CN108998739B - Hot-rolled pickled strip steel with high hole expanding performance and production method thereof - Google Patents
Hot-rolled pickled strip steel with high hole expanding performance and production method thereof Download PDFInfo
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—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
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—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
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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
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
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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
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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Abstract
The invention discloses a hot-rolled acid-washing strip steel with low cost and high hole-expanding performance and a production method thereof, wherein the hot-rolled acid-washing strip steel comprises the following raw materials in percentage by mass: 0.05-0.1% of C; si 0.1-0.7%; 0.9-1.6% of Mn; p is less than or equal to 0.02 percent; s is less than or equal to 0.015 percent; 0.01-0.05% of Nb; 0.01-0.07% of Al; RE 0.002-0.05%; the balance being Fe and unavoidable impurities. The production method of the hot-rolled acid-washed strip steel with high hole expansion performance comprises the following steps: the method comprises the following steps of molten iron pretreatment, converter smelting, refining, continuous casting, hot rolling, leveling and acid pickling. The microstructure of the strip steel produced by the invention is ferrite and bainite, wherein the volume ratio of the bainite structure is 10-20%, the tensile strength of the strip steel is more than or equal to 590MPa, the hole expansion ratio lambda is more than or equal to 95%, and the strip steel has excellent surface quality.
Description
Technical Field
The invention relates to a hot-rolled acid-pickled strip steel with low cost and high hole expanding performance and a production method thereof, belonging to the technical field of hot-rolled acid-pickled strip steel production processes.
Background
The hot-rolled pickled product is an intermediate product between cold rolling and hot rolling, has the surface quality close to that of a cold plate, simultaneously maintains the mechanical property of the hot-rolled product, has a very wide application range and has a better market prospect. Compared with the common hot rolled plate, the hot rolled pickled plate removes surface iron scale, improves the surface quality of steel, replaces a cold rolled plate with the pickled plate, can obviously reduce the cost for enterprises, and is widely used for manufacturing automobile body structural parts, chassis systems and the like at present. With the development of the automobile industry, the automobile industry has higher and higher requirements on light weight, safety, cost control reduction and fuel economy, and the adoption of high-strength steel and advanced high-strength steel is a necessary trend for adapting to the development of the automobile industry.
As one of Advanced High Strength Steels (AHSS), hot rolled and pickled high-expansion bore steel has been widely used for manufacturing structural members such as automobile spokes, chassis, various frames of automobile bodies, etc. due to its high strength and high-expansion bore performance, compared with conventional low-alloy high-strength, ferritic-martensitic dual-phase steel.
Compared with the traditional low-alloy high-strength steel and ferrite martensite dual-phase steel, the hot-rolled ferrite bainite strip steel has good cold formability matching, good hole expansion performance and fatigue performance due to the small hardness difference of two phases (ferrite and bainite) in the matrix structure.
In the existing hot-rolled and acid-washed high-reaming steel production technology, high reaming ratio and excellent surface quality of strip steel are difficult to obtain. For example, C, P element with higher content of component system is unfavorable for hole-expanding performance of strip steel due to more carbide and grain boundary P segregation, while iron olivine (2 FeO-SiO) is caused by higher Si content2) Scale formation makes it difficult to remove and to obtain a hot-rolled pickled strip of high-grade surface quality.
The S element is used as a harmful element, and MnS inclusions generated by the S element seriously influence the hole expansion rate. In the actual production process of a plurality of steel mills, the S content can be less than or equal to 0.006 percent through refining procedures such as LF, LF and RH, and the like, so that the adverse effect of the excessive S content on the hole expansion rate is eliminated. The rare earth element RE is introduced into the composition system, the MnS form of inclusions is optimized, the hole expansion rate of the product is improved, and the horizontal hole expansion rate of the S content less than or equal to 0.006 percent is achieved. By the method, the requirement of the high-hole-expansion steel on the S content of the product can be obviously reduced, and the production can be realized through a refining process with lower cost.
Disclosure of Invention
The invention aims to provide a hot-rolled pickled strip steel with high hole expanding performance and capable of improving the hole expanding rate and excellent surface quality of the strip steel and a production method thereof.
