CN105385938B - Alloy system, heat treatment method for Bainite steel rail of alloy system and Bainite steel rail - Google Patents
Alloy system, heat treatment method for Bainite steel rail of alloy system and Bainite steel rail Download PDFInfo
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- CN105385938B CN105385938B CN201510919742.9A CN201510919742A CN105385938B CN 105385938 B CN105385938 B CN 105385938B CN 201510919742 A CN201510919742 A CN 201510919742A CN 105385938 B CN105385938 B CN 105385938B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
- C21D1/20—Isothermal quenching, e.g. bainitic hardening
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
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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
- C21D9/04—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rails
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
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Abstract
The invention provides an alloy system, a heat treatment method for a Bainite steel rail of the alloy system and the Bainite steel rail. The alloy system comprises, by mass, 0.22-0.27% of C, 1.65-1.85% of Si, 1.60-1.80% of Mn, 1.30-1.90% of Cr, 0.25-0.85% of Mo, 0.25-0.95% of Ni, 0.040-0.060% of V or 0.020-0.040% of Nb, 0.015% or less of P, 0.015% or less of S, and the balance Fe and inevitable impurity elements. The impurity elements are strictly controlled according to the standards that (1) gas content: molten steel [H]<=2.0 ppm, casting blanks [H]<=1.5 ppm, [O]<=25 ppm, and [N]<=70 ppm; and (2) residual elements: Al<=0.006%, Cu<=0.15%, Sn<=0.010%, and Sb<=0.010%. The heat treatment method has the production characteristics that refining of austenite structures as well as segregation and unevenness of elements and microstructures are effectively controlled, so that fine and even lower Bainite structures are obtained easily after the cooling phase change, it is guaranteed that phase change of the lower Bainite structures of the steel rail occurs completely through effective control, and accordingly the Bainite steel rail high in performance is obtained.
Description
Technical field
The invention belongs to the technical field of heat treatment of bainite rail, is specifically related to a kind of alloy system and its bainite
The heat treatment method and bainite rail of rail.
Background technology
China's heavy haul railway annual traffic has surpassed hundred million tons, and two of which fortune coal heavy haul railway main line Shuohuang Railway year transports coal
Amount surpass 200,000,000 tons, year of expanding on Dalian-Qinhuangdao Railway fortune coal amount fortune coal amount surpass 400,000,000 tons.Train shaft weight is also improved constantly, and Shuohuang Railway axle weighs 30 tons
Heavy haul train is tested successfully.With the raising of railway transporting amount, the serious trauma of tensile strength 980MPa level pearlite steel rail is
Become the bottleneck of ferrum freight volume raising.Low-alloy high-strength bainite rail more than 1200MPa levels is selected, becomes last decade
Carry out the Main way of heavy haul railway rail exploitation.
In low-alloy high-strength bainite rail technical field, successively there are up to ten remainder patents to be authorized, specifically
It is as follows：Patent of invention number：02158853.8, wear-resistant, high-strength tenacity meta-bainite rail and its manufacture method.Patent of invention
Number：200510047907.4, the rail and its production method of the bainite structure with excellent anti-fatigue performance.Patent of invention
Number：2011104191837, a kind of high strength bainite steel rail and its Technology for Heating Processing.Patent of invention number：2011100778921,
A kind of corrosion-resistant bainite rail.Patent of invention number:98112095.4, high speed quasi high-speed highway road basin high-performance abrasion-proof steel and its
Manufacture method.Patent of invention number：2009100635812, a kind of ultra-high strength bainite rail steel and its manufacture method.Invention
The patent No.：02158852.X, wear-resistant, high-strength tenacity meta-bainite railroad turnout steel rail and its production technology.Patent of invention number：
200610012673.4, dedicated tungsten-containing bainite forged steel for railway frog crossing and its manufacture method.Patent of invention number：99800029.9,
Bainitic steel rail with high resistance to surface fatigue defect and high-wearing feature.Patent of invention number：94101720.6, have excellent
The manufacture method of the bainite high duty rails of resistance to rolling contact fatigue trauma.
