CN106103772B - rail and its manufacturing method - Google Patents

rail and its manufacturing method Download PDF

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Publication number
CN106103772B
CN106103772B CN201580013144.3A CN201580013144A CN106103772B CN 106103772 B CN106103772 B CN 106103772B CN 201580013144 A CN201580013144 A CN 201580013144A CN 106103772 B CN106103772 B CN 106103772B
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rail
less
rolling
deviation
cooling
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CN106103772A (en
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木村达己
高岛由纪雄
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JFE Engineering Corp
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NKK Corp
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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
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
    • 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
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • 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
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • 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
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • 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
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • 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
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium

Abstract

The present invention provides a kind of hardness deviation for inhibiting rail length direction and ensures the rail of excellent wear resistance.The rail is formed with following component：Contain C：0.60~1.0%, Si：0.1~1.5%, Mn：0.01~1.5%, P：Less than 0.035%, S：Less than 0.030% and Cr：0.1~2.0%, surplus is made of Fe and inevitable impurity, and the deviation of the case hardness of the rail length direction is below ± HB15 point.

Description

Rail and its manufacturing method
Technical field
The present invention relates to rail, more particularly to the small rail of the deviation of high rigidity and hardness and its manufacturing method.
Background technology
For cargo conveying, mine railway, since Weight Loaded is than car weight, the load of the axle of lorry Greatly, the contact environment between rail and wheel is very harsh.As the rail for this environment, it is desirable that have wear resistance, mesh Before, use the steel with pearlitic structrure.
In recent years, in order to which railway transportation is efficient, cargo, the Weight Loaded of mineral further increase etc., the abrasion of rail It is further exacerbated by, the rail replacement lost of life.Therefore, in order to extend the replacement service life of rail, it is desirable that improve the wear-resistant of rail Property, it is proposed that a variety of high rigidity rail for improving rail hardness.
For example, being disclosed in patent document 1, patent document 2, patent document 3 and patent document 4 increases the carburizing scale of construction Hypereutectoid rail and its manufacturing method.In addition, it is disclosed in patent document 5, patent document 6 and patent document 7 by right The steel of eutectoid carbon grade makes the stratiform interval miniaturization of pearlitic structrure and realizes the technology of high rigidity.
On the manufacturing method of rail, a kind of excellent high-strength of fatigue failure inside head is proposed in patent document 8 Spend the manufacturing method of rail, which is characterized in that in the rolling of rail steel disc, at 850 DEG C~1050 DEG C of head surface temperature The finish rolling for retaining final finish rolling is carried out, after the passage interval time of 3 seconds or more and less than 1 minute, in head surface temperature The final finish rolling of 1 passage or multi-pass is carried out at 800 DEG C~950 DEG C of degree with reduction ratio of every a time below 10%, then, The acceleration cooling of 2~4 DEG C/sec of speed is begun to cool down between 0.1~10 second, will be less than 5mm's under the surface in head and corner Temperature is cooled to Ar1It is then cold as 4 DEG C/sec or more and less than 30 DEG C/sec using the maximum cooling velocity on surface below transformation temperature But speed is cooled down.
A kind of manufacturing method for the high tenacity rail that pearlite metal structure is presented is shown in patent document 9, it is special Sign is, will contain C：The steel disc roughing of 0.60~1.00% carbon steel or low alloy steel is into rail shape, then in the rail Surface temperature be 850~1000 DEG C between implement the sections of 3 passage each of the above passages to reduce reduction ratio be 5~30% to roll The continuous finish rolling of system, and rolling pass is at intervals of less than 10 seconds, then natural cooling or with 2~15 DEG C/sec from 700 DEG C or more Temperature be cooled between 700~500 DEG C.
