CN110195192A - A kind of ultra-low-carbon bainite steel, rail and preparation method thereof - Google Patents
A kind of ultra-low-carbon bainite steel, rail and preparation method thereof Download PDFInfo
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- CN110195192A CN110195192A CN201810156086.5A CN201810156086A CN110195192A CN 110195192 A CN110195192 A CN 110195192A CN 201810156086 A CN201810156086 A CN 201810156086A CN 110195192 A CN110195192 A CN 110195192A
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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
-
- 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
- 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
-
- 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
-
- 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
- C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
-
- 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
-
- 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
-
- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
-
- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B5/00—Rails; Guard rails; Distance-keeping means for them
- E01B5/02—Rails
-
- 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
Abstract
The present invention discloses a kind of ultra-low-carbon bainite steel, rail and preparation method thereof, is related to railway steel technical field.Bainitic steel composition includes: C:0.01-0.10wt%, Mn:1.8-2.3wt%, Si:0.3-1.5wt%, Cr:0.1-0.6wt%, Ni:0.5-2.0wt%, Mo:0.1-0.5wt%, V:0.01-0.25wt%；Remaining is Fe and inevitable impurity element, and the content of each element meets C+ (Mn+Si)/6+Ni/15+ (Cr+Mo+V)/50≤0.8, has high-intensitive, high tenacity, and welding performance is good.The present invention also provides the preparation methods of a kind of ultra-low-carbon bainite steel rail and the rail, and the bainite rail intensity is big, and low-temperature flexibility is high, and welding performance is good, high comprehensive performance；It is greater than 250 kilometers of high-speed railway suitable for speed per hour.
Description
Technical field
The present invention relates to railway steel technical fields.More particularly, to a kind of ultra-low-carbon bainite steel, rail and its system
Preparation Method.
Background technique
China express railway (hereinafter referred to as high-speed rail) rapidly develops, until the end of the year 2016, China's high-speed rail operation total kilometrage are more than
2.2 ten thousand kilometers, 60% or more of world's high-speed rail operation total kilometrage is accounted for, becomes China one and opens glittering new business card.And high-speed rail steel
Rail, track switch are the critical components for influencing high-speed rail operation security, and it is high-speed rail that especially track switch, which is constantly subjected to strong high speed impact,
Most weak one of the link of track.
The material that high-speed rail rail, track switch use at present is using U75MnG and U75VG pearlite steel rail, such material
Middle carbon content is respectively 0.65-0.75wt% and 0.71-0.80wt%, and microscopic structure is pearlite.Higher carbon content is brought
Two main security risks, first is that poor toughness, the impact flexibility of U75MnG and U75VG pearlite steel rail generally only has 20-
There is phenomenon of rupture during operation in 30J, has seriously affected the operation security (railway society, 27 (6), 2005) of high-speed rail；
Second is that phosphorus content is excessively high, welding performance is bad, and the tendency that cold crack generates in welding process is larger, while joint hardness point
Cloth is uneven, causes very big security risk, also affects the comfort (railway construction, 8,2016) of high-speed rail operation.
In recent years, bainite rail obtains domestic and foreign scholars due to its excellent toughness, wearability and anti-fatigue performance
Concern.For example, Iron and Steel Research Geueral Institute has applied for " heat treatment method and the shellfish of a kind of alloy system and its bainite rail
Family name's body rail " (CN 105385938A), disclosed bainite rail carbon content is 0.22-0.27wt%, just for heavy duty
The application of railway, is not suitable for high-speed railway.Beijing Special Metallurgy Industry &. Trade Co., Ltd. has applied for that " curve and heavy-duty steel rail are used
Bainitic steel and bainite rail and its production method " (CN 101921971A), disclosed bainite rail carbon content are
0.16-0.25wt% is directed to curve and heavy-duty steel rail, is not suitable for high-speed railway.
In conclusion high-speed rail pearlite steel rail leads to its poor toughness since its carbon content is excessively high at present, welding performance is not
It is good.And presently disclosed bainite rail is just for heavy haul railway, and its carbon content is still higher, welding performance cannot obtain
To breakthrough, low-temperature flexibility improvement is limited, is not suitable for high-speed railway.Therefore, it is necessary to develop a kind of novel used for high-speed railway
Rail material.
Summary of the invention
It is an object of the present invention to provide a kind of ultra-low-carbon bainite steels comprising ultralow carbon content and reasonable
Alloying element proportion, has high-intensitive, high tenacity, and welding performance is good.
