CN115449707A - Ultrahigh-strength hot-rolled complex-phase steel and preparation method thereof - Google Patents
Ultrahigh-strength hot-rolled complex-phase steel and preparation method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 116
- 239000010959 steel Substances 0.000 title claims abstract description 116
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 239000000126 substance Substances 0.000 claims abstract description 23
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 238000001816 cooling Methods 0.000 claims description 84
- 238000005096 rolling process Methods 0.000 claims description 53
- 229910001563 bainite Inorganic materials 0.000 claims description 28
- 238000010438 heat treatment Methods 0.000 claims description 19
- 238000007670 refining Methods 0.000 claims description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- 229910000734 martensite Inorganic materials 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 12
- 238000003723 Smelting Methods 0.000 claims description 8
- 238000005266 casting Methods 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 239000000306 component Substances 0.000 description 19
- 230000000694 effects Effects 0.000 description 15
- 230000008092 positive effect Effects 0.000 description 13
- 238000005728 strengthening Methods 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 9
- 229910001566 austenite Inorganic materials 0.000 description 8
- 238000001556 precipitation Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 6
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- 239000000463 material Substances 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 230000002411 adverse Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 229910052796 boron Inorganic materials 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 239000013078 crystal Substances 0.000 description 3
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- 239000002244 precipitate Substances 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
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- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium 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
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
-
- 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
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
-
- 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
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
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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
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
-
- 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
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention particularly relates to ultrahigh-strength hot-rolled complex-phase steel and a preparation method thereof, belonging to the field of hot-rolled steel preparation. The ultrahigh-strength hot-rolled complex-phase steel comprises the following chemical components in percentage by mass: c:0.07-0.15%, si:0.10 to 0.50%, mn:1.0-2.0%, P: less than or equal to 0.015 percent, S: less than or equal to 0.003 percent, nb:0.01-0.06%, ti:0.08-0.17%, cr:0.30-0.50%, mo:0.10-0.30%, N: less than or equal to 0.005 percent, B:0.001-0.004%, and the balance of Fe and inevitable impurities. The hot-rolled complex phase steel can solve the technical problems of poor forming performance and low fatigue performance of the existing hot-rolled complex phase steel.
Description
Technical Field
The invention belongs to the field of hot rolled steel preparation, and particularly relates to ultrahigh-strength hot rolled complex phase steel and a preparation method thereof.
Background
As one of the advanced high-strength steels, the complex phase steel has been developed for twenty years in international advanced iron and steel enterprises represented by Thiessen and Atilor. The complex phase steel belongs to the super high strength steel series, the microstructure is mainly ferrite/bainite, and contains a small amount of martensite, retained austenite and pearlite. The crystal grain is fine, and the tensile strength is higher. Compared with the dual-phase steel with the same tensile strength, the yield strength of the steel is obviously higher, and the steel has the characteristics of high bending property, high hole expansion property and the like. The steel has high energy absorption capacity, good mechanical property, forming property and welding property, is particularly suitable for production of safety parts of automobiles, is mainly used for automobile chassis suspension parts, B columns, bumpers, back cushion side beams, seat sliding rails and the like, and has wide market prospect. The hot-rolled complex phase steel is mainly used for manufacturing chassis core components with higher requirements on forming and fatigue. The yield strength of the traditional ultrahigh-strength hot-rolled complex phase steel is more than or equal to 720MPa, but the product has the problems of poor forming, low fatigue performance and the like.
Disclosure of Invention
The application aims to provide ultrahigh-strength hot-rolled complex phase steel and a preparation method thereof, and aims to solve the technical problems that the existing hot-rolled complex phase steel is poor in forming performance and low in fatigue performance.
The embodiment of the invention provides ultrahigh-strength hot-rolled complex phase steel, which comprises the following chemical components in percentage by mass:
c:0.07-0.15%, si:0.10 to 0.50%, mn:1.0-2.0%, P: less than or equal to 0.015 percent, S: less than or equal to 0.003 percent, nb:0.01-0.06%, ti:0.08-0.17%, cr:0.30-0.50%, mo:0.10-0.30%, N: less than or equal to 0.005%, B:0.001-0.004%, and the balance of Fe and inevitable impurities.