In addition, the manufacture Patent Document 10 discloses the excellent perlite rail of a kind of wear resistance and ductility Method is by terms of quality %, containing C：0.65~1.20%, Si：0.05~2.00%, Mn：0.05~2.00%, And by the steel rail rolling that Fe and inevitable impurity are formed at least to carry out roughing and finish rolling with steel disc wear-resistant to manufacture for surplus The method of property and the excellent perlite rail of ductility, which is characterized in that in the finish rolling, be on rail's end portion surface Less than 900 DEG C~Ar3The accumulation contraction percentage of area on progress head is within the scope of temperature more than transformation temperature or Arcm transformation temperatures More than 20% and reaction force than the rolling for more than 1.25, the reaction force ratio is removed with the counterforce values of rolling mill With value obtained from the counterforce values at 950 DEG C identical of the accumulation contraction percentage of area and rolling temperature, then, after finish rolling Rail's end portion surface accelerates to cool down or naturally cool at least 550 DEG C for 2~30 DEG C/sec with cooling velocity.
For the high axis weight Rail for railway based on cargo conveying, mine railway, in order to improve the durable of rail Property and require the rail of excellent in wear resistance, propose the rail towards various high rigidity as described above.
Prior art literature
Patent document
Patent document 1：No. 4272385 publications of Japanese Patent No.
Patent document 2：No. 3078461 publications of Japanese Patent No.
Patent document 3：No. 3081116 publications of Japanese Patent No.
Patent document 4：No. 3513427 publications of Japanese Patent No.
Patent document 5：No. 4390004 publications of Japanese Patent No.
Patent document 6：Japanese Unexamined Patent Publication 2009-108396 publications
Patent document 7：Japanese Unexamined Patent Publication 2009-235515 publications
Patent document 8：No. 3423811 publications of Japanese Patent No.
Patent document 9：No. 3113137 publications of Japanese Patent No.
Patent document 10：Japanese Unexamined Patent Publication 2008-50687 publications
The content of the invention
The subject that the invention solves
However, rail carries out hot rolling to steel raw material and manufactures, length reaches more than 100m, because of manufacturing method not Together, hardness deviation is had in rail length direction, cannot be played fully due to generating uneven wear sometimes when being laid with Effect.Therefore, the deviation for reducing the hardness in mill length direction is extremely important, but on the deviation of the hardness, it is above-mentioned There is no record in Patent Documents 1 to 10.
Therefore, it is an object of the present invention to propose a kind of hardness deviation for inhibiting rail length direction and ensure excellent The rail of wear resistance, and its manufacturing method is proposed together.
The method to solve the problem
Inventors etc. choose from the steel with pearlitic structrure for being equivalent to different hardness rail and are tried for rail abrasion The test film tested carries out wear test and has studied the relation of hardness and wear extent.Its result of study is shown in Fig. 1.
It should be noted that wear test uses the western former formula wear test that can evaluate wear resistance in a short time Machine simultaneously simulates the contact conditions of actual pearlitic steel rail and wheel and is used as comparative test.That is, as shown in Fig. 2, making from steel The western former formula wear test piece 1 for the outer diameter 30mm that rail head portion chooses contacts with tire test piece 2 and rotates and tested.The figure In arrow represent the direction of rotation of western former formula wear test piece 1 and tire test piece 2 respectively.Tire test piece is from JIS standards The pole of diameter 32mm is chosen on the head for the common rail that E1101 is recorded, and Brinell hardness (Brinell loads 29.4kN) is HB370 carries out heat treatment so that tissue becomes tempered martensite, and then implementation processing, is processed as shape shown in Fig. 2, Tire test piece is made.It should be noted that western former formula wear test piece 1 selects as shown in Figure 3 from two positions of rail's end portion 3 It takes.The test film chosen from the surface layer of rail's end portion 3 is set to western former formula wear test piece 1a, the test film that will be chosen from inside It is set to western former formula wear test piece 1b.The length direction of the western former formula wear test piece 1b chosen from the inside of rail's end portion 3 Center is located at the depth of 24~26mm of upper surface (average value 25mm) away from rail's end portion 3.Experimental enviroment condition is drying regime, In contact：1.2GPa, sliding ratio (slip ratio)：- 10%, rotating speed：750rpm's (tire test piece is 750rpm) Under the conditions of measure rotation 1.8 × 105Wear extent after turning.The front and rear experiment sheet weight of experiment is measured, is gone out according to its mathematic interpolation Wear extent.
