CN114058813A - Control method of hypereutectoid rare earth steel rail network carbide - Google Patents
Control method of hypereutectoid rare earth steel rail network carbide Download PDFInfo
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- CN114058813A CN114058813A CN202111394026.5A CN202111394026A CN114058813A CN 114058813 A CN114058813 A CN 114058813A CN 202111394026 A CN202111394026 A CN 202111394026A CN 114058813 A CN114058813 A CN 114058813A
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- hypereutectoid
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 91
- 239000010959 steel Substances 0.000 title claims abstract description 91
- 238000000034 method Methods 0.000 title claims abstract description 21
- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 13
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 13
- 238000001816 cooling Methods 0.000 claims abstract description 76
- 238000010438 heat treatment Methods 0.000 claims abstract description 21
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 12
- 238000010791 quenching Methods 0.000 claims abstract description 10
- 230000000171 quenching effect Effects 0.000 claims abstract description 10
- 229910001567 cementite Inorganic materials 0.000 claims abstract description 9
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 claims abstract description 9
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 238000005096 rolling process Methods 0.000 claims abstract description 8
- 239000000463 material Substances 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- 238000001556 precipitation Methods 0.000 abstract description 3
- 238000005422 blasting Methods 0.000 abstract 1
- 229910052799 carbon Inorganic materials 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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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
- 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
- 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
-
- 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
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
-
- 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
- C21D2211/009—Pearlite
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
The invention discloses a control method of hypereutectoid rare earth steel rail network carbide, the steel rail directly enters an online heat treatment production line for accelerated cooling after finishing rolling, air blasting cooling is carried out, the temperature of the steel rail entering a quenching line is 730-780 ℃, the cooling speed of rail heads of a cooling 1 section and a cooling 2 section is controlled at 6-7 ℃/s, the temperature of the rail heads reaches 580-630 ℃ after the steel rail is rapidly cooled by the cooling 1 section and the cooling 2 section, then the steel rail is continuously and rapidly cooled in a cooling 3 section and a cooling 4 section, the cooling speed is reduced, the cooling speed of the rail heads is controlled at 2-3 ℃/s, the steel rail is taken out of an online heat treatment unit after the cooling 3 section and the cooling 4 section are finished, at the moment, the temperature of the rail heads is controlled at 540-560 ℃, and the steel rail is taken out of the quenching line and naturally cooled to the room temperature. The invention obtains the pearlite structure with finer lamellar spacing, the density of the cementite phase in the pearlite is higher, the precipitation of the reticular cementite in the hypereutectoid steel rail is effectively reduced, and the toughness of the steel rail is improved.
Description
Technical Field
The invention relates to the field of metallurgical materials, in particular to a control method of hypereutectoid rare earth steel rail network carbide.
Background
At present, the rapid development of railways in China increases the line traffic year by year, the service conditions of steel rails for heavy-duty railways are more and more rigorous, and how to prolong the service life of the steel rails, improve the wear resistance of the steel rails and ensure the transportation safety is an urgent problem to be solved according to the service effect of the steel rails in the Qin railway line of China. At present, the way of improving the wear resistance of the steel rail is to improve the toughness of the steel rail, the main way is to improve the carbon content and the alloy content of the steel rail, and the rapid cooling process is carried out after the steel rail is rolled, the pearl body type steel rail head is rapidly cooled by adopting compressed air or water mist and other modes, fine lamellar pearlite structures are obtained in the two modes, the synchronous improvement of the toughness of the steel rail is realized through the refinement of crystal grains, and the wear resistance and the contact fatigue resistance of the steel rail are improved. Production practices show that the increase of the carbon content of the steel rail enables the steel rail components to reach the hypereutectoid pearlite component range, and the precipitation of reticular cementite at the grain boundary can be caused, so that cracks are easy to form at the cementite, and can be continuously expanded along the reticular structure, the grain boundary energy is reduced, and the toughness of the steel rail is greatly reduced.
Disclosure of Invention
The invention aims to provide a control method of hypereutectoid rare earth steel rail network carbide, which adopts the method of increasing the carbon content to the hypereutectoid composition range, adding alloy elements of Cr, Ni and rare earth Ce, and obtaining a pearlite structure with finer lamellar spacing through an after-rolling online heat treatment process, wherein the density of a cementite phase in the pearlite is higher, the precipitation of the network cementite in the hypereutectoid steel rail is effectively reduced, and the toughness of the steel rail is improved.