Second object of the present invention is to provide a kind of ultra-low-carbon bainite steel rail, and the bainite rail intensity is big, low
Warm toughness is high, and welding performance is good, high comprehensive performance.
Third object of the present invention is to provide a kind of ultra-low-carbon bainite steel rail as described above and is greater than 250 in speed per hour
Application in the high-speed railway of kilometer, the rail can effectively improve safety and the comfort of high-speed railway.
Fourth object of the present invention is to provide a kind of preparation method of ultra-low-carbon bainite steel rail, and the preparation method is logical
Controlled cooling process and tempering process are crossed, can get the ultra-low-carbon bainite steel rail with Ultra-low carbon ferrite bainite tissue.
According to the first object of the present invention, the present invention provides a kind of ultra-low-carbon bainite steel, and composition includes:
C:0.01-0.10wt%, Mn:1.8-2.3wt%, Si:0.3-1.5wt%, Cr:0.1-0.6wt%, Ni:0.5-
2.0wt%, Mo:0.1-0.5wt%, V:0.01-0.25wt%；Remaining is Fe and inevitable impurity element, microscopic structure
Predominantly Ultra-low carbon ferrite bainite tissue；
And the content of each element meets following relationship: C+ (Mn+Si)/6+Ni/15+ (Cr+Mo+V)/50≤0.8, the pass
It is the relational expression that formula is carbon equivalent, the ultra-low-carbon bainite steel for meeting the relational expression has excellent welding performance.
Preferably, its composition of the ultra-low-carbon bainite steel includes:
C:0.01-0.08wt%, Mn:2.0-2.1wt%, Si:0.8-1.2wt%, Cr:0.2-0.5wt%, Ni:1.0-
1.2wt%, Mo:0.3-0.4wt%, V:0.04-0.08wt%；Remaining is Fe and inevitable impurity element, microscopic structure
Predominantly Ultra-low carbon ferrite bainite tissue；
And the content of each element meets following relationship: C+ (Mn+Si)/6+Ni/15+ (Cr+Mo+V)/50≤0.8.
In the present invention, the performance of each element is as follows:
Carbon C: there is strong solution strengthening effect, be conducive to the raising of steel grade intensity, steel grade can be significantly improved
Harden ability, but when carbon content is excessively high, is unfavorable for the welding of rail, and when carbon content is ultralow, the microscopic structure of steel is mostly ferrite, by force
It spends relatively low, is not able to satisfy requirement of the rail to intensity.
Manganese element Mn: it is to move to right steel grade CCT curve, dramatically increases the element of harden ability.In contrast, manganese element energy
High-temperature region ferrite and pearlite is significantly delayed to change, and the influence of centering low-temperature space bainite transformation is smaller, reaches and centainly contains
When amount (>=1.5wt%), it can make occur the upper and lower and distinct typical high temperature transformation of left and right directions in steel grade CCT curve
Area and medium temperature bainite transformation area, considerably increase steel grade harden ability, are conducive to the thicker product of size from austenitizing high temperature
The air-cooled bainite structure that can be obtained function admirable, convenient for simplifying production technology and reducing cost.In addition, manganese element has admittedly
The effect of molten reinforcing, is conducive to the raising of intensity, and manganese element content increases, and is conducive to the corrosion-resistant ability for improving steel and right
The corrosion resistance of marine atmosphere.But if manganese element too high levels be easy to cause the segregation of ingredient, influence structure property stability.
Element silicon Si: can inhibit brittle Carbide Precipitation, conducive to the shape of the film of retained austenite of toughness plasticity no-float
At.Silicon can prevent formation sour in rusty scale, keep interior rusty scale fine and close, hinder chloride ion intrusion, improve resistance to corrosion.With other
Being used cooperatively for element such as Cr etc. can make steel weatherability effect more preferable.But if silicon content is excessively high, it will affect continuous casting billet
Casting, influence the quality of steel billet.
Chromium Cr: having the function of solution strengthening, is conducive to the raising of intensity.Meanwhile chromium can improve steel grade
Harden ability is conducive to the uniformity of performance inside and outside rail head of rail part.It, can be in steel but if chromium content is higher
Excessive martensite is formed, the toughness for influencing rail improves.
