CN112662855A - Method for improving low-temperature impact toughness of 380 MPa-grade hot-rolled wheel steel - Google Patents
Method for improving low-temperature impact toughness of 380 MPa-grade hot-rolled wheel steel Download PDFInfo
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- CN112662855A CN112662855A CN202011305335.6A CN202011305335A CN112662855A CN 112662855 A CN112662855 A CN 112662855A CN 202011305335 A CN202011305335 A CN 202011305335A CN 112662855 A CN112662855 A CN 112662855A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 48
- 239000010959 steel Substances 0.000 title claims abstract description 48
- 238000000034 method Methods 0.000 title claims abstract description 35
- 238000005096 rolling process Methods 0.000 claims abstract description 75
- 238000001816 cooling Methods 0.000 claims abstract description 17
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 230000009467 reduction Effects 0.000 claims description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000000463 material Substances 0.000 description 30
- 239000011162 core material Substances 0.000 description 18
- 230000000694 effects Effects 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- 230000008901 benefit Effects 0.000 description 6
- 239000012466 permeate Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000013386 optimize process Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
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Abstract
The invention discloses a method for improving low-temperature impact toughness of 380 MPa-level hot-rolled wheel steel, which comprises the following steps: rough rolling is carried out on an intermediate billet, and the intermediate billet is used for manufacturing the 380 MPa-level hot-rolled wheel steel; after the rough rolling of the intermediate blank is finished and the last pass of rolling is carried out, cooling is carried out on the intermediate blank so as to increase the temperature difference between the surface of the intermediate blank and the core part; and performing finish rolling on the intermediate billet.
Description
Technical Field
The application relates to the field of metallurgy, in particular to a method for improving low-temperature impact toughness of 380 MPa-level hot-rolled wheel steel.
Background
At present, 380 MPa-grade hot-rolled wheel steel is mainly used for manufacturing spokes and rims of automobiles such as commercial vehicles, passenger vehicles and the like, and the low-temperature impact toughness directly determines the quality of a final wheel product, so that the safety of automobile use and the service life are related. Among them, the degree of grain breakage of the hot-rolled wheel steel material has a great influence on impact toughness. In the process of rolling the hot-rolled wheel steel, when the thickness of the intermediate billet is larger, the limitation of rolling deformation characteristics and deformation is realized, the deformation is smaller when the material is closer to the center of the thickness direction of a rolled piece, and the smaller the deformation is, the lower the crushing degree of material grains is, and the larger the grain size is. This causes the grain size of the material in the thickness direction of the produced hot rolled wheel steel to be inconsistent, i.e., the grain size of the material in the center portion in the thickness direction of the wheel steel is larger. The larger the grain size of the material, the lower its impact toughness.
At present, the impact toughness is often improved by adjusting the chemical composition of the material.
Disclosure of Invention
The invention provides a method for improving the low-temperature impact toughness of 380 MPa-level hot-rolled wheel steel, which aims to solve or partially solve the problem of how to improve the deformation of a 380 MPa-level hot-rolled wheel steel core part material and optimize the deformation uniformity of an intermediate blank in the thickness direction, thereby achieving the effect of improving the stability of the low-temperature impact toughness.
In order to solve the technical problem, the invention provides a method for improving the low-temperature impact toughness of 380 MPa-grade hot-rolled wheel steel, which comprises the following steps:
rough rolling is carried out on an intermediate billet, and the intermediate billet is used for manufacturing the 380 MPa-level hot-rolled wheel steel;
after the rough rolling of the intermediate blank is finished and the last pass of rolling is carried out, cooling is carried out on the intermediate blank so as to increase the temperature difference between the surface of the intermediate blank and the core part;
and performing finish rolling on the intermediate billet.
Preferably, the rough rolling of the intermediate slab specifically includes:
and carrying out rough rolling on the intermediate blank, and controlling the temperature of the intermediate blank after finishing the rough rolling for the last pass to be 940-960 ℃.