It is micro- that above-mentioned patented technology employs the alloy such as addition Cr, Mo, Ni and V, Nb in the high Mn alloy systems of the high Si of middle C
The technology path without carbon bainite steel of alloying element.Purpose is desirable to just obtain shellfish under the conditions of air cooling only with hot rolling production
Family name's body microstructure, so as to obtain high intensity and high-plasticity energy.But the core feature without carbon bainite is still upper shellfish
The structure and morphology feature of lath bainitic ferrite and retained austenite in family name's body.Pass through Si, Mn, Mo through the research of scholar
Alloy content regulation and control, it is suppressed that too growing up simultaneously for bainite ferrite lath, make retained austenite in meta-bainite
Number size is effectively controlled, and microscopic observation is to be similar to non-isometry ferrite pattern, but partial austenitic but with geneva
Body phase is more goed deep into micro analysiss and is shown in the form of becoming, and meta-bainite still has lath bainitic ferrite pattern, i.e.,
So-called to define the new atypical quasi-bainite steel of Si-Mn-Mo series, this bainite can not still be completely free of plate
Bar bainite ferrite Facial Features, i.e. upper bainite tissue signature, the increase however as Mn, Mo content but increased rail
The probability that section local martensitic structure quantity increases can not be effectively controlled, in the quasi-bainite steel that current document is announced
Contain a small amount of martensitic structure, in actual applications effect is not very good for this line and staff control's rail.
Show that so-called hot rolling and air cooling bainite rail is required at the tempering after rolling in specific actual production and application
Reason, is beneficial to the stability for reducing bainitic steel high residual stress inherently to ensure rail military service performance.Even if such as
This, detection and analysis shows that the residual stress of bainite rail is higher than still pearlite steel rail.Simultaneously because rail shaped steel section becomes
Change it is big, and bainite structure it is sensitive to cooling condition the characteristics of, bainite rail in actual hot rolling production, either carbon-free shellfish
Because of its high silicomanganese content, to significantly cause composition inclined for rail different parts cooling rate inconsistent for family name's body or meta-bainite rail
Analysis, local produce martensitic structure or retained austenite coarsening, and residual stress is too high, and Aging Characteristic is obvious, rail entire body
Can inconsistent, section performance change it is very prominent the characteristics of big, when being acted on by external force such as Wheel Rail Contact rub condition
Under, there is acute variation in localized micro tissue and performance, and the phenomenons such as rail break, stripping, fish scale wound occur.Its result is upper track clothes
There is mixed phenomenon in the labour life-span, and the popularization for making bainite rail is constantly subjected to limit.It is stable and prolongation bainite rail
Service life has become the emphasis of bainite rail exploitation.
In sum, need to develop a kind of structure stability, obdurability, the higher lower bainite tissue steel of fatigue performance
Rail.Lower bainite has following characteristics of organizational structure：1. the spatial shape of lower bainite is in lenticular, with sample flour milling phase
Hand in the form of sheets or needle-like.2. formed on austenite grain boundary, but it is internally formed in austenite crystal.3. lower bainite
In ferritic substructure be dislocation, its dislocation density is ferritic higher than in upper bainite.The ferrite of lower bainite is included
There is oversaturated carbon, its solid solution capacity is higher than upper bainite, and reduce and increase with temperature is formed.Comparatively speaking in lower bainite
Retained austenite no matter quantity and size are less than or less than content in upper bainite.The intensity of lower bainite is higher, toughness
Also preferably, the low intensity of upper bainite, toughness is very poor, and forms the reduction of temperature with bainite, and intensity and toughness are progressively carried
Height, plasticity and toughness are similarly improved with the reduction for forming temperature.Carbides In Lower Bainite granule is less, grain amount
It is more, so contribution of the carbide to lower bainite is also larger.Because upper bainite ferrite bar is arranged in parallel with each other bunchy, bar
Seem a crystal grain with the meta of bar to poor very little, and position is very big to difference between lower bainite ferrite lamellae.Go up shellfish
The Effective grain size diameter of family name's body is far longer than lower bainite, and in addition the carbide of upper bainite is distributed in ferrite in sequential like
Between bar, upper bainite performance is result in relatively poor.