Molybdenum element Mo: the strong harden ability for improving steel grade is conducive to can be obtained bainite structure under the conditions of rail is air-cooled
With the uniformity consistency of performance.In addition, molybdenum makes the rusty scale of steel fine and close, it is anticorrosive in naval air environment that steel can be improved
Ability.Mo in rusty scale can inhibit the intrusion of chloride ion, so that chloride ion concentrates on outside rusty scale.In addition, molybdenum element can mention
High steel belt roof bolt drag.But if molybdenum element too high levels, it on the one hand will increase the cost of steel, on the other hand will also result in
The segregation of ingredient influences structure property stability.
Nickel element Ni: be conducive to improve the toughness of steel, the especially raising of low-temperature impact toughness.If nickel element content mistake
Height will increase the cost of alloy of steel.
Vanadium V: the comprehensive mechanical performances such as the intensity, toughness, ductility and thermal fatigue resistance of steel can be improved, and have steel
There is good solderability.But if vanadium too high levels, easily there is big VN particle and occur, influence the toughness of steel.
According to the second object of the invention, the present invention provides a kind of ultra-low-carbon bainite steel rail, and the rail is by institute as above
The ultra-low-carbon bainite steel stated is made.
Third purpose according to the present invention, the present invention provide a kind of ultra-low-carbon bainite steel rail as described above in speed per hour
The application in high-speed railway greater than 250 kilometers.
4th purpose according to the present invention, the present invention provide a kind of preparation method of ultra-low-carbon bainite steel rail, including
Following steps:
(1) raw material of the ultra-low-carbon bainite steel with above-mentioned composition smelted using process for making, cast, must be cast
Base；
(2) slab is heated, cogging, roughing, finish rolling, obtains rail prototype；
(3) by rail prototype tyre tread with constant cooling rate continuous coo1ing to bainite start temperature hereinafter, then from
It is so cooled to room temperature, is heat-treated, obtain ultra-low-carbon bainite steel rail.Preferably, the constant cooling rate is 2-50 DEG C/s；Into
One step preferably, is cooled to bainite start temperature or less at rail prototype tyre tread first with the cooling velocity of 2-50 DEG C/s
20-200 DEG C of temperature, then cooled to room temperature.When the cooling velocity of rail tread is 2-50 DEG C/s, it is ensured that
The microscopic structure of rail is based on ferrite bainite；It is cooled to 20-200 DEG C of bainite start temperature or less, can effectively be kept away
Exempting to return temperature causes microscopic structure a large amount of pro-eutectoid ferrite occur, to improve the intensity and toughness of rail；Later by rail
Cooled to room temperature can avoid a large amount of martensite occur, effectively improve rail toughness.It should be noted that the bayesian
It is that above-mentioned ultra-low-carbon bainite steel is made to slab that body, which changes start temperature, measures the bainite transformation of slab under continuous coo1ing
Start temperature, measuring method can refer to the YB/T5128-1993 " measuring method (expansion of the continuous cooling transformation (CCT) curve figure of steel
Method) ".
Preferably, the middle heating of step (2), which refers to, is heated to 1150-1250 DEG C, keeps the temperature 2-3 hours.
Preferably, the method for the continuous coo1ing is one or more of the cold or air-cooled combination of air-cooled, mist, this field
Technical staff can select according to the actual situation, can reach scheduled cooling effect.
Preferably, the heat treatment is tempering, and the temperature of tempering is 200-500 DEG C, the heat preservation of tempering
Time is 20-60 hours, divides lath of bainite to merge with promotion division, stablizes Ultra-low carbon ferrite bainite tissue, reduces tough crisp turn
Temperature.
Beneficial effects of the present invention are as follows:
1, ultra-low-carbon bainite steel of the invention and ultra-low-carbon bainite steel rail are by controlling the ultralow same time control of carbon content
The rational proportion for making each alloying element effectively improves the welding performance and low-temperature flexibility of bainitic steel and bainite rail.
2, the present invention is matched by using ultralow carbon content and reasonable alloying element, in conjunction with accurate preparation process,
Especially Controlled cooling process and tempering process obtain the ultra-low-carbon bainite steel with Ultra-low carbon ferrite bainite tissue
Rail improves the welding performance and low-temperature flexibility of bainite rail.The ultra-low-carbon bainite steel rail that the present invention obtains it is comprehensive
It can be obviously improved, specifically, tensile strength >=800MPa, yield strength >=700MPa, elongation percentage >=15%, impact
Toughness >=200J/cm2, ductile-brittle transition temperature is lower than -20 DEG C；Intensity >=700MPa of welding heat affected zone, heat affected area it is tough
Property >=100J/cm2。
3, ultra-low-carbon bainite steel rail of the invention is suitable for the high-speed railway that speed per hour is greater than 250 kilometers, to raising high speed
The operation security and comfort of railway have great importance.
