railway transport capacity, alleviating the nervous contradiction of shipping, realizing railway intension expansion formula regenerative ratio, and it is significant that promotion Chinese Railway enters the heavy haul transport epoch.
The weight of train of general heavy haul transport, often more than 5000 tons, because loading capacity is large, is proposed very high requirement to the intensity of rail and toughness (wearability).Conventional organizing of rail is pearlitic structrure substantially at present, although improve the intensity of pearlite alloys steel by alloying or heat treatment technics, close to the limit, fundamentally cannot solve the problem keeping better toughness while improving intensity.The all good Pattern Bainite Alloy steel of the intensity occurred in recent years, toughness, plasticity, processing characteristics meets the requirement of heavy haul transport to track, therefore in heavy-haul line, wears away more serious region at first, as minor radius section is applied.The technical barrier just becoming and bainitic steel path changes paving is welded between the pearlite steel rail do not changed and the bainite rail of replacing.
The exothermic welding welding material occurred in prior art is all be applicable to the welding between rail of the same race.As publication number CN102029486A (publication date on April 27th, 2011), denomination of invention " high rigidity rail aluminum heat flux and welding method thereof " disclose a kind of solder flux being applicable to the exothermic welding of high rigidity rail, be made up of aluminium powder, iron oxide and alloy additive, wherein the active aluminium content of aluminium powder is greater than 98%, granularity 30 ~ 60 order; Iron oxide is oxidized formation in heating rolling steel process, and granularity is 18 ~ 80 orders; Other alloy additive comprises shot, ferrosilicon, ferromanganese, ferrochrome, vanadium iron, rare earth alloy.And for example the Chinese invention patent application of publication number CN104625480A (publication date on May 22nd, 2015), denomination of invention " a kind of rail aluminum heat flux and welding method thereof ", discloses a kind of aluminum heat flux for having bainite structure, high strength railway rail.Described aluminum heat flux, by weight percentage, it comprises aluminium powder 18.4% ~ 18.8%, iron oxide 67.0% ~ 67.6%, Cr1.4% ~ 1.6%, Ni0.31% ~ 0.33%, Mo0.14% ~ 0.16%, surplus are cast iron pellets.This aluminum heat flux makes weld structure be bainite, and its hardness can match with bainite rail mother metal.
Adopt traditional pearlitic steel aluminum heat flux (exothermic welding welding material), chemical composition and the pearlite mother metal of weld seam are close; Accordingly, adopt bainitic steel aluminum heat flux, the chemical composition of weld seam is then close with bainite mother metal.And the component difference of pearlite and bainite is larger: the phosphorus content of pearlitic steel 0.7% ~ 0.85%, alloying element total content about about 1.5%; And the phosphorus content of bainitic steel is 0.15% ~ 0.25%, alloying element content is total with about about 4%.Therefore, adopt the welding of pearlite solder flux, because the bainite rail side of carbon to high alloy content is spread, can abnormal structure be produced, cause property of welded joint poor, do not meet technical standard, bring potential safety hazard to the operation of train.
Therefore, be necessary to develop a kind of new aluminum weld material, to solve heavy-haul line pearlite steel rail and bainite rail Welding Problems.
Summary of the invention
For the problems referred to above, one object of the present invention is to provide a kind of new rail aluminum weld aluminum weld material.After this aluminum weld material can guarantee welding, in welding point, in carbon content and bainite rail, carbon content is basically identical, weld seam and melting interface there will not be abnormal structure, thus eliminate the carburetting impact that pearlite steel rail brings, and achieve two kinds of rail and well merge.After measured, joint meets current standard requirement completely, ensure that traffic safety.
In order to realize foregoing invention object, present invention employs following technical scheme:
A kind of bainitic steel and pearlitic steel aluminum weld material, be made up of aluminium powder, iron oxide, iron powder and alloy additive, alloy additive comprises ferromanganese, ferrochrome, ferrosilicon and molybdenum-iron.
Preferably, described bainitic steel and pearlitic steel aluminum weld material, the weight percent content of each component is: aluminium powder 18% ~ 19%, iron oxide 68% ~ 69%, ferromanganese 2.7% ~ 2.8%, ferrochrome 0.6% ~ 0.7%, ferrosilicon 1.1% ~ 1.2%, molybdenum-iron 0.4% ~ 0.6%, all the other are iron powder.