Therefore, the production technology of bainite rail of the exploitation based on lower bainite, can really play its high intensity, high-ductility
Property and long-life feature be the present invention emphasis.However, the controlling of production process for obtaining lower bainite is complex, it is difficult to pass through
The method of alloy system regulation and control is obtained.Experiment shows by adding alloying element Ni, V, Nb come stable residual austenite and reduction
The effect of residual stress is not obvious, it is therefore desirable to obtained by Heat Treatment Measures.The present invention develops bayesian under fine grain
The production technology of body rail, and in the actual application of laying a railway track of heavy haul railway, achieve the effect of good resistance to rolling contact fatigue.
The content of the invention
It is an object of the present invention to provide the heat treatment method of a kind of bainite rail alloy system and its bainite rail and
Bainite rail.The productive prospecting of the technique is, the refinement of effective control austenite structure and the segregation of element and microstructure
And uneven phenomenon, it is beneficial to after cooling phase-change and obtains tiny uniform lower bainite tissue.In production Technology for Heating Processing, it is ensured that
There is completely the phase transformation of lower bainite tissue in effective control rail, so as to obtain high performance bainite rail.Therefore, in bayesian
After body rail hot rolling production, need to carry out secondary heat treatment work, i.e., the present invention adopts normalizing+quenched Technology for Heating Processing road twice
Line, effectively reduces the residual stress of component segregation, has refined bainite structure, decomposed refinement and stabilisation retained austenite
Microstructure, eliminates a small amount of martensitic structure, makes the microstructure and hardness of rail section more uniform, full-scale rail
Properties are stable in narrow fluctuation range.So as to the military service performance of rail greatly improved.
Technical scheme is as follows：
One aspect of the present invention provides a kind of alloy system of bainite rail, it is characterised in that：Described alloy system
Composition it is as follows by percentage to the quality：C：0.22~0.27；Si：1.65~1.85；Mn：1.60~1.80；Cr：1.30~
1.90；Mo：0.25~0.85；Ni：0.25~0.95；V：0.040~0.060 or Nb：0.020~0.040, P：≤0.015、S：
≤0.015；Balance of Fe and inevitable impurity element；Wherein impurity element is strictly controlled：(1) gas content：
Molten steel [H]≤2.0ppm, strand [H]≤1.5ppm, [O]≤25ppm, [N]≤70ppm；(2) residual elements：Al≤
0.006%, Cu≤0.15%, Sn≤0.010%, Sb≤0.010%.
The production technology of generally bainite rail is, after rail hot rolling or hot rolling and air cooling is reheated to 850- to after room temperature
950 DEG C of austenitizings, are then controlled rate of cooling and (are about existed by pearlitic ferrite transition temperature area with very fast rate of cooling
Between 550-700 DEG C), its rate of cooling is more than 0.3 DEG C/s, it is therefore an objective to avoid ferritic-pearlitic phase transformation.Then control
With less than 5 DEG C/s, to room temperature, the purpose of the stage control cooling rate is to try to make phase transformation air cooling rate of cooling after being cooled to 200 DEG C
Occur in bainite rate of cooling control interval, rather than because too fast cooling rate produces martensite.In order to stablize microstructure and
Retained austenite, eliminates residual stress, in addition it is also necessary to carry out temper in 300-400 DEG C of interval.Above-mentioned bainite rail production
Complexity be exactly to need to coordinate the actual rhythm of Rolling production, cooling velocity after rolling is constantly adjusted, simultaneously because the section of rail
Change, it is impossible to make the section rate of cooling of rail always, causes section hardness skewness, and corner local and it is internal into
Segregation place is divided to be easy to produce the deterioration of martensitic structure or local grain abnormal phenomena so as to cause bainite rail performance,
The performance of final impact rail.