Detailed description of the invention
Specific embodiments of the present invention will be described in further detail with reference to the accompanying drawing.
Fig. 1 shows the microstructure picture of 1 gained ultra-low-carbon bainite steel rail of embodiment.
Fig. 2 shows the microstructure pictures of 3 gained ultra-low-carbon bainite steel rail of embodiment.
Fig. 3 shows the microstructure picture of 4 gained ultra-low-carbon bainite steel rail of embodiment.
Specific embodiment
In order to illustrate more clearly of the present invention, the present invention is done further below with reference to preferred embodiments and drawings
It is bright.It will be appreciated by those skilled in the art that specifically described content is illustrative and be not restrictive below, it should not be with
This is limited the scope of the invention.
Table 1 shows the constituent content (mass percent) of bainitic steel in following embodiment and comparative example, wherein miscellaneous
Matter refers to inevitable impurity.
The constituent content (mass percent) of bainitic steel in each embodiment of table 1 and comparative example
Embodiment 1
Measure the bainite start temperature of slab made of the embodiment is 550 DEG C.Measuring method reference
YB/T5128-1993 " measuring method (plavini) of the continuous cooling transformation (CCT) curve figure of steel ".
(1) according to the formula of the present embodiment in table 1, using conventional process for making, smelt by converter or electric furnace and
Refining, then cast by the way of continuous casting, obtain slab；
(2) slab is heated to 1250 DEG C, keeps the temperature 2 hours, cogging, roughing, finish rolling obtains rail prototype；
(3) 350 DEG C will be cooled to the cooling velocity of 50 DEG C/s at rail prototype tyre tread by air-cooled, then natural cooling
It is tempered 20 hours to room temperature, then between 400 DEG C, obtains ultra-low-carbon bainite steel rail.
As shown in Figure 1, its microscopic structure is based on Ultra-low carbon ferrite bainite tissue.
The mechanical property of the ultra-low-carbon bainite steel rail is measured using the method for test example 1 are as follows: tensile strength 800-
850MPa, yield strength 700-775MPa, elongation percentage 15-18%, impact flexibility 300J/cm2, -50 DEG C of ductile-brittle transition temperature,
After flash butt welding, the tensile strength of heat affected area is 700-900MPa, impact flexibility 200J/cm2。
Embodiment 2
Measure the bainite start temperature of slab made of the embodiment is 530 DEG C.
(1) according to the formula of the present embodiment in table 1, using conventional process for making, smelt by converter or electric furnace and
Refining, then cast by the way of continuous casting, obtain slab；
(2) slab is heated to 1200 DEG C, keeps the temperature 2 hours, cogging, roughing, finish rolling obtains rail prototype；
(3) 400 DEG C will be cooled to the cooling velocity of 30 DEG C/s at rail prototype tyre tread by air-cooled, then natural cooling
It is tempered 30 hours to room temperature, then between 460 DEG C, obtains ultra-low-carbon bainite steel rail, the microscopic structure of the rail is with ultralow carbon plate
Based on bainite structure.
Measure the mechanical property of the ultra-low-carbon bainite steel rail are as follows: tensile strength 900-950MPa, yield strength 750-
800MPa, elongation percentage 15-20%, impact flexibility 300J/cm2, -40 DEG C of ductile-brittle transition temperature, after flash butt welding, hot shadow
The tensile strength for ringing area is 850-980MPa, impact flexibility 160J/cm2。
Embodiment 3
Measure the bainite start temperature of slab made of the embodiment is 510 DEG C.
(1) according to the formula of the present embodiment in table 1, using conventional process for making, smelt by converter or electric furnace and
Refining, then cast by the way of continuous casting, obtain slab；
(2) slab is heated to 1200 DEG C, keeps the temperature 3 hours, cogging, roughing, finish rolling obtains rail prototype；
(3) 450 DEG C will be cooled to the cooling velocity of 25 DEG C/s at rail prototype tyre tread by the way that mist is cold, then natural cooling
It is tempered 60 hours to room temperature, then between 400 DEG C, obtains ultra-low-carbon bainite steel rail.
