CN117051336A - High-strength bainite steel rail with good impact toughness and production method thereof - Google Patents
High-strength bainite steel rail with good impact toughness and production method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 90
- 239000010959 steel Substances 0.000 title claims abstract description 90
- 229910001563 bainite Inorganic materials 0.000 title claims abstract description 23
- 238000004519 manufacturing process Methods 0.000 title abstract description 7
- 238000005096 rolling process Methods 0.000 claims abstract description 31
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 239000000126 substance Substances 0.000 claims abstract description 8
- 238000010438 heat treatment Methods 0.000 claims description 35
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 35
- 238000005266 casting Methods 0.000 claims description 28
- 238000000034 method Methods 0.000 claims description 28
- 238000010079 rubber tapping Methods 0.000 claims description 28
- 238000001816 cooling Methods 0.000 claims description 26
- 238000007664 blowing Methods 0.000 claims description 21
- 238000009849 vacuum degassing Methods 0.000 claims description 21
- 239000000203 mixture Substances 0.000 claims description 19
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 14
- 238000009749 continuous casting Methods 0.000 claims description 14
- 229910052742 iron Inorganic materials 0.000 claims description 14
- 239000002893 slag Substances 0.000 claims description 14
- 238000005496 tempering Methods 0.000 claims description 14
- 230000004048 modification Effects 0.000 claims description 9
- 238000012986 modification Methods 0.000 claims description 9
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 7
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 7
- 238000003723 Smelting Methods 0.000 claims description 7
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 7
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 7
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- 229910052786 argon Inorganic materials 0.000 claims description 7
- 229910052788 barium Inorganic materials 0.000 claims description 7
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 claims description 7
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 7
- 229910052918 calcium silicate Inorganic materials 0.000 claims description 7
- 239000000378 calcium silicate Substances 0.000 claims description 7
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 claims description 7
- 230000003009 desulfurizing effect Effects 0.000 claims description 7
- 238000009826 distribution Methods 0.000 claims description 7
- 230000000694 effects Effects 0.000 claims description 7
- 239000010436 fluorite Substances 0.000 claims description 7
- 239000004571 lime Substances 0.000 claims description 7
- 239000011574 phosphorus Substances 0.000 claims description 7
- 229910052698 phosphorus Inorganic materials 0.000 claims description 7
- 239000000843 powder Substances 0.000 claims description 7
- 238000003825 pressing Methods 0.000 claims description 7
- 238000007670 refining Methods 0.000 claims description 7
- 230000000630 rising effect Effects 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 7
- 239000011593 sulfur Substances 0.000 claims description 7
- 229910052717 sulfur Inorganic materials 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 229910001566 austenite Inorganic materials 0.000 description 6
- 229910000734 martensite Inorganic materials 0.000 description 6
- 239000000498 cooling water Substances 0.000 description 5
- 230000002572 peristaltic effect Effects 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 3
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
Classifications
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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
-
- 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
-
- 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
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- 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
- 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
- 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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- 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 Steel (AREA)
Abstract
The invention discloses a high-strength bainite steel rail with good impact toughness and a production method thereof, wherein the high-strength bainite steel rail comprises the following chemical components in percentage by mass: c:0.17 to 0.18 percent; si:1.00 to 1.10 percent; mn:1.70 to 2.00 percent; p is less than or equal to 0.018 percent; s is less than or equal to 0.010 percent; nb:0.02 to 0.03 percent; v:0.04 to 0.06 percent; cr:0.70 to 0.80 percent; ni:0.02 to 0.04 percent; mo:0.30 to 0.35 percent, and the balance of Fe and unavoidable impurities; the high-strength bainite steel rail provided by the invention not only has higher strength and hardness, but also has higher room-temperature impact toughness, the room-temperature impact energy can reach more than 100J, and the high-strength bainite steel rail can be suitable for heavy-load railway lines, and lines with small curve radius, severe line conditions and serious rolling contact fatigue damage of the steel rail.
Description
Technical Field
The invention belongs to the field of steel rail production and application, and particularly relates to a high-strength bainite steel rail with good (room temperature) impact toughness and a production method thereof.