As shown in Figure 1, with the rising of hardness, wear resistance improves.For example, when the hardness of rail is more than HB400, with General heat-treated rail (HB370) is compared, and wear resistance can be made to improve 15%.But the hardness of rail length direction When deviation is larger, difference can be generated on abrasional behavior at the hard part and soft part.For example, hardness is inclined in HB415 points Difference is in the case of less than ± 15 (discrete in the scope of more than HB400 and below HB430), and the variation of wear extent is from 0.37g Change as 0.3g, therefore the deviation of wear extent is within 20%.On the other hand, it is contemplated that in HB415 points hardness deviation for ± During the situation of 30 (discrete in the scope of more than HB385 and below HB445), the variation of wear extent is from 0.40g variations 0.27g, therefore the deviation of wear extent also becomes 33%.Accordingly, since rail with wheel in use by contacting And wear, therefore it is preferably as far as possible uniformly worn out in length direction, rail is reduced by the high rigidity with rail In the hardness deviation of length direction, it can realize the uniform wear of rail, help to improve rail life.In view of above-mentioned abrasion Experiment it turns out that, preferably the hardness deviation of rail length direction is the wear extent deviation within 20%, makes case hardness Deviation is within ± HB15, it may thereby be ensured that excellent wear resistance along its length, helps to improve rail life, from And complete the present invention.
That is, purport of the invention is as follows.
(1) a kind of rail is formed with following component：In terms of quality %, contain
C：0.60~1.0%,
Si：0.1~1.5%,
Mn：0.01~1.5%,
P：Less than 0.035%,
S：Less than 0.030% and
Cr：0.1~2.0%,
Surplus is made of Fe and inevitable impurity,
Wherein, the case hardness deviation of the rail's end portion of the rail length direction is below ± HB15 point.
Here, the case hardness deviation of rail length direction refers to, along mill length direction with 5m spacing to full length rail (such as 25~100m) measures the Brinell hardness at the top of rail head, and according to the average value that measurement result calculates and each measuring point Ball hardness number difference.That is, the case hardness deviation of rail along its length is refers to below ± HB15 points, according between 5m (situation of overall length 25m is 6 points to whole hardness measurements away from measure, the situation of overall length 50m is 11 points, the situation of overall length 100m Measured value for 21 points) average value of Brinell hardness is obtained, the difference maximum of the average value and the Brinell hardness for each measuring point Within ± 15 points.It should be noted that when measuring Brinell hardness, the de- of more than 0.5mm is being removed in advance with grinder etc. It is measured after carbon-coating.
(2) rail described in above-mentioned (1), wherein, it is described into being grouped into terms of quality %, also containing a kind or 2 in following Kind or more,
Cu：Less than 1.0%,
Ni：Less than 0.5%,
Mo：Less than 0.5% and
V：Less than 0.15%.
(3) rail described in above-mentioned (1) or (2), wherein, the case hardness of the rail's end portion is more than HB400.
(4) rail any one of above-mentioned (1)~(3), wherein, the deviation of the case hardness for ± HB10 points with Under.
(5) a kind of manufacturing method of rail, this method include：Steel raw material is heated to 1200 DEG C or more, is then implemented Hot rolling and manufacture rail,
In the hot rolling, the temperature range below 1000 DEG C carries out including rolling for multiple passages along rail length direction System, the deviation of the passage interval time of rail length direction when carrying out the rolling was set within 15 seconds, will become rail The accumulation contraction percentage of area of the part on head is set to more than 40% and final rolling temperature is set to 900 DEG C or more, after the hot rolling Continue to carry out the beginning of cooling temperature to rail's end portion：800 DEG C or more, cooling stopping temperature：Less than 600 DEG C and cooling velocity：1~ 10 DEG C/sec of cooling,
The steel raw material is formed with following component：In terms of quality %, contain
C：0.60~1.0%,
Si：0.1~1.5%,
Mn：0.01~1.5%,
P：Less than 0.035%,
S：Less than 0.030% and
Cr：0.1~2.0%,
Surplus is made of Fe and inevitable impurity.
