CN115466833A - Heat treatment method for improving low-temperature toughness of pearlitic steel rail - Google Patents
Heat treatment method for improving low-temperature toughness of pearlitic steel rail Download PDFInfo
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- CN115466833A CN115466833A CN202210957188.3A CN202210957188A CN115466833A CN 115466833 A CN115466833 A CN 115466833A CN 202210957188 A CN202210957188 A CN 202210957188A CN 115466833 A CN115466833 A CN 115466833A
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- steel rail
- heat treatment
- temperature
- cooling
- cooled
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 49
- 239000010959 steel Substances 0.000 title claims abstract description 49
- 238000010438 heat treatment Methods 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000001816 cooling Methods 0.000 claims abstract description 25
- 230000008569 process Effects 0.000 claims abstract description 13
- 238000004519 manufacturing process Methods 0.000 claims abstract description 5
- 238000010791 quenching Methods 0.000 claims abstract description 5
- 230000000171 quenching effect Effects 0.000 claims abstract description 5
- 239000002826 coolant Substances 0.000 claims abstract description 3
- 239000003595 mist Substances 0.000 claims abstract description 3
- 238000005096 rolling process Methods 0.000 claims description 13
- 238000005520 cutting process Methods 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 2
- 238000007689 inspection Methods 0.000 claims description 2
- 238000004806 packaging method and process Methods 0.000 claims description 2
- 238000010079 rubber tapping Methods 0.000 claims description 2
- 238000005303 weighing Methods 0.000 claims description 2
- 239000002918 waste heat Substances 0.000 abstract description 7
- 229910001562 pearlite Inorganic materials 0.000 abstract description 4
- 239000000463 material Substances 0.000 description 6
- 238000005070 sampling Methods 0.000 description 6
- 238000011161 development Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000007546 Brinell hardness test Methods 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000599 Cr alloy Inorganic materials 0.000 description 1
- 229910000756 V alloy Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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
- 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
- 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
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
-
- 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
Abstract
The invention discloses a heat treatment method for improving the low-temperature toughness of a pearlite steel rail, which comprises the steps of on-line waste heat quenching, wherein a cooling medium is pure wind or a wind-mist mixed medium; the temperature for starting the waste heat treatment is 740-850 ℃, the steel rail head is taken out of the heat treatment production line after the on-line heat treatment is carried out for 140-180 s, the top surface, the two sides, the lower jaw and the rail bottom of the steel rail head are cooled strongly in the first on-line stage, the actual cooling speed of the cooling section is 3 ℃/s-8 ℃/s, the cooling time is 40 s-80 s, and the surface temperature of the cooled rail head is 600-700 ℃; the second stage of weak cooling, wherein the top surface of the steel rail, the two sides of the rail head, the lower jaw of the gauge angle and the rail bottom are cooled at the cooling speed of 1.0-2.5 ℃/s for 60-100 s; and the third stage of weak cooling, wherein the cooling speed is less than or equal to 1.5 ℃/s, the temperature of the outlet railhead is 420-520 ℃, and the air is naturally cooled to the room temperature. The invention utilizes the on-line waste heat treatment process to improve the strength and the hardness of the steel rail.
Description
Technical Field
The invention relates to the technical field of materials, in particular to a heat treatment method for improving the low-temperature toughness of a pearlitic steel rail.
Background
At present, the steel rail for the railway is basically a high-carbon pearlite material, the carbon content is generally more than 0.70%, and the strength of the steel rail is improved by increasing the content of C according to the service requirement of a line, so that the service requirement and the service life of the steel rail are prolonged. With the development of the heat treatment process, the steel rail is rapidly cooled in the pearlite transformation temperature range on line, the internal structure of the steel rail is refined, and the toughness is improved. However, the material composition of the steel rail does not break through the traditional design concept, and the heat treatment cooling process is designed according to the material characteristics, so that the heat treatment process of the high-carbon pearlite steel rail at present is basically not changed greatly. Along with the development of railway construction, the service working condition environment of the steel rail is more and more responsible, and factors influencing the service life of the steel rail under different environments are different. The width of our country is broad, the north, the northwest and partial southwest regions face low-temperature environment, the steel rail may have brittle failure problem in the long-term service under the low-temperature environment, and the safety of railway transportation is directly influenced. At present, relatively few published documents related to the study of the low-temperature performance of the steel rail at home and abroad are published, and the research and the development of the steel rail with high tensile strength and high tread hardness and the application of line laying are focused. Therefore, the development of the low-temperature resistant steel rail has important significance for low-temperature environments in the northwest and southwest.
