CN117947337A - High fracture toughness girder steel with tensile strength of 700MPa and preparation method thereof - Google Patents
High fracture toughness girder steel with tensile strength of 700MPa and preparation method thereof Download PDFInfo
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- CN117947337A CN117947337A CN202311700488.4A CN202311700488A CN117947337A CN 117947337 A CN117947337 A CN 117947337A CN 202311700488 A CN202311700488 A CN 202311700488A CN 117947337 A CN117947337 A CN 117947337A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 54
- 239000010959 steel Substances 0.000 title claims abstract description 54
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 4
- 238000001816 cooling Methods 0.000 claims description 21
- 238000005096 rolling process Methods 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 13
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 229910052758 niobium Inorganic materials 0.000 claims description 5
- 238000002791 soaking Methods 0.000 claims description 4
- 229910052684 Cerium Inorganic materials 0.000 claims description 2
- 229910001563 bainite Inorganic materials 0.000 abstract description 8
- 239000000047 product Substances 0.000 description 29
- 239000010955 niobium Substances 0.000 description 11
- 238000013461 design Methods 0.000 description 5
- 230000001105 regulatory effect Effects 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 229910000677 High-carbon steel Inorganic materials 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 150000002910 rare earth metals Chemical class 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- 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
- C22C38/04—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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- 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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- 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
A high fracture toughness girder steel with tensile strength of 700MPa and a preparation method thereof. In the girder steel with the tensile strength of 700 MPa: 0.08% of C element, 0.10% of Si element, 1.50% of Mn element, 0.015% of Nb element, 0.012% of Ti element, 0.0006% of B element, 0.015% of Ce element, and the balance of Fe element and unavoidable impurities. The finally obtained strip steel product is low-carbon bainite steel, not only has conventional high-strength performance, but also greatly improves the fracture toughness at low temperature, the fracture toughness value at-20 ℃ is 150 MPa-m 1/2, the fracture toughness value at-40 ℃ is 145 MPa-m 1/2, and the fracture toughness value of the strip steel product is about twice of that of the existing product with the same specification.
Description
Technical Field
The invention relates to the technical field of plate and strip rolling, in particular to high-fracture-toughness girder steel with tensile strength of 700MPa and a preparation method thereof.
Background
In order to meet the requirements of safety, long service life, high endurance, high bearing quality and light weight manufacturing of load and commercial vehicles, the high-strength girder steel products are increasingly widely applied, and meanwhile, because the use conditions are complex, the requirements of basic mechanical properties of the products are met, and clear requirements are also put forward on the fracture toughness of the products. For the high-strength 700L girder steel with larger current consumption, the yield strength reaches 600MPa and the tensile strength reaches 700MPa by adopting a method of adding various alloy elements, but with the increase of the types and the contents of the alloy elements, the toughness of the product can be reduced, particularly the fracture toughness in a low-temperature environment is reduced, the comprehensive service performance is further influenced, and the mass application of the product in northern cold regions cannot be satisfied. Therefore, a brand new design of chemical components and preparation process of 700MPa girder steel is necessary to obtain a high-strength automobile girder steel product with high fracture toughness.
The Chinese patent document CN 107604256A discloses a preparation method of 700MPa grade automobile chassis Liang Gangdai, wherein 0.05-0.07% of Ti and 0.03-0.07% of Nb are added into components, and finally a product with the tensile strength of 700-800 MPa and the thickness of 2.5-3.0 mm is obtained, and the low-temperature fracture toughness of the product is not involved.
Chinese patent document CN 115627417A discloses an economical high-strength and high-toughness 700 MPa-grade girder steel and a production method thereof, wherein 0.08-0.15% of Ti and 0.025-0.055% of Nb are added into components, and finally, a product with the tensile strength of 720-840 MPa is obtained, the full-size impact energy at-20 ℃ is more than or equal to 160J, and the low-temperature fracture toughness of the product is not involved.