Preferably, after the rough rolling of the intermediate blank is finished for the last pass, the intermediate blank is cooled, and the method specifically comprises the following steps:
and carrying out water cooling on the upper surface and the lower surface of the intermediate blank.
Preferably, the temperature reduction amplitude of the cooling is controlled to be 30-40 ℃.
Preferably, the finish rolling of the intermediate slab specifically includes:
and controlling the finish rolling start temperature of the intermediate billet to be 900-920 ℃.
Preferably, the finish rolling of the intermediate slab specifically includes:
and controlling the reduction rate of a finish rolling F1 machine frame, the reduction rate of a F2 machine frame, the reduction rate of a F3 machine frame and the reduction rate of a F4 machine frame, and carrying out finish rolling on the intermediate billet.
Preferably, the screw-down rate of the F1 machine frame is more than or equal to 22%, the screw-down rate of the F2 machine frame is more than or equal to 20%, the screw-down rate of the F3 machine frame is more than or equal to 18%, and the screw-down rate of the F4 machine frame is more than or equal to 17%.
Preferably, before the rough rolling of the intermediate slab, the method further includes:
obtaining the intermediate blank and heating the intermediate blank.
Preferably, after the finish rolling of the intermediate slab, the method further includes:
and carrying out laminar cooling and curling on the intermediate billet to obtain the 380 MPa-grade hot-rolled wheel steel.
Preferably, the 380 MPa-grade hot-rolled wheel steel has the low-temperature impact toughness of 250J-310J.
Through one or more technical schemes of the invention, the invention has the following beneficial effects or advantages:
the invention discloses a method for improving 380 MPa-level hot-rolled wheel steel low-temperature impact toughness, which is characterized in that the surface of an intermediate blank is cooled and cooled before rough rolling of the hot-rolled intermediate blank is finished and finish rolling is carried out, so that the temperature difference between the surface of the intermediate blank and a core part is increased, the material deformation resistance of the intermediate blank close to the surface part is increased, the material deformation permeates to the core part in the thickness direction, the deformation uniformity in the thickness direction of the intermediate blank is optimized, and the effect of improving the low-temperature impact toughness stability is achieved.
Furthermore, the reduction rates of the finish rolling F1 machine frame, the finish rolling F2 machine frame, the finish rolling F3 machine frame and the finish rolling F4 machine frame are optimized, after the surface of the intermediate billet is cooled and enters the finish rolling, the deformation of the central material in the thickness direction of the intermediate billet is increased through the action of the four machine frames on the rolling thickness direction of the intermediate billet, so that the deformation of the core material is increased, the crushing degree of the crystal grains of the material is increased, and the stability of the low-temperature impact toughness of the 380 MPa-level hot rolling wheel steel can be improved without adjusting the chemical composition system of the intermediate billet.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 shows a flow chart of a method for improving the low-temperature impact toughness of 380MPa hot-rolled wheel steel.
Detailed Description
In order to make the present application more clearly understood by those skilled in the art to which the present application pertains, the following detailed description of the present application is made with reference to the accompanying drawings by way of specific embodiments.
In the rolling process of the hot-rolled wheel steel, due to the limitation of rolling deformation characteristics and deformation, the closer to the material in the center of the intermediate billet in the thickness direction, the smaller the deformation is, the lower the crushing degree of material grains is, and the larger the grain size is, so that the grain size of the material in the thickness direction of the produced hot-rolled wheel steel is inconsistent, namely the grain size of the material at the core part in the thickness direction of the wheel steel is larger. The larger the grain size of the material, the lower its impact toughness. In the embodiment, before the rough rolling of the hot-rolled intermediate billet is finished and the finish rolling is carried out, the surface of the intermediate billet is cooled, so that the temperature difference between the surface of the intermediate billet and the core is increased, the material deformation resistance of the intermediate billet close to the surface is increased, and the material is deformed and permeates into the core in the thickness direction, so that the deformation uniformity in the thickness direction of the intermediate billet is optimized, and the effect of improving the stability of the low-temperature impact toughness is achieved.