(6) manufacturing method of the rail described in above-mentioned (5), wherein, into being grouped into terms of quality %, also containing in following It is one kind or two or more,
Cu：Less than 1.0%,
Ni：Less than 0.5%,
Mo：Less than 0.5% and
V：Less than 0.15%.
(7) manufacturing method of the rail described in above-mentioned (5) or (6), wherein, in the cooling, by rail length direction The deviation of cooling velocity be set to less than ± 1 DEG C/sec.
The effect of invention
According to the present invention it is possible to make the hardness deviation of rail length direction very small, especially for parcel railway, It is extremely effective in terms of the durability raising (long lifetime) for the rail being laid in the high axis weight environment such as mine railway, industrially send out Wave remarkable result.
Description of the drawings
Fig. 1 is the chart of the relation of the hardness and wear extent that show rail material.
Fig. 2 is the figure for the western former formula wear test piece for showing evaluation wear resistance, and (a) is top view, and (b) is side view.
Fig. 3 is the rail's end portion sectional view for the chosen position for showing western former formula wear test piece.
Specific embodiment
First, the restriction reason of each ingredient into being grouped into of rail is described below.It should be noted that only Without special instruction, the meaning of " % " expression " quality % " in ingredient.
C：0.60~1.0%
C (carbon) is to form cementite in pearlite steel rail and improve hardness, intensity, so as to improve the important of wear resistance Element.But these effect unobvious when less than 0.60%, therefore be 0.60% by lower limit set.On the other hand, although C The increase of amount means the increase of the carburizing scale of construction, can expect the increase of hardness, intensity, still, ductility reduction.In addition, C amounts Increase expand γ+theta temperature scope, the softening of welding heat affected zone can be promoted.In view of these influences, the upper limit of C is set It is set to 1.0%.Preferred scope is 0.73~0.85%.
Si：0.1~1.5%
Si (silicon) is to strengthen pearl as the deoxidation material of rail material and for raising equilibrium phase change temperature (TE) Body of light tissue (caused by the miniaturization of lamellar tissue hardness increase) and add, but when less than 0.1%, these effects compared with It is small.On the other hand, the increase of Si promotes decarburization, the generation for the surface defect for promoting rail, therefore the upper limit is set as 1.5%. Preferably 0.5~1.3% scope.
Mn：0.01~1.5%
Mn (manganese), which has, makes actual pearlitic transformation temperature reduce and make the effect of pearlite stratiform interval densification, is to use In the effective element for reaching high rigidity, but when less than 0.01%, effect is smaller.On the other hand, due to can also make quenching Property improve, therefore while adding more than 1.5%, easily mutually becomes bainite, martensite, therefore the upper limit is set as 1.5%.It is preferred that For 0.3~1.2% scope.
P：Less than 0.035%
If P (phosphorus) is more than 0.035%, toughness, ductility reduction.Therefore, the upper limit of P is set as 0.035%.Make For preferred scope, it is set as the upper limit by 0.025%.On the other hand, for lower limit, due to that can be led whens carrying out special refining etc. Melting cost is caused to increase, therefore is preferably set to 0.001%.
S：Less than 0.030%
S (sulphur) is formed in the coarse MnS of rolling direction stretching, extension, reduces ductility, toughness.Therefore, by the upper of the content of S Limit is set as 0.030%.On the other hand, when less than 0.0005%, the cost that melting processing time increases when meltings is notable Increase, therefore preferred lower limit is 0.0005%.Preferably 0.001~0.015%.