Background
The railway in China is developing at high speed and large traffic, and the indexes of wear resistance, toughness, safety and the like of the steel rail are gradually improved. The bainite frog rail can still maintain high toughness under the condition of ensuring high strength, the service life of the frog rail is greatly prolonged, compared with a pearlitic switch rail, the service life of the frog rail can be prolonged by more than 3 times, the toughness is improved, and the running safety of a train is greatly ensured. However, there is still a need for further improvement in the impact toughness of current bainitic steel rails.
Disclosure of Invention
Aiming at the problems in the prior art, one aspect of the invention provides a high-strength bainite steel rail with good impact toughness, which comprises the following chemical components in percentage by mass: c:0.17 to 0.18 percent; si:1.00 to 1.10 percent; mn:1.70 to 2.00 percent; p is less than or equal to 0.018 percent; s is less than or equal to 0.010 percent; nb:0.02 to 0.03 percent; v:0.04 to 0.06 percent; cr:0.70 to 0.80 percent; ni:0.02 to 0.04 percent; mo:0.30 to 0.35 percent, and the balance of Fe and unavoidable impurities;
the mechanical properties of the high-strength bainite steel rail meet the following conditions: the yield strength is more than or equal to 1100MPa, the tensile strength is more than or equal to 1300MPa, the elongation is more than or equal to 14%, the tread hardness is 370-440 HBW, and the room temperature impact energy is more than or equal to 100J.
The invention also provides a production method of the high-strength bainite steel rail with good impact toughness, which comprises the following steps:
1) And (3) molten iron pretreatment: the sulfur content in molten iron is less than or equal to 0.011 percent, and the phosphorus content is less than or equal to 0.10 percent;
2) Smelting in a converter: the content of C in tapping is controlled to be more than or equal to 0.09%, the tapping temperature is controlled to be more than or equal to 1550 ℃, lime, calcium silicate barium and fluorite are added after tapping, deoxidation and slag modification are carried out, argon blowing effect is ensured in the tapping process, and slag ejection phenomenon is avoided when molten steel is refined in place;
3) Refining in an LF furnace: desulfurizing according to the composition and temperature of the molten steel of the converter, and performing fine adjustment and temperature rising operation of the composition;
4) Vacuum degassing by VD: the deep vacuum degassing time is more than or equal to 18min, the soft blowing after vacuum degassing is more than or equal to 20min, the soft blowing is performed at Cheng Yaqi, the flow is stable, and the molten steel is not exposed due to creeping;
5) Continuous casting: the continuous casting process adopts protection casting, adopts low-aluminum casting powder, adopts weak cold water distribution in the second cooling section, is operated at a constant pulling speed in the whole process, and has the pulling speed of 0.60-0.65 m/min, and the electric stirring and the light pressing of the casting machine are started to ensure the quality of casting blanks;
6) Heating a steel billet: heating time is more than or equal to 4 hours, and heating temperature is more than or equal to 1200 ℃;
7) Rolling steel billets: the initial rolling temperature is 1150-1200 ℃, the final rolling temperature is 900-960 ℃, the billet is rolled for 13 times, and then enters a cooling bed to be cooled to room temperature at a cooling speed of 0.25-0.35 ℃/s after final rolling, tempering heat treatment is adopted for 240-260 ℃ plus 23-25 hours, and the steel rail is slowly cooled to room temperature after tempering heat treatment.
The invention has the advantages that: the invention provides a high-strength bainite steel rail with good impact toughness, which can optimize the structure of a steel rail structure by adding a proper amount of Nb and V microalloy into steel rail components and combining with control of a production process, and can ensure that the obtained steel rail has good room-temperature impact toughness while ensuring that the steel rail has stronger hardness and strength. The mechanical properties of the high-strength bainite steel rail provided by the invention can be as follows: the yield strength is more than or equal to 1100MPa, the tensile strength is more than or equal to 1300MPa, the elongation is more than or equal to 14%, the tread hardness is 370-440 HBW, the room temperature impact energy is more than or equal to 100J, and the preferable conditions are as follows: the steel rail has high strength and high hardness, has good toughness, and is suitable for heavy-duty railway lines, small curve radius, severe line conditions and serious rolling contact fatigue damage of the steel rail.