The martensitic transformation temperature of the alloy system of above-mentioned bainite rail is 320 DEG C, and lower bainite forms 360 DEG C of temperature
Below.Microstructure does not produce martensitic structure or ferritic-pearlitic tissue, steel in order to ensure heat treatment bainite rail
Rail quenching final temperature is controlled between 320 DEG C -360 DEG C, and then long-time isothermal phase change is processed.Control i.e. in quenched quenching process
Rail chilling temperature processed thinks more than temperature in martensite and Lower Bainite Transformation temperature temperature below is interval.Retained austenite
Stability contorting, the elimination of residualinternal stress in bainite structure is the key that bainite rail ensures service life.Therefore need
Prolonged normalizing and annealing.
Another aspect of the present invention additionally provides a kind of heat treatment side of the bainite rail prepared using above-mentioned alloy system
Method, it is characterised in that described heat treatment method is specific as follows：
Normalizing+adjustment is processed：Normalizing temperature is 900-940 DEG C of austenite warm area heating, and stove inside holding went out more than 8 hours
Stove air cooling is to room temperature；
Quenching：After Ac3+50~70 DEG C austenite (about 830-900 DEG C) warm area scope inside holding 7 hours, water-cooled is direct
It is quenched between martensitic transformation temperature above 320-350 DEG C；
Isothermal phase change：Then rail stacking is put into into holding pit isothermal holding at 320-350 DEG C, is performed for more than 5 hours etc.
Warm phase transformation is processed；
Temper process：Bainite rail is carried out into temper after isothermal phase change process, temperature is 320-370
DEG C, it is air cooled to room temperature after being incubated more than 9 hours.
Another aspect of the present invention additionally provides the shellfish that a kind of heat treatment method using above-mentioned bainite rail is prepared
Family name's body rail, described bainite rail performance meets following index：Yield strength Rp0.2>1240MPa；Tensile strength Rm>
1500MPa；Elongation percentage A%>15；Ballistic work AkuRoom temperature>110J；Reduction of area Z%>50；FATIGUE FRACTURE TOUGHNESS K1C>90MPam1/2,
Rail section Hardness Control is in 39-42HRC.
For carbon-free bainite rail microscopic structure typically by lath ferrite and the second phase composition, second mutually include carbon
Compound, martensite or retained austenite, i.e., it is so-called without carbon bainite steel.And to obtain phase transition temperature and be generally below
350 DEG C of needle-like lower bainite piece tissue.Its alloys producing and span of control are as follows：
Carbon：Carbon is the element that gap solution strengthening and carbide precipitation reinforcing are produced in martensitic phase transformation, and is that steel is obtained
Obtain the essential element of high intensity.When carbon content is more than 0.45%, hard and crisp high carbon martensite phase is easily generated, in rolling surface
Easily produce and peel off and other layerings.And carbon content is difficult to obtain the intensity needed for bainite structure, carbon when being less than 0.15%
Content is too low, and the hard carbon compound played an important role to wearability is difficult to be formed in rolling friction.Therefore, this is steel carbon content
Generally between 0.22%~0.27%.Additionally, carbon can also increase the cold brittleness and aging sensitivity of steel.
Silicon：The elastic limit of steel, yield point and tensile strength can be significantly improved.Move to right bainitic transformation area, solid solution is strong
Change bainite, improve the wearability of bainite rail.Silicon can suppress the precipitation of cementite, when the addition of silicon is enough,
During certain cooling rate during bainitic transformation, with the formation of bainitic ferrite, carbon is rich at its adjacent overcooling austenite
Collection, improves the stability of overcooling austenite, and partial austenitic is retained to room temperature, defines main by bainitic ferrite and residual
The precipitation of the carbide-free Bainite cementite of remaining austenite composition is suppressed completely.Si promotes to form remaining difficult to understand in bainite
Family name's body thin film, can postpone one-step temper embrittlement again.Temperature can be improved to 300 DEG C increases toughness and anti-delayed fracture
Performance.When Si contents are more than 2.0%, easily there is surface defect in rail.Therefore, bainite rail steel grade Si contents are usually
Between 1.65%~1.85%.Si and Cr, Mo can be combined, and be improved corrosion resistance and antioxidative effect.
Manganese：The effect of Mn, Cr element:All it is to suppress low Bs points element, improves bainite quenching degree and intensity, improves steel
Hot-working character..When Cr, Mn content is more than 3.0%, too crisp carbide is easily produced, reduce the toughness of bainite structure.