Optionally, the metallographic structure of the steel comprises granular bainite, lower bainite and martensite.
Optionally, the metallographic structure includes, by volume percent: 5-10% of granular bainite, 3-8% of martensite and the balance lower bainite.
Based on the same inventive concept, the embodiment of the invention also provides a preparation method of the ultrahigh-strength hot-rolled complex phase steel, which comprises the following steps:
sequentially carrying out converter smelting, LF refining and RH refining to obtain molten steel according with the chemical components;
continuously casting the molten steel to obtain a steel billet;
heating, rough rolling and finish rolling the billet to obtain a hot rolled plate;
and cooling and coiling the hot rolled plate to obtain the ultrahigh-strength hot-rolled complex phase steel.
Optionally, the thickness of the hot-rolled plate is 1.8-5mm.
Optionally, the rolling speed of the finish rolling is 5-10m/s.
Optionally, the heating temperature is 1230-1280 ℃.
Optionally, the finishing temperature of the rough rolling is 1050-1100 ℃, and the finishing temperature of the finish rolling is 830-890 ℃.
Optionally, the cooling includes rapid cooling, air cooling, and water cooling performed in sequence.
Optionally, the final temperature of the rapid cooling is 420-480 ℃, and the cooling rate of the rapid cooling is more than or equal to 80 ℃/s; the air cooling end point temperature is 380-440 ℃, and the water cooling end point temperature is 250-350 ℃.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
according to the ultrahigh-strength hot-rolled complex phase steel provided by the embodiment of the invention, the chemical components of the steel are designed, and the C content is controlled, so that the lower C content is controlled on the basis of ensuring the strength, and the forming performance and toughness of the basis are ensured; c forms carbide with microalloy Nb and Ti elements, and forms carbide with Mo element, so that the precipitation strengthening effect can be improved, and the strength of the complex phase steel can be improved; the solid solution strengthening and fine crystal strengthening effects are effectively achieved by controlling the content of Mn; the hot brittleness of the steel is reduced by controlling the S content to be a lower level; the cold brittleness of the steel is reduced by controlling the content of P to be a lower level; the hardenability of steel is improved by controlling elements such as B, cr, mo, etc., and excellent fatigue properties are easily obtained.
The above description is only an overview of the technical solutions of the present invention, and the present invention can be implemented in accordance with the content of the description so as to make the technical means of the present invention more clearly understood, and the above and other objects, features, and advantages of the present invention will be more clearly understood.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a flow chart of a method provided by an embodiment of the invention.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are illustrative of the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention. For example, room temperature may refer to a temperature in the interval of 10 to 35 ℃.
Unless otherwise specifically indicated, various raw materials, reagents, instruments, equipment and the like used in the present invention may be commercially available or may be prepared by existing methods.
In order to solve the technical problems, the general idea of the embodiment of the application is as follows:
according to an exemplary embodiment of the present invention, there is provided an ultra-high strength hot-rolled complex phase steel, the chemical composition of which comprises, in mass percent:
c:0.07-0.15%, si:0.10 to 0.50%, mn:1.0-2.0%, P: less than or equal to 0.015 percent, S: less than or equal to 0.003 percent, nb:0.01-0.06%, ti:0.08-0.17%, cr:0.30-0.50%, mo:0.10-0.30%, N: less than or equal to 0.005%, B:0.001-0.004%, and the balance of Fe and inevitable impurities.
The actions and the limited ranges of the main alloy elements are explained in detail as follows:
in the embodiment of the application, the positive effect that the mass fraction of C is 0.07-0.15% is that in the mass fraction range, the C element is the most important solid solution strengthening element and the element ensuring precipitation in the steel; when the value of the mass fraction is larger than the maximum value of the end point of the range, the content of C is too high, the strength of the steel is too high, the formability of the steel is affected, and when the value of the mass fraction is smaller than the minimum value of the end point of the range, the content of C is too low, and the strength of the steel cannot be ensured.