Cr：0.1~2.0%
Cr (chromium) makes equilibrium phase change temperature (TE) raise and contribute to the miniaturization at pearlite stratiform interval, makes hardness, strong Degree increases.Therefore, it is necessary to add more than 0.2%.On the other hand, when addition is more than 2.0%, the hair of weld defect can not only be increased It is raw, and increase hardenability, promote the generation of martensite, therefore, the upper limit is set as 2.0%.More preferably 0.26~ 1.00% scope.
In addition to above-mentioned chemical composition, Cu can also be added：Less than 1.0%, Ni：Less than 0.5%, Mo：0.5% with Lower and V：It is one kind or two or more in less than 0.15%.
Cu：Less than 1.0%
Cu (copper) is the element that further high rigidity can be realized by solution strengthening.In addition, for inhibiting decarburization Also it is effective.In order to obtain the effect, preferably it is added with more than 0.01%.On the other hand, add more than 1.0% continuous During casting, rolling when easily generate face crack, therefore the upper limit is preferably set as 1.0%.In addition, still more preferably it is 0.05~0.6% scope.
Ni：Less than 0.5%
Ni (nickel) is to improving toughness, the effective element of ductility.Further, since be by with Cu it is compound addition and to suppression The effective element of Cu crackles processed, therefore preferably Ni is added in the case where adding Cu.It, can not be true but when less than 0.01% Recognize these effects, be more than 0.01% preferably by lower limit set in the case of addition therefore.On the other hand, addition is more than 0.5% can improve hardenability and promote the generation of martensite, therefore the upper limit preferably is set as 0.5%.More preferably 0.05~ 0.50% scope.
Mo：Less than 0.5%
Mo (molybdenum) is for the effective element of high intensity, and when less than 0.01%, effect is smaller, preferably sets lower limit It is set to 0.01%.On the other hand, when addition is more than 0.5%, hardenability improves, and as a result can generate martensite, so that toughness, Ductility terrifically reduces.Therefore, the upper limit is preferably set to 0.5%.More preferably 0.05~0.30% scope.
V：Less than 0.15%
V (vanadium) forms VC or VN etc. and is imperceptibly precipitated in ferrite, is helped by ferritic precipitation strength In the element of high intensity.In addition, the solid solubility temperature of VC or VN is substantially lower than Ti and Nb, austenite during to rolling is tied again It influences also small caused by brilliant behavior, therefore, is influenced caused by the characteristic deviation rail length direction also small.And then also conduct The capture site of hydrogen and play a role, can expect inhibit delayed fracture effect.It is therefore preferable that it is carried out with more than 0.001% Addition.On the other hand, when addition is more than 0.15%, above-mentioned each effect saturation, the increase of cost of alloy is very big, therefore the upper limit is excellent Choosing is set as 0.15%.More preferably 0.005~0.12% scope.
It should be noted that the surplus beyond above-mentioned ingredient is Fe and inevitable impurity.
For example, as inevitable impurity, N can allow to 0.006%, O allow to 0.003%.In addition, Al Although being effective as deoxidation material, the tufted AlN of shape can substantially reduce rolling contact fatigue (rolling fatigue) spy Property, it is therefore preferable that Al is set as less than 0.003%.In addition, on the Nb and Ti that contain as inevitable impurity, As described below.
Nb：Less than 0.003%
Ti：Less than 0.003%
Nb (niobium) and Ti (titanium) form carbide or carbonitride and strengthen matrix, therefore are to improving hardness, wear-resistant The effective element of property.But be the harmful element for the hardness deviation for promoting rail length direction, therefore do not add substantially, But as inevitable mixed amount, less than 0.003% can be allowed.That is, when adding Nb, Ti, heated, rolled according to raw material System or cooling condition and the variation of hardness is made increase, therefore can be sensitively to the mill length directions of these adjoint condition deviations Firmness change impacts.It is believed that in terms of metallurgy, while the inhomogeneities of heating austenite grain is promoted, inhibit The variation of the pearlitic transformation temperature for recrystallizing and accompanying with this of austenite in rolling is not than adding the steel of Nb, Ti greatly very It is more, therefore promote the deviation of hardness.