The invention relates to a hot-rolled acid-washing strip steel with high hole-expanding performance, which comprises the following raw materials in percentage by mass: 0.05-0.1% of C; si 0.1-0.7%; 0.9-1.6% of Mn; p is less than or equal to 0.02 percent; s is less than or equal to 0.015 percent; 0.01-0.05% of Nb; 0.01-0.07% of Al; RE 0.002-0.05%; the balance being Fe and unavoidable impurities.
In another aspect, the present invention also relates to a method for producing the above hot-rolled acid-washed strip steel with high hole expansibility, comprising:
(1) pretreating molten iron, smelting and refining the molten iron by a converter to obtain molten steel with the components, and then continuously casting the molten steel to obtain a plate blank;
(2) heating the plate blank, and then carrying out rough rolling and finish rolling to obtain a hot rolled plate;
(3) cooling the hot rolled plate by stages, and coiling the cooled hot rolled plate into a hot rolled coil;
(4) and flattening and pickling the hot rolled coil to obtain a finished product.
Description
The invention provides a hot-rolled acid-washing strip steel with high hole-expanding performance, which comprises the following raw materials in percentage by mass: 0.05-0.1% of C; si 0.1-0.7%; 0.9-1.6% of Mn; p is less than or equal to 0.02 percent; s is less than or equal to 0.015 percent; 0.01-0.05% of Nb; 0.01-0.07% of Al; RE 0.002-0.05%; the balance being Fe and unavoidable impurities.
The following are descriptions of the role of the main components involved in the invention and their limitations:
carbon: carbon is an austenite element, and the level of carbon content largely determines the tensile strength grade of the steel plate, and is an important index influencing the carbon equivalent. According to the invention, the content of the C element is controlled to be 0.05-0.1%, so that the steel grade can be toughened at high strength and has good forming and welding properties.
Manganese: according to the invention, the transformation of pearlite is delayed by using manganese, the hardenability of steel is improved, the transformation temperature of bainite is reduced, and the microstructure of steel is refined. Therefore, the invention adopts 0.8-1.2% of Mn content, and has good formability on the premise of ensuring the tensile strength of the product.
Rare earth elements: the rare earth element RE can optimize the MnS form of inclusions and improve the hole expanding rate of products, and the RE content is limited to 0.002-0.05 percent.
Niobium: the invention utilizes the microalloy element niobium to promote the fine-grained strengthening of ferrite grains, and is beneficial to reducing the strength difference between bainite/ferrite matrixes, thereby improving the stretch flangeability of steel. In the invention, the content of Nb element is controlled to be 0.01-0.05%.
Aluminum: aluminum is a nitride-forming element, and is mainly used for fixing nitrogen in steel, and is beneficial to improving the aging performance of the steel. The Al content is limited to 0.01-0.07%.
Silicon: silicon has a certain strengthening effect but deteriorates corrosion resistance, and the present invention limits the Si content to 0.3 to 1.0% for promoting purity in a ferrite matrix.
Phosphorus: phosphorus in steel is generally dissolved in ferrite in a solid manner, so that the solid solution strengthening effect is strong, the strength of the steel is improved, the toughness of the steel is reduced, but P with too high content is unfavorable for welding performance and is a harmful element, so that the phosphorus content is reduced as much as possible, and the P content is less than or equal to 0.02 percent.
Sulfur: the sulfur content and the form of sulfides are main factors influencing the formability, and the larger the amount of sulfides is, the larger the size is, the more adverse to the hole expansion performance is, so the actual control level of the S content of the product in the invention is not strictly limited, and the S content is less than or equal to 0.015 percent.
The internal microstructure of the hot-rolled pickled strip steel is ferrite and bainite.
Further, the internal microstructure of the hot-rolled pickled steel strip consists of 80-90% of ferrite and 10-20% of bainite in volume fraction. The proportion of the structure type can ensure that the tensile strength of the hot-rolled pickled strip steel is more than or equal to 590MPa, the hole expansion rate lambda is more than or equal to 95 percent, and the surface quality of the strip steel is excellent.