The positive effect that the mass fraction of Si is 0.1-0.5% is that in the mass fraction range, because Si is a solid solution strengthening element of steel, si can promote C element to be enriched to austenite, improve the hardenability of austenite, simultaneously purify ferrite phase and improve the elongation of steel; when the mass fraction is larger than the maximum value at the end of the range, the surface quality of the steel material is deteriorated.
The positive effect that the mass fraction of Mn is 1.0-2.0% is that in the mass fraction range, mn has an important effect on the strengthening of the mechanical properties of steel materials because Mn is an important element for solid solution strengthening and austenite stabilizing; when the value of the mass fraction is larger than the maximum value of the end point of the range, the Mn content is too high, the structure segregation is easy to cause, the cracking of the steel in the forming process is caused, the mechanical property of the steel is deteriorated, and when the value of the mass fraction is smaller than the minimum value of the end point of the range, the Mn content is insufficient, and the solid solution strengthening and fine grain strengthening effects cannot be effectively achieved.
The positive effect that P is less than or equal to 0.015 percent is that in the mass fraction range, when the mass fraction is greater than the maximum value of the end point of the range, the grain boundary strength is reduced, and the mechanical property of the material is deteriorated.
The positive effect that S is less than or equal to 0.003 percent is that in the mass fraction range, S is a harmful element and can be combined with Mn to generate MnS, and when the value of the mass fraction is greater than the maximum value of the end point of the range, the mechanical property of the steel is deteriorated.
The positive effect that the mass fraction of Nb is 0.01-0.06% is that in the mass fraction range, nb can be ensured to be combined with C or N to form a nano precipitated phase, thereby playing the roles of refining grains and precipitation strengthening, having obvious effects of improving the tissue morphology and increasing the yield strength, simultaneously refining the austenite grain size in the heating process, finally obtaining hard phase dispersion, and having positive effects of improving the forming performance and the fatigue performance; when the mass fraction is greater than the maximum value of the end point of the range, the elongation of the steel material is reduced, and when the mass fraction is less than the minimum value of the end point of the range, because the content of Nb is insufficient, sufficient nano precipitated phase cannot be formed, and the effects of grain formation and precipitation strengthening cannot be achieved.
The positive effect that the mass fraction of Ti is 0.08-0.17% is that in the mass fraction range, ti can be ensured to be combined with C to form a nano precipitated phase, so that the effects of refining grains and precipitation strengthening are achieved, the remarkable effects of improving the structure form and the yield strength are achieved, the austenite grain size in the heating process is refined, the dispersion of a hard phase is finally obtained, and the positive effect of improving the fatigue performance is achieved; when the mass fraction is larger than the maximum value of the end point of the range, the elongation of the steel material is reduced, and when the mass fraction is smaller than the minimum value of the end point of the range, because the content of Ti is insufficient, sufficient nano precipitated phase cannot be formed, and the functions of grain formation and precipitation strengthening cannot be achieved.
The positive effect that the mass fraction of Mo is 0.1-0.3% is that the positive effect of improving the hardenability is achieved within the mass fraction range; when the mass fraction is greater than the maximum of the end of the range, the resulting adverse effect is high cost, and when the mass fraction is less than the minimum of the end of the range, the resulting adverse effect is insufficient hardenability.
The positive effect that the mass fraction of N is less than or equal to 0.005 percent is that in the mass fraction range, when the value of the mass fraction is larger than the maximum value of the end point of the range, the content of N is excessive, micron-sized TiN precipitates are increased, and the formation of a sufficient number of nano-sized precipitates cannot be ensured, so that the performance of the steel is influenced.