Mn reduces Ms points, remained austenite content increase in steel after quenching is made, so as to reduce the size distortion after quenching.Because manganese aggravates back
Fiery fragility and superheated susceptivity, preferably with the compound addition of Cr, Mo, V.Mn contents are too high easily to cause microstructure segregation, therefore actually makes
Properties dispersion is occurred in that with the middle bainitic steel for crossing high Mn content greatly and military service unstable properties phenomenon.Therefore, Mn
Content major part is between 1.60%~1.80%.
Chromium：Chromium is ferrite former, and in Fe-Cr binary systems, it reduces austenitic area, but in Fe-Cr-Ni tri-
In system of unit, situation contrast, Cr does not only hinder the formation that can also promote austenite phase on the contrary.To obtain enough quenching
Permeability, dissolves in and cause in matrix displacement solution strengthening, and Cr all favourable to anticorrosive and oxidation；Cr promote cementite unstability and
M2C-shaped into, replace Mo2Mo forms (Mo, Cr) in C2C, promotes post-curing reaction, forms small and dispersed precipitation.The big portion of Cr contents
Divide between 1.30%~1.90%.
Nickel：Nickel is intensity, the quenching degree that uniquely can have both improved steel, and the element of toughness can be improved again；It is to expand difficult to understand
Family name's body p-block element p, it is ensured that retained austenite has enough stability in steel；Solution strengthening is produced, ductil-brittle transition is reduced
Temperature；The carbide precipitation of high Ni contents and small and dispersed is this kind of steel high intensity, the fundamental cause of high tenacity；The toughness of material
Depending on the complexity of dislocation commutative Banach aglebra during plastic deformation, Ni can make screw dislocation be susceptible to decompose, it is ensured that commutative Banach aglebra
Generation, improve steel toughness.But to wearability, post-curing performance without contribution, and it is (malleable substantially to deteriorate processing performance
Property, the property of softening and machinability).Molybdenum：Molybdenum can make the crystal grain refinement of steel, increase quenching degree, produce solution strengthening, also suppress tempering
The effect of fragility；Suppress and delay the aggregation of alloy carbide and grow up, so that age softening process shifts to higher temperature,
Corrosion stability can be improved.Mo can make steel that enough intensity and creep resisting ability are kept in high temperature, and (being subject at high temperature for a long time should
Power, deforms, and claims creep)；Improve anti-superheated susceptivity and obdurability.Molybdenum is added in structural steel, mechanical performance can be improved.Also
The fragility that steel alloy can be suppressed to cause due to tempering.Vanadium：The strong crystal grain thinning of vanadium, strong raising wearability and post-curing
Ability, improves anti-superheated susceptivity；But what content excessively can substantially deteriorate steel can forgeability and grinding performance.
Copper：Have the disadvantage easily to be produced in hot-working hot-short.
Phosphorus：In general, phosphorus is harmful element in steel, increases the cold brittleness of steel, makes welding performance degenerate, and reduces modeling
Property, make cold-bending property degenerate.Therefore usually require that phosphorus content is less than 0.045% in steel, bainitic steel requires some more low being less than
0.015%.
Sulfur：Sulfur is also under normal conditions harmful element.Make steel produce red brittleness, reduce the ductility and toughness of steel,
Crackle is caused when forging and rolling.Sulfur is also unfavorable to welding performance, reduces corrosion resistance.So bainitic steel sulfur content is less than
0.015%.
Trace element such as boron, titanium and hydrogen etc. can produce certain impact on its toughness in steel.Boron is by segregation in austenite crystal
Boundary and significantly postpone ferrite forming core.To avoid the formation of boron nitride, the effect of boron is affected, therefore be suitably added aluminum with fixed nitrogen.
The Hydrogen Embrittlement of 1000MPa level above steel is dramatically increased, and control hydrogen content is in below 1.5ppm.Other gas content oxygen,
Nitrogen is also required to strict restriction, is beneficial to the control of field trash pattern and size.