In the application, elements such as C, Si, Mn and the like improve the yield strength and the tensile strength of the strip steel through the solid solution strengthening effect; the yield strength and the tensile strength of the product are further improved by the Nb element through solid solution strengthening, fine grain strengthening and precipitation strengthening, and the elongation and the hole expansion rate are improved; the rare earth element RE is mainly used for improving the type of the inclusion so as to improve the hole expanding rate of the product. The elements are combined to ensure that the performance of the material meets the standard requirement.
The invention also provides a production method of the hot-rolled acid-washed strip steel with high hole expanding performance, which comprises the following steps:
(1) pretreating molten iron, smelting and refining the molten iron by a converter to obtain molten steel with the components, and then continuously casting the molten steel to obtain a plate blank;
(2) heating the plate blank, and then carrying out rough rolling and finish rolling to obtain a hot rolled plate;
(3) cooling the hot rolled plate by stages, and coiling the cooled hot rolled plate into a hot rolled coil;
(4) and flattening and pickling the hot rolled coil to obtain a finished product.
According to the production method of the hot-rolled pickled strip steel, in the step (2), constant-speed rolling is adopted during the finish rolling, the thickness specification change range of the hot-rolled plate is controlled to be 1.8-5.5 mm, and the rolling speed is controlled to be 5-11 m/s due to thickness change. The change of the rolling speed is mainly determined by the difference between the finish rolling inlet temperature and the finish rolling temperature to ensure that the strip steel smoothly passes through the rolling mill at a target temperature point. The stability of air cooling time is ensured during constant-speed rolling, and if the constant speed is not adopted, the air cooling time is difficult to control, so that the stability of later-stage structure is not facilitated, and the hole expanding rate is influenced.
According to the production method of the hot-rolled pickled strip steel, in the step (2), the finish temperature of rough rolling is controlled to be 1000-1080 ℃, and the finish temperature of finish rolling is controlled to be 830-890 ℃. Acicular ferrite is easy to form due to overhigh temperature, and the plasticity is poor; and the low temperature is easy to form elongated ferrite grains or enter a gamma + alpha two-phase region. The finish temperature of rough rolling is controlled to be 1000-1080 ℃, the finish temperature of finish rolling is controlled to be 820-900 ℃, and the steel plate can be ensured to have good matching of strength and elongation percentage in the temperature range.
According to the production method of the hot-rolled pickled strip steel, in the step (3), the staged cooling comprises the steps of rapidly cooling the hot-rolled plate to 600-680 ℃, then carrying out air cooling for 5-10 s, and finally carrying out water cooling to 400-500 ℃. The temperature of 600-680 ℃ is a fast nucleation area of a ferrite (alpha) phase, fast cooling to the temperature point is beneficial to nucleation of the ferrite phase, the air cooling time of 5-10S ensures that the ferrite phase has enough growth time, and the cooling temperature of 400-500 ℃ is to form a bainite structure, the temperature is too high, so that pearlite is easy to form, and the temperature is too low, so that martensite and other structures are easy to form.
According to the production method of the hot-rolled pickling strip steel, in the step (4), the hot-rolled coil is cooled to room temperature and then flattened, and the flattening elongation is controlled to be 1-3%.
According to the production method of the hot-rolled pickled strip steel, in the step (4), the running speed of the flattened hot-rolled coil during pickling is controlled to be 60-100 m/min. The pickling speed is too low, the over pickling is easily caused, the under pickling is easily caused when the speed is too high, and the FB-grade surface quality requirement on the surface of the strip steel cannot be met.
Further, the pickling temperature of the last pickling tank is controlled to be 80-90 ℃ and the concentration of iron ions is controlled to be 30-40 g/L in the pickling process, so that the strip steel in a production place meets the requirement of surface FB level surface quality.
According to the hot-rolled pickled strip steel with high hole expanding performance and the production method thereof, the microcosmic metallographic structure of the produced strip steel is ferrite and bainite through controlling chemical components and parameters of rolling and pickling processes, wherein the volume ratio of the bainite structure is 10-20%, the tensile strength of the strip steel is more than or equal to 590MPa, the hole expanding rate is more than or equal to 95%, and the surface quality of the strip steel is excellent.