The positive effect that the mass fraction of B is 0.001-0.004% is that in the mass fraction range, the effect in the steel is mainly to be segregated at the original austenite crystal boundary and inhibit the formation of proeutectoid ferrite; boron added into the steel can also greatly improve the hardenability of the steel, and is combined with chromium to improve the structure of a welding heat affected zone. When the value of the mass fraction is larger than the maximum value of the end point of the range, boride is precipitated; when the mass fraction is less than the minimum at the end of the range, insufficient hardenability will be the resulting disadvantage.
As an alternative embodiment, the metallographic structure of the steel comprises granular bainite, lower bainite and martensite.
The reason why the metallographic structure of the steel is controlled to include granular bainite, lower bainite, and martensite is that: the series of structures are beneficial to obtaining ultrahigh strength, and simultaneously, better forming performance and fatigue performance are ensured, and good comprehensive capacity of steel is ensured.
As an alternative embodiment, the metallographic structure comprises, in volume percent: 5-10% of granular bainite, 3-8% of martensite and the balance lower bainite.
The reason for controlling the above ratio is that: when the volume fraction of the granular bainite is larger or smaller than the end value of the range, the strength or elongation of the steel is insufficient, and when the volume fraction of the martensite is larger or smaller than the end value of the range, the elongation or strength of the steel is insufficient, and the final fatigue performance is affected.
According to another exemplary embodiment of the present invention, there is provided a method of manufacturing the ultra-high strength hot-rolled complex phase steel provided above, including the steps of:
s1, sequentially carrying out converter smelting, LF refining and RH refining to obtain the molten steel according with the chemical components.
And S2, continuously casting the molten steel to obtain a steel billet.
And S3, heating, rough rolling and finish rolling the steel billet to obtain a hot rolled plate.
And S4, cooling and coiling the hot rolled plate to obtain the ultrahigh-strength hot-rolled complex phase steel.
As an alternative embodiment, the thickness of the hot-rolled plate is 1.8 to 5mm.
As an alternative embodiment, the rolling speed of the finish rolling is 5 to 10m/s.
The reason why the rolling speed is controlled is that: when the speed is greater or less than the end point of the range, the adverse effect is rolling instability or inefficiency.
As an alternative embodiment, the temperature of the heating is 1230 to 1280 ℃.
The reason why the heating temperature is controlled is that: in the temperature range, the alloy elements can be ensured to be fully dissolved; when the temperature is greater than or less than the end point of this range, the adverse effect is coarsening of the prior austenite or insufficient solid solution of the alloying elements.
In an alternative embodiment, the finishing temperature of the rough rolling is 1050 to 1100 ℃, and the finishing temperature of the finish rolling is 830 to 890 ℃.
The reason why the rough rolling end point temperature is controlled is as follows: in the temperature range, the microstructure of the steel plate after finishing rough rolling can be ensured to be uniformly distributed, and the mechanical property of the steel plate is ensured; when the temperature is higher or lower than the end point of the range, the microstructure of the steel plate is insufficient in uniformity, and a uniform microstructure cannot be effectively formed.
The reason why the finishing temperature is controlled is that: in the temperature range, the microstructure of the steel plate can be ensured to be uniformly distributed, and the mechanical property of the steel plate can be ensured; when the temperature value is greater than the end value of the range, the structure distribution of the steel plate is uneven, and when the temperature value is less than the end value of the range, the deformation resistance of the hot rolled plate is increased, edge cracking is easy to occur, and good structure performance is not facilitated.
As an alternative embodiment, the cooling includes rapid cooling, air cooling, and water cooling sequentially.
As an optional embodiment, the end point temperature of the quick cooling is 420-480 ℃, and the cooling rate of the quick cooling is more than or equal to 80 ℃/s; the air cooling end point temperature is 380-440 ℃, and the water cooling end point temperature is 250-350 ℃.
The reason for sequentially adopting three stages of cooling and controlling the end point temperature is that: and the rapid cooling avoids the precipitation of ferrite and pearlite, the air cooling ensures that the precipitation quotient of granular bainite ensures the elongation and the hole expansion rate, and the water cooling ensures that enough lower bainite and a small amount of martensite are formed.
