CN101412050A - Abrasion-proof cast iron roll collar for straightening steel rail and preparation method thereof - Google Patents

Abstract

The invention provides a wear resistant cast iron roll collar used for aligning a steel rail and a preparation method, which belong to the technical field of steel rail processing. The prior wear resistant cast iron roll collar used for aligning the steel rail has the defects of easy occurrence of cracks, complicated manufacture process and the like in quenching process. The method is to compound a wear resistant outer layer with a magnesium iron inner layer into an integral roll collar by centrifuge casting, wherein the wear resistant outer layer comprises the following ingredients in weight percentage: 3.0 to 3.4 percent of C, 1.5 to 2.0 percent of Si, 1.2 to 1.6 percent of Mn, 0.2 to 0.4 percent of Nb, 0.03 to 0.06 percent of RE, 0.03 to 0.06 percent of Mg, 2.5 to 3.0 percent of Ni, 0.4 to 0.6 percent of Mo, 0.8 to 1.2 percent of Cu, 1.5 to 1.8 percent of Cr, 1.0 to 1.4 percent of V, 0.03 to 0.08 percent of B, 0.002 to 0.005 percent of Te, 0.01 to 0.03 percent of Ba, less than or equal to 0.06 percent of P, less than 0.03 percent of S, and the balancing being Fe. The invention has the advantages of high hardness of the roll collar, good wear resistance, simple production process and low production cost.

Description

A kind of straightening of kinked rail cast iron roll collar and preparation method thereof

Technical field

The invention belongs to the rail processing technique field, be specifically related to a kind of centrifugal casting cast iron roll collar and preparation method thereof, particularly a kind of straightening of kinked rail cast iron roll collar and preparation method thereof.

Background technology

The rail glacing flatness is decision rail service life and the important parameter that influences train running speed, is one of important indicator of weighing the rail quality in kind, and it also directly influences the security and the comfortableness of train operation.Various countries advanced person's Rail Production factory all attaches great importance to the steel rail straightening technology.At several main flatness defects of rail, developed multiple method for aligning.China satisfies speed per hour to surpass 200 kilometers Line for Passenger Transportation and the high-speed railway needs to the high straightness rail, from external many covers steel rail straightening equipment of having introduced.Roll leveller is the equipment for straightening commonly used of straightening of kinked rail, except the aligning that is used for rail, also can be used for the aligning of other steel rolling section bars.

Rail straghtener in the course of the work, smoothing roll rotation, and contact with rail, powerful straightening force is aligned rail between smoothing roll and the rail, the very big frictional force of generation makes smoothing roll produce wearing and tearing gradually simultaneously.Therefore, the wearing and tearing of smoothing roll are that inevitably the main failure forms of smoothing roll is the wearing and tearing of outer circumference surface.The mode that smoothing roll after the wearing and tearing is generally taked is the integral replacing smoothing roll at present.The expensive wrought alloy steel of the general employing of the material of smoothing roll, the annual smoothing roll cost lot of materials of changing is taken.Because the wearing and tearing of smoothing roll only occur in the outer circumference surface that smoothing roll contacts with rail, and the diameter of rail straghtener smoothing roll is bigger, for the purpose that reaches economical with materials, reduces cost, forged steel roll shaft and collars can be in the same place by interference fit, obtain the combination smoothing roll, combination smoothing roll appearance and size after both assemblings is identical with original smoothing roll appearance and size, replaces original smoothing roll with the combination smoothing roll.The combination smoothing roll is in the actual straightening process, and collars can wear and tear gradually, and the wearing and tearing back only needs to change collars, and the roll shaft at center does not need to change, can reuse, so just change original situation about needing, thereby can reach the purpose of economical with materials whole smoothing roll replacing of having worn and torn.At present, the rail straghtener collars generally adopts alloy forged steel such as 9Cr, 9Cr2, Cr12MoV to process both at home and abroad, intensity height, good toughness, but be prone to crackle in the heat-treatment quenching process, and the manufacturing process complexity, stock utilization is low, collars production cost height.Chinese invention patent CN1060501 discloses a kind of high alloy heat-resistance and wear-resistance steel, its chemical analysis percentage by weight is: 1.3-2.4C ,≤1.50Mn ,≤1.50Si, 23-32Cr, 3-8Ni ,≤0.70Mo ,≤0.20Ti, ≤ 0.05P, ≤ 0.05S, surplus is Fe, the like product life-span that the smoothing roll that this steel is made after casting, fine finishining, roll extrusion, lonneal oil immersion, compression roller and cold roll geometric ratio tradition material are made improves more than 3 times.But contain more alloying element, production cost is higher, and casting character is relatively poor.