For illustrating and explaining the invention in detail, referring to fig. 1, the embodiment of the invention discloses a method for improving the low-temperature impact toughness of 380MPa grade hot-rolled wheel steel.
The method comprises the following steps:
step 101, rough rolling is carried out on the intermediate billet.
Wherein the intermediate billet is used for manufacturing the 380 MPa-grade hot-rolled wheel steel. Before the intermediate blank is subjected to rough rolling, the intermediate blank is obtained and heated by a heating furnace, so that the intermediate blank enters the rough rolling process at a qualified temperature.
The rough rolling process of the embodiment adopts a conventional rough rolling process, but after the intermediate blank is subjected to rough rolling for the last pass, the temperature of the intermediate blank is controlled to be 940-960 ℃, so that a foundation is laid for a subsequent cooling process.
And step 102, after the rough rolling of the intermediate blank is finished and the last rolling is carried out, cooling the intermediate blank to increase the temperature difference between the surface of the intermediate blank and the core part.
Since this example is directed to a hot rolled wheel steel product of 380MPa class, the objective is to improve the-40 ℃ low temperature impact toughness of the material. Therefore, in the embodiment, before the hot-rolled intermediate billet enters the finishing mill, the process of cooling the surface of the intermediate billet is added to reduce the surface temperature of the slab and increase the temperature difference between the surface of the intermediate billet and the core, so that the deformation resistance of the material of the intermediate billet close to the surface is increased, the material deformation permeates into the core in the thickness direction, and the deformation uniformity of the intermediate billet in the thickness direction is optimized.
In a specific cooling process, the upper surface and the lower surface of the intermediate blank are cooled by water. Furthermore, the surface temperature of the intermediate blank is reduced, and the temperature reduction amplitude of the intermediate blank during cooling is controlled to be 30-40 ℃, so that the deformation resistance of the material at the position, close to the surface, of the intermediate blank is increased, and the material is deformed and permeates into the core part in the thickness direction.
And 103, finish rolling the intermediate billet.
In this example, the initial rolling temperature of the intermediate slab finish rolling was controlled to 900 to 920 ℃, and then the intermediate slab was rolled by using 4 finish rolling stands in the finish rolling process.
Specifically, the reduction rate of a finish rolling F1 machine frame, the reduction rate of a F2 machine frame, the reduction rate of a F3 machine frame and the reduction rate of a F4 machine frame are respectively controlled to finish rolling the intermediate billet so as to achieve the effect of improving the deformation amount of the core material, and the deformation uniformity of the intermediate billet in the thickness direction is better optimized by combining a cooling process.
Further, in this embodiment, the pressing rates of the frames are respectively controlled as follows: the screw-down rate of the F1 machine frame is more than or equal to 22 percent, the screw-down rate of the F2 machine frame is more than or equal to 20 percent, the screw-down rate of the F3 machine frame is more than or equal to 18 percent, and the screw-down rate of the F4 machine frame is more than or equal to 17 percent.
By adopting a special treatment mode in the process, the low-temperature impact toughness of the 380 MPa-grade hot-rolled wheel steel can reach 250J-310J.
As an alternative example, after the finish rolling process, the intermediate blank may be subjected to laminar cooling and curling to obtain the 380 MPa-grade hot-rolled wheel steel, and a-40 ℃ low-temperature impact toughness performance test is performed thereon to prove the stability of the low-temperature impact toughness thereof in this example.
It can be seen that, compared with the mode of achieving the same effect by adjusting the chemical composition system of the product, the embodiment has the advantages of low cost, short development time and small process variation compared with the mode of achieving the same effect by adjusting the chemical composition system of the product, by improving the production process of 380 MPa-level hot-rolled wheel steel, and by cooling the surface of the intermediate blank before the rough rolling of the hot-rolled intermediate blank is completed and the finish rolling is performed, so as to increase the temperature difference between the surface of the intermediate blank and the core, increase the deformation resistance of the material at the position close to the surface of the intermediate blank, and enable the material deformation to permeate to the core in the thickness direction, thereby optimizing the deformation uniformity in the thickness direction of the intermediate blank.