The present application will be described in detail below with reference to examples, comparative examples, and experimental data.
Example 1
The chemical components of the ultrahigh-strength hot-rolled complex-phase steel are represented by mass percent in the following table 1.
Table 1 chemical composition (wt%) of the substrate of example 1
The metallographic structure comprises the following components in percentage by volume: 8% of granular bainite, 4% of martensite and the balance lower bainite.
The preparation method of the ultrahigh-strength hot-rolled complex phase steel comprises the following steps:
s1, sequentially carrying out converter smelting, LF refining and RH refining to obtain molten steel according with chemical components.
And S2, continuously casting the molten steel to obtain a billet.
And S3, heating, rough rolling and finish rolling the steel billet to obtain a hot rolled plate.
Wherein:
the thickness of the hot-rolled plate is 3mm;
the rolling speed of finish rolling is 8m/s;
the heating temperature is 1250 ℃;
the finishing temperature of rough rolling is 1060 ℃, and the finishing temperature of finish rolling is 850 ℃;
and S4, cooling and coiling the hot rolled plate to obtain the ultrahigh-strength hot-rolled complex-phase steel.
Wherein:
the cooling comprises rapid cooling, air cooling and water cooling which are sequentially carried out, wherein the end point temperature of the rapid cooling is 470 ℃, and the cooling rate of the rapid cooling is 105 ℃/s; the final temperature of air cooling was 400 ℃ and the final temperature of water cooling was 280 ℃.
Example 2
The chemical components of the ultrahigh-strength hot-rolled complex-phase steel are represented by mass percent in the following table 2.
Table 2 chemical composition (wt%) of substrate of example 2
The metallographic structure comprises the following components in percentage by volume: 5% of granular bainite, 7% of martensite and the balance lower bainite.
The preparation method of the ultrahigh-strength hot-rolled complex phase steel comprises the following steps:
s1, sequentially carrying out converter smelting, LF refining and RH refining to obtain molten steel according with chemical components.
And S2, continuously casting the molten steel to obtain a billet.
And S3, heating, rough rolling and finish rolling the steel billet to obtain a hot rolled plate.
Wherein:
the thickness of the hot-rolled plate is 2.5mm;
the rolling speed of finish rolling is 9.5m/s;
the heating temperature is 1260 ℃;
the finishing temperature of rough rolling is 1080 ℃, and the finishing temperature of finish rolling is 870 ℃;
and S4, cooling and coiling the hot rolled plate to obtain the ultrahigh-strength hot-rolled complex-phase steel.
Wherein:
the cooling comprises rapid cooling, air cooling and water cooling which are sequentially carried out, wherein the final temperature of the rapid cooling is 450 ℃, and the cooling rate of the rapid cooling is 115 ℃/s; the final temperature of air cooling was 390 ℃ and the final temperature of water cooling was 260 ℃.
Example 3
The chemical components of the ultrahigh-strength hot-rolled complex-phase steel are represented by the following table 3 in percentage by mass.
Table 3 chemical composition (wt%) of substrate of example 3
The metallographic structure comprises the following components in percentage by volume: 5% of granular bainite, 7% of martensite and the balance lower bainite.
The preparation method of the ultrahigh-strength hot-rolled complex phase steel comprises the following steps:
s1, sequentially carrying out converter smelting, LF refining and RH refining to obtain molten steel according with chemical components.
And S2, continuously casting the molten steel to obtain a billet.
And S3, heating, rough rolling and finish rolling the steel billet to obtain a hot rolled plate.
Wherein:
the thickness of the hot-rolled plate is 4mm;
the rolling speed of finish rolling is 6m/s;
the heating temperature is 1250 ℃;
the finishing temperature of rough rolling is 1070 ℃, and the finishing temperature of finish rolling is 880 ℃;
and S4, cooling and coiling the hot rolled plate to obtain the ultrahigh-strength hot-rolled complex phase steel.