The Chinese patent document CN 111809110A discloses a thick 700 MPa-grade automobile girder steel belt treated by rare earth and a manufacturing method thereof, wherein 0.07-0.10 percent of Ti, 0.04-0.06 percent of Nb and 10 ppm-30 ppmCe are added into components, the thickness of a product is 10.0-16.0 mm, the impact value at minus 40 ℃ is more than or equal to 70J, and the low-temperature fracture toughness of the product is not related.
The above patents all meet the requirement of tensile strength of 700MPa by adding alloy components Ti element and Nb element, the cost is relatively high, and the fracture toughness of 700MPa girder steel at low temperature is not related.
Chinese patent document CN 103849812A discloses a low brittleness 700MPa grade steel for automobile girder and its manufacturing method, 0.08-0.10% Ti and 0.035-0.050% Nb are added into the components, finally 700MPa grade product with good low temperature toughness is obtained, and the impact power at minus 60 ℃ is 80J.
The Chinese patent document CN 112030075A discloses 700 MPa-level automobile girder steel with stable impact toughness and a production method, wherein 0.07-0.12% of Ti and 0.02-0.08% of Nb are added into components, and the steel is a 700MPa product with stable impact toughness and 12.0-16.0 mm, and the impact energy of a full-size sample at-20 ℃ is 150-180J.
Both patents relate to the impact property of 700MPa automobile girder steel at low temperature, and do not relate to the low-temperature fracture toughness of products.
Chinese patent document CN 111172467B discloses a high-fracture-toughness medium-high carbon steel, wherein the content of Ca in the steel is controlled to reduce D-type inclusions, meanwhile, the size and shape of soft-phase inclusions are regulated and controlled to improve the crack-stopping effect, so that the room-temperature fracture toughness K Q value of the steel is improved from 78.2MPa m 1/2 to 109.3MPa m 1/2, the method related to the patent is only applicable to the medium-high carbon steel, and the product effect does not relate to low-temperature fracture toughness.
The Chinese patent document CN 111363896A discloses a treatment method for improving the fracture toughness of micro-niobium carbon steel by tempering, after polishing, quenching and tempering treatment, the fracture toughness K Q value of the product at room temperature is improved from 78.7 MPa.m 1/2 to 86.8 MPa.m 1/2, the process is only applicable to high-carbon steel, and the product effect does not relate to low-temperature fracture toughness.
Chinese patent document CN 113166904A discloses a high-strength steel plate with excellent low-temperature fracture toughness and a manufacturing method thereof, wherein 0.3 percent of Mo is required to be added in the components, the cost is high, the strength of the obtained product does not reach 700MPa, and only the DWTT performance of a thick plate product is tested and is different from the low-temperature fracture toughness evaluation of a girder steel product.
All three patents relate to low-temperature fracture toughness, but cannot be directly applied to the improvement of the low-temperature fracture toughness of the 700MPa automobile girder steel product.
In summary, for the girder steel with the tensile strength of 700MPa, the patent on the aspect of greatly improving the low-temperature fracture toughness by regulating and controlling the structure morphology of the final product through design components and process routes is not related at present. Under the background of application requirements of large-scale load and commercial vehicles, high-strength girder steel products are satisfied, and meanwhile, high low-temperature fracture toughness is urgently needed. Based on the method, the invention provides a preparation method of high fracture toughness girder steel with the tensile strength of 700 MPa.
Disclosure of Invention
The invention aims to provide a preparation method of high fracture toughness and high tensile strength 700MPa girder steel, which mainly regulates and controls the structure morphology of a product through the design of components and a hot rolling process, and ensures that the product has higher low-temperature fracture toughness while the high strength is not influenced, thereby improving the comprehensive use performance and expanding the application of the product in a low-temperature environment.
The technical scheme of the invention is as follows: a high fracture toughness girder steel with tensile strength of 700MPa comprises the following elements in percentage by mass: 0.07 to 0.09 percent of C element, 0.08 to 0.12 percent of Si element, 1.48 to 1.52 percent of Mn element, 0.013 to 0.017 percent of Nb element, 0.011 to 0.013 percent of Ti element, 0.0005 to 0.0007 percent of B element, 0.014 to 0.016 percent of Ce element, and the balance of Fe element and unavoidable impurities.