Preferred, described bainitic steel and pearlitic steel aluminum weld material, the weight percent content of each component is: aluminium powder 18.8%, iron oxide 68.8%, ferromanganese 2.79%, ferrochrome 0.62%, ferrosilicon 1.12%, molybdenum-iron 0.5%, and all the other are iron powder.
Preferably, the granularity of described aluminium powder is 10 ~ 80 orders.
Preferably, the granularity of described iron oxide is 30 ~ 60 orders.
Preferably, the granularity of described iron powder is 10 ~ 80 orders.
Preferably, the granularity of described ferrochrome is 10 ~ 60 orders.
Preferably, the granularity of described molybdenum-iron is 10 ~ 60 orders.
Another object of the present invention is the preparation method providing described bainitic steel and pearlitic steel aluminum weld material, comprises and prepares each component according to said ratio, mix, to obtain final product.
A further object of the invention is to provide above-mentioned bainitic steel welding the application in bainitic steel and pearlitic steel with pearlitic steel aluminum weld material; Application particularly in welding bainite rail and pearlite steel rail.
In addition, a further object of the invention is to provide a kind of rail aluminum weld technique adopting above-mentioned bainitic steel and pearlitic steel aluminum weld material, and described rail aluminum weld technique comprises the steps:
(1) sand mold is installed: be placed in sand mold by the termination of two one steel rails to be welded; Be fixed on by sand mold on rail, the left and right two ends of sealing sand mold, make sand mold inside form the chamber that opening is arranged at only top, the termination of two rail is positioned at chamber;
(2) termination preheating: preheating is carried out to the termination being arranged in sand mold by preheating lance, the termination to two one steel rails to be welded is all even up and down in shiny red;
(3) cast aluminum heat flux: after termination preheating completes, is placed on the top of described sand mold opening immediately by the crucible that described bainitic steel and pearlitic steel aluminum weld material are housed, make the corresponding opening in the sprue gate of crucible; Light the high-temperature match be arranged in the middle of aluminum heat flux, cause aluminothermy chemistry, bottom the aluminothermy molten steel fusion crucible of generation from fused plug, pour in sand mold by described opening immediately;
(4) postwelding cooling: aluminothermy molten steel naturally cools to 900 ~ 1000 DEG C in atmosphere; Excise unnecessary weld metal; Then continue to be cooled to room temperature in air, remove residue.
Preferably, in described step (1), the rail gap width 26 ~ 32mm between rail to be welded.
Preferably, in described step (2), preheating lance apart from the height 40 ~ 50mm of rail to be welded, preheating time 5 ~ 6min.
Preferably, in described step (3), welding 60kg/m rail, the consumption of described bainitic steel and pearlitic steel aluminum weld material is 15.9kg ~ 16.3kg.
Also preferred, in described step (3), welding 75kg/m rail, the consumption of described bainitic steel and pearlitic steel aluminum weld material is 17.8kg ~ 18.2kg.
Preferably, in described step (3), after solder flux is lighted, the redox reaction time 2 ~ 10s of solder flux in crucible, is poured into the tranquil time 2 ~ 10s before sand mold after reaction terminates.
The emphasis of welding bainite rail and pearlite steel rail solves Carbon diffusion problem.In welding process, rail interface near zone to be welded, more than 1500 DEG C, melts, to reach welding object by the aluminothermy liquid steel temperature of high temperature casting.But the pearlite side phosphorus content of thawing is more than 0.7%, and the carbon content of bainite side then only has 0.15% ~ 0.25%, and both differ 2 ~ 3 times.According to First Law of Diffusion,
J＝-D·▽C，
Wherein, D is diffusion coefficient, and C is the volumetric concentration (or mass fraction) of diffusion constituent element.Carbon will spread to weld seam from pearlite side.And alloying element content is total and about about 4% in bainite solder flux, far above about 1.5% alloy content in pearlite steel rail, the binding ability of alloying element and carbon is extremely strong, therefore further enhancing the trend that carbon spreads to weld seam from pearlite steel rail.If the component of welding material is inappropriate, all can there is abnormal structure in the interface of aluminothermy molten steel and two kinds of rail to be welded, and two interfaces of weld seam are not all merged very well, cause property of welded joint not reach Industry code requirements.