Wherein:
the cooling comprises rapid cooling, air cooling and water cooling which are sequentially carried out, wherein the end point temperature of the rapid cooling is 470 ℃, and the cooling rate of the rapid cooling is 120 ℃/s; the final temperature of air cooling was 420 ℃ and the final temperature of water cooling was 290 ℃.
Comparative example 1
The chemical components of the ultrahigh-strength hot-rolled complex-phase steel are represented by mass percent in the following table 4.
Table 4 chemical composition (wt%) of substrate of comparative example 1
The metallographic structure comprises the following components in percentage by volume: 15% of granular bainite, 2% of martensite and the balance lower bainite.
The preparation method of the ultrahigh-strength hot-rolled complex phase steel comprises the following steps:
s1, sequentially carrying out converter smelting, LF refining and RH refining to obtain molten steel according with chemical components.
And S2, continuously casting the molten steel to obtain a billet.
And S3, heating, rough rolling and finish rolling the steel billet to obtain a hot rolled plate.
Wherein:
the thickness of the hot-rolled plate is 4mm;
the rolling speed of finish rolling is 6m/s;
the heating temperature is 1250 ℃;
the finishing temperature of rough rolling is 1070 ℃, and the finishing temperature of finish rolling is 880 ℃;
and S4, cooling and coiling the hot rolled plate to obtain the ultrahigh-strength hot-rolled complex-phase steel.
Wherein:
the cooling comprises rapid cooling, air cooling and water cooling which are sequentially carried out, wherein the end point temperature of the rapid cooling is 520 ℃, and the cooling rate of the rapid cooling is 75 ℃/s; the final temperature of air cooling was 480 ℃ and that of water cooling was 400 ℃.
Comparative example 2
The chemical components of the ultrahigh-strength hot-rolled complex-phase steel are represented by mass percent in the following table 5.
Table 5 chemical composition (wt%) of substrate of comparative example 2
The metallographic structure comprises the following components in percentage by volume: 2% of granular bainite, 12% of martensite and the balance lower bainite.
The preparation method of the ultrahigh-strength hot-rolled complex phase steel comprises the following steps:
s1, sequentially carrying out converter smelting, LF refining and RH refining to obtain molten steel according with chemical components.
And S2, continuously casting the molten steel to obtain a billet.
And S3, heating, rough rolling and finish rolling the steel billet to obtain a hot rolled plate.
Wherein:
the thickness of the hot-rolled plate is 2.5mm;
the rolling speed of finish rolling is 9.5m/s;
the heating temperature is 1260 ℃;
the finishing temperature of rough rolling is 1090 ℃, and the finishing temperature of finish rolling is 880 ℃;
and S4, cooling and coiling the hot rolled plate to obtain the ultrahigh-strength hot-rolled complex-phase steel.
Wherein:
the cooling comprises rapid cooling, air cooling and water cooling which are sequentially carried out, wherein the end point temperature of the rapid cooling is 400 ℃, and the cooling rate of the rapid cooling is 145 ℃/s; the final temperature of air cooling was 320 ℃ and the final temperature of water cooling was 200 ℃.
Examples of the experiments
The ultrahigh-strength hot-rolled complex-phase steel provided in examples 1 to 3 and comparative examples 1 to 2 was subjected to performance tests, and the specific results are shown in the following table.
| Yield strength/MPa | Tensile strength/MPa | The ratio of hole enlargement λ/%) | Elongation A80/%) | |
| Example 1 | 830 | 995 | 35 | 10.5 |
| Example 2 | 850 | 1005 | 36 | 9.5 |
| Example 3 | 815 | 1022 | 35 | 9 |
| Comparative example 1 | 774 | 965 | 30 | 10.5 |
| Comparative example 2 | 845 | 1085 | 25 | 7.5 |
As can be seen from the above table, the ultrahigh-strength hot-rolled complex phase steel provided in the examples 1-3 has excellent performance, the yield strength is not less than 800MPa, the tensile strength is not less than 980MPa, the hole expansion ratio lambda is not less than 30%, the elongation A80 is not less than 9%, the ultrahigh-strength hot-rolled complex phase steel has excellent forming performance and fatigue resistance, and the comprehensive performance is obviously better than that of the comparative examples 1-2.