As shown in Fig. 2, the microscopic structure of the rail is based on Ultra-low carbon ferrite bainite tissue.
Measure the mechanical property of the ultra-low-carbon bainite steel rail are as follows: tensile strength 875-925MPa, yield strength 775-
800MPa, elongation percentage 16-20%, impact flexibility 280J/cm2, -40 DEG C of ductile-brittle transition temperature, after flash butt welding, hot shadow
The tensile strength for ringing area is 750-875MPa, impact flexibility 180J/cm2。
Embodiment 4
Measure the bainite start temperature of slab made of the embodiment is 540 DEG C.
(1) according to the formula of the present embodiment in table 1, using conventional process for making, smelt by converter or electric furnace and
Refining, then cast by the way of continuous casting, obtain slab；
(2) slab is heated to 1150 DEG C, keeps the temperature 3 hours, cogging, roughing, finish rolling obtains rail prototype；
(3) 520 DEG C will be cooled to the cooling velocity of 10 DEG C/s at rail prototype tyre tread by air-cooled, then natural cooling
To room temperature；It is tempered 60 hours between 200 DEG C again, obtains ultra-low-carbon bainite steel rail.
As shown in figure 3, the microscopic structure of the rail is based on Ultra-low carbon ferrite bainite tissue.
Measure the mechanical property of the ultra-low-carbon bainite steel rail are as follows: tensile strength 850-900MPa, yield strength 700-
750MPa, elongation percentage 16-18%, impact flexibility 280J/cm2, -30 DEG C of ductile-brittle transition temperature, after flash butt welding, hot shadow
The tensile strength for ringing area is 850-950MPa, impact flexibility 120J/cm2。
Embodiment 5
Measure the bainite start temperature of slab made of the embodiment is 480 DEG C.
(1) according to the formula of the present embodiment in table 1, using conventional process for making, smelt by converter or electric furnace and
Refining, then cast by the way of continuous casting, obtain slab；
(2) slab is heated to 1200 DEG C, keeps the temperature 2 hours, cogging, roughing, finish rolling obtains rail prototype；
(3) 300 DEG C will be cooled to the cooling velocity of 2 DEG C/s at rail prototype tyre tread by the way that mist is cold, then natural cooling
To room temperature；It is tempered 40 hours between 500 DEG C again, obtains ultra-low-carbon bainite steel rail, the microscopic structure of the rail is with ultralow carbon plate
Based on bainite structure.
Measure the mechanical property of the ultra-low-carbon bainite steel rail are as follows: tensile strength 975-1050MPa, yield strength 900-
950MPa, elongation percentage 15-17%, impact flexibility 200J/cm2, -20 DEG C of ductile-brittle transition temperature, after flash butt welding, hot shadow
The tensile strength for ringing area is 950-1100MPa, impact flexibility 100J/cm2。
Comparative example 1
Embodiment 1 is repeated, difference is, the direct cooled to room temperature of rail prototype in step (3) after heating.Gained
Rail tensile strength is 400-500MPa.
Comparative example 2
Embodiment 2 is repeated, difference is, is not tempered rail 30 hours between 460 DEG C in step (3).Gained steel
Rail ductile-brittle transition temperature is -15 DEG C；
Comparative example 3
Embodiment 5 is repeated, difference is, carbon content 0.18wt.%.Gained rail impact flexibility is 80J, ductile-brittle transiton
Temperature is 25 DEG C.
Comparative example 4
Embodiment 2 is repeated according to the formula of this comparative example in table 1, difference is carbon content difference, C+ (Mn+Si)/6+Ni/
15+(Cr+Mo+V)/50=0.86 > 0.8.Gained rail impact flexibility is 50J, and ductile-brittle transition temperature is 10 DEG C, using flash of light
To postwelding, the tensile strength of heat affected area is 1300-1400MPa, impact flexibility 20J/cm2, and there is weld horizontal crackle.
Test example 1
Mechanics Performance Testing test
By universal tensile testing machine, determined respectively using standard tensile specimen according to the regulation of concerned countries standard
The mechanical property of each embodiment and the rail sample of comparative example preparation.By test result as can be seen that the present invention obtain it is super
The mechanical property of low-carbon bainite rail is obviously improved, specifically, tensile strength >=800MPa, and yield strength >=
700MPa, elongation percentage >=15%, impact flexibility >=200J/cm2, ductile-brittle transition temperature is lower than -20 DEG C；Welding heat affected zone
Intensity >=700MPa, toughness >=100J/cm of heat affected area2, there is high-intensitive, high tenacity superperformance.