Novel aluminum thermal weld material provided by the invention, by utilizing diffusion effect, obtains a kind of weld metal of new chemical composition.The weld seam (it adopts the welding material of embodiment 1-3 respectively) obtained for embodiment 4-6, its metal ingredient is as shown in table 1.
The metal chemical composition that table 1 welding material of the present invention obtains
| Element (%) | C | Mn | Si | Cr | Mo | Al |
| Embodiment 4 | 0.217 | 1.428 | 1.174 | 0.529 | 0.354 | 0.104 |
| Embodiment 5 | 0.22 | 1.39 | 1.25 | 0.50 | 0.41 | 0.15 |
| Embodiment 6 | 0.23 | 1.44 | 1.15 | 0.61 | 0.32 | 0.17 |
Above-mentioned weld metal can realize well fusing with pearlitic steel and the bainite steel capital.
Bainitic steel of the present invention and pearlitic steel aluminum weld material, because it specifically forms, simplify welding procedure, molten steel casting is in weld seam, naturally cooling can complete welding process in atmosphere, do not need to carry out welding after-baking, just can reach surface chemistry homogenization of composition effect, the performance of weld seam reaches instructions for use.
Accompanying drawing explanation
Below, describe embodiment of the present invention in detail by reference to the accompanying drawings, wherein:
What Fig. 1 showed is two kinds of rail medium pearlite rail of embodiment 4 welding and the microphoto of aluminum weld material melting interface; Wherein 1A is the microphoto of amplification 50 times, and 1B is the microphoto of amplification 500 times.
Fig. 2 display be the microphoto of bainite rail and aluminum weld material melting interface in two kinds of rail welding of embodiment 4; Wherein 2A is the microphoto of amplification 50 times, and 2B is the microphoto of amplification 500 times.
What Fig. 3 showed is the bainite rail of embodiment 4 welding and the microscopic structure of pearlite steel rail weld seam.
What Fig. 4 showed is the bainite rail of embodiment 5 welding and the microscopic structure of pearlite steel rail weld seam.
What Fig. 5 showed is the bainite rail of embodiment 6 welding and the microscopic structure of pearlite steel rail weld seam.
What Fig. 6 showed is the bainite rail of comparative example 3 welding and the microscopic structure of pearlite steel rail weld seam.
What Fig. 7 showed is the bainite rail of comparative example 4 welding and the microscopic structure of pearlite steel rail weld seam.
What Fig. 8 showed is the bainite rail of comparative example 5 welding and the microscopic structure of pearlite steel rail weld seam.
What Fig. 9 showed is in experimental example 2, and welding point Brinell hardness locates.
Detailed description of the invention
Referring to specific embodiment, the present invention is described.It will be appreciated by those skilled in the art that these embodiments are only for illustration of the present invention, its scope do not limited the present invention in any way.
Experimental technique in following embodiment, if no special instructions, is conventional method.Medicinal raw material used in following embodiment, reagent material etc., if no special instructions, be commercially available purchase product.
embodiment 1a kind of bainitic steel and pearlitic steel aluminum weld material
Consisting of of described bainitic steel and pearlitic steel aluminum weld material:
Aluminium powder 18.8%, iron oxide 68.8%, ferromanganese 2.79%, ferrochrome 0.62%, ferrosilicon 1.12%, molybdenum-iron 0.5%.All the other are iron powder.
Wherein, the granularity of described aluminium powder is 10 ~ 80 orders; The granularity of described iron oxide is 30 ~ 60 orders; The granularity of described iron powder is 10 ~ 80 orders; The granularity of described ferrochrome is 10 ~ 60 orders; The granularity of described molybdenum-iron is 10 ~ 60 orders.
Said components is mixed, namely obtains described bainitic steel and pearlitic steel aluminum weld material.
In the present embodiment, the total amount of alloy additive is 5.03%.
embodiment 2a kind of bainitic steel and pearlitic steel aluminum weld material
Consisting of of described bainitic steel and pearlitic steel aluminum weld material:
Aluminium powder 18.8%, iron oxide 68.8%, ferromanganese 2.7%, ferrochrome 0.6%, ferrosilicon 1.2%, molybdenum-iron 0.6%.All the other are iron powder.