Chinese invention patent CN101153377 discloses a kind of smoothing roll and manufacturing process thereof.Its material comprises: C:0.60-1.10wt%, Si:0.20-1.0wt%, Mn:0.20-0.60wt%, Ni:0.20-1.00wt%, Cr:4.00-6.00wt%, Mo:0.20-1.00wt%, V:0.10-0.50wt%, P≤0.02wt%, S≤0.02wt%, all the other are iron and unavoidable impurities.Its manufacturing process flow comprises: electric furnace smelting → external refining → ingot casting → rolling electrode → electrode roughing → electroslag remelting → ingot casting → diffusion annealing processing → forging → conditioning treatment → ultrasonic examination+high macroscopic examination → roughing → modified heat treatment → semifinishing → final heat treatment → fine finishining → finished product.The novel smoothing roll of this invention can improve smoothing roll service life and strip surface quality, but needs electroslag remelting and forge processing, complex procedures, and the energy consumption height, stock utilization is low, smoothing roll production cost height.Chinese invention patent CN101161846 also discloses a kind of shaped steel smoothing roll low nickel-chrome-molybdenum alloy cast iron wear-resistant material, and its chemical composition is by weight percentage: C:2.9-3.7%, Si:0.6-1.2%, Mn:0.4-1.2%, Cr:0.6-1.2%, Ni≤0.05%, Mo≤0.03%; Also have tension-active element B, Ti, Sb:0.3%, its ratio range is at 8.5-11.7: 3.8-5.3: 0.9-1.1; Surplus is Fe and inevitable P, S trace element.The high-abrasive material of this invention is mainly used in metal pattern centrifugal casting shaped steel smoothing roll, owing to adopted tension-active element B, Ti, Sb, has enlarged cast iron spoken parts in traditional operas district, makes that its scope reaches deeply that 20mm is above, body of roll working surface hardness is up to HRC55-65.Be not less than the life-span of the nickel chromium triangle molybdenum infinitely chilled ductile cast iron smoothing roll of common employing service life.But this cast iron materials toughness is low, and fragility is big, and when being used for straightening of kinked rail, because the rail strength height, resistance of deformation is big, and roll surface is prone to crackle, even peels off.Therefore, the straightening of kinked rail collars material and the manufacturing process thereof of exploitation good combination property for improving the straightener operating rate, reduce the steel rail straightening cost, improve the glacing flatness of straightening of kinked rail, are extremely important.

Summary of the invention

The objective of the invention is to solve the problems of the prior art, and provide a kind of outer hardness height, wearability good, internal layer intensity height, good toughness adopt straightening of kinked rail that the centrifugal composite casting method produces with cast iron roll collar and preparation method.

A kind of straightening of kinked rail provided by the present invention is the carbide-containing bainite ductile iron with the skin of cast iron roll collar, and outer layer thickness is 60-70mm, and internal layer is a low-alloy spheroidal graphite cast-iron; The outer field chemical composition (wt%) of described collars is: 3.0-3.4C, 1.5-2.0Si, 1.2-1.6Mn, 0.2-0.4Nb, 0.03-0.06RE, 0.03-0.06Mg, 2.5-3.0Ni, 0.4-0.6Mo, 0.8-1.2Cu, 1.5-1.8Cr, 1.0-1.4V, 0.03-0.08B, 0.002-0.005Te, 0.01-0.03Ba ， ≦ 0.06P,＜0.03S, surplus Fe, wherein, 0.06% ≦ RE+Mg ≦ 0.10%; The chemical composition of internal layer (wt%) is 3.3-3.6C, 2.2-2.6Si, and＜0.5Mn,＜0.3Cr, 0.2-0.5Ni, 0.2-0.4Cu, 0.03-0.06RE, 0.03-0.06Mg,＜0.08P,＜0.03S, surplus Fe, wherein, 0.06% ≦ RE+Mg ≦ 0.10%.