The high fracture toughness high tensile strength 700MPa girder steel comprises the following elements in percentage by mass: 0.08% of C element, 0.10% of Si element, 1.50% of Mn element, 0.015% of Nb element, 0.012% of Ti element, 0.0006% of B element, 0.015% of Ce element, and the balance of Fe element and unavoidable impurities.
A preparation method of high fracture toughness girder steel with tensile strength of 700MPa specifically comprises the following steps: heating, rolling, cooling and coiling a plate blank; and an air cooling relaxation treatment process is additionally arranged between the final rolling stage of rolling and the cooling start stage of cooling.
The temperature of the air cooling relaxation treatment process is reduced to 50 ℃.
The heating temperature of the slab heating is 1200 ℃.
The thickness of the slab is 220mm, the heating temperature is 1200 ℃, and the heating soaking heat preservation time is 60min; the slab is rolled after being heated, and rough rolling is carried out to obtain an intermediate billet, wherein the thickness of the intermediate billet is 58mm; the finish rolling start temperature is 1070 ℃, and the finish rolling finish temperature is 850 ℃; the cooling temperature of the cooling is 800 ℃; the steel strip was cooled to 350℃at a cooling rate of 50℃per second and coiled to obtain a steel strip having a thickness of 8 mm.
The basis of the composition design and control method is as follows: based on the low-cost regulation and control requirement, nb element with the mass percentage of 0.015% is adopted for regulating and controlling the high-temperature austenite grain size, and experiments prove that the original austenite grain size can be effectively controlled at 45 mu m +/-5 mu m when the finishing temperature is 850 ℃, thereby being beneficial to subsequent bainite transformation and improving the strength and toughness of the steel. In order to effectively improve the low-temperature fracture toughness of the steel, a composite adding mode of 0.012 percent of Ti element, 0.0006 percent of B element and 0.015 percent of rare earth Ce element is adopted, and N element, O element and S element in the steel are regulated and controlled, so that the quenching degree of the material is properly improved, the size of inclusions is concentrated to 0.5-1 mu m and the inclusions are spherical, and the damage to the low-temperature fracture toughness of the steel is reduced to the greatest extent. By combining a hot rolling process, the micro-alloy element is completely solid when the soaking temperature is 1200 ℃, which is favorable for inhibiting the growth of austenite grain size under the action of high-temperature solid solution dragging and is favorable for regulating nano precipitation in bainite in the following process; after the finish rolling temperature and before the cooling temperature, an air cooling relaxation treatment process exists, the temperature is reduced to 50 ℃, dislocation can be effectively recovered to a certain extent, and the phase transformation of the subsequent high-toughness bainite is facilitated; the coiling temperature is 350 ℃, and the temperature is mainly obtained by the isothermal transformation curve of the bainite obtained by testing the composition and is mainly the lower bainite with high toughness. In the coiling and slow cooling process, the microalloy element Nb which is completely dissolved in the high-temperature stage generates certain nano precipitation, and the average size of the precipitation is 3nm, so that the strength is improved and the good fracture toughness is ensured.
The invention has the beneficial effects that: the invention designs the component composition and the preparation process of the girder steel with the tensile strength of 700MPa, and further regulates and controls the finally obtained strip steel product to be the low-carbon bainite steel, so that the strip steel product not only has the conventional high-strength performance, but also has greatly improved fracture toughness at low temperature, the fracture toughness at-20 ℃ is 150 MPa-m 1/2, the fracture toughness at-40 ℃ is 145 MPa-m 1/2, and the fracture toughness value of the existing product with the same specification is about twice.
Drawings
FIG. 1 is a microstructure of a high fracture toughness, 700MPa tensile strength girder steel prepared in this example.
Detailed Description
The invention is further described below with reference to examples and figures.