Wherein, the granularity of described aluminium powder is 10 ~ 80 orders; The granularity of described iron oxide is 30 ~ 60 orders; The granularity of described iron powder is 10 ~ 80 orders; The granularity of described ferrochrome is 10 ~ 60 orders; The granularity of described molybdenum-iron is 10 ~ 60 orders.
Said components is mixed, namely obtains described bainitic steel and pearlitic steel aluminum weld material.
In the present embodiment, the total content of alloy additive is 5.1%.
embodiment 3a kind of bainitic steel and pearlitic steel aluminum weld material
Consisting of of described bainitic steel and pearlitic steel aluminum weld material:
Aluminium powder 18.8%, iron oxide 68.8%, ferromanganese 2.8%, ferrochrome 0.7%, ferrosilicon 1.1%, molybdenum-iron 0.4%.All the other are iron powder.
Wherein, the granularity of described aluminium powder is 10 ~ 80 orders; The granularity of described iron oxide is 30 ~ 60 orders; The granularity of described iron powder is 10 ~ 80 orders; The granularity of described ferrochrome is 10 ~ 60 orders; The granularity of described molybdenum-iron is 10 ~ 60 orders.
Said components is mixed, namely obtains described bainitic steel and pearlitic steel aluminum weld material.
In the present embodiment, the total content of alloy additive is 5.0%.
comparative example 1a kind of aluminum weld material
Consisting of of aluminum weld material described in this comparative example:
Aluminium powder 18.8%, iron oxide 68.8%, ferromanganese 3.0%, ferrochrome 0.6%, ferrosilicon 1.5%, molybdenum-iron 0.5%.All the other are iron powder.
Wherein, the granularity of described aluminium powder is 10 ~ 80 orders; The granularity of described iron oxide is 30 ~ 60 orders; The granularity of described iron powder is 10 ~ 80 orders; The granularity of described ferrochrome is 10 ~ 60 orders; The granularity of described molybdenum-iron is 10 ~ 60 orders.
Said components is mixed, namely obtains described aluminum weld material.
In this comparative example, the total content of alloy additive is 5.6%.
comparative example 2a kind of aluminum weld material
Consisting of of aluminum weld material described in this comparative example:
Aluminium powder 18.8%, iron oxide 68.8%, ferromanganese 2.65%, ferrochrome 0.6%, ferrosilicon 1.0%, molybdenum-iron 0.4%.All the other are iron powder.
Wherein, the granularity of described aluminium powder is 10 ~ 80 orders; The granularity of described iron oxide is 30 ~ 60 orders; The granularity of described iron powder is 10 ~ 80 orders; The granularity of described ferrochrome is 10 ~ 60 orders; The granularity of described molybdenum-iron is 10 ~ 60 orders.
Said components is mixed, namely obtains described aluminum weld material.
In this comparative example, the total content of alloy additive is 4.65%.
embodiment 4-6the welding procedure of a kind of pearlitic steel and bainitic steel
Described welding procedure adopts bainitic steel and the pearlitic steel aluminum weld material of embodiment 1-3 respectively, and rail to be welded is 75kg/m pearlite steel rail and 75kg/m bainite rail; Concrete steps are as follows:
(1) sand mold is installed: be placed in sand mold by the termination of two one steel rails to be welded; Be fixed on by sand mold on rail, the rail gap width between pearlite steel rail to be welded and bainite rail is 26 ~ 32mm, the left and right two ends of sealing sand mold, and make sand mold inside form the chamber that opening is arranged at only top, the termination of two rail is positioned at chamber;
(2) termination preheating: preheating is carried out to the termination being arranged in sand mold by preheating lance, preheating lance apart from the height 40 ~ 50mm of rail to be welded, preheating time 5 ~ 6min, the termination to two one steel rails to be welded is all even up and down in shiny red;
(3) cast aluminum heat flux: after termination preheating completes, is placed on the top of described sand mold opening immediately by the crucible that bainitic steel described in 18kg and pearlitic steel aluminum weld material are housed, make the corresponding opening in the sprue gate of crucible; Light the high-temperature match be arranged in the middle of aluminum heat flux, cause aluminothermy chemistry, reaction time 2 ~ 10s; Reaction terminate after tranquil time 2 ~ 10s, bottom the aluminothermy molten steel fusion crucible of generation from fused plug, pour in sand mold by described opening immediately;
(4) postwelding cooling: aluminothermy molten steel naturally cools to 900 ~ 1000 DEG C in atmosphere; Excise unnecessary weld metal; Then continue to be cooled to room temperature in air, remove residue.