A kind of straightening of kinked rail provided by the present invention preparation method of cast iron roll collar may further comprise the steps:

1. the outer cast iron of melting: earlier with ordinary scrap steel, graphite block, ferrochrome, ferrosilicon, ferromanganese, molybdenum-iron, ferro-niobium, nickel plate and the fusing of copper coin Hybrid Heating, the molten clear back of molten iron adds vanadium iron, the stokehold is adjusted to branch and temperature is risen to 1520-1550 ℃ after qualified, then come out of the stove, outer molten iron is come out of the stove in the process, with 75Si-Fe and baric Si-Fe molten iron being carried out current-following inoculation handles, and pour method with the magnesium-rare earth employing and carry out spheroidising, when molten iron is come out of the stove 40-60%, ferro-boron and tellurium iron are crushed to the fritter that granularity is 6-10mm, directly throw away in the ladle after living with paper bag, molten iron is through leaving standstill, to be cast after skimming;

2. melting internal layer cast iron: earlier with ordinary scrap steel, graphite block, ferrochrome, ferrosilicon, ferromanganese, nickel plate and the fusing of copper coin Hybrid Heating, the stokehold is adjusted to branch and temperature is risen to 1480-1520 ℃ after qualified, then come out of the stove, the internal layer molten iron is come out of the stove in the process, with 75Si-Fe molten iron being carried out current-following inoculation handles, and pour method with the magnesium-rare earth employing and carry out spheroidising, molten iron is to be cast after leaving standstill, skimming;

3. on centrifuge, pour into a mould collars: pour into a mould outer molten iron earlier, outer layer thickness is controlled at 60-70mm, outer molten steel pouring temperature is 1400-1440 ℃, behind outer molten steel solidification, when internal surface temperature is lower than solidus temperature 20-50 ℃, pour into the internal layer molten iron, the internal layer molten steel pouring temperature is 1350-1380 ℃;

4. carry out stress relief annealing directly into annealing furnace after collars solidifies and handle, heating-up temperature is 420-450 ℃, and temperature retention time is 12-15 hour, and air cooling to room temperature obtained the straightening of kinked rail cast iron roll collar after stove was chilled to and is less than or equal to 180 ℃.

The performance of collars is by the metallographic structure decision, and certain tissue depends on chemical composition, and the chemical composition of collars wear resistant outer layer of the present invention is to determine like this:

C:C is the basic element in the cast iron, and the existence form in cast iron mainly contains two kinds: the one, exist with free state graphite; Another kind is that the form with carbide exists.In magnesium iron, carbon mainly exists with globular graphite, and after the spheroidization of graphite, graphite quantity is just no longer fairly obvious to the adverse effect of mechanical performance.After adding strong carbide forming elements such as Cr, V, Nb in the cast iron, C adds makes the easy high rigidity carbide that forms in the foundry goods tissue, helps improving the foundry goods wearability.In addition, in order to improve the molten iron casting character, when eutectic composition is following, carbon is always maintained at high level, utilize graphited expansion with compensate for shrinkage, increase the compactness of foundry goods, be beneficial to and guarantee that foundry goods has higher comprehensive mechanical performance, increase the absorptivity that phosphorus content can improve magnesium simultaneously, help nodularization.Therefore, the appropriate C addition is 3.0-3.4%.

The graphitizability of Si:Si is equivalent to 1/3 of C, promotes graphitization strongly, can increase graphite nodule quantity so increase Si, and it is very abundant that the increase of si content often makes magnesium iron breed, and obtaining many and graphite rounding of quantity is that eutectic cell is fined; Silicon can also promote bainitic transformation; In addition, silicon can be well in and manganese element to the illeffects of bainite ductile iron.But Si measures too high meeting causes graphite thick.Suitable Si content should be controlled at 1.5-2.0%.

Mn:Mn can significantly postpone perlitic transformation, and perlitic transformation district in the cooling curve and bainite transformation district are obviously separated, and it is to increase the stronger cheap element of quenching degree ability.But it is thick that Mn organizes foundry goods, and heat crack resistance descends, and for preventing to occur hot tearing in the foundry goods, so the addition of Mn is also unsuitable too high, and suitable Mn content is controlled at 1.2-1.6%.

Ni, Mo and Cu:Ni, Mo and Cu obtain as-cast bainite magnesium iron alloying element commonly used.Ni enlarges the austenitic area, hinders austenite and decomposes, and reduces the sensitiveness of bainite transformation product to casting section thickness.Because of the outer wear resistant cast iron thickness of composite ring of the present invention has only 60-70mm, therefore, Ni content needn't add too much, otherwise as-cast structure mainly is an austenite, and the bainite amount is unfavorable for improving the cast iron wearability very little.The great advantage of Mo is to improve quenching degree, hinders perlitic transformation, does not separate out and do not hinder acicular ferrite, because its normal segregation in cast iron is inclined to, can offset the negative segregation effect of Ni.The effect of Cu is similar with Ni, but it is strong to be not so good as Ni, and is cheap because of it, be commonly used to replace part Ni, Cu also plays the effect of stable austenite, again can thinning microstructure, reduction also has reinforced ferrite along the sensitiveness of section metallographic structure, improves its hardness and the effect that improves wearability.Suitable Ni addition is 2.5-3.0%, and the Mo addition of alloy is 0.4-0.6%, and the Cu addition of alloy is 0.8-1.2%.