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 for the purpose of illustrating 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.
Example 1
The embodiment of the invention provides a hot-rolled pickled strip steel with high hole expanding performance, which comprises the following chemical components in percentage by weight: 0.07% of C, 0.3% of Si, 1.2% of Mn, 0.012% of P, 0.012% of S, 0.03% of Nb, 0.05% of Al, 0.05% of RE, and the balance of Fe and inevitable impurities.
The production method comprises the following steps: the method comprises the following steps of molten iron pretreatment, converter smelting, refining, continuous casting, hot rolling, leveling and acid pickling. Wherein the finishing temperature of rough rolling is controlled to be 1040 ℃, and the finishing temperature of finish rolling is controlled to be 860 ℃; constant-speed rolling is adopted during rough rolling and finish rolling, the rough rolling speed is controlled at 5m/s, and the finish rolling speed is controlled at 10 m/s; after rolling, a staged cooling process is adopted, the hot rolled plate after finish rolling is rapidly cooled to 620 ℃ at a cooling rate of 80 ℃/S, then air cooling is carried out for 7S, and finally water cooling is carried out to 410 ℃ at a cooling rate of 90 ℃/S. And flattening the strip steel cooled to room temperature, and controlling the elongation of the strip steel to be 1.5%. During acid cleaning, shallow slot turbulent acid cleaning is adopted, the running speed of the strip steel is 80m/min, the acid cleaning temperature of a No. 5 acid cleaning tank (the last acid cleaning tank) is controlled to be 85 ℃, and the concentration of iron ions is 34 g/L. The surface color of the pickled strip steel is grey white, and the finished product is obtained after drying, double-sided electrostatic spraying of anti-rust oil, coiling and packaging, so that the hot-rolled pickled strip steel with high hole expanding performance is produced.
The microstructure of the strip steel finally produced by the embodiment is ferrite and bainite, wherein the volume ratio of the bainite structure is 15%, the tensile strength of the strip steel is 600MPa, the hole expansion rate lambda is 100%, and the surface quality is FB grade.
Example 2
The embodiment of the invention provides a hot-rolled pickled strip steel with high hole expanding performance, which comprises the following chemical components in percentage by weight: 0.09% of C, 0.3% of Si, 1.5% of Mn, 0.015% of P, 0.015% of S, 0.015% of Nb, 0.04% of Al, 0.002% of RE, and the balance of Fe and inevitable impurities.
The production method comprises the following steps: the method comprises the following steps of molten iron pretreatment, converter smelting, refining, continuous casting, hot rolling, leveling and acid pickling. Wherein the finish temperature of rough rolling is controlled to be 1000 ℃, and the finish temperature of finish rolling is controlled to be 840 ℃; constant-speed rolling is adopted during rough rolling and finish rolling, the rough rolling speed is controlled at 8m/s, and the finish rolling speed is controlled at 11 m/s; after rolling, a staged cooling process is adopted, the hot rolled plate after finish rolling is rapidly cooled to 610 ℃ at a cooling rate of 90 ℃/S, then air cooling is carried out for 6S, and finally water cooling is carried out to 430 ℃ at a rate of 80 ℃/S. And flattening the strip steel cooled to room temperature, and controlling the elongation of the strip steel to be 1.8%. During acid washing, shallow slot turbulent acid washing is adopted, the running speed of the strip steel is 90m/min, the acid washing temperature of a No. 5 acid washing tank is controlled to be 82 ℃, and the concentration of iron ions is controlled to be 36 g/L. The surface color of the pickled strip steel is grey white, and the finished product is obtained after drying, double-sided electrostatic spraying of anti-rust oil, coiling and packaging, so that the hot-rolled pickled strip steel with high hole expanding performance is produced.
The microstructure of the strip steel finally produced by the embodiment is ferrite and bainite, wherein the volume ratio of the bainite structure is 12%, the tensile strength of the strip steel is 595MPa, the hole expansion ratio lambda is 105%, and the surface quality is FB grade.