Except above-mentioned into addition to being grouped into, it is important to make the case hardness deviation of rail length direction for ± HB15 points with Under.The reason is that when hardness deviation is more than ± HB15 points, the variation of rail abrasion amount reaches more than 20%.It is as long as in addition, hard The deviation of degree is below ± HB10 point, so that it may so that the variation of rail abrasion amount is less than 15%, therefore more preferably rail length side To case hardness deviation for below ± HB10 points.
Then, the manufacturing condition of rail is specifically described.
For steel raw material, it is preferable to use slab as steel raw material, the slab is to utilize blast furnace, iron Water pretreatment, converter, RH degassing etc. smelting processes technique, and using continuous casting process to be adjusted to mentioned component composition molten steel into Obtained from row casting.
By common groove rolling (caliber rolling), universal rolling (universal rolling) to the steel Raw material carry out hot rolling, are thus shaped to rail shape.Hereinafter, at this time heating, rolling condition, with and subsequent cooling The restriction reason of condition illustrates.
[the heating temperature before hot rolling：1200 DEG C or more]
The steel raw material of melting needs to be heated to 1200 DEG C or more.Here, main purpose is by fully reducing deformation Resistance and mitigate rolling load, purpose also reside in realization homogenization.In order to fully obtain these effects, it is necessary to will heating temperature Degree is set as 1200 DEG C or more.It should be noted that the upper limit need not especially be set, but oxide skin is lost, inhibition takes off from inhibiting From the viewpoint of carbon, less than 1300 DEG C are preferably set to.
[temperature range below 1000 DEG C along rail length direction carry out the rolling of multiple passages when, by rail length The deviation setting of the passage interval time in direction is within 15 seconds]
Heated steel raw material is shaped to rail shape by hot rolling as described above, at this point, it is critical that In the rolling of the multi-pass of less than 1000 DEG C progress, reduced by the way that the rolling in a direction is repeated between the passage in rolling Every the deviation of time.It should be noted that the passage interval time in rolling refers to (roll from the length direction of steel rail rolling material Direction processed) certain part bite roll and rise to the time for biting next roll.Moreover, the passage interval time is in steel rail rolling The top (front end) of material and bottom (tail end) difference are maximum.
In addition, in the case of previous reverse rolling, for rolling top (front end), stung from certain passage roll Enter to next passage and started the time bitten, since since next passage be to be sequentially sent to roll rolling bottom (tail end) The form of roller, therefore roll the passage interval time extension at top.On the other hand, since rolling bottom (tail end) passes through certain passage Roll is bitten first in next passage afterwards, therefore passage interval time shortens.Before such reverse rolling is specific The difference of the passage interval time of end and tail end can influence austenite structure state, influence the hardness deviation after pearlitic transformation.Phase Than under, in continuous rolling in one direction, the difference substantially very little of the passage interval time of rolling stock front end and tail end. Therefore, the inhomogeneities of the austenite structure generated by difference of above-mentioned passage interval time can be eliminated.Thus, it is desirable to by the road The difference of minor tick time was set as within 15 seconds.That is, as long as the difference of passage interval time was set as within 15 seconds, with regard to energy Enough inhibit the hardness deviation of rail length direction.Within preferably 12 seconds.
Above-mentioned restriction applies to the condition of the rolling carried out in hot rolling below 1000 DEG C, for being represented in roughing operation Property be more than 1000 DEG C of the rolling of temperature range for, reverse rolling can be used.As long as in short, it can connect in one direction The continuous rolling for carrying out less than 1000 DEG C, then the rolling in its leading portion being more than 1000 DEG C of temperature range is arbitrary.In hot rolling The rolling carried out below 1000 DEG C is preferably carried out with 2~7 passages.This is because for 1 passes, rolling is negative It carries increase and is difficult to moulding, whereas if more than 7 passages, then the state there are austenite is slightly uneven and deviation of hardness Increased tendency.