V and Cr:V and Cr are the strong carbide forming elements, add the MC and the M that easily form high rigidity in the magnesium iron ₃C type carbide help improving the hardness and the wearability of cast iron, but addition is too much, and carbide quantity increases and is thick, the intensity and the toughness of infringement cast iron, and suitable V addition is 1.0-1.4%, appropriate C r addition is 1.5-1.8%.

Nb:Nb atomic radius and Fe are close, can only form limited solid solution in austenite, hold effect according to solute, and the Nb that is dissolved in the austenite improves the stability of overcooling austenite, thereby improves its quenching degree.Nb has strong inoculation(effect) and is not subjected to time restriction, also promotes spheroidization of graphite simultaneously, and grain refinement, eutectic mass size are reduced, and diffusion length shortens when making the carbon precipitation, helps reducing the concentration of carbon in the austenite, thereby helps the forming core and the growth of bainite.Nb also forms the NbC disperse in matrix in magnesium iron, can prevent the slippage between crystallites in the flow of metal process effectively, hinders the expansion of crackle.Therefore, Nb adds in the bainite ductile iron and helps improving bainite ductile iron tissue, improves its mechanical property, and addition is much excessively, easily forms the thick Nb carbide that contains, and damages the intensity and the toughness of bainite ductile iron, and suitable Nb addition is 0.2-0.4%.

B:B reduces the cast iron critical speed, increases the element of quenching degree, and B also increases the hardness of spheroidal graphite cast-iron, helps improving the spheroidal graphite cast-iron wearability, adds the effect that B also has refinement as-cast ball iron bainite pin, helps improving cast iron intensity, and improves its toughness.But addition is too much, easily forms the boron carbon compound, damages the intensity and the toughness of cast iron on the contrary.B is a tension-active element, but when handling with magnesium-rare earth, the anti-spheroidizing of boron is not strong.Rare earth and magnesium total content contain 0.03-0.08%B greater than 0.06%, can obtain tiny graphite nodule, and after B content was above 0.08%, part graphite became sheet, and cast iron intensity and toughness descend, and suitable B addition is 0.03-0.08%.

The boiling point of Te:Te is very low, and in molten iron, early solidification can be used as crystallization nuclei with the gaseous state disperse, is solidifying the intermediary and later stages, and Te mainly is enriched in its colony forward position, makes molten iron produce serious constitutional supercooling, thereby changes solidification mode, and austenite and Fe appear in the part ₃The C eutectic structure.In addition, Te is enriched in the eutectic forward position, hinders the diffusion of carbon to graphite, makes the too much carbon of delay in the molten iron, thus refinement graphite nodule.Trace Te can also impel casting section centre graphite rounding, graphite nodule homogenising.In the eutectoid reaction stage, Te reduces eutectoid temperature, thereby increases the eutectoid reaction degree of supercooling, promotes forming core, the growth of upper bainite, and the upper bainite amount is increased.Suitable Te addition is 0.002-0.005%.

Ba:Ba brings into from baric ferrosilicon inovulant, the wear-resistant bainite magnesium iron adopts the baric ferrosilicon to breed, has the effect that obvious enhancing is bred, can make graphite nodule tiny, be evenly distributed, help improving the intensity and the toughness of cast iron, baric ferrosilicon addition is 0.3-0.4%, and the residual quantity of Ba is 0.01-0.03%.

RE and Mg: the main purpose that adds RE and Mg in the magnesium iron has been the effect of deoxidation, desulfuration and purifying molten iron, help spheroidization of graphite, addition is very few, graphite is difficult for balling-up, and addition is too much, the waste nodulizer, increase the castings production cost, suitable R E addition is 0.03-0.06%, and suitable Mg addition is 0.03-0.06%, and 0.06% ≦ RE+Mg ≦ 0.10%.