Disclosure of Invention
In order to solve the above-mentioned problems, an object of the present invention is to provide a heat treatment method for improving the low-temperature toughness of a pearlitic rail.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention relates to a heat treatment method for improving the low-temperature toughness of a pearlitic steel rail, which comprises an online heat treatment process and is characterized in that the online heat treatment process specifically comprises online waste heat quenching, wherein a cooling medium for the online waste heat quenching is a pure air or air-mist mixed medium; the temperature of the steel rail for starting the waste heat treatment is 740-850 ℃, the steel rail is taken out of the heat treatment production line after the online heat treatment is carried out for 140-180 s, the top surface, two sides, a gauge angle lower jaw and a rail bottom of the steel rail head are cooled strongly in the online first stage, the actual cooling speed of a cooling section is 3 ℃/s-8 ℃/s, the cooling time is 40-80 s, and the surface temperature of the steel rail head is 600-700 ℃ after the steel rail is cooled; the second stage of weak cooling, the top surface of the steel rail, the two sides of the rail head, the lower jaw of the gauge angle and the rail bottom are cooled, the cooling speed is 1.0-2.5 ℃/s, and the cooling time is 60-100 s; and the third stage of weak cooling, wherein the cooling speed is less than or equal to 1.5 ℃/s, the temperature of the rear outlet railhead is 420-520 ℃, and then the air is naturally cooled to the room temperature.
Further, the rolling process of the steel rail comprises the following steps: square billet → saw cutting → heating → BD1 rolling → BD2 rolling → CCS universal mill tandem rolling → the on-line heat treatment process → saw cutting → cooling → head and tail cutting → straightening → inspection → packaging → weighing → warehousing; the temperature of a square billet heating preheating section is not more than 900 ℃; the heating time is not less than 3 hours and 15 minutes; the tapping temperature is not lower than 1150 ℃, the initial rolling temperature is not lower than 1100 ℃, and the final rolling temperature is 910-940 ℃; .
Further, the steel rail comprises the following chemical components in percentage by mass: 0.50 to 0.65 percent of C; si 0.35-0.60%; 0.50 to 1.00 percent 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 0.45 percent of Cr; v0.02-0.10%; the balance of Fe and inevitable impurities, and the mass fraction is 100 percent in total.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention utilizes the on-line waste heat treatment process to improve the strength and the hardness of the steel rail, simultaneously reasonably designs components and adds the optimal Cr and V alloy elements into the steel rail, and can improve the performances of the steel rail such as tensile strength, elongation, tread hardness, impact toughness and the like under the rolling process. The heat-treated steel rail produced by using the composite material has good tensile strength, tread hardness and impact energy.
The low-temperature-resistant and wear-resistant heat-treated steel rail has a unique production process, is high in production efficiency, energy-saving and environment-friendly, has good economic benefit, is suitable for large-scale production, and has good popularization value.
Detailed Description
The chemical compositions of the materials for preparing the rails of each example are shown in table 1.
Table 1 ingredients of examples (mass%/%)
Specific examples of the rail heat treatment process are shown in table 2.
TABLE 2 examples of heat treatment process for steel rail materials
Rolled steel sample performance: the tensile sample specification is that the diameter d0=10mm, and the gauge length Lo =5do. Randomly sampling tread hardness on a steel rail, wherein the length of a sample is 250mm, the top surface of a rail head is ground to be 0.5mm, 5 test points are used for carrying out Brinell hardness test, the average value is calculated, the test temperature is 20 ℃ and soil is 5 ℃, and the sampling method, the sampling position and the sampling size of the sample are in accordance with the TB/T2344-2012 standard. Impact sampling according to GB/T229-2007, with the sampling position in the centre of the tread, the direction being longitudinal, the dimensions 10mm x 50mm, being A KU2 And (4) forming notches. The results of the experiment are shown in table 3.
TABLE 3 mechanical Properties of the examples
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 heat treatment method for improving the low-temperature toughness of a pearlitic steel rail comprises an online heat treatment process, and is characterized in that the online heat treatment process specifically comprises online residual heat quenching, wherein a cooling medium for the online residual heat quenching is a pure air or air-mist mixed medium; the steel rail begins the heat treatment temperature of the residual heat to be 740-850 ℃, the steel rail is taken out of the heat treatment production line after the on-line heat treatment for 140-180 s, the top surface, two sides, a gauge angle lower jaw and a rail bottom of the steel rail are cooled strongly in the first stage, the actual cooling speed of the cooling section is 3 ℃/s-8 ℃/s, the cooling time is 40 s-80 s, and the surface temperature of the steel rail head is 600-700 ℃ after the steel rail is cooled; the second stage of weak cooling, wherein the top surface of the steel rail, the two sides of the rail head, the lower jaw of the gauge angle and the rail bottom are cooled at the cooling speed of 1.0-2.5 ℃/s for 60-100 s; and the third stage of weak cooling, wherein the cooling speed is less than or equal to 1.5 ℃/s, the temperature of the rear outlet railhead is 420-520 ℃, and then the air is naturally cooled to the room temperature.
2. The heat treatment method for improving the low-temperature toughness of the pearlitic steel rail according to claim 1, wherein the rolling process of the steel rail comprises the following steps: square billet → saw cutting → heating → BD1 rolling → BD2 rolling → CCS universal mill tandem rolling → the on-line heat treatment process → saw cutting → cooling → head and tail cutting → straightening → inspection → packaging → weighing → warehousing; the temperature of a square billet heating preheating section is not more than 900 ℃; the heating time is not less than 3 hours and 15 minutes; the tapping temperature is not lower than 1150 ℃, the initial rolling temperature is not lower than 1100 ℃, and the final rolling temperature is 910-940 ℃; .
3. The heat treatment method for improving the low-temperature toughness of the pearlitic steel rail according to claim 1, wherein the steel rail comprises the following chemical components in percentage by mass: 0.50 to 0.65 percent of C; si 0.35-0.60%; 0.50 to 1.00 percent 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 0.45 percent of Cr; v0.02-0.10%; the balance of Fe and inevitable impurities, and the mass fraction is 100 percent.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210957188.3A CN115466833A (en) | 2022-08-10 | 2022-08-10 | Heat treatment method for improving low-temperature toughness of pearlitic steel rail |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210957188.3A CN115466833A (en) | 2022-08-10 | 2022-08-10 | Heat treatment method for improving low-temperature toughness of pearlitic steel rail |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115466833A true CN115466833A (en) | 2022-12-13 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210957188.3A Pending CN115466833A (en) | 2022-08-10 | 2022-08-10 | Heat treatment method for improving low-temperature toughness of pearlitic steel rail |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115466833A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107475616A (en) * | 2017-10-10 | 2017-12-15 | 攀钢集团研究院有限公司 | High-strength tenacity pearlite steel rail and its manufacture method |
| CN107723594A (en) * | 2017-10-10 | 2018-02-23 | 攀钢集团研究院有限公司 | Resistance to internal injury pearlite steel rail and its manufacture method |
| CN113388778A (en) * | 2021-05-14 | 2021-09-14 | 包头钢铁（集团）有限责任公司 | Production method of high-low temperature fracture toughness steel rail |
| CN113637914A (en) * | 2021-08-18 | 2021-11-12 | 攀钢集团攀枝花钢铁研究院有限公司 | High-strength and high-toughness steel rail and preparation method thereof |
-
2022
- 2022-08-10 CN CN202210957188.3A patent/CN115466833A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107475616A (en) * | 2017-10-10 | 2017-12-15 | 攀钢集团研究院有限公司 | High-strength tenacity pearlite steel rail and its manufacture method |
| CN107723594A (en) * | 2017-10-10 | 2018-02-23 | 攀钢集团研究院有限公司 | Resistance to internal injury pearlite steel rail and its manufacture method |
| CN113388778A (en) * | 2021-05-14 | 2021-09-14 | 包头钢铁（集团）有限责任公司 | Production method of high-low temperature fracture toughness steel rail |
| CN113637914A (en) * | 2021-08-18 | 2021-11-12 | 攀钢集团攀枝花钢铁研究院有限公司 | High-strength and high-toughness steel rail and preparation method thereof |
Non-Patent Citations (1)
| Title |
|---|
| 倪红军等: "普通高等教育系列教材 工程材料", 31 August 2021, 机械工业出版社, pages: 159 * |
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