Detailed Description
The following describes the invention in detail by way of specific examples, which are intended to aid in understanding the invention and are not intended to limit the invention.
Example 1:
this example produces a specific bainitic rail with the chemical composition described below, mainly according to the following process steps: c:0.17%; si:1.05%; mn:2.00%; p:0.012%; s:0.008%; cr:0.79%; ni:0.03%; mo:0.35%; nb:0.03%; v:0.05% of Fe and the balance of unavoidable impurities;
1) And (3) molten iron pretreatment: the sulfur content in the molten iron is 0.011%, and the phosphorus content is 0.10%.
2) Smelting in a converter: the content of C in tapping is controlled to be 0.10%, the tapping temperature is 1565 ℃, lime, calcium silicate barium and fluorite are added after tapping, deoxidation and slag modification are carried out, the argon blowing effect is ensured in the tapping process, and the slag is not blocked when molten steel is refined in place.
3) Refining in an LF furnace: desulfurizing according to the composition and temperature of the molten steel of the converter, and performing fine adjustment of the composition and temperature rising operation.
4) Vacuum degassing by VD: the deep vacuum degassing time is 18min, soft blowing is carried out for 20min after vacuum degassing, the soft blowing is carried out for Cheng Yaqi, the flow is stable, and the peristaltic movement of molten steel is not exposed.
5) Continuous casting: the continuous casting process adopts protection casting, adopts low-aluminum casting powder, adopts weak cooling water distribution in the second cooling section, is operated at a constant pulling speed of 0.62m/min in the whole process, and starts the electromechanical stirring and light pressing of the casting machine to ensure the quality of the casting blank.
6) Heating a steel billet: the heating time was 4.5 hours and the heating temperature was 1250 ℃.
7) Rolling steel billets: the initial rolling temperature is 1155 ℃, the final rolling temperature is 950 ℃, the steel billet is rolled for 13 times, and then enters a cooling bed to be cooled to room temperature at a cooling speed of 0.3 ℃/s after final rolling, and tempering heat treatment is adopted for 250 ℃ plus 24 hours, and the steel rail is slowly cooled to room temperature after the tempering heat treatment.
After cooling, the mechanical properties of the steel rail are detected, the yield strength of the steel rail is 1131MPa, the tensile strength is 1332MPa, the elongation is 14%, the tread hardness is 404HBW, the room-temperature impact power is 109J, and the metallographic structure is bainite, martensite and trace residual austenite.
Example 2
This example produces a specific bainitic rail with the chemical composition described below, mainly according to the following process steps: c:0.18%; si:1.02%; mn:1.70%; p:0.012%; s:0.010%; cr:0.70%; ni:0.04%; mo:0.31%; nb:0.02%; v:0.06% of Fe and the balance of unavoidable impurities;
1) And (3) molten iron pretreatment: the sulfur content in molten iron is 0.01 percent and the phosphorus content is 0.10 percent.
2) Smelting in a converter: the content of C in tapping is controlled to be 0.10%, the tapping temperature is 1555 ℃, lime, calcium silicate barium and fluorite are added after tapping, deoxidation and slag modification are carried out, the argon blowing effect is ensured in the tapping process, and the slag is not blocked when molten steel is refined in place.
3) Refining in an LF furnace: desulfurizing according to the composition and temperature of the molten steel of the converter, and performing fine adjustment of the composition and temperature rising operation.
4) Vacuum degassing by VD: the deep vacuum degassing time is 20min, soft blowing is carried out for 25min after vacuum degassing, the soft blowing is carried out for Cheng Yaqi, the flow is stable, and the peristaltic movement of molten steel is not exposed.
5) Continuous casting: the continuous casting process adopts protection casting, adopts low-aluminum casting powder, adopts weak cooling water distribution in the second cooling section, is operated at a constant pulling speed of 0.65m/min in the whole process, and starts the electromechanical stirring and light pressing of the casting machine to ensure the quality of the casting blank.