P:P solubility in solid iron is limited, and is little to the graphitization influence.But the increase of P can make the shrinkage cavity, shrinkage porosite of cast iron and tearing tendency increase, during P also has and the effect of Mo.In addition, because very easily segregation of P, general P content is near 0.1% iron phosphide eutectic that 2-3% will occur, and the foundry goods wall is thick more, and segregation is serious more.Because formed iron phosphide eutectic fusing point is low, in the ductile iron solidification process, keep liquid always, constantly squeezed by eutectic cell, last " expulsion " solidifies there to the eutectic cell border.Iron phosphide eutectic is cerioid and is distributed on the eutectic cell border.Because the shape of iron phosphide eutectic and distribution are very big to the mechanical performance influence of spheroidal graphite cast-iron, cerioid, hard crisp iron phosphide eutectic cause stress to concentrate easily, impact slight crack when being subjected to impact load always along the iron phosphide eutectic edge distribution, thereby reduced plasticity, toughness and the intensity of spheroidal graphite cast-iron.Consider raw-material influence, P content is controlled at below 0.06%.

S:S can stablize cementite, stops graphitization.Its major part is present in the cast iron with forms such as FeS, MnS and CeS, and is distributed on the crystal boundary, and wherein the FeS fusing point is low, fragility is big, is distributed in intensity and toughness that crystal boundary significantly reduces cast iron; MnS fusing point height, and with the graininess distribution, little to the cast iron intensity effect, but make the molten iron retrogradation, mobile decline; S content height has a strong impact on the nodularization effect, increases the consumption of nodulizer.Therefore lower better, during batching in the molten iron original S be controlled at below 0.04%, after nodularization was skimmed, S content should be lower than 0.03%.

Compared with prior art, the present invention has following beneficial effect:

1) directly obtain bainite ductile iron under the collars as cast condition of the present invention owing to saved high-temperature heat treatment, thereby have energy-conservation, save time, shorten the production cycle and improve advantage such as production environment.

2) collars of the present invention contains the 15-20% carbide on the as-cast bainite matrix, makes the as-cast bainite collars keep having high rigidity and excellent abrasive under high strength and the high tenacity prerequisite, and its tensile strength is greater than 900Mpa, and impact flexibility is greater than 15J/cm ², hardness is 56-58HRC, the roll surface difference of hardness is less than 2HRC.

3) collars of the present invention is compared with wrought alloy steel rider ring, the stock utilization height, and processing capacity is few, and production cost is low; Compare with common cast iron roll collar, overcome that common cast iron roll collar toughness is low, fragility is big, be prone to crackle in the use, peel off and fall the phenomenon that piece etc. influences the normal operation of equipment.

4) cast iron roll collar of the present invention is used for rail straghtener, each straightening of kinked rail amount reaches ten thousand tons of 1.5-1.6, each monolateral reconditioning quality is 0.8-1.0mm, not only straightening of kinked rail quantity is many, and reconditioning quality is few, and is safe in utilization, reliable, flawless in the use, peels off and falls the piece phenomenon and occur, and straightening of kinked rail glacing flatness height, can satisfy the requirement of 300km/h high speed rail.Use collars of the present invention, also can improve the equipment for straightening production operational availability, alleviate labor strength, reduce the steel rail straightening cost, have remarkable economical and social benefit.

Description of drawings

Fig. 1, the straightening of kinked rail provided by the present invention structural representation of cast iron roll collar, wherein, 1 is collars skin (wearing layer), 2 is internal layer.

The invention will be further described below in conjunction with the drawings and specific embodiments.

The specific embodiment

All adopt skin and the internal layer of 1500 kilograms of medium-frequency induction furnace melting straightening of kinked rail among the following embodiment with cast iron roll collar.

Embodiment 1

1. the outer cast iron of melting: earlier with ordinary scrap steel, graphite block, ferrochrome, ferrosilicon, ferromanganese, molybdenum-iron, ferro-niobium, nickel plate and the fusing of copper coin Hybrid Heating, the molten clear back of molten iron adds vanadium iron, the stokehold is adjusted to branch and temperature is risen to 1540 ℃ after qualified, then come out of the stove, outer molten iron is come out of the stove in the process, with 75Si-Fe and baric Si-Fe (5-7%Ba, 65-70%Si, 0.8-1.5%Ca, 1.0-1.8%Al, surplus Fe) molten iron is carried out current-following inoculation and handle, and pour method with the magnesium-rare earth employing and carry out spheroidising, when molten iron is come out of the stove 40-60%, ferro-boron and tellurium iron are crushed to the fritter of granularity 6-10mm, directly throw away in the ladle after living with paper bag, molten iron is through leaving standstill, after skimming, can pour into a mould;