[by being set as more than 40% as the accumulation contraction percentage of area of the part of rail's end portion]
, it is necessary to which the contraction percentage of area caused by less than 1000 DEG C of rolling is set as more than 40% in terms of accumulation.This is Due in order to promote the recrystallization grain refined of austenite, it is necessary to carry out more than 40% section shrinkage processing below 1000 DEG C. In the case that the contraction percentage of area of rolling below 1000 DEG C is less than 40%, the recrystallization grain refined of austenite is insufficient, office The coarse austenite of portion's remaining, as a result makes the hardness deviation of rail length direction (rolling direction) increase.
[final rolling temperature：900 DEG C or more]
By carrying out continuous rolling in one direction come when reducing the deviation of passage interval time of rolling stock overall length, It is preferred that final rolling temperature is set as 900 DEG C or more.This is because, when final rolling temperature is less than 900 DEG C, because continuing to implement after rolling Burning optimization on line the beginning of cooling temperature low temperature, pearlitic transformation (high temperature) etc. reasons, hardness is promoted integrally to reduce, partially Difference increase.Such hardness reduces in order to prevent, and final rolling temperature preferably is set as 900 DEG C or more.
And then continue to carry out cooling treatment under conditions of as described below after above-mentioned hot rolling.
" carry out the beginning of cooling temperature in rail's end portion：800 DEG C or more, cooling stopping temperature：Less than 600 DEG C, cooling speed Degree：1~10 DEG C/sec of cooling "
First, the beginning of cooling temperature is preferably 800 DEG C or more.That is, when the beginning of cooling temperature is less than 800 DEG C, Wu Fachong Dividing ensures degree of supercooling, there is the hidden danger that cannot obtain enough case hardnesses.Cooling, which stops temperature, to be needed to carry out to less than 600 DEG C. This is because enough hardness can not be obtained at 600 DEG C or more.It is not particularly limited for lower limit, even if but due to being cooled to Less than 400 DEG C hardness also can saturation, and interfere productivity when extending cooling time, therefore preferably stop at 400 DEG C or more Cooling.
Cooling velocity is 1~10 DEG C/sec of scope.When cooling velocity is more than 10 DEG C/sec, pearlite phase can not be substantially ensured The time of change, can bainite, martensite and make toughness, ductility, fatigue failure reduce.On the other hand, less than 1 DEG C/ Enough hardness can not be obtained during the second.Preferably 2~8 DEG C/sec of scope.
Additionally, it is preferred that the deviation in the cooling velocity in mill length direction is made to be less than ± 1 DEG C/sec.This is because pass through Make the deviation of cooling velocity that can further reduce the deviation at pearlite stratiform interval for less than ± 1 DEG C/sec, can realize hard The deviation of degree is ± below HB10, further reduces deviation in terms of wear resistance, endurance destructiveness along rail length direction.
In addition, the cooling continued after above-mentioned hot rolling preferably carries out air blast cooling or misting cooling.Here, air blast is cold But refer to by rail's end portion blows air being forced to carry out acceleration cooling.In addition, misting cooling refers to mix water and air Merging makes water change nebulize to rail's end portion injection.
In order to which the cooling velocity of controlled rolling length direction makes deviation smaller, for example, in the case that air-blast cooled, it is necessary to With the Separation control air pressure of below 5m (preferably below 3m), the temperature of rail length direction of the online progress with being measured before cooling down is inclined The adjusting of the corresponding air pressure of difference is constant cooling velocity in length direction control.The situation of misting cooling is similarly excellent The water of selected control length direction, pressure are cooled down.
By above into being grouped into and rolled and cooled down, the case hardness that can obtain rail length direction is preferably More than HB400, its deviation is below ± HB15 points and in the small uniform high rigidity pearlite of mill length direction hardness deviation Steel rail.
Embodiment
Melting has the steel of the chemical composition shown in table 1, the slab obtained by continuously casting is heated, hot rolling, Then implement cooling, thus manufacture the rail of 136 pounds or 141 pounds respectively.By its manufacturing condition, case hardness and its deviation Result of study is shown in table 2 together.