6) Heating a steel billet: the heating time was 4.5 hours and the heating temperature was 1220 ℃.
7) Rolling steel billets: the initial rolling temperature is 1170 ℃, the final rolling temperature is 910 ℃, the billet is rolled for 13 times, and then enters a cooling bed to be cooled to room temperature at a cooling speed of 0.3 ℃/s after final rolling, tempering heat treatment is adopted for 250 ℃ plus 24 hours, and the steel rail is slowly cooled to the room temperature after the tempering heat treatment.
After cooling, the mechanical properties of the steel rail are detected, the yield strength of the steel rail is 1142MPa, the tensile strength is 1357MPa, the tread hardness is 403HBW, the elongation is 14.5%, the room-temperature impact power is 105J, and the metallographic structure is bainite, martensite and trace residual austenite.
Example 3
This example produces a specific bainitic rail with the chemical composition described below, mainly according to the following process steps: c:0.18%; si:1.07%; mn:1.85%; p:0.012%; s:0.010%; cr:0.74%; ni:0.02%; mo:0.32%; nb:0.03%; v:0.05% of Fe and the balance of unavoidable impurities;
1) And (3) molten iron pretreatment: the sulfur content in the molten iron is 0.011%, and the phosphorus content is 0.10%.
2) Smelting in a converter: the content of C in tapping is controlled to be 0.09%, the tapping temperature is 1565 ℃, lime, calcium silicate barium and fluorite are added after tapping, deoxidation and slag modification are carried out, the argon blowing effect is ensured in the tapping process, and the slag is not blocked when molten steel is refined in place.
3) Refining in an LF furnace: desulfurizing according to the composition and temperature of the molten steel of the converter, and performing fine adjustment of the composition and temperature rising operation.
4) Vacuum degassing by VD: the deep vacuum degassing time is 18min, soft blowing is carried out for 22min after vacuum degassing, the soft blowing is carried out for Cheng Yaqi, the flow is stable, and the peristaltic movement of molten steel is not exposed.
5) Continuous casting: the continuous casting process adopts protection casting, adopts low-aluminum casting powder, adopts weak cooling water distribution in the second cooling section, is operated at a constant pulling speed of 0.63m/min in the whole process, and starts the electromechanical stirring and light pressing of the casting machine to ensure the quality of the casting blank.
6) Heating a steel billet: heating time is 4.5 hours, heating temperature is 1240 ℃.
7) Rolling steel billets: the initial rolling temperature is 1185 ℃, the final rolling temperature is 952 ℃, the steel billet is rolled for 13 times, and then enters a cooling bed to be cooled to room temperature at the cooling speed of 0.3 ℃/s after final rolling, and tempering heat treatment is adopted for 250 ℃ plus 24 hours, and the steel rail is slowly cooled to room temperature after the tempering heat treatment.
After cooling, the mechanical properties of the steel rail are detected, the yield strength of the steel rail is 1134MPa, the tensile strength is 1358MPa, the tread hardness is 401HBW, the elongation is 14.5%, the room-temperature impact power is 102J, and the metallographic structure is bainite, martensite and trace residual austenite.
Comparative example 1:
this example produces a specific bainitic rail with the chemical composition described below, mainly according to the following process steps: c:0.17%; si:1.05%; mn:2.00%; p:0.012%; s:0.008%; cr:0.79%; ni:0.03%; mo:0.35%; nb:0.08%, the balance of Fe and unavoidable impurities;
1) And (3) molten iron pretreatment: the sulfur content in the molten iron is 0.011%, and the phosphorus content is 0.10%.
2) Smelting in a converter: the content of C in tapping is controlled to be 0.10%, the tapping temperature is 1565 ℃, lime, calcium silicate barium and fluorite are added after tapping, deoxidation and slag modification are carried out, the argon blowing effect is ensured in the tapping process, and the slag is not blocked when molten steel is refined in place.
3) Refining in an LF furnace: desulfurizing according to the composition and temperature of the molten steel of the converter, and performing fine adjustment of the composition and temperature rising operation.