2. melting internal layer cast iron: earlier with ordinary scrap steel, graphite block, ferrochrome, ferrosilicon, ferromanganese, nickel plate and the fusing of copper coin Hybrid Heating, the stokehold is adjusted to branch and temperature is risen to 1498 ℃ after qualified, then come out of the stove, the internal layer molten iron is come out of the stove in the process, with 75Si-Fe molten iron being carried out current-following inoculation handles, and pour method with the magnesium-rare earth employing and carry out spheroidising, molten iron can be poured into a mould after leaving standstill, skimming;

3. pour into a mould collars on centrifuge: first outer 1 molten iron of cast, outer 1 THICKNESS CONTROL be at 60-70mm, 1422 ℃ of outer 1 molten steel pouring temperatures; Behind outer 1 molten steel solidification, when internal surface temperature is lower than solidus temperature 20-50 ℃, pour into internal layer 2 molten iron, 1375 ℃ of internal layer 2 molten steel pouring temperatures;

4. carry out stress relief annealing directly into annealing furnace after collars solidifies and handle, 440 ℃ of heating-up temperatures, temperature retention time 14 hours, air cooling was machined to given size and precision at last to room temperature after stove was chilled to 180 ℃.The collars composition sees Table 1, and the outer mechanical property of collars sees Table 2.

Element	C	Si	Mn	P	S	RE	Mg	Nb
									Outer	3.21	1.78	1.44	0.039	0.016	0.038	0.051	0.28
Internal layer	3.47	2.36	0.31	0.042	0.020	0.040	0.046	-
									Element	Ni	Mo	Cu	Cr	V	B	Te	Ba
Outer	2.80	0.54	0.99	1.68	1.25	0.046	0.003	0.024
									Internal layer	0.27	-	0.31	0.18	-	-	-	-

The chemical composition of table 1 cast iron roll collar (weight %)

Tensile strength/MPa	Impact flexibility/(J/cm 2)	Hardness/HRC	Roll surface difference of hardness/HRC
				938.3	16.2	57.1	1.4

The outer mechanical property of table 2 collars

Embodiment 2

1. the outer cast iron of melting: earlier with ordinary scrap steel, graphite block, ferrochrome, ferrosilicon, ferromanganese, molybdenum-iron, ferro-niobium, nickel plate and the fusing of copper coin Hybrid Heating, the molten clear back of molten iron adds vanadium iron, the stokehold is adjusted to branch and temperature is risen to 1522 ℃ after qualified, then come out of the stove, outer molten iron is come out of the stove in the process, with 75Si-Fe and baric Si-Fe (5-7%Ba, 65-70%Si, 0.8-1.5%Ca, 1.0-1.8%A1, surplus Fe) molten iron is carried out current-following inoculation and handle, and pour method with the magnesium-rare earth employing and carry out spheroidising, when molten iron is come out of the stove 40-60%, ferro-boron and tellurium iron are crushed to the fritter of granularity 6-10mm, directly throw away in the ladle after living with paper bag, molten iron is through leaving standstill, after skimming, can pour into a mould;

2. melting internal layer cast iron: earlier with ordinary scrap steel, graphite block, ferrochrome, ferrosilicon, ferromanganese, nickel plate and the fusing of copper coin Hybrid Heating, the stokehold is adjusted to branch and temperature is risen to 1509 ℃ after qualified, then come out of the stove, the internal layer molten iron is come out of the stove in the process, with 75Si-Fe molten iron being carried out current-following inoculation handles, and pour method with the magnesium-rare earth employing and carry out spheroidising, molten iron can be poured into a mould after leaving standstill, skimming;

3. pour into a mould collars on centrifuge: the first outer molten iron 1 of cast, outer 1 THICKNESS CONTROL be at 60-70mm, 1407 ℃ of outer 1 molten steel pouring temperatures; Behind outer 1 molten steel solidification, when internal surface temperature is lower than solidus temperature 20-50 ℃, pour into internal layer 2 molten iron, 1378 ℃ of internal layer 2 molten steel pouring temperatures;

4. carry out stress relief annealing directly into annealing furnace after collars solidifies and handle, 420 ℃ of heating-up temperatures, temperature retention time 15 hours, air cooling was machined to given size and precision at last to room temperature after stove was chilled to 180 ℃.The collars composition sees Table 3, and the outer mechanical property of collars sees Table 4.