Example 3
The embodiment of the invention provides a hot-rolled pickled strip steel with high hole expanding performance, which comprises the following chemical components in percentage by weight: 0.06% of C, 0.6% of Si, 1.2% of Mn, 0.01% of P, 0.015% of S, 0.04% of Nb, 0.03% of Al, 0.02% of RE and the balance of Fe and inevitable impurities.
The production method comprises the following steps: the method comprises the following steps of molten iron pretreatment, converter smelting, refining, continuous casting, hot rolling, leveling and acid pickling. Wherein the finish temperature of rough rolling is controlled to be 1020 ℃, and the finish temperature of finish rolling is controlled to be 850 ℃; constant-speed rolling is adopted during rough rolling and finish rolling, the rough rolling speed is controlled at 6m/s, and the finish rolling speed is controlled at 9 m/s; after rolling, a staged cooling process is adopted, the hot rolled plate after finish rolling is rapidly cooled to 670 ℃ at a cooling rate of 68 ℃/S, then air cooling is carried out for 8S, and finally water cooling is carried out to 480 ℃ at a cooling rate of 70 ℃/S. And flattening the strip steel cooled to room temperature, and controlling the elongation of the strip steel to be 2.0%. During acid washing, shallow slot turbulent acid washing is adopted, the running speed of the strip steel is 70m/min, the acid washing temperature of a No. 5 acid washing tank is controlled to be 88 ℃, and the concentration of iron ions is 39 g/L. The surface color of the pickled strip steel is grey white, and the finished product is obtained after drying, double-sided electrostatic spraying of anti-rust oil, coiling and packaging, so that the hot-rolled pickled strip steel with high hole expanding performance is produced.
The microstructure of the strip steel finally produced by the embodiment is ferrite and bainite, wherein the volume ratio of the bainite structure is 12%, the tensile strength of the strip steel is 600MPa, the hole expansion rate lambda is 98%, and the surface quality is FB grade.
Example 4
The embodiment of the invention provides a hot-rolled pickled strip steel with high hole expanding performance, which comprises the following chemical components in percentage by weight: 0.08 percent of C, 0.3 percent of Si, 1.1 percent of Mn, 0.008 percent of P, 0.012 percent of S, 0.05 percent of Nb, 0.02 percent of Al, 0.015 percent of RE, and the balance of Fe and inevitable impurities.
The production method comprises the following steps: the method comprises the following steps of molten iron pretreatment, converter smelting, refining, continuous casting, hot rolling, leveling and acid pickling. Wherein the finish temperature of rough rolling is controlled to 1060 ℃, and the finish temperature of finish rolling is controlled to 870 ℃; constant-speed rolling is adopted during rough rolling and finish rolling, the rough rolling speed is controlled at 7m/s, and the finish rolling speed is controlled at 10.5 m/s; after rolling, a staged cooling process is adopted, the hot rolled plate after finish rolling is rapidly cooled to 630 ℃ at a cooling rate of 85 ℃/S, then air cooling is carried out for 9S, and finally water cooling is carried out to 490 ℃ at a rate of 65 ℃/S. And flattening the strip steel cooled to room temperature, and controlling the elongation of the strip steel to be 2.5%. During acid washing, shallow slot turbulent acid washing is adopted, the running speed of the strip steel is 68m/min, the acid washing temperature of a No. 5 acid washing tank is controlled to be 84 ℃, and the concentration of iron ions is controlled to be 37 g/L. The surface color of the pickled strip steel is grey white, and the finished product is obtained after drying, double-sided electrostatic spraying of anti-rust oil, coiling and packaging, so that the hot-rolled pickled strip steel with high hole expanding performance is produced.
The microstructure of the strip steel finally produced by the embodiment is ferrite and bainite, wherein the volume ratio of the bainite structure is 18%, the tensile strength of the strip steel is 605MPa, the hole expansion ratio lambda is 100%, and the surface quality is FB grade.