Description of the drawings
Fig. 1 is the schematic diagram of bainite rail prepared by the present invention；
In figure：1st, away from surface 5mm, remaining dot spacing is 5mm to the 1st point of rail head；D, E line and lower jaw are apart from 5mm；B, C line
For the angular bisector of A, E line；2nd, web of the rail spacing 15mm；3rd, flange of rail spacing 20mm.
Specific embodiment
With reference to specific embodiment to the steel alloy of the present invention and its production method and essence of finish rolling deformed bar
Roll spiral to be described in detail, the steel product ingredient of each embodiment is shown in Table 1.
In a detailed embodiment, the invention provides a kind of alloy system of bainite rail, described alloy
The composition of system is as follows by percentage to the quality：C：0.22~0.27；Si：1.65~1.85；Mn：1.60~1.80；Cr：1.30
~1.90；Mo：0.25~0.85；Ni：0.25~0.95；V：0.040~0.060 or Nb：0.020~0.040, P：≤0.015、
S：≤0.015；Balance of Fe and inevitable impurity element；Wherein impurity element is strictly controlled：(1) gas contains
Amount：Molten steel [H]≤2.0ppm, strand [H]≤1.5ppm, [O]≤25ppm, [N]≤70ppm；(2) residual elements：Al≤
0.006%, Cu≤0.15%, Sn≤0.010%, Sb≤0.010%.
In another embodiment, present invention also offers a kind of bainite prepared using above-mentioned alloy system
The heat treatment method of rail, described heat treatment method is specific as follows：
Normalizing+adjustment is processed：Normalizing temperature is 900-940 DEG C of austenite warm area heating, and stove inside holding went out more than 8 hours
Stove air cooling is to room temperature；
Quenching：After Ac3+50~70 DEG C austenite (about 830-900 DEG C) warm area scope inside holding 7 hours, water-cooled is direct
It is quenched between martensitic transformation temperature above 320-350 DEG C；
Isothermal phase change：Then rail stacking is put into into holding pit isothermal holding at 320-350 DEG C, is performed for more than 5 hours etc.
Warm phase transformation is processed；
Temper process：Bainite rail is carried out into temper after isothermal phase change process, temperature is 320-370
DEG C, it is air cooled to room temperature after being incubated more than 9 hours.
In another embodiment, present invention also offers a kind of heat treatment side using above-mentioned bainite rail
The bainite rail that method is prepared, described bainite rail performance meets following index：Yield strength Rp0.2>1240MPa；
Tensile strength Rm>1500MPa；Elongation percentage A%>15；Ballistic work AkuRoom temperature>110J；Reduction of area Z%>50；FATIGUE FRACTURE TOUGHNESS K1C
>90MPam1/2, rail section Hardness Control is in 39-42HRC.
The Technology for Heating Processing of the bainite rail of the embodiment of the present invention 1~4 is given in table 1；Table 2 gives of the invention real
The bainite rail mechanical property for applying example 1~4 improves situation；Table 3 gives the bainite rail section hardness of embodiment 1~4
Situation can be improved.
The bainite rail Technology for Heating Processing of table 1
The bainite rail mechanical property of table 2 improves situation
The bainite rail section hardness of table 3 can improve situation HRC
The above, the only present invention preferably specific embodiment, but protection scope of the present invention is not limited thereto,
Any those familiar with the art the invention discloses technical scope in, the change or replacement that can be readily occurred in,
All should be included within the scope of the present invention.