The steel rail production process comprises converter smelting, LF refining, vacuum degassing, continuous casting, billet heating, rolling and the like, but the processes are not particularly limited, the processes are carried out according to a normal steel rail production process system, steel rail components are smelted according to a specific range, and after the steel rail is rolled, heat treatment is carried out according to a reasonable online heat treatment process system of the invention.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention relates to a control method of hypereutectoid rare earth steel rail network carbide, the steel rail directly enters an online heat treatment production line for accelerated cooling after finishing rolling, the cooling mode is air-jet cooling, the temperature of the steel rail entering a quenching line is 730-780 ℃, the cooling speed of rail heads of a cooling 1 section and a cooling 2 section is controlled at 6-7 ℃/s, the temperature of the rail heads reaches 580-630 ℃ after the steel rail is rapidly cooled by the cooling 1 section and the cooling 2 section, then the steel rail is continuously and rapidly cooled in a cooling 3 section and a cooling 4 section, the cooling speed is reduced, the cooling speed of the rail heads is controlled at 2-3 ℃/s, the steel rail is taken out of an online heat treatment unit after the cooling 3 section and the cooling 4 section are finished, the temperature of the rail heads is controlled at 540-560 ℃, and the steel rail is naturally cooled to room temperature after being taken out of the quenching line.
Further, the steel rail material comprises the following chemical components in percentage by mass: 0.90-1.00% of C; 0.50-0.60% of Si; 0.90-1.00% of Mn; p is less than or equal to 0.025 percent; s is less than or equal to 0.025 percent; 0.15 to 0.50 percent of Ni; 0.15-0.30% of Cr0.15; the rare earth Ce accounts for 15-20 ppm, the balance is Fe and inevitable impurities, and the steel rail material in the composition range is a hypereutectoid pearlite material.
Furthermore, the metallographic structure of the steel rail is a pearlite structure without netlike cementite, the mechanical property of the steel rail is that the tensile strength Rm is more than or equal to 1330MPa, the elongation A is more than or equal to 10 percent, and the tread hardness is 400-430 HB.
Compared with the prior art, the invention has the beneficial technical effects that:
after heat treatment, the hypereutectoid pearlite steel rail has the mechanical properties of tensile strength Rm of more than or equal to 1330MPa, elongation A of more than or equal to 10 percent, tread hardness of 400-430 HB and a pearlite metallographic structure.
Drawings
The invention is further illustrated in the following description with reference to the drawings.
FIG. 1 is a metallographic structure photograph of a steel rail according to example 1;
FIG. 2 is a metallographic structure photograph of a steel rail according to example 2;
FIG. 3 is a metallographic photograph of a steel rail according to example 3.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments thereof so that the present invention may be more clearly understood.
The production method is used for specific component ranges and heat treatment processes, and can effectively ensure that the mechanical properties such as the strength, the hardness and the like of the steel rail meet requirements after heat treatment, and the steel rail material comprises the following chemical components in percentage by mass: 0.94 percent of C; 0.56 percent of Si; 0.96 percent of Mn; p is 0.016 percent; 0.004 percent of S; 0.20 percent of Ni; 0.42 percent of Cr; 20ppm of rare earth Ce, and the balance of Fe and inevitable impurities. The steel rail with the composition is adopted to carry out three different online heat treatment process experiments. Examples 1, 2 and 3, respectively. And (4) comparing and analyzing the influence of different heat treatment processes on the performance of the steel rail and the net-shaped carbide.
Example 1
And after finishing the steel rail rolling, directly entering a cooling bed to be cooled at room temperature, wherein the cooling speed is 0.5 ℃/s, directly cooling the steel rail from 930 ℃ to room temperature, and detecting the mechanical property of the steel rail.
Example 2
After finishing the finish rolling of the steel rail, directly entering an online heat treatment production line for accelerated cooling, wherein the cooling mode is air-jet cooling, the temperature of the steel rail entering a quenching line is 742 ℃, the cooling speed of rail heads of a cooling 1 section and a cooling 2 section is controlled at 8 ℃/s, the temperature of the rail head reaches 560 ℃ after the steel rail is rapidly cooled by the cooling 1 section and the cooling 2 section, then the steel rail is continuously and rapidly cooled in a cooling 3 section and a cooling 4 section, the cooling speed is reduced, the cooling speed of the rail head is controlled at 3.3 ℃/s, the steel rail is taken out of an online heat treatment unit after the cooling 3 section and the cooling 4 section are finished, at the moment, the temperature of the rail head is controlled at 450 ℃, and the steel rail is naturally cooled to room temperature after being taken out of the quenching line. And (5) inspecting the final mechanical property of the steel rail.
Example 3
After finishing rolling, the steel rail directly enters an online heat treatment production line for accelerated cooling, the cooling mode is air blast cooling, the temperature of the steel rail entering a quenching line is 752 ℃, the cooling speed of rail heads of a cooling 1 section and a cooling 2 section is controlled at 6.5 ℃/s, after the steel rail is rapidly cooled by the cooling 1 section and the cooling 2 section, the temperature of the rail head reaches 584 ℃, then the steel rail is continuously and rapidly cooled in a cooling 3 section and a cooling 4 section, the cooling speed is reduced, the cooling speed of the rail head is controlled at 2.5 ℃/s, the steel rail is taken out of an online heat treatment unit after the cooling 3 section and the cooling 4 section are finished, at the moment, the temperature of the rail head is controlled at 505 ℃, and the steel rail is naturally cooled to the room temperature after being taken out of the quenching line. And (5) inspecting the final mechanical property of the steel rail.