For explaining and explaining the invention, the invention is applied to the production of 380 MPa-level wheel steel in a certain hot-rolled strip steel plant, after the final rough rolling pass is finished, the surface of the intermediate blank is rapidly cooled by water, and the control conditions of comparing each key process parameter of the steel coils by adopting the optimized process with the steel coils normally produced are shown in Table 1. Obviously, the production process provided by the invention not only obviously improves the average value of the low-temperature impact toughness at minus 40 ℃ of 380 MPa-grade hot-rolled wheel steel, but also obviously improves the stability of the low-temperature impact toughness.
TABLE 1 comparison of the results of the impact toughness measurements with the production process
Through one or more embodiments of the present invention, the present invention has the following advantageous effects or advantages:
the invention discloses a method for improving 380 MPa-level hot-rolled wheel steel low-temperature impact toughness, which is characterized in that the surface of an intermediate blank is cooled and cooled before rough rolling of the hot-rolled intermediate blank is finished and finish rolling is carried out, so that the temperature difference between the surface of the intermediate blank and a core part is increased, the material deformation resistance of the intermediate blank close to the surface part is increased, the material deformation permeates to the core part in the thickness direction, the deformation uniformity in the thickness direction of the intermediate blank is optimized, and the effect of improving the low-temperature impact toughness stability is achieved.
Furthermore, the reduction rates of the finish rolling F1 machine frame, the finish rolling F2 machine frame, the finish rolling F3 machine frame and the finish rolling F4 machine frame are optimized, after the surface of the intermediate billet is cooled and enters the finish rolling, the deformation of the central material in the thickness direction of the intermediate billet is increased through the action of the four machine frames on the rolling thickness direction of the intermediate billet, so that the deformation of the core material is increased, the crushing degree of the crystal grains of the material is increased, and the stability of the low-temperature impact toughness of the 380 MPa-level hot rolling wheel steel can be improved without adjusting the chemical composition system of the intermediate billet.
While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.
Claims (10)
1. A method for improving the low-temperature impact toughness of 380 MPa-level hot-rolled wheel steel is characterized by comprising the following steps:
rough rolling is carried out on an intermediate billet, and the intermediate billet is used for manufacturing the 380 MPa-level hot-rolled wheel steel;
after the rough rolling of the intermediate blank is finished and the last pass of rolling is carried out, cooling is carried out on the intermediate blank so as to increase the temperature difference between the surface of the intermediate blank and the core part;
and performing finish rolling on the intermediate billet.
2. The method for improving the low-temperature impact toughness of 380 MPa-grade hot-rolled wheel steel according to claim 1, wherein the rough rolling is performed on the intermediate blank, and specifically comprises the following steps:
and carrying out rough rolling on the intermediate blank, and controlling the temperature of the intermediate blank after finishing the rough rolling for the last pass to be 940-960 ℃.
3. The method for improving the low-temperature impact toughness of 380 MPa-grade hot-rolled wheel steel as claimed in claim 1, wherein after the intermediate blank is subjected to rough rolling for the last pass, the intermediate blank is cooled, and the method specifically comprises the following steps:
and carrying out water cooling on the upper surface and the lower surface of the intermediate blank.
4. The method for improving the impact toughness of the 380MPa grade hot-rolled wheel steel according to claim 1 or 3, wherein the temperature drop amplitude of cooling is controlled to be 30-40 ℃.
5. The method for improving the low-temperature impact toughness of 380 MPa-grade hot-rolled wheel steel according to claim 1, wherein the finish rolling is performed on the intermediate billet, and specifically comprises the following steps:
and controlling the finish rolling start temperature of the intermediate billet to be 900-920 ℃.