comparative example 3the welding procedure of a kind of pearlitic steel and bainitic steel
Described welding procedure adopts bainitic steel and the pearlitic steel aluminum weld material of embodiment 1, and rail to be welded is 75kg/m pearlite steel rail and 75kg/m bainite rail; Concrete steps:
(1) ~ (3): identical with step (1) ~ (3) of embodiment 4;
(4) postwelding cooling: aluminothermy molten steel quenching is to 900 ~ 1000 DEG C; Excise unnecessary weld metal; Then continue to be cooled to room temperature in air, remove residue.
comparative example 4-5the welding procedure of a kind of pearlitic steel and bainitic steel
Described welding procedure adopts the aluminum weld material of comparative example 1 and 2 respectively, and rail to be welded is 75kg/m pearlite steel rail and 75kg/m bainite rail; Concrete steps are identical with embodiment 4.
experimental example 1weld seam chemical composition detects and microstructure observation
The bainite rail of detected object: embodiment 4-6 and comparative example 3-5 welding and the weld seam of pearlite steel rail
1.1 weld seam chemical compositions detect
Require sampling according to TB/T2344-2012, adopt direct-reading spectrometer to carry out chemical composition and relict element inspection, the results are shown in Table 2.
The weld seam chemical composition testing result of each embodiment of table 2 and comparative example
| Element (%) | C | Mn | Si | Cr | Mo | Al |
| Embodiment 4 | 0.217 | 1.428 | 1.174 | 0.529 | 0.354 | 0.104 |
| Embodiment 5 | 0.22 | 1.39 | 1.25 | 0.50 | 0.41 | 0.15 |
| Embodiment 6 | 0.23 | 1.44 | 1.15 | 0.61 | 0.32 | 0.17 |
| Comparative example 3 | 0.217 | 1.428 | 1.174 | 0.529 | 0.354 | 0.104 |
| Comparative example 4 | 0.22 | 1.65 | 1.77 | 0.51 | 0.35 | 0.13 |
| Comparative example 5 | 0.19 | 1.29 | 1.1 | 0.69 | 0.31 | 0.18 |
The weld metal composition of embodiment 4-6, close to bainite parent, can realize well fusing with pearlitic steel and the bainite steel capital.And the composition of the weld metal that the aluminum weld material of the low-alloy content that the aluminum weld material of the high alloy content that comparative example 4 adopts and comparative example 5 adopt obtains all has larger difference, the particularly content of Mn, Si with the composition of bainite parent steel.
1.2 solder flux and rail merge situation to be investigated
To melt run sampling requirement in foundation TB/T1632.3-2014, the weld seam sampling of the bainite rail weld embodiment 4 and pearlite steel rail, observes the fusion situation of weld metal and bainite rail, pearlite steel rail respectively under 50 times and 500 power microscopes after sampling.The results are shown in Figure 1 and Fig. 2, wherein shown in Fig. 1 is the microphoto of pearlite steel rail and aluminum weld material melting interface, and shown in Fig. 2 is the microphoto weld seam of bainite rail and aluminum weld material melting interface.
As can be seen from Fig. 1 and Fig. 2, the solder flux of embodiment 1 all can well be merged the rail of two kinds of unlike materials by the welding procedure described in embodiment 4, does not occur the harmful structure such as martensite, ferrite, retained austenite.
1.3 weld seam microstructure observations
According to the requirement according to Resistance of Weld Metal sample position in TB/T1632.3-2014, carry out microstructure observation from the bainite rail of embodiment 4-6 and comparative example 3-5 welding and the weld seam sampling of pearlite steel rail, the results are shown in Table 3 and Fig. 3-8.