The high fracture toughness high tensile strength 700MPa girder steel of the embodiment has the thickness of 8mm, and the mass percentages of the elements are as follows: 0.08% of C element, 0.10% of Si element, 1.50% of Mn element, 0.015% of Nb element, 0.012% of Ti element, 0.0006% of B element, 0.015% of Ce element, and the balance of Fe element and unavoidable impurities. The production method comprises the steps of slab heating, rolling, cooling and coiling. The specific steps are as follows:
The thickness of the plate blank is 220mm, the heating temperature is 1200 ℃, the heating soaking heat preservation time is 60min, the plate blank is rolled after being heated, the thickness of the intermediate blank is 58mm, the finish rolling start temperature is 1070 ℃, the finish rolling temperature is 850 ℃, the cooling start temperature is 800 ℃, and then the plate blank is cooled to 350 ℃ at the cooling rate of 50 ℃/s for coiling.
The mechanical properties of the high fracture toughness girder steel with the tensile strength of 700MPa are as follows: the yield strength is 675MPa, the tensile strength is 750MPa, the fracture toughness value at-20 ℃ is 150 MPa-m 1/2, the fracture toughness value at-40 ℃ is 145 MPa-m 1/2, the microstructure under the steel strip transmission electron microscope is shown in figure 1, and the metallographic structure is lower bainite as shown in figure 1.
Claims (6)
1. The high fracture toughness high tensile strength 700MPa girder steel is characterized by comprising the following elements in percentage by mass: 0.07 to 0.09 percent of C element, 0.08 to 0.12 percent of Si element, 1.48 to 1.52 percent of Mn element, 0.013 to 0.017 percent of Nb element, 0.011 to 0.013 percent of Ti element, 0.0005 to 0.0007 percent of B element, 0.014 to 0.016 percent of Ce element, and the balance of Fe element and unavoidable impurities.
2. The high fracture toughness tensile strength 700MPa girder steel according to claim 1, wherein the high fracture toughness tensile strength 700MPa girder steel comprises the following elements in mass percent: 0.08% of C element, 0.10% of Si element, 1.50% of Mn element, 0.015% of Nb element, 0.012% of Ti element, 0.0006% of B element, 0.015% of Ce element, and the balance of Fe element and unavoidable impurities.
3. A preparation method of high fracture toughness girder steel with tensile strength of 700MPa is characterized by comprising the following steps: heating, rolling, cooling and coiling a plate blank; and an air cooling relaxation treatment process is additionally arranged between the final rolling stage of rolling and the cooling start stage of cooling.
4. The method for producing high fracture toughness, 700MPa, high tensile strength girder steel according to claim 3, wherein the temperature drop during the air cooling relaxation treatment is 50 ℃.
5. The method for producing high fracture toughness, 700MPa, high tensile strength, girder steel according to claim 3 or 4, wherein the heating temperature for slab heating is 1200 ℃.
6. The method for preparing high fracture toughness and high tensile strength 700MPa girder steel according to claim 5, wherein the thickness of the slab is 220mm, the heating temperature is 1200 ℃, and the heating soaking and heat preserving time is 60min; the slab is rolled after being heated, and rough rolling is carried out to obtain an intermediate billet, wherein the thickness of the intermediate billet is 58mm; the finish rolling start temperature is 1070 ℃, and the finish rolling finish temperature is 850 ℃; the cooling temperature of the cooling is 800 ℃; the steel strip was cooled to 350℃at a cooling rate of 50℃per second and coiled to obtain a steel strip having a thickness of 8 mm.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311700488.4A CN117947337A (en) | 2023-12-12 | 2023-12-12 | High fracture toughness girder steel with tensile strength of 700MPa and preparation method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311700488.4A CN117947337A (en) | 2023-12-12 | 2023-12-12 | High fracture toughness girder steel with tensile strength of 700MPa and preparation method thereof |
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| Publication Number | Publication Date |
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| CN117947337A true CN117947337A (en) | 2024-04-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202311700488.4A Pending CN117947337A (en) | 2023-12-12 | 2023-12-12 | High fracture toughness girder steel with tensile strength of 700MPa and preparation method thereof |
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2023
- 2023-12-12 CN CN202311700488.4A patent/CN117947337A/en active Pending
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