6. The method for improving the low-temperature impact toughness of the 380 MPa-grade hot-rolled wheel steel according to claim 1 or 5, wherein the finish rolling is performed on the intermediate billet, and specifically comprises the following steps:
and controlling the reduction rate of a finish rolling F1 machine frame, the reduction rate of a F2 machine frame, the reduction rate of a F3 machine frame and the reduction rate of a F4 machine frame, and carrying out finish rolling on the intermediate billet.
7. The method for improving the low-temperature impact toughness of 380 MPa-grade hot-rolled wheel steel according to claim 6, wherein the F1 stand reduction rate is not less than 22%, the F2 stand reduction rate is not less than 20%, the F3 stand reduction rate is not less than 18%, and the F4 stand reduction rate is not less than 17%.
8. The method for improving the low-temperature impact toughness of 380MPa grade hot-rolled wheel steel of claim 1, before the rough rolling of the intermediate blank, the method further comprises:
obtaining the intermediate blank and heating the intermediate blank.
9. The method for improving the low-temperature impact toughness of the 380 MPa-grade hot-rolled wheel steel according to claim 1, wherein after the intermediate blank is subjected to finish rolling, the method further comprises the following steps:
and carrying out laminar cooling and curling on the intermediate billet to obtain the 380 MPa-grade hot-rolled wheel steel.
10. The method for improving the low-temperature impact toughness of 380MPa grade hot-rolled wheel steel according to claim 1, wherein the low-temperature impact toughness of the 380MPa grade hot-rolled wheel steel is 250J-310J.
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| CN202011305335.6A CN112662855A (en) | 2020-11-20 | 2020-11-20 | Method for improving low-temperature impact toughness of 380 MPa-grade hot-rolled wheel steel |
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| CN202011305335.6A CN112662855A (en) | 2020-11-20 | 2020-11-20 | Method for improving low-temperature impact toughness of 380 MPa-grade hot-rolled wheel steel |
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|---|---|---|---|---|
| CN101280387A (en) * | 2008-05-20 | 2008-10-08 | 莱芜钢铁股份有限公司 | Steel belt for rim of vehicle wheel and manufacturing method thereof |
| CN103937950A (en) * | 2014-03-25 | 2014-07-23 | 济钢集团有限公司 | Production technology of thick high-grade pipeline steel with low compression ratio |
| CN103938078A (en) * | 2014-03-26 | 2014-07-23 | 首钢总公司 | Steel for heavy-truck super-thick steel-made spokes and manufacturing method of steel |
| CN108411188A (en) * | 2018-01-04 | 2018-08-17 | 江苏省沙钢钢铁研究院有限公司 | A kind of high crack arrest and fatigue strength steel plate and preparation method thereof |
| CN109174981A (en) * | 2018-08-31 | 2019-01-11 | 东北大学 | A kind of hot continuous rolling intermediate blank cooling device and its application method |
-
2020
- 2020-11-20 CN CN202011305335.6A patent/CN112662855A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101280387A (en) * | 2008-05-20 | 2008-10-08 | 莱芜钢铁股份有限公司 | Steel belt for rim of vehicle wheel and manufacturing method thereof |
| CN103937950A (en) * | 2014-03-25 | 2014-07-23 | 济钢集团有限公司 | Production technology of thick high-grade pipeline steel with low compression ratio |
| CN103938078A (en) * | 2014-03-26 | 2014-07-23 | 首钢总公司 | Steel for heavy-truck super-thick steel-made spokes and manufacturing method of steel |
| CN108411188A (en) * | 2018-01-04 | 2018-08-17 | 江苏省沙钢钢铁研究院有限公司 | A kind of high crack arrest and fatigue strength steel plate and preparation method thereof |
| CN109174981A (en) * | 2018-08-31 | 2019-01-11 | 东北大学 | A kind of hot continuous rolling intermediate blank cooling device and its application method |
Non-Patent Citations (1)
| Title |
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| 轧制技术及连轧自动化国家重点实验室（东北大学）: "《热轧板带钢新一代TMCP工艺与装备技术开发及应用》", 31 December 2015 * |
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Application publication date: 20210416 |