Element	C	Si	Mn	P	S	RE	Mg	Nb
									Outer	3.01	1.97	1.20	0.041	0.019	0.031	0.058	0.38
Internal layer	3.58	2.20	0.35	0.046	0.021	0.058	0.030	-
									Element	Ni	Mo	Cu	Cr	V	B	Te	Ba
Outer	2.99	0.40	0.81	1.52	1.05	0.080	0.003	0.012
									Internal layer	0.48	-	0.20	0.14	-	-	-	-

The chemical composition of table 3 cast iron roll collar (weight %)

Tensile strength/MPa	Impact flexibility/(J/cm 2)	Hardness/HRC	Roll surface difference of hardness/HRC
				914.6	16.4	56.4	1.6

The outer mechanical property of table 4 collars

Embodiment 3

1. the outer cast iron of melting: earlier with ordinary scrap steel, graphite block, ferrochrome, ferrosilicon, ferromanganese, molybdenum-iron, ferro-niobium, nickel plate and the fusing of copper coin Hybrid Heating, the molten clear back of molten iron adds vanadium iron, the stokehold is adjusted to branch and temperature is risen to 1549 ℃ after qualified, then come out of the stove, outer molten iron is come out of the stove in the process, with 75Si-Fe and baric Si-Fe (5-7%Ba, 65-70%Si, 0.8-1.5%Ca, 1.0-1.8%A1, surplus Fe) molten iron is carried out current-following inoculation and handle, and pour method with the magnesium-rare earth employing and carry out spheroidising, when molten iron is come out of the stove 40-60%, ferro-boron and tellurium iron are crushed to the fritter of granularity 6-10mm, directly throw away in the ladle after living with paper bag, molten iron is through leaving standstill, after skimming, can pour into a mould;

2. melting internal layer cast iron: earlier with ordinary scrap steel, graphite block, ferrochrome, ferrosilicon, ferromanganese, nickel plate and the fusing of copper coin Hybrid Heating, the stokehold is adjusted to branch and temperature is risen to 1483 ℃ after qualified, then come out of the stove, the internal layer molten iron is come out of the stove in the process, with 75Si-Fe molten iron being carried out current-following inoculation handles, and pour method with the magnesium-rare earth employing and carry out spheroidising, molten iron can be poured into a mould after leaving standstill, skimming;

3. pour into a mould collars on centrifuge: first outer 1 molten iron of cast, outer 1 THICKNESS CONTROL be at 60-70mm, 1438 ℃ of outer 1 molten steel pouring temperatures; Behind outer 1 molten steel solidification, when internal surface temperature is lower than solidus temperature 20-50 ℃, pour into internal layer 2 molten iron, 1351 ℃ of internal layer 2 molten steel pouring temperatures;

4. carry out stress relief annealing directly into annealing furnace after collars solidifies and handle, 450 ℃ of heating-up temperatures, temperature retention time 12 hours, air cooling was machined to given size and precision at last to room temperature after stove was chilled to 180 ℃.The collars composition sees Table 5, and the outer mechanical property of collars sees Table 6.

Element	C	Si	Mn	P	S	RE	Mg	Nb
									Outer	3.39	1.50	1.58	0.037	0.015	0.055	0.032	0.20
Internal layer	3.30	2.58	0.41	0.045	0.021	0.031	0.056	-
									Element	Ni	Mo	Cu	Cr	V	B	Te	Ba
Outer	2.54	0.57	1.16	1.50	1.39	0.032	0.005	0.027
									Internal layer	0.21	-	0.40	0.21	-	-	-	-

The chemical composition of table 5 cast iron roll collar (weight %)

Tensile strength/MPa	Impact flexibility/(J/cm 2)	Hardness/HRC	Roll surface difference of hardness/HRC
				948.0	15.5	57.7	1.4

The outer mechanical property of table 6 collars

Cast iron roll collar of the present invention has been carried out commerical test respectively on rail horizontal roller straightener and edger roll straightener, horizontal roller straightener top roll ring size is: outside diameter φ 1280mm, diameter of bore φ 750mm, collars height 85mm; Edger roll straightener top roll ring size is: outside diameter φ 801mm, diameter of bore φ 460mm, collars height 168mm.The horizontal roller straightener is aligned rail on the X-X direction, smoothing roll quantity: 8; Drive roll quantity: 8; The horizontal roller spacing:〉1500mm; The maximum straightening force of single roller:〉3000kN; Axial adjusting range: ± 40mm; Aligning speed: 0.3-2.0m/s (when wherein straightener had just begun to start, aligning speed was 0.3m/s, and the speed of aligning then progressively reaches 1.0m/s, and exit aligning speed reaches 2.0m/s).The edger roll straightener is aligned rail on Y-Y direction.Smoothing roll quantity: 7; Drive roll quantity: 4; The edger roll spacing:〉600mm; The maximum straightening force of single roller:〉1500kN; Axial adjusting range: ± 25mm; Aligning speed: 0.3-2.0m/s.The replacing of smoothing roll and balance adopt the high-pressure and hydraulic device to finish.