4) Vacuum degassing by VD: the deep vacuum degassing time is 18min, soft blowing is carried out for 20min after vacuum degassing, the soft blowing is carried out for Cheng Yaqi, the flow is stable, and the peristaltic movement of molten steel is not exposed.
5) Continuous casting: the continuous casting process adopts protection casting, adopts low-aluminum casting powder, adopts weak cooling water distribution in the second cooling section, is operated at a constant pulling speed of 0.62m/min in the whole process, and starts the electromechanical stirring and light pressing of the casting machine to ensure the quality of the casting blank.
6) Heating a steel billet: the heating time was 4.5 hours and the heating temperature was 1250 ℃.
7) Rolling steel billets: the initial rolling temperature is 1155 ℃, the final rolling temperature is 950 ℃, the steel billet is rolled for 13 times, and then enters a cooling bed to be cooled to room temperature at a cooling speed of 0.3 ℃/s after final rolling, and tempering heat treatment is adopted for 250 ℃ plus 24 hours, and the steel rail is slowly cooled to room temperature after the tempering heat treatment.
After cooling, the mechanical properties of the steel rail are detected, wherein the yield strength of the steel rail is 1124MPa, the tensile strength of the steel rail is 1317MPa, the elongation is 14%, the tread hardness is 395HBW, the room-temperature impact energy is 91J, and the metallographic structure is bainite, martensite and trace residual austenite.
Comparative example 2:
this example produces a specific bainitic rail with the chemical composition described below, mainly according to the following process steps: c:0.17%; si:1.05%; mn:2.00%; p:0.012%; s:0.008%; cr:0.79%; ni:0.03%; mo:0.35%; v:0.08%, the balance of Fe and unavoidable impurities;
1) And (3) molten iron pretreatment: the sulfur content in the molten iron is 0.011%, and the phosphorus content is 0.10%.
2) Smelting in a converter: the content of C in tapping is controlled to be 0.10%, the tapping temperature is 1565 ℃, lime, calcium silicate barium and fluorite are added after tapping, deoxidation and slag modification are carried out, the argon blowing effect is ensured in the tapping process, and the slag is not blocked when molten steel is refined in place.
3) Refining in an LF furnace: desulfurizing according to the composition and temperature of the molten steel of the converter, and performing fine adjustment of the composition and temperature rising operation.
4) Vacuum degassing by VD: the deep vacuum degassing time is 18min, soft blowing is carried out for 20min after vacuum degassing, the soft blowing is carried out for Cheng Yaqi, the flow is stable, and the peristaltic movement of molten steel is not exposed.
5) Continuous casting: the continuous casting process adopts protection casting, adopts low-aluminum casting powder, adopts weak cooling water distribution in the second cooling section, is operated at a constant pulling speed of 0.62m/min in the whole process, and starts the electromechanical stirring and light pressing of the casting machine to ensure the quality of the casting blank.
6) Heating a steel billet: the heating time was 4.5 hours and the heating temperature was 1250 ℃.
7) Rolling steel billets: the initial rolling temperature is 1155 ℃, the final rolling temperature is 950 ℃, the steel billet is rolled for 13 times, and then enters a cooling bed to be cooled to room temperature at a cooling speed of 0.3 ℃/s after final rolling, and tempering heat treatment is adopted for 250 ℃ plus 24 hours, and the steel rail is slowly cooled to room temperature after the tempering heat treatment.
After cooling, the mechanical properties of the steel rail are detected, the yield strength of the steel rail is 1074MPa, the tensile strength of the steel rail is 1328MPa, the elongation rate of the steel rail is 14.5%, the tread hardness is 394HBW, the room-temperature impact energy is 90J, and the metallographic structure is bainite, martensite and trace residual austenite.