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 (1)
1. A method of producing a hot rolled pickled strip steel having high hole expansibility, comprising:
(1) pretreating molten iron, smelting and refining the molten iron by a converter to obtain molten steel, and then continuously casting the molten steel to obtain a plate blank; wherein the raw materials comprise the following chemical components in percentage by mass (%): 0.05-0.1% of C; si 0.1-0.7%; 0.9-1.6% of Mn; p is less than or equal to 0.02 percent; s is less than or equal to 0.015 percent; 0.01-0.05% of Nb; 0.01-0.07% of Al; RE 0.002-0.02%; the balance of Fe and inevitable impurities;
(2) heating the plate blank, and then carrying out rough rolling and finish rolling to obtain a hot rolled plate;
(3) cooling the hot rolled plate by stages, and coiling the cooled hot rolled plate into a hot rolled coil; the staged cooling comprises the steps of rapidly cooling the hot rolled plate to 600-680 ℃, then carrying out air cooling for 5-10 s, and finally carrying out water cooling to 400-500 ℃;
(4) flattening and pickling the hot rolled coil to obtain a finished product;
wherein the internal microstructure of the hot-rolled pickled strip steel consists of 80-90% of ferrite and 10-20% of bainite by volume fraction;
in the step (2), constant-speed rolling is adopted during finish rolling, the thickness specification change range of the hot-rolled plate is controlled to be 1.8-5.5 mm, and the rolling speed is controlled to be 5-11 m/s due to thickness change; the finish temperature of the rough rolling is controlled to be 1000-1080 ℃, and the finish temperature of the finish rolling is controlled to be 830-890 ℃; in the step (4), the hot-rolled coil is cooled to room temperature and then flattened, and the flattening elongation is controlled to be 1-3%;
controlling the running speed of the leveled hot rolled coil in pickling to be 60-100 m/min;
the pickling temperature of the last pickling tank in the pickling process is controlled to be 80-90 ℃, and the concentration of iron ions is controlled to be 30-40 g/L.
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| CN109536845B (en) * | 2019-02-01 | 2021-09-21 | 本钢板材股份有限公司 | Hot-rolled ferrite-bainite dual-phase steel strip with tensile strength of 590MPa for wheel and preparation method thereof |
| CN109898016A (en) * | 2019-03-01 | 2019-06-18 | 鞍钢股份有限公司 | 500MPa grades or more high reaming hot rolling acid-cleaning steel plate and its manufacturing method |
| CN111519107B (en) * | 2020-06-03 | 2021-11-19 | 首钢集团有限公司 | Hot-rolled and acid-washed low-alloy high-strength steel with enhanced hole expanding performance and production method thereof |
| CN114107798A (en) * | 2020-08-31 | 2022-03-01 | 宝山钢铁股份有限公司 | 980 MPa-grade bainite high-reaming steel and manufacturing method thereof |
| CN112195404B (en) * | 2020-09-28 | 2022-04-19 | 首钢集团有限公司 | 700MPa grade boron-containing steel for automobile torsion beam and preparation method thereof |
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| JP3125397B2 (en) * | 1991-12-26 | 2001-01-15 | 日本鋼管株式会社 | Manufacturing method of high tensile alloyed hot-dip galvanized steel sheet with excellent stretch flangeability |
| CN102400038A (en) * | 2011-12-06 | 2012-04-04 | 首钢总公司 | Hot-rolled dual-phase steel and production method thereof |
| CN103469068B (en) * | 2013-10-08 | 2015-07-08 | 武汉钢铁(集团)公司 | Ferrite bainitic steel with tensile strength of 540MPa and high pore broadening performance and production method thereof |
| CN105506476A (en) * | 2014-09-26 | 2016-04-20 | 鞍钢股份有限公司 | 600 MPa-grade highly-chambered steel plate for automotive chassis and manufacturing method thereof |
| CN104630623B (en) * | 2015-01-30 | 2017-03-01 | 首钢总公司 | There is hot rolling acid-cleaning strip steel and its production method of high reaming performance |
| CN106011646B (en) * | 2016-07-15 | 2018-06-26 | 武汉钢铁有限公司 | Tensile strength is 590MPa grades of great surface quality automobile hot rolling acid-cleaning steel and production method |
| CN106521327B (en) * | 2016-12-27 | 2018-08-21 | 首钢集团有限公司 | A kind of hot rolling acid-cleaning strip and its production method with high reaming performance |
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