Table 3 pearlite steel rail and bainite rail Microstructure of Weld Metal testing result
With the welding material of embodiment of the present invention 1-3 by welding procedure of the present invention, the microstructures of weld metals obtained is all carbide-free Bainite, tissue without exception and crackle.
Comparative example 3 have employed the welding material of the embodiment of the present invention 1, but improper owing to cooling, and causes the appearance of weld crack.
Comparative example 4 have employed the welding material of the high comparative example of alloy content 1, although welding procedure and technique provided by the invention are as good as, has occurred abnormal structure near melt run.
Comparative example 5 have employed the welding material of the low comparative example of alloy content 2, although welding procedure and technique provided by the invention are as good as, has occurred ferrite in seam organization.
1.4 conclusion
With aluminum weld material of the present invention, by welding procedure of the present invention, welding pearlitic steel rail and bainitic steel rail, weld metal chemical composition is close to bainitic steel, and microstructures of weld metals is carbide-free Bainite, free from flaw and abnormal structure.And no matter be the composition or change welding procedure (mainly the type of cooling) that change welding material, all can there is exception in the microstructures of weld metals obtained, cause adverse influence to the mechanical property of weld seam.Illustrate that aluminum heat flux of the present invention and welding procedure thereof are the specific solutions of welding this specific technical problem for pearlitic steel and bainitic steel.
experimental example 2property of welded joint measures
2.1 welding point hardness tests
The weld seam of the pearlite steel rail that tested object: embodiment 4-6 and comparative example 3-5 welds and bainite rail and weld seam both sides mother metal
Method: according to the method specified by GB/T231.1-2009, end face Weld pipe mill lateral attitude is carried out in-orbit, detects 3 Brinell hardness, calculates average hardness value, is designated as weld hardness; By Fig. 9, weld seam both sides mother metal shows that position detects 3 points respectively, calculate average hardness value, be designated as mother metal average hardness Hp.
Measurement result: in table 4.
Table 4 welding point Determination of Hardness result
Conclusion: according to the regulation of 5.2.4 bar in TB/T1632.3-2014, the welding between different steel grade rail, the quality requirement of welding point performs according to the rail that intensity rank is lower.Measurement result shows, and embodiment 4-6 weld seam realizes mating the good hardness of two kinds of rail, meets current standard requirement.The weld seam of comparative example 3-4 all can not meet current standard; Wherein, comparative example 3 is improper owing to cooling, and crack appears in seam organization, and hardness is higher; The welding material alloy content that comparative example 4 adopts is higher, though be conducive to promoting welding point tread hardness, occur lower bainite in weld metal, property of welded joint reduces; The welding material alloy content that comparative example 5 adopts is lower, and weld metal hardness is on the low side.
1.2 quiet curved tests
Tested object: the pearlite steel rail that embodiment 4 is welded and bainite rail
Method of testing: the method specified according to TB/T1632.3-2014, at welding point after flaw detection, carries out quiet curved test.Long 1.2m ~ the 1.3m of test specimen, Weld pipe mill is positioned at test specimen central authorities.Test specimen is placed on the bearing of offset distance 1m, and weld seam is placed in the middle, and concentrfated load is born at center.Test condition: test specimen temperature 10 DEG C ~ 40 DEG C, pressure head loading speed is not more than 80kN/s.
Measurement result: in table 5.
The quiet curved measurement result of table 5 joint
Conclusion:
With aluminum weld material of the present invention, by welding procedure of the present invention, welding pearlitic steel rail and bainitic steel rail, welding point has good mechanical property, hardness, quietly curved etc. all meets existing professional standard.
In a word, the invention provides a kind of bainitic steel and pearlitic steel aluminum weld material and corresponding welding procedure, weld metal can realize well merging with two ends bainitic steel and the pearlite steel capital, the properties of welding point all meets existing professional standard, thus the problem of poor welding quality between bainitic steel rail and pearlitic steel rail solving that heavy haul railway occurs in replacement process, ensure that traffic safety.
Specific description of embodiments of the present invention does not above limit the present invention, and those skilled in the art can make various change or distortion according to the present invention, only otherwise depart from spirit of the present invention, all should belong to the scope of claims of the present invention.