Obviously, the above embodiment of the present invention be only to clearly illustrate example of the present invention, and not be pair
The restriction of embodiments of the present invention may be used also on the basis of the above description for those of ordinary skill in the art
To make other variations or changes in different ways, all embodiments can not be exhaustive here, it is all to belong to this hair
The obvious changes or variations that bright technical solution is extended out are still in the scope of protection of the present invention.
Claims (10)
1. a kind of ultra-low-carbon bainite steel, which is characterized in that its composition includes:
C:0.01-0.10wt%, Mn:1.8-2.3wt%, Si:0.3-1.5wt%, Cr:0.1-0.6wt%, Ni:0.5-
2.0wt%, Mo:0.1-0.5wt%, V:0.01-0.25wt%；Remaining is Fe and inevitable impurity element, microscopic structure
Predominantly Ultra-low carbon ferrite bainite tissue；
And the content of each element meets following relationship: C+ (Mn+Si)/6+Ni/15+ (Cr+Mo+V)/50≤0.8.
2. a kind of ultra-low-carbon bainite steel according to claim 1, which is characterized in that its composition includes:
C:0.01-0.08wt%, Mn:2.0-2.1wt%, Si:0.8-1.2wt%, Cr:0.2-0.5wt%, Ni:1.0-
1.2wt%, Mo:0.3-0.4wt%, V:0.04-0.08wt%；Remaining is Fe and inevitable impurity element, microscopic structure
Predominantly Ultra-low carbon ferrite bainite tissue；
And the content of each element meets following relationship: C+ (Mn+Si)/6+Ni/15+ (Cr+Mo+V)/50≤0.8.
3. a kind of ultra-low-carbon bainite steel rail, which is characterized in that be made of ultra-low-carbon bainite steel described in claim 1.
4. a kind of ultra-low-carbon bainite steel rail as claimed in claim 3 answering in high-speed railway of the speed per hour greater than 250 kilometers
With.
5. a kind of preparation method of ultra-low-carbon bainite steel rail, which comprises the following steps:
(1) raw material of the ultra-low-carbon bainite steel formed with claim 1 smelted using process for making, cast, obtained
Slab；
(2) slab is heated, cogging, roughing, finish rolling, obtains rail prototype；
(3) by rail prototype tyre tread with constant cooling rate continuous coo1ing to bainite start temperature hereinafter, then naturally cold
But it to room temperature, is heat-treated, obtains ultra-low-carbon bainite steel rail.
6. the preparation method of ultra-low-carbon bainite steel rail according to claim 5, which is characterized in that described in step (3)
Constant cooling rate is 2-50 DEG C/s.
7. the preparation method of ultra-low-carbon bainite steel rail according to claim 5, which is characterized in that step (3) is by rail
With 20-200 DEG C below constant cooling rate continuous coo1ing to bainite start temperature at prototype tyre tread, room is then naturally cooled to
Temperature obtains ultra-low-carbon bainite steel rail.
8. the preparation method of ultra-low-carbon bainite steel rail according to claim 5, which is characterized in that heating in step (2)
Refer to and be heated to 1150-1250 DEG C, keeps the temperature 2-3 hours.
9. the preparation method of ultra-low-carbon bainite steel rail according to claim 5, which is characterized in that the continuous coo1ing
Method is one or more of cold or air-cooled for air-cooled, mist.
10. the preparation method of ultra-low-carbon bainite steel rail according to claim 5, which is characterized in that described in step (3)
Heat treatment is tempering, and the temperature of tempering is 200-500 DEG C, and the soaking time of tempering is 20-60 hours.
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| CN201810156086.5A CN110195192B (en) | 2018-02-24 | 2018-02-24 | Ultra-low carbon bainite steel, steel rail and preparation method thereof |
| PCT/CN2019/075365 WO2019161760A1 (en) | 2018-02-24 | 2019-02-18 | Ultra-low carbon bainitic steel, steel rail, and preparation method therefor |
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| CN201810156086.5A CN110195192B (en) | 2018-02-24 | 2018-02-24 | Ultra-low carbon bainite steel, steel rail and preparation method thereof |
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| WO2019161760A1 (en) | 2019-08-29 |
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