According to the above examples 1-3, the bainite steel rail produced by the method has higher strength and hardness (the yield strength is not less than 1100MPa, the tensile strength is not less than 1300MPa, the elongation is not less than 14%, the tread hardness is 370-440 HBW, and the conditions that the yield strength is not less than 1130MPa, the tensile strength is not less than 1320MPa, the elongation is not less than 14%, and the tread hardness is 400-440 HBW) are preferably satisfied, and the bainite steel rail also has good room temperature impact toughness, and the room temperature impact energy can reach more than 100J. The steel rails produced in comparative examples 1 to 2 were also steel rails having a metallographic structure of bainite, martensite and a trace of retained austenite, but had a lower tread hardness and room temperature impact toughness than those of examples 1 to 3, indicating that the simultaneous addition of Nb and V elements improved the performance of the steel rails more than the single addition thereof, and had a synergistic effect, when the total amount of Nb and V added was the same. Therefore, the steel rail produced by the invention is more suitable for heavy-load railway lines, and is small in curve radius, harsh in line conditions and serious in rolling contact fatigue damage.
Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the technical solutions described in the foregoing embodiments, or that equivalents may be substituted for part of the technical features thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (2)
1. The high-strength bainite steel rail with good impact toughness is characterized by comprising the following chemical components in percentage by mass: c:0.17 to 0.18 percent; si:1.00 to 1.10 percent; mn:1.70 to 2.00 percent; p is less than or equal to 0.018 percent; s is less than or equal to 0.010 percent; nb:0.02 to 0.03 percent; v:0.04 to 0.06 percent; cr:0.70 to 0.80 percent; ni:0.02 to 0.04 percent; mo:0.30 to 0.35 percent, and the balance of Fe and unavoidable impurities;
the mechanical properties of the high-strength bainite steel rail meet the following conditions: the yield strength is more than or equal to 1100MPa, the tensile strength is more than or equal to 1300MPa, the elongation is more than or equal to 14%, the tread hardness is 370-440 HBW, and the room temperature impact energy is more than or equal to 100J.
2. A method of producing a high strength bainitic steel rail according to claim 1, comprising the steps of:
1) And (3) molten iron pretreatment: the sulfur content in molten iron is less than or equal to 0.011 percent, and the phosphorus content is less than or equal to 0.10 percent;
2) Smelting in a converter: the content of C in tapping is controlled to be more than or equal to 0.09%, the tapping temperature is controlled to be more than or equal to 1550 ℃, lime, calcium silicate barium and fluorite are added after tapping, deoxidation and slag modification are carried out, argon blowing effect is ensured in the tapping process, and slag ejection phenomenon is avoided when molten steel is refined in place;
3) Refining in an LF furnace: desulfurizing according to the composition and temperature of the molten steel of the converter, and performing fine adjustment and temperature rising operation of the composition;
4) Vacuum degassing by VD: the deep vacuum degassing time is more than or equal to 18min, the soft blowing after vacuum degassing is more than or equal to 20min, the soft blowing is performed at Cheng Yaqi, the flow is stable, and the molten steel is not exposed due to creeping;
5) Continuous casting: the continuous casting process adopts protection casting, adopts low-aluminum casting powder, adopts weak cold water distribution in the second cooling section, is operated at a constant pulling speed in the whole process, and has the pulling speed of 0.60-0.65 m/min, and the electric stirring and the light pressing of the casting machine are started to ensure the quality of casting blanks;
6) Heating a steel billet: heating time is more than or equal to 4 hours, and heating temperature is more than or equal to 1200 ℃;
7) Rolling steel billets: the initial rolling temperature is 1150-1200 ℃, the final rolling temperature is 900-960 ℃, the billet is rolled for 13 times, and then enters a cooling bed to be cooled to room temperature at a cooling speed of 0.25-0.35 ℃/s after final rolling, tempering heat treatment is adopted for 240-260 ℃ plus 23-25 hours, and the steel rail is slowly cooled to room temperature after tempering heat treatment.
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| CN202310846257.8A CN117051336A (en) | 2023-07-11 | 2023-07-11 | High-strength bainite steel rail with good impact toughness and production method thereof |
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| CN202310846257.8A CN117051336A (en) | 2023-07-11 | 2023-07-11 | High-strength bainite steel rail with good impact toughness and production method thereof |
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