TABLE 1 results of mechanical properties of steel rails tested at different cooling rates
Comparing the three different processes of example 1, example 2 and example 3, the example 3 is carried out completely according to the heat treatment process system formulated by the invention, the mechanical property and the metallographic structure of the steel rail can meet the requirements, the steel rail of the example 1 is cooled at room temperature, the cooling speed is too low, the mechanical property of the steel rail can not meet the requirements, and the mesh cementite is too much, thereby greatly influencing the toughness of the steel rail and having low elongation. The cooling speed of the steel rail online heat treatment process in the embodiment 2 is too high, the strength and the hardness of the steel rail are both higher, but bainite and martensite metallographic structures appear, and the toughness of the steel rail is reduced.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.
Claims (3)
1. A control method of hypereutectoid rare earth steel rail network carbide is characterized in that: after finishing rolling of the steel rail, the steel rail directly enters an online heat treatment production line for accelerated cooling, the cooling mode is air-jet cooling, the temperature of the steel rail entering a quenching line is 730-780 ℃, the cooling speed of rail heads in a cooling 1 section and a cooling 2 section is controlled at 6-7 ℃/s, after the steel rail is rapidly cooled in the cooling 1 section and the cooling 2 section, the temperature of the rail heads reaches 580-630 ℃, then the steel rail is continuously and rapidly cooled in a cooling 3 section and a cooling 4 section, the cooling speed is reduced, the cooling speed of the rail heads is controlled at 2-3 ℃/s, the steel rail exits the online heat treatment unit after the cooling 3 section and the cooling 4 section are finished, at the moment, the temperature of the rail heads is controlled at 540-560 ℃, and the steel rail exits the quenching line and is naturally cooled to room temperature.
2. The method for controlling hypereutectoid rare earth steel rail network carbide according to claim 1, wherein: the steel rail material comprises the following chemical components in percentage by mass: 0.90-1.00% of C; 0.50-0.60% of Si; 0.90-1.00% of Mn0.90; p is less than or equal to 0.025 percent; s is less than or equal to 0.025 percent; 0.15-0.50% of Ni0; 0.15-0.30% of Cr0.15; the steel rail material comprises 15-20 ppm of rare earth Ce, and the balance Fe and inevitable impurities, and is a hypereutectoid pearlite material.
3. The method for controlling hypereutectoid rare earth steel rail network carbide according to claim 1, wherein: the metallographic structure of the steel rail is a pearlite structure, no netlike cementite exists, the mechanical property of the steel rail is that the tensile strength Rm is more than or equal to 1330MPa, the elongation A is more than or equal to 10%, and the tread hardness is 400-430 HB.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111394026.5A CN114058813A (en) | 2021-11-23 | 2021-11-23 | Control method of hypereutectoid rare earth steel rail network carbide |
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| CN202111394026.5A CN114058813A (en) | 2021-11-23 | 2021-11-23 | Control method of hypereutectoid rare earth steel rail network carbide |
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| CN114058813A true CN114058813A (en) | 2022-02-18 |
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| CN202111394026.5A Pending CN114058813A (en) | 2021-11-23 | 2021-11-23 | Control method of hypereutectoid rare earth steel rail network carbide |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115369229A (en) * | 2022-09-13 | 2022-11-22 | 包头钢铁（集团）有限责任公司 | Production control method for improving flatness of turnout steel rail after on-line heat treatment quenching |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104046765A (en) * | 2014-02-20 | 2014-09-17 | 攀钢集团攀枝花钢铁研究院有限公司 | Hypereutectoid steel rail heat treatment method |
| CN111411208A (en) * | 2020-05-28 | 2020-07-14 | 内蒙古科技大学 | Heat treatment method for reducing hypereutectoid steel rail reticular cementite precipitation |
| CN113373371A (en) * | 2021-05-21 | 2021-09-10 | 包头钢铁（集团）有限责任公司 | Super-high wear-resistance hypereutectoid pearlite steel rail material added with rare earth and nickel elements |
-
2021
- 2021-11-23 CN CN202111394026.5A patent/CN114058813A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104046765A (en) * | 2014-02-20 | 2014-09-17 | 攀钢集团攀枝花钢铁研究院有限公司 | Hypereutectoid steel rail heat treatment method |
| CN111411208A (en) * | 2020-05-28 | 2020-07-14 | 内蒙古科技大学 | Heat treatment method for reducing hypereutectoid steel rail reticular cementite precipitation |
| CN113373371A (en) * | 2021-05-21 | 2021-09-10 | 包头钢铁（集团）有限责任公司 | Super-high wear-resistance hypereutectoid pearlite steel rail material added with rare earth and nickel elements |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115369229A (en) * | 2022-09-13 | 2022-11-22 | 包头钢铁（集团）有限责任公司 | Production control method for improving flatness of turnout steel rail after on-line heat treatment quenching |
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Application publication date: 20220218 |