Collars hardness height of the present invention, uniformity of hardness are good, and intensity height, wearability are good, and each straightening of kinked rail amount reaches ten thousand tons of 1.5-1.6, and each monolateral reconditioning quality is 0.8-1.0mm.And forge the each straightening of kinked rail amount of Cr12MoV collars only is ten thousand tons of 1.0-1.2, and each monolateral reconditioning quality is 1.0-1.2mm; The each straightening of kinked rail amount of import cast iron roll collar only is ten thousand tons of 0.8-1.3, and each monolateral reconditioning quality is 1.0-1.5mm, and crackle often occurs, peel off and fall phenomenons such as piece.Collars of the present invention is safe in utilization, reliable, and not only straightening of kinked rail quantity is many, and reconditioning quality is few, and flawless in the use, peel off and fall the piece phenomenon and occur, and straightening of kinked rail glacing flatness height, can satisfy the requirement of 300km/h high speed rail.Use collars of the present invention, also can improve the equipment for straightening production operational availability, alleviate labor strength, reduce the steel rail straightening cost, have remarkable economical and social benefit.

Claims (2)

1, a kind of straightening of kinked rail cast iron roll collar is characterized in that, the outer field chemical composition wt% of described collars is: 3.0-3.4C, 1.5-2.0Si, 1.2-1.6Mn, 0.2-0.4Nb, 0.03-0.06RE, 0.03-0.06Mg, 2.5-3.0Ni, 0.4-0.6Mo, 0.8-1.2Cu, 1.5-1.8Cr, 1.0-1.4V, 0.03-0.08B, 0.002-0.005Te, 0.01-0.03Ba ≦ 0.06P,＜0.03S, surplus Fe, wherein, 0.06% ≦ RE+Mg ≦ 0.10%, outer field thickness are 60-70mm; The chemical composition of internal layer (wt%) is 3.3-3.6C, 2.2-2.6Si, and＜0.5Mn,＜0.3Cr, 0.2-0.5Ni, 0.2-0.4Cu, 0.03-0.06RE, 0.03-0.06Mg,＜0.08P,＜0.03S, surplus Fe, wherein, 0.06% ≦ RE+Mg ≦ 0.10%.

2, a kind of straightening of kinked rail according to claim 1 is characterized in that with the preparation method of cast iron roll collar, may further comprise the steps:

1. the outer cast iron of melting: earlier with ordinary scrap steel, graphite block, ferrochrome, ferrosilicon, ferromanganese, molybdenum-iron, ferro-niobium, nickel plate and the fusing of copper coin Hybrid Heating, the molten clear back of molten iron adds vanadium iron, the stokehold is adjusted to branch and temperature is risen to 1520-1550 ℃ after qualified, then come out of the stove, outer molten iron is come out of the stove in the process, with 75Si-Fe and baric Si-Fe molten iron being carried out current-following inoculation handles, and pour method with the magnesium-rare earth employing and carry out spheroidising, when molten iron is come out of the stove 40-60%, ferro-boron and tellurium iron are crushed to the fritter that granularity is 6-10mm, directly throw away in the ladle after living with paper bag, molten iron is through leaving standstill, to be cast after skimming;

2. melting internal layer cast iron: earlier with ordinary scrap steel, graphite block, ferrochrome, ferrosilicon, ferromanganese, nickel plate and the fusing of copper coin Hybrid Heating, the stokehold is adjusted to branch and temperature is risen to 1480-1520 ℃ after qualified, then come out of the stove, the internal layer molten iron is come out of the stove in the process, with 75Si-Fe molten iron being carried out current-following inoculation handles, and pour method with the magnesium-rare earth employing and carry out spheroidising, molten iron is to be cast after leaving standstill, skimming;

3. on centrifuge, pour into a mould collars: pour into a mould outer molten iron earlier, outer layer thickness is controlled at 60-70mm, outer molten steel pouring temperature is 1400-1440 ℃, behind outer molten steel solidification, when internal surface temperature is lower than solidus temperature 20-50 ℃, pour into the internal layer molten iron, the internal layer molten steel pouring temperature is 1350-1380 ℃;

4. carry out stress relief annealing directly into annealing furnace after collars solidifies and handle, heating-up temperature is 420-450 ℃, and temperature retention time is 12-15 hour, and air cooling to room temperature obtained the straightening of kinked rail cast iron roll collar after stove was chilled to and is less than or equal to 180 ℃.

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