Here, the deviation of the passage interval time under rolling condition refers to, from being rolled the front end of rolling stock under To the difference of next time rolled time once rolled time and the tail end from rolling stock are rolled.As described above, In the rolling inversely rolled in previous utilization, the passage interval time for rolling top extends, and on the other hand, rolls the road of bottom The minor tick time shortens.In this way, in reverse rolling, during the road minor tick of the front end (top) of rolling stock and tail end (bottom) Between difference it is more apparent.In contrast, in continuous rolling in one direction, between rolling stock front end and the adjoint passage of tail end It is small every the subtractive of time, therefore the inhomogeneities of the tissue of generation can be eliminated, the situation is as shown in table 2.
In addition, the beginning of cooling temperature and the temperature that stops are with thermoviewer (thermoviewer) measurement rail corner Surface temperature obtained from result.It is according to the cold of length direction 5m distance measurements for the cooling velocity of rail But start temperature, cooling stop temperature and cooling time, measure cooling velocity and make obtained from it equalizes.On the other hand, For the cooling velocity deviation of length direction, whether the difference that the maxima and minima of each cooling velocity deviation is obtained is big In ± 1 DEG C/sec or for less than ± 1 DEG C/sec.
In addition, for the rail of manufacture, the case hardness and microstructure on its head are had rated.For rail's end portion surface Hardness for, using grinder remove more than 0.5mm decarburized layers, measure cloth respectively in the point of the 5m spacing of rail length direction Family name's hardness.Microscope example is similarly cut out, observes microstructure.
By these evaluation result is shown in table 2.
Rail according to the present invention, the hardness deviation of length direction is minimum, is ± below HB15, in contrast, for Into for being grouped into the rail that is departed from the scope of the present invention with any one of rolling condition, the deviation of hardness has been more than ± HB15。

Claims (5)

1. a kind of rail is formed with following component：In terms of quality %, contain
C：0.60~1.0%,
Si：0.1~1.5%,
Mn：0.01~1.5%,
P：Less than 0.035%,
S：Less than 0.030% and
Cr：0.1~2.0%,
Surplus is made of Fe and inevitable impurity,
Wherein, the case hardness deviation of the rail's end portion of the rail length direction is below ± HB10 point.
2. rail according to claim 1, wherein, it is described into being grouped into terms of quality %, also containing a kind in following or Two or more,
Cu：Less than 1.0%,
Ni：Less than 0.5%,
Mo：Less than 0.5% and
V：Less than 0.15%.
3. rail according to claim 1 or 2, wherein, the case hardness of the rail's end portion is more than HB400.
4. a kind of manufacturing method of rail, this method include：Steel raw material is heated to 1200 DEG C or more, then implement hot rolling and Manufacture rail,
In the hot rolling, the temperature range below 1000 DEG C carries out the rolling for including multiple passages along rail length direction, The deviation of the passage interval time of rail length direction when carrying out the rolling was set within 15 seconds, rail's end portion will be become The accumulation contraction percentage of area of part be set to more than 40% and final rolling temperature be set to 900 DEG C or more, continue after the hot rolling The beginning of cooling temperature is carried out to rail's end portion：800 DEG C or more, cooling stopping temperature：Less than 600 DEG C and cooling velocity：1~10 DEG C/sec cooling, in the cooling, the deviation of the cooling velocity of rail length direction is set to less than ± 1 DEG C/sec,
The steel raw material is formed with following component：In terms of quality %, contain
C：0.60~1.0%,
Si：0.1~1.5%,
Mn：0.01~1.5%,
P：Less than 0.035%,
S：Less than 0.030% and
Cr：0.1~2.0%,
Surplus is made of Fe and inevitable impurity.
5. the manufacturing method of rail according to claim 4, wherein, it is described into being grouped into terms of quality %, under also containing It is one kind or two or more in stating,
Cu：Less than 1.0%,
Ni：Less than 0.5%,
Mo：Less than 0.5% and
V：Less than 0.15%.
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