Claims (10)
1. bainitic steel and a pearlitic steel aluminum weld material, be made up of aluminium powder, iron oxide, iron powder and alloy additive, it is characterized in that, alloy additive comprises ferromanganese, ferrochrome, ferrosilicon and molybdenum-iron; Described bainitic steel and pearlitic steel aluminum weld material, the weight percent content of each component is: aluminium powder 18% ~ 19%, iron oxide 68% ~ 69%, ferromanganese 2.7% ~ 2.8%, ferrochrome 0.6% ~ 0.7%, ferrosilicon 1.1% ~ 1.2%, molybdenum-iron 0.4% ~ 0.6%, all the other are iron powder.
2. bainitic steel according to claim 1 and pearlitic steel aluminum weld material, it is characterized in that, described bainitic steel and pearlitic steel aluminum weld material, the weight percent content of each component is: aluminium powder 18.8%, iron oxide 68.8%, ferromanganese 2.79%, ferrochrome 0.62%, ferrosilicon 1.12%, molybdenum-iron 0.5%, all the other are iron powder.
3. bainitic steel according to claim 1 and 2 and pearlitic steel aluminum weld material, is characterized in that, the granularity of described aluminium powder is 10 ~ 80 orders;
Preferably, the granularity of described iron oxide is 30 ~ 60 orders;
Preferably, the granularity of described iron powder is 10 ~ 80 orders;
Preferably, the granularity of described ferrochrome is 10 ~ 60 orders;
Preferably, the granularity of described molybdenum-iron is 10 ~ 60 orders.
4. the preparation method of the bainitic steel according to any one of claims 1 to 3 and pearlitic steel aluminum weld material, comprises and prepares each component according to said ratio, mix, to obtain final product.
5. the bainitic steel according to any one of claims 1 to 3 is welding the application in bainitic steel and pearlitic steel with pearlitic steel aluminum weld material, the application preferably in welding bainite rail and pearlite steel rail.
6. the bainitic steel of employing according to any one of claims 1 to 3 and the rail aluminum weld technique of pearlitic steel aluminum weld material, described rail aluminum weld technique comprises the steps:
(1) sand mold is installed: be placed in sand mold by the termination of two one steel rails to be welded; Be fixed on by sand mold on rail, the left and right two ends of sealing sand mold, make sand mold inside form the chamber that opening is arranged at only top, the termination of two rail is positioned at chamber;
(2) termination preheating: preheating is carried out to the termination being arranged in sand mold by preheating lance, the termination to two one steel rails to be welded is all even up and down in shiny red;
(3) cast aluminum heat flux: after termination preheating completes, is placed on the top of described sand mold opening immediately by the crucible that described bainitic steel and pearlitic steel aluminum weld material are housed, make the corresponding opening in the sprue gate of crucible; Light the high-temperature match be arranged in the middle of aluminum heat flux, cause aluminothermy chemistry, bottom the aluminothermy molten steel fusion crucible of generation from fused plug, pour in sand mold by described opening immediately;
(4) postwelding cooling: aluminothermy molten steel naturally cools to 900 ~ 1000 DEG C in atmosphere; Excise unnecessary weld metal; Then continue to be cooled to room temperature in air, remove residue.
7. welding procedure according to claim 6, is characterized in that, in described step (1), and the rail gap width 26 ~ 32mm between rail to be welded.
8. the welding procedure according to claim 6 or 7, is characterized in that, in described step (2), preheating lance apart from the height 40 ~ 50mm of rail to be welded, preheating time 5 ~ 6min.
9. the welding procedure according to any one of claim 6 to 8, is characterized in that, in described step (3), and welding 60kg/m rail, the consumption of described bainitic steel and pearlitic steel aluminum weld material is 15.9kg ~ 16.3kg;
Welding 75kg/m rail, the consumption of described bainitic steel and pearlitic steel aluminum weld material is 17.8kg ~ 18.2kg.
10. the welding procedure according to any one of claim 6 to 9, it is characterized in that, in described step (3), after solder flux is lighted, the redox reaction time 2 ~ 10s of solder flux in crucible, is poured into the tranquil time 2 ~ 10s before sand mold after reaction terminates.
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| 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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