Finally, it should be further noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention 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 such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. The ultrahigh-strength hot-rolled complex-phase steel is characterized by comprising the following chemical components in percentage by mass:
c:0.07-0.15%, si:0.10 to 0.50%, mn:1.0-2.0%, P: less than or equal to 0.015 percent, S: less than or equal to 0.003 percent, nb:0.01-0.06%, ti:0.08-0.17%, cr:0.30-0.50%, mo:0.10-0.30%, N: less than or equal to 0.005 percent, B:0.001-0.004%, and the balance of Fe and inevitable impurities.
2. The ultra-high strength hot rolled complex phase steel of claim 1, wherein said steel metallographic structure comprises granular bainite, lower bainite, and martensite.
3. The ultra-high strength hot rolled complex phase steel according to claim 2, wherein said metallographic structure comprises, in volume percent:
5-10% of granular bainite, 3-8% of martensite and the balance lower bainite.
4. A method for producing an ultra high strength hot rolled complex phase steel as claimed in any one of claims 1 to 3, comprising the steps of:
sequentially carrying out converter smelting, LF refining and RH refining to obtain molten steel according with the chemical components;
continuously casting the molten steel to obtain a steel billet;
heating, rough rolling and finish rolling the billet to obtain a hot rolled plate;
and cooling and coiling the hot rolled plate to obtain the ultrahigh-strength hot-rolled complex phase steel.
5. The method of producing an ultra-high strength hot rolled complex phase steel as claimed in claim 4, wherein the thickness of said hot rolled plate is 1.8-5mm.
6. The method for preparing an ultra-high strength hot-rolled complex phase steel according to claim 4, wherein the finish rolling speed is 5 to 10m/s.
7. The method of producing an ultra-high strength hot rolled complex phase steel as claimed in claim 4, wherein the temperature of said heating is 1230-1280 ℃.
8. The method for preparing the ultra-high strength hot-rolled complex phase steel according to claim 4, wherein the finish rolling temperature of the rough rolling is 1050-1100 ℃ and the finish rolling temperature of the finish rolling is 830-890 ℃.
9. The method of claim 4, wherein the cooling comprises rapid cooling, air cooling and water cooling in sequence.
10. The preparation method of the ultra-high strength hot-rolled complex phase steel as claimed in claim 9, wherein the end point temperature of the rapid cooling is 420-480 ℃, and the cooling rate of the rapid cooling is more than or equal to 80 ℃/s; the air cooling end point temperature is 380-440 ℃, and the water cooling end point temperature is 250-350 ℃.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1477226A (en) * | 2003-08-01 | 2004-02-25 | 清华大学 | Medium-low carbon manganese system self-hardening bainite steel |
| JP2007169722A (en) * | 2005-12-22 | 2007-07-05 | Furukawa Sky Kk | Method for manufacturing hot rolled aluminum sheet having excellent balance between strength and elongation and also excellent fatigue strength |
| CN112210727A (en) * | 2020-09-28 | 2021-01-12 | 马鞍山钢铁股份有限公司 | Hot-rolled complex phase steel with tensile strength of 850MPa and production method thereof |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1477226A (en) * | 2003-08-01 | 2004-02-25 | 清华大学 | Medium-low carbon manganese system self-hardening bainite steel |
| JP2007169722A (en) * | 2005-12-22 | 2007-07-05 | Furukawa Sky Kk | Method for manufacturing hot rolled aluminum sheet having excellent balance between strength and elongation and also excellent fatigue strength |
| CN112210727A (en) * | 2020-09-28 | 2021-01-12 | 马鞍山钢铁股份有限公司 | Hot-rolled complex phase steel with tensile strength of 850MPa and production method thereof |
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