Alloying control method for ultrahigh-strength steel with 980MPa-grade tensile strength
By using segmented continuous annealing and precisely controlled hot-dip galvanizing and air knife blowing processes, the problem of uneven Fe-Zn phase layer caused by alloying temperature fluctuations was solved, achieving uniform alloying of galvanized sheets, improving coating adhesion and toughness, and enhancing product quality.
Patent Information
- Application Number
- CN202510894295.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-10-17
AI Technical Summary
In the existing technology, it is difficult to control the degree of alloying. Alloying temperature fluctuations are prone to occur, resulting in uneven Fe-Zn phase layer, affecting the adhesion of the coating, leading to powdering and dezincification problems, and seriously affecting the product qualification rate and customer performance.
A segmented continuous annealing process is adopted, including a soaking zone and a slow cooling zone. The temperature and exit temperature are controlled. Hot-dip galvanizing is carried out using a zinc-aluminum plating solution with a set aluminum content. The spacing and height are controlled by air knife blowing, combined with precise control of alloying temperature, to achieve uniform alloying of galvanized sheet.
This achieves uniform alloying of galvanized sheets, improves the toughness and adhesion of the coating, reduces the length of surface powdering, and enhances product quality and service life.
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Figure CN120796887A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the alloying technology field of ultrahigh-strength steel, in particular to a method for controlling the alloying of ultrahigh-strength steel with a tensile strength of 980 MPa. BACKGROUND
[0002] JAC980YL is a high-strength automobile steel, and the corrosion resistance and formability thereof need to be improved through hot galvanizing and alloying processes. However, in the prior art, the alloying degree is difficult to control, and the Fe-Zn phase layer is not uniform due to alloying temperature fluctuations, which affects the adhesion of the coating, and thus leads to the problem of zinc powdering and dezincification, resulting in substandard surface quality, seriously affecting the product qualification rate and customer performance, and a systematic control method is urgently needed. SUMMARY
[0003] The application provides a method for controlling the alloying of ultrahigh-strength steel with a tensile strength of 980 MPa, to solve the technical problem of how to improve the alloying uniformity of ultrahigh-strength steel with a tensile strength of 980 MPa.
[0004] In a first aspect, the application provides a method for controlling the alloying of ultrahigh-strength steel with a tensile strength of 980 MPa, which comprises the following steps:
[0005] segmented continuous annealing of the strip steel to obtain an annealed plate; wherein the segmented continuous annealing comprises a soaking section and a slow cooling section arranged in sequence, and the temperature of the soaking section and the outlet temperature of the slow cooling section are controlled;
[0006] hot galvanizing of the annealed plate using a zinc-aluminum plating solution containing a set aluminum content to obtain a galvanized plate;
[0007] blowing and scraping of the galvanized plate using an air knife, and controlling the spacing between the edge baffle of the air knife and the galvanized plate, and the height of the air knife;
[0008] alloying of the blown and scraped galvanized plate, and controlling the temperature of the alloying to obtain an alloyed galvanized plate.
[0009] Optionally, the temperature of the soaking section is 760-800 DEG C; and / or,
[0010] the outlet temperature of the slow cooling section is 660-700 DEG C.
[0011] Optionally, the cooling rate of the slow cooling section is ≤10 DEG C / s.
[0012] Optionally, the set aluminum content is 0.12-0.16 wt%.
[0013] Optionally, the spacing between the edge baffle of the air knife and the galvanized plate is ≤5 mm; and / or,
[0014] The height of the air knife is 200mm-350mm.
[0015] Optionally, the cooling medium of the air knife comprises nitrogen.
[0016] Optionally, the temperature of the alloying is 500-540℃.
[0017] Optionally, the running speed of the continuously annealed strip steel is ≤80m / min.
[0018] Optionally, the dew point temperature of the furnace nose of the hot dipping is <-40℃.
[0019] Optionally, the cross-section temperature difference of the strip steel in the furnace of the continuous annealing is ≤15℃.
[0020] The above technical solution provided by the embodiments of the present application has the following advantages compared with the prior art:
[0021] The method for controlling the alloying of the tensile strength 980MPa grade ultra-high strength steel provided by the embodiments of the present application comprises: continuously annealing a strip steel in a segmented manner to obtain an annealed plate; wherein the continuous annealing in a segmented manner comprises a soaking section and a slow cooling section arranged in sequence, and the temperature of the soaking section and the outlet temperature of the slow cooling section are controlled; using a zinc-aluminum plating solution containing a set aluminum content to hot dip the annealed plate to obtain a galvanized plate; using an air knife to blow and scrape the galvanized plate, and controlling the distance between the edge baffle of the air knife and the galvanized plate and the height of the air knife; alloying the blown and scraped galvanized plate, and controlling the temperature of the alloying to obtain an alloyed galvanized plate. The continuous annealing of the strip steel in a segmented manner, the temperature control of the soaking section, the outlet temperature control of the slow cooling section, the use of the zinc-aluminum plating solution containing a set aluminum content, the use of the air knife to blow and scrape the galvanized plate, and the control of the distance between the edge baffle of the air knife and the galvanized plate and the height of the air knife can precisely control the uniformity of the coating of the galvanized plate and the alloying uniformity of the galvanized plate, thereby improving the coating toughness of the galvanized plate and reducing the powdering length on the surface of the galvanized plate. 13 ) generation, thereby improving the coating toughness and reducing the powdering length on the surface of the galvanized plate. BRIEF DESCRIPTION OF DRAWINGS
[0022] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the present application and, together with the description, further serve to explain the principles of the application.
[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the accompanying drawings required to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.
[0024] Figure 1 A flowchart of a method for alloying control of a 980MPa-grade ultra-high-strength steel with tensile strength provided by the embodiments of the present application. DETAILED DESCRIPTION
[0025] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative effort fall within the scope of protection of the present application.
[0026] Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is merely for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the described range has specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the described range, such as 1, 2, 3, 4, 5 and 6, which applies to any range. In addition, whenever a numerical range is indicated in this document, it refers to any cited number (fraction or integer) within the indicated range.
[0027] In the present application, the orientation words such as "upper" and "lower" are the directions of the drawing surface in the drawings unless otherwise specified. In addition, in the description of the present application, the terms "include", "contain" and the like mean "including but not limited to". In the present text, the relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. In the present text, "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the following cases: A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural. In the present text, "at least one" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of the items, including any combination of single item or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple.
[0028] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.
[0029] In a first aspect, the embodiments of the present application provide a method for alloying control of a 980MPa-grade ultra-high strength steel, Figure 1 A flowchart of a method for alloying control of a 980MPa-grade ultra-high strength steel provided by the embodiments of the present application is shown in FIG. 1. Please refer to Figure 1 The method comprises the following steps:
[0030] S1, the strip steel is subjected to a segmented continuous annealing to obtain an annealed plate; wherein the segmented continuous annealing comprises a soaking section and a slow cooling section arranged in sequence, and the temperature of the soaking section and the outlet temperature of the slow cooling section are controlled;
[0031] By controlling the temperature of the soaking section, the diffusion of alloying elements in the strip steel is promoted to be uniform. The uniform distribution of alloying elements can avoid performance differences in different parts of the steel, thereby ensuring the stability of product quality. At the same time, the size of the grain can also be further optimized to improve the mechanical properties of the steel, such as refining the grain size to improve the strength and toughness of the steel. The purpose of controlling the outlet temperature of the slow cooling section is to improve the shape of the strip steel out of the zinc pot and improve the uniformity. A reasonable slow cooling temperature can make the internal stress distribution of the strip steel more uniform during the cooling process, reduce the occurrence of shape defects, and ensure the operability of the strip steel in subsequent processing. The continuous annealing process includes a preheating section, a heating section, a soaking section, a slow cooling section, a fast cooling section, and an equalizing section.
[0032] In some embodiments, the temperature of the soaking section is 760-800°C; and / or,
[0033] The outlet temperature of the slow cooling section is 660-700°C.
[0034] The temperature of the soaking section can be 760-800°C to ensure complete austenitization of the strip steel, uniform diffusion of alloying elements, and control of grain size to ensure strength. For example, the temperature of the soaking section can be 760°C, 770°C, 780°C, 790°C, 800°C, etc. The outlet temperature of the slow cooling section can be 660-700°C to improve the shape of the strip steel out of the zinc pot and improve the uniformity. For example, the outlet temperature of the slow cooling section can be 660°C, 670°C, 680°C, 690°C, 700°C, etc.
[0035] In some embodiments, the cooling rate of the slow cooling section is ≤10°C / s.
[0036] The cooling rate of the slow cooling section can be ≤10°C / s to avoid martensitic transformation, reduce residual stress, ensure the flatness of the strip steel, improve the shape of the strip steel out of the zinc pot, and improve the uniformity. For example, the cooling rate of the slow cooling section can be 10°C / s, 9°C / s, 8°C / s, 7°C / s, 6°C / s, 5°C / s, 4°C / s, etc.
[0037] S2, hot-dip plating the annealed plate using a zinc-aluminum plating solution containing a set aluminum content to obtain a galvanized plate;
[0038] The use of a zinc-aluminum plating solution containing a set aluminum content for hot-dip plating precisely controls the Fe-Zn reaction rate as an inhibitor. This control measure balances the relationship between the thickness of the coating and the adhesion. Excessive coating thickness can lead to increased costs and some performance problems, while insufficient adhesion can affect the service life and protective effect of the coating. Through the inhibitory effect of aluminum, the coating thickness can be brought to an appropriate level while ensuring the protective performance of the coating.
[0039] In some embodiments, the aluminum content is set to be 0.12wt% to 0.16wt%.
[0040] In the hot-dip process, aluminum exists as an inhibitor in the zinc-aluminum plating solution. The aluminum content can be set to 0.12wt% to 0.16wt%, which can accurately regulate the Fe-Zn reaction rate. Aluminum can form a thin protective film on the surface of the strip steel, inhibiting the excessively rapid reaction between iron and zinc. A suitable aluminum content helps to balance the relationship between coating thickness and adhesion. And when alloying, the appropriate amount of aluminum helps to promote the uniform growth of the δ phase (FeZn7), while inhibiting the generation of excessive brittle ζ phase (FeZn13). For example, the aluminum content can be set to 0.12wt%, 0.13wt%, 0.14wt%, 0.15wt%, 0.16wt%, etc.
[0041] S3, using an air knife to blow and scrape the galvanized sheet, and controlling the distance between the edge baffle of the air knife and the galvanized sheet, and the height of the air knife;
[0042] Controlling the distance between the edge baffle of the air knife and the galvanized sheet, and the height of the air knife, plays a key role in reducing the thickening of the strip steel edge coating and improving the uniformity of the coating thickness. Excessive thickening of the edge coating not only causes material waste, but also may affect the appearance and performance of the product. By precisely controlling the air knife parameters, the air flow can be more uniformly applied to the surface of the strip steel, thereby obtaining a uniform coating thickness.
[0043] In some embodiments, the distance between the edge baffle of the air knife and the galvanized sheet is ≤5mm; and / or,
[0044] The height of the air knife is 200mm to 350mm.
[0045] The distance between the edge baffle of the air knife and the galvanized sheet can be ≤5mm, which can reduce the thickening of the strip steel edge coating and improve the uniformity of the strip steel coating thickness. The height of the air knife can be 200mm to 350mm. The strip steel often has more than 50 meters from the zinc pot to the cooling tower, and the vibration caused by the air knife blowing can cause the distance between the strip steel and the air knife to change constantly, making it difficult to control the coating weight and thickness. By strictly controlling the height of the air knife, the vibration of the strip steel can be effectively reduced, thereby improving the uniformity of the zinc layer. For example, the distance between the edge baffle of the air knife and the galvanized sheet can be 5mm, 4mm, 3mm, etc. The height of the air knife can be 200mm, 250mm, 300mm, 350mm, etc.
[0046] In some embodiments, the cooling medium of the air knife includes nitrogen.
[0047] The air knife can be cooled using nitrogen to accelerate the solidification of the zinc layer.
[0048] S4, alloying the zinc-coated sheet after the blowing and scraping, and controlling the temperature of the alloying to obtain an alloyed zinc-coated sheet.
[0049] Controlling the alloying temperature can promote the uniform growth of the δ phase (FeZn7), and the uniform distribution of the δ phase is positively correlated with the corrosion resistance and mechanical properties of the coating. Shortening the residence time of the zinc-coated sheet after the blowing and scraping can inhibit the excessive generation of the brittle ζ phase (FeZn 13 ), which can reduce the toughness of the coating and cause problems such as surface powdering of the zinc-coated sheet. By controlling the alloying process, the toughness of the coating is improved, the surface powdering length is reduced, and the quality and service life of the product are improved. The powdering degree at the edge, middle and edge positions of the strip steel is detected by the tape stripping method to ensure that the surface powdering width of the zinc-coated sheet is ≤7 mm.
[0050] In some embodiments, the temperature of the alloying is 500-540°C.
[0051] The temperature of the alloying can be 500-540°C, which can provide suitable conditions for the growth of the δ phase (FeZn7) and make the δ phase uniformly distributed on the surface of the zinc-coated sheet. The uniformly grown δ phase can improve the corrosion resistance of the coating and enhance the protective effect of the coating on the steel substrate. At the same time, the uniformity of the δ phase can also help to improve the appearance quality of the coating and reduce surface defects caused by uneven phase distribution. When the alloying temperature is 500-540°C, the excessive generation of the ζ phase (FeZn 13 ) can be effectively inhibited. The ζ phase is a brittle phase, and its excessive generation can reduce the toughness of the coating and easily cause problems such as cracking and peeling of the zinc-coated sheet during subsequent processing or use. By controlling the temperature to inhibit the generation of the ζ phase, the toughness of the coating can be improved, the surface powdering length of the zinc-coated sheet can be reduced, and the reliability and service life of the product can be improved. Alloying at this temperature range can shorten the residence time (20-40 s) of the zinc-coated sheet after the blowing and scraping while ensuring the alloying effect. Exemplarily, the temperature of the alloying can be 500°C, 510°C, 520°C, 530°C, 540°C, etc.
[0052] In some embodiments, the running speed of the continuously annealed strip steel is ≤80 m / min.
[0053] The running speed of the continuously annealed strip steel is ≤80 m / min, which can ensure the speed, improve the alloying and cooling time of the strip steel, reduce the cooling rate, and improve the plate shape on the basis of ensuring the output of the unit. Exemplarily, the running speed of the continuously annealed strip steel can be 80 m / min, 79 m / min, 78 m / min, 77 m / min, 76 m / min, 75 m / min, 74 m / min, etc.
[0054] In some embodiments, the dew point temperature of the hot-dip galvanizing furnace snout is <-40℃.
[0055] The dew point temperature of the hot-dip galvanizing furnace snout can be <-40℃, which inhibits the reaction of water vapor and zinc liquid at the furnace snout to generate zinc oxide, avoiding surface defects of the plated layer. For example, the dew point temperature of the hot-dip galvanizing furnace snout can be -41℃, -42℃, -43℃, -44℃, etc.
[0056] In some embodiments, the cross-sectional temperature difference of the strip steel in the continuous annealing furnace is ≤15℃.
[0057] The cross-sectional temperature difference of the strip steel in the continuous annealing furnace can be ≤15℃, and a too large temperature difference is prone to occur in the furnace, which can improve the stability of the production process control and improve the transverse uniformity. For example, the cross-sectional temperature difference of the strip steel in the continuous annealing furnace can be 15℃, 14℃, 13℃, 12℃, 10℃, 9℃, etc. The hydrogen volume concentration in the continuous annealing furnace can be 5% to 8%.
[0058] The embodiments of the present application provide a method for alloying control of a tensile strength of 980MPa grade (super-high-strength steel JAC980YL) super-high-strength steel, which has the following advantages:
[0059] 1. Microstructure optimization: By controlling the soaking section temperature in the continuous annealing process, the diffusion of alloying elements of the strip steel can be uniform, and the grain size can be regulated, thereby laying a microstructure foundation for obtaining good material performance.
[0060] 2. Improvement of shape and uniformity: Controlling the outlet temperature of the slow cooling section helps to improve the shape of the strip steel when it comes out of the zinc pot, improve the uniformity of the performance of the strip steel, reduce the shape defects caused by uneven temperature changes, and improve the product quality.
[0061] 3. Improvement of plated layer performance: By setting a specific aluminum content in the zinc-aluminum plating solution, the Fe-Zn reaction rate can be accurately regulated, and the plated layer thickness and adhesion can be balanced, so that the plated layer has good protective performance and is firmly attached to the surface of the strip steel and is not easy to fall off.
[0062] 4. Improvement of plated layer thickness uniformity: By using an air knife to scrape the galvanized sheet and controlling the distance between the edge baffle of the air knife and the galvanized sheet and the height of the air knife, the plated layer thickening phenomenon at the edge of the strip steel can be reduced, the uniformity of the plated layer thickness of the strip steel can be improved, and the protective performance of the galvanized sheet at different positions is more consistent.
[0063] 5. Good alloying effect: By controlling the alloying temperature, the uniform growth of δ phase (FeZn7) is promoted, the residence time of the galvanized sheet is shortened, the generation of excessive brittle ζ phase (FeZn 13 ) is inhibited, the toughness of the plated layer is improved, the powder length on the surface of the galvanized sheet is reduced, and the comprehensive performance of the plated layer is improved.
[0064] 6. Overall performance optimization: The method realizes precise control of the uniformity of the coating of the galvanized sheet and the uniformity of the alloying of the galvanized sheet through precise control of each process link.
[0065] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not used to limit the scope of the present application. The experimental methods in the following examples without specific conditions are generally determined according to the national standards. If there is no corresponding national standard, the general international standards, conventional conditions or the conditions suggested by the manufacturers are used.
[0066] Example 1
[0067] A method for controlling the alloying of a 980MPa-grade ultra-high-strength steel with tensile strength, comprising:
[0068] The strip steel is subjected to segmented continuous annealing to obtain an annealed sheet; wherein the segmented continuous annealing comprises a soaking section and a slow cooling section arranged in sequence, and the temperature of the soaking section and the outlet temperature of the slow cooling section are controlled; the strip steel is JAC980YL with a thickness of 1.5mm and a width of 1250mm, the temperature of the soaking section is 760℃, the outlet temperature of the slow cooling section is 680℃, the running speed of the strip steel is 70m / min, the volume concentration of hydrogen in the furnace is 5%, the temperature difference of the cross section of the strip steel in the furnace is 10℃, and the cooling rate of the slow cooling section is 8℃ / s;
[0069] The annealed sheet is subjected to hot galvanizing using a zinc-aluminum plating solution containing a set aluminum content to obtain a galvanized sheet; the dew point temperature of the furnace nose of the hot galvanizing is -45℃, and the set aluminum content is 0.14wt%;
[0070] The galvanized sheet is subjected to blow scraping using an air knife, and the distance between the edge baffle of the air knife and the galvanized sheet and the height of the air knife are controlled; the air knife uses nitrogen cooling, the distance between the edge baffle of the air knife and the galvanized sheet is 5mm, and the height of the air knife is 280mm;
[0071] The blow-scraped galvanized sheet is subjected to alloying, and the temperature of the alloying is controlled to obtain an alloyed galvanized sheet; the temperature of the alloying furnace is 530℃, and the residence time is 35s.
[0072] Example 2
[0073] A method for controlling the alloying of a 980MPa-grade ultra-high-strength steel with tensile strength, comprising:
[0074] The strip steel is subjected to sectional continuous annealing to obtain an annealed plate; wherein the sectional continuous annealing comprises a soaking section and a slow cooling section arranged in sequence, and the temperature of the soaking section and the outlet temperature of the slow cooling section are controlled; the strip steel is JAC980YL with a thickness of 2.0 mm and a width of 1100 mm, the temperature of the soaking section is 780 ℃, the outlet temperature of the slow cooling section is 680 ℃, the running speed of the strip steel is 65 m / min, the volume concentration of hydrogen in the furnace is 7%, the temperature difference of the cross section of the strip steel in the furnace is 15 ℃, and the cooling rate of the slow cooling section is 10 ℃ / s;
[0075] The annealed plate is subjected to hot galvanizing using a zinc-aluminum plating solution containing a set aluminum content to obtain a galvanized plate; the dew point temperature of the furnace nose of the hot galvanizing is -60 ℃, and the set aluminum content is 0.14 wt%;
[0076] The galvanized plate is subjected to blow scraping using an air knife, and the distance between the edge baffle of the air knife and the galvanized plate and the height of the air knife are controlled; the air knife is cooled using nitrogen, the distance between the edge baffle of the air knife and the galvanized plate is 5 mm, and the height of the air knife is 260 mm;
[0077] The galvanized plate after blow scraping is subjected to alloying, and the temperature of the alloying is controlled to obtain an alloyed galvanized plate; the temperature of the alloying furnace is 525 ℃, and the residence time is 37 s.
[0078] Example 3
[0079] A method for controlling the alloying of a tensile strength 980 MPa grade ultra-high strength steel, comprising:
[0080] The strip steel is subjected to sectional continuous annealing to obtain an annealed plate; wherein the sectional continuous annealing comprises a soaking section and a slow cooling section arranged in sequence, and the temperature of the soaking section and the outlet temperature of the slow cooling section are controlled; the strip steel is JAC980YL with a thickness of 1.32 mm and a width of 910 mm, the temperature of the soaking section is 780 ℃, the outlet temperature of the slow cooling section is 700 ℃, the running speed of the strip steel is 80 m / min, the volume concentration of hydrogen in the furnace is 7%, the temperature difference of the cross section of the strip steel in the furnace is 15 ℃, and the cooling rate of the slow cooling section is 10 ℃ / s;
[0081] The annealed plate is subjected to hot galvanizing using a zinc-aluminum plating solution containing a set aluminum content to obtain a galvanized plate; the dew point temperature of the furnace nose of the hot galvanizing is -60 ℃, and the set aluminum content is 0.14 wt%;
[0082] The galvanized plate is subjected to blow scraping using an air knife, and the distance between the edge baffle of the air knife and the galvanized plate and the height of the air knife are controlled; the air knife is cooled using nitrogen, the distance between the edge baffle of the air knife and the galvanized plate is 5 mm, and the height of the air knife is 260 mm;
[0083] The galvanized plate after blow scraping is subjected to alloying, and the temperature of the alloying is controlled to obtain an alloyed galvanized plate; the temperature of the alloying furnace is 525 ℃, and the residence time is 37 s.
[0084] Comparative Example 1
[0085] A method for alloying control of a tensile strength 980 MPa grade ultra-high strength steel, comprising:
[0086] carrying out sectional continuous annealing on the strip steel to obtain an annealed plate; wherein the sectional continuous annealing comprises a soaking section and a slow cooling section arranged in sequence, and the temperature of the soaking section and the outlet temperature of the slow cooling section are controlled; the strip steel is JAC980YL with a thickness of 1.5 mm and a width of 1250 mm, the temperature of the soaking section is 800 ℃, the outlet temperature of the slow cooling section is 720 ℃, the running speed of the strip steel is 75 m / min, the volume concentration of hydrogen in the furnace is 5%, the temperature difference of the cross section of the strip steel in the furnace is 30 ℃, and the cooling rate of the slow cooling section is 10 ℃ / s;
[0087] carrying out hot galvanizing on the annealed plate using a zinc-aluminum plating solution containing a set aluminum content to obtain a galvanized plate; the dew point temperature of the furnace nose of the hot galvanizing is -45 ℃, and the set aluminum content is 0.14 wt%;
[0088] blowing and scraping the galvanized plate using an air knife, and controlling the distance between the edge baffle of the air knife and the galvanized plate and the height of the air knife; the air knife uses nitrogen cooling, the distance between the edge baffle of the air knife and the galvanized plate is 5 mm, and the height of the air knife is 320 mm;
[0089] carrying out alloying on the blown and scraped galvanized plate, and controlling the temperature of the alloying to obtain an alloyed galvanized plate; the temperature of the alloying furnace is 540 ℃, and the residence time is 32 s.
[0090] Comparative Example 2
[0091] A method for alloying control of a tensile strength 980 MPa grade ultra-high strength steel, comprising:
[0092] carrying out sectional continuous annealing on the strip steel to obtain an annealed plate; wherein the sectional continuous annealing comprises a soaking section and a slