CN113817970A - High-strength high-toughness 60AT1 bainite switch rail and heat treatment process thereof - Google Patents
High-strength high-toughness 60AT1 bainite switch rail and heat treatment process thereof Download PDFInfo
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- CN113817970A CN113817970A CN202111009110.0A CN202111009110A CN113817970A CN 113817970 A CN113817970 A CN 113817970A CN 202111009110 A CN202111009110 A CN 202111009110A CN 113817970 A CN113817970 A CN 113817970A
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- rail
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- bainite
- steel rail
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/08—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling structural sections, i.e. work of special cross-section, e.g. angle steel
- B21B1/085—Rail sections
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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
- 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
- C22C38/18—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
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
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- 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
- C21D2211/008—Martensite
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- 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 high-strength and high-toughness 60AT1 bainite turnout steel rail, which comprises the following chemical components in percentage by mass: 0.12-0.30% of C; 0.60-1.20% of Si; 1.60-2.30% of Mn; p is less than or equal to 0.025 percent; s is less than or equal to 0.025 percent; 0.50-1.0% of Cr; 0.20-0.60% of Mo; 0.20 to 0.60 percent of Ni, and the balance of Fe and inevitable impurities. Its heat treatment process is also disclosed. The turnout steel rail produced by the method has the characteristics of high strength and high toughness, and the toughness of the turnout steel rail is 3-4 times of that of a pearlite turnout steel rail with the same strength, so that the good toughness of the bainite steel rail not only can meet the gradually harsh railway transportation environment, but also can improve the safety and stability of the railway operation process, thereby reducing the operation cost of the railway.
Description
Technical Field
The invention relates to the field of steel rail production and application, in particular to a high-strength and high-toughness 60AT1 bainite turnout steel rail and a heat treatment process thereof.
Background
The rise and development of high-speed and heavy-duty railways in various countries worldwide greatly increase the running speed and the axle weight of the trains, and the increase of the axle weight of the trains inevitably causes the increase of the contact stress of wheel rails and the internal shear stress of rail heads, thereby causing the deterioration of the service environment of the rails and the increase of contact fatigue damage, particularly the increase of rail abrasion, stripping and chipping, crushing, nuclear damage and the like of turnout areas year by year. Compared with pearlite steel rails, bainite steel rails have good strength, plasticity, impact toughness, wear resistance and rolling contact fatigue resistance, so that bainite alloy turnout steel rails with high strength and high toughness are adopted to meet the development requirements of railway turnout in railway development planning in China.
Disclosure of Invention
The invention aims to provide a 60AT1 bainite switch rail with high strength and toughness and a heat treatment process thereof, the invention develops a bainite/martensite multiphase online heat treatment bainite switch rail production process, the switch rail produced has the characteristics of high strength and high toughness, and the toughness is 3-4 times of that of pearlite switch rail with the same strength, so that the good strength and toughness of the bainite rail can meet the gradually harsh railway transportation environment, and meanwhile, the safety and stability of the railway operation process can be improved, thereby reducing the operation cost of the railway.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention relates to a high-strength and high-toughness 60AT1 bainite turnout steel rail, which comprises the following chemical components in percentage by mass: 0.12-0.30% of C; 0.60-1.20% of Si; 1.60-2.30% of Mn; p is less than or equal to 0.025 percent; s is less than or equal to 0.025 percent; 0.50-1.0% of Cr; 0.20-0.60% of Mo; 0.20 to 0.60 percent of Ni, and the balance of Fe and inevitable impurities.
A heat treatment process of a high-strength and high-toughness 60AT1 bainite turnout rail comprises the steps of heating a steel billet in a stepping heating furnace for 4-4.5 hours AT a tapping temperature of 1200-1250 ℃, rolling the steel billet into 60AT1 turnout rail size requirements after rough rolling for 7 passes, medium rolling for 3 passes and finish rolling for 3 passes, wherein the final rolling temperature is 930-950 ℃, rapidly feeding the steel rail into an online heat treatment production line, rapidly cooling the steel rail by air injection AT 710-810 ℃, cooling the rail head to 250-350 ℃, stopping cooling, naturally returning the rail head to 300-380 ℃, naturally cooling the rail head to a cooling bed for close arrangement, and straightening the steel rail below 80 ℃; and tempering for 8-48 hours at the temperature of 220-320 ℃ after straightening.
Compared with the prior art, the invention has the beneficial technical effects that:
the bainite turnout steel rail produced by the method has the characteristics of high strength and high toughness, and the toughness of the turnout steel rail is 3-4 times of that of a pearlite turnout steel rail with the same strength, so that the good toughness and toughness of the bainite steel rail not only can meet the gradually harsh railway transportation environment, but also can improve the safety and stability of the railway operation process, and the operation cost of the railway is reduced.
The mechanical property of the steel rail meets the conditions that Rm is more than or equal to 1280MPa, A% is more than or equal to 13%, and the tread hardness is 360-430 HBW; impact energy A at room temperatureKU2≥70J。
Detailed Description
An on-line heat treatment process of bainite switch steel rail of bainite of Bama multiphase, its chemical composition includes in terms of steel rail mass percent: 0.12-0.30% of C; 0.60-1.20% of Si; 1.60-2.30% of Mn; p is less than or equal to 0.025 percent; s is less than or equal to 0.025 percent; 0.50-1.0% of Cr; 0.20-0.60% of Mo; 0.20 to 0.60 percent of Ni, and the balance of Fe and inevitable impurities.
The billet is heated by a stepping heating furnace for 4.5 hours AT 1230 ℃, and is rolled into 60AT1 turnout steel rail size requirement after 7 passes of rough rolling, 3 passes of intermediate rolling and 3 passes of finish rolling, and the final rolling temperature is 936 ℃.
TABLE 1 comparison of rail heat treatment processes
As can be seen from Table 1, the phase transition temperature of the pearlite steel rail is about 520 ℃, the pearlite steel rail is subjected to heat treatment close to the phase transition temperature point, the bainite steel rail needs to be cooled to the martensite and lower bainite phase transition temperature point interval (250-350 ℃), and the steel rail is controlled to be in the martensite and lower bainite phase transition interval at a higher cooling speed (not less than 3 ℃/S) after being rolled. At the moment, the surface of the steel rail is influenced by the diffusion of heat of the center part and the web part of the rail head to the surface layer of the rail head and the latent heat of phase change, the surface of the rail head is cooled at a certain speed to offset the transferred heat and the latent heat of phase change, and the long-time and synchronous isothermal transformation is ensured to be carried out at the position of 0-30mm of the steel rail, so that the aims of refining and homogenizing the structure are fulfilled. The rail head of the steel rail naturally returns to 300-380 ℃, enters a cooling bed for close packing and natural cooling, and certain temperature return temperature and low-temperature tempering treatment can be beneficial to the transformation of low-carbon martensite and the stability of residual austenite. Thereby effectively improving the mechanical property, the mechanical stability and the service performance of the steel rail and realizing the optimal matching of high strength, high toughness and plasticity and high wear resistance. The steel rail finishes the organization phase change in the control cooling unit, thereby ensuring the good straightness of the steel rail and reducing the high residual stress attached to the steel rail straightening. Compared with the online heat treatment process of the pearlite steel rail, the method is quite different, and the pearlite turnout steel rail is not subjected to a low-temperature tempering process.
TABLE 2 test results of mechanical Properties of rails
The test results in table 2 show that the pearlite steel rail and the bainite steel rail both meet the technical requirements on strength and hardness, but compared with the pearlite H370 grade steel rail, the elongation of the steel rail in the range from 1# to 4# implemented by the invention is obviously improved by about 4.5-6%, and the normal temperature impact is improved by 73J-81J. Compared with pearlite H370 grade steel rail, the elongation of the high strength and toughness 60AT1 bainite switch steel rail of the invention is improved by about 45% -60%, and the normal temperature impact is improved by about 480% -540%. The steel rail has high toughness and is more suitable for being applied to service in turnout areas. The 60AT1 bainite steel rail turnout has the advantages of good combination of high strength, high hardness and high toughness, and not only can meet the gradually harsh railway transportation environment, but also can improve the safety and stability of the railway operation process, thereby reducing the operation cost of the railway.
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 (2)
1. A60 AT1 bainite switch rail with high strength and toughness is characterized in that the chemical components by mass percent comprise: 0.12-0.30% of C; 0.60-1.20% of Si; 1.60-2.30% of Mn; p is less than or equal to 0.025 percent; s is less than or equal to 0.025 percent; 0.50-1.0% of Cr; 0.20-0.60% of Mo; 0.20 to 0.60 percent of Ni, and the balance of Fe and inevitable impurities.
2. The heat treatment process of the high strength and toughness 60AT1 bainite switch rail according to claim 1, wherein, the billet is heated by a step-by-step heating furnace for 4-4.5 hours, the tapping temperature is 1200-1250 ℃, the billet is rolled into 60AT1 switch rail size requirement after being roughly rolled for 7 passes, middle rolled for 3 passes and finish rolled for 3 passes, the final rolling temperature is 930-950 ℃, the rail rapidly enters an on-line heat treatment production line, the rail is rapidly cooled by air injection AT 710-810 ℃, the rail head is cooled to 250-350 ℃ to stop cooling, the rail head naturally returns to 300-380 ℃, enters a cooling bed for close-row natural cooling, and the rail is straightened below 80 ℃; and tempering for 8-48 hours at the temperature of 220-320 ℃ after straightening.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111009110.0A CN113817970A (en) | 2021-08-31 | 2021-08-31 | High-strength high-toughness 60AT1 bainite switch rail and heat treatment process thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111009110.0A CN113817970A (en) | 2021-08-31 | 2021-08-31 | High-strength high-toughness 60AT1 bainite switch rail and heat treatment process thereof |
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| Publication Number | Publication Date |
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| CN113817970A true CN113817970A (en) | 2021-12-21 |
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| CN202111009110.0A Pending CN113817970A (en) | 2021-08-31 | 2021-08-31 | High-strength high-toughness 60AT1 bainite switch rail and heat treatment process thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115505713A (en) * | 2022-09-16 | 2022-12-23 | 包头钢铁（集团）有限责任公司 | Heat treatment process for reducing residual stress of Baimi online heat treatment bainite steel rail |
| CN115961207A (en) * | 2022-12-15 | 2023-04-14 | 攀钢集团攀枝花钢铁研究院有限公司 | Production method of steel for nickel microalloyed bainite frog |
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| CN110951943A (en) * | 2019-11-08 | 2020-04-03 | 包头钢铁（集团）有限责任公司 | Baimamu multiphase steel rail and heat treatment method thereof |
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| CN1127790A (en) * | 1995-01-25 | 1996-07-31 | 包头钢铁公司 | Steel rail in-line exhaust-heat strengthening process and its apparatus |
| CN1510155A (en) * | 2002-12-24 | 2004-07-07 | 鞍山钢铁集团公司 | Wearproof and tough quasi bainite points and rails and their production |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115505713A (en) * | 2022-09-16 | 2022-12-23 | 包头钢铁（集团）有限责任公司 | Heat treatment process for reducing residual stress of Baimi online heat treatment bainite steel rail |
| CN115505713B (en) * | 2022-09-16 | 2023-09-26 | 包头钢铁（集团）有限责任公司 | Heat treatment process for reducing residual stress of hundred-meter online heat-treated bainitic steel rail |
| CN115961207A (en) * | 2022-12-15 | 2023-04-14 | 攀钢集团攀枝花钢铁研究院有限公司 | Production method of steel for nickel microalloyed bainite frog |
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Application publication date: 20211221 |