Claims (2)
1. a kind of heat treatment method of bainite rail, it is characterised in that：The composition of the alloy system of the bainite rail with
Mass percent meter is as follows：C：0.22~0.27；Si：1.65~1.85；Mn：1.60~1.80；Cr：1.30~1.90；Mo：
0.25~0.85；Ni：0.25~0.95；V：0.040~0.060 or Nb：0.020~0.040, P：≤0.015、S：≤0.015；
Balance of Fe and inevitable impurity element；Wherein impurity element is strictly controlled：(1) gas content：Molten steel [H]≤
2.0ppm, strand [H]≤1.5ppm, [O]≤25ppm, [N]≤70ppm；(2) residual elements：Al≤0.006%, Cu≤
0.15%, Sn≤0.010%, Sb≤0.010%；
Described heat treatment method is specific as follows：
Normalizing+adjustment is processed：Normalizing temperature is the heating of 900-940 DEG C of austenite warm area, stove inside holding more than 8 hours, sky of coming out of the stove
It is as cold as room temperature；
Quenching：After Ac3+50~70 DEG C austenite warm area scopes inside holding 7 hours, water-cooled direct quenching to 320-350 DEG C it
Between；
Isothermal phase change：Then rail stacking is put into into holding pit isothermal holding at 320-350 DEG C, is performed for more than 5 hours isothermal phases
Change is processed；
Temper process：Bainite rail is carried out into temper after isothermal phase change process, temperature is 320-370 DEG C,
Room temperature is air cooled to after being incubated more than 9 hours.
2. the bainite rail that a kind of heat treatment method of the bainite rail described in employing claim 1 is prepared, it is special
Levy and be, described bainite rail performance meets following index：Yield strength Rp0.2>1240MPa；Tensile strength Rm>
1500MPa；Elongation percentage A%>15；Ballistic work AkuRoom temperature>110J；Reduction of area Z%>50；FATIGUE FRACTURE TOUGHNESS K1C>90MPam1/2,
Rail section Hardness Control is in 39-42HRC.
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| CN110343974B (en) * | 2019-08-27 | 2021-09-21 | 郑州大学 | The specific strength-elongation product is higher than 6.0 GPa%/gcm-3High-carbon low-alloy low-density steel and heat treatment process thereof |
| CN110592354B (en) * | 2019-09-12 | 2021-01-05 | 北京交通大学 | Method for preparing 1380 MPa-level bainite steel rail through waste heat quenching-self-distribution |
| CN113388791B (en) * | 2020-03-13 | 2022-05-13 | 钢铁研究总院 | High-strength and high-toughness tempered martensite frog steel and heat treatment method thereof |
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| CN111876569B (en) * | 2020-07-30 | 2022-03-04 | 江苏大学 | Heat treatment method considering precipitation strengthening and lower bainite phase transformation strengthening |
| CN112647011B (en) * | 2020-12-19 | 2022-07-26 | 台州学院 | Preparation method of fine-grain high-strength and high-toughness bainitic steel |
| CN113088825B (en) * | 2021-04-14 | 2023-02-28 | 江苏永钢集团有限公司 | Medium carbon microalloyed steel and method for eliminating mixed crystal structure thereof |
| CN114000034B (en) * | 2021-11-02 | 2022-11-08 | 攀钢集团攀枝花钢铁研究院有限公司 | Low-yield-ratio high-strength bainite steel rail and production method thereof |
| CN114686661B (en) * | 2022-03-21 | 2023-03-24 | 燕山大学 | Method for regulating and controlling segregation in bainitic steel and poor matrix performance and steel workpiece |
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| CN1721565A (en) * | 2004-07-13 | 2006-01-18 | 铁道科学研究院 | Full-bainite steel frog containing stable residual austenite and production process thereof |
| CN100471974C (en) * | 2005-12-05 | 2009-03-25 | 鞍钢股份有限公司 | Bainite steel rail with excellent fatigue resistance and production method thereof |
| CN103160736B (en) * | 2011-12-14 | 2015-09-02 | 鞍钢股份有限公司 | High-strength bainite steel rail and heat treatment process thereof |
| CN103436663A (en) * | 2013-08-09 | 2013-12-11 | 内蒙古包钢钢联股份有限公司 | Technique for improving hot-rolling elongation of steel for bainite steel rail |
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Address after: 100081 No. 76 South College Road, Beijing, Haidian District Co-patentee after: Advanced Steel Technology Co., Ltd. Patentee after: Central Iron & Steel Research Institute Co-patentee after: Zhejiang Bell Rail Equipment Co., Ltd. Address before: 100081 No. 76 South College Road, Beijing, Haidian District Co-patentee before: Advanced Steel Technology Co., Ltd. Patentee before: Central Iron & Steel Research Institute Co-patentee before: Zhejiang Bell Communication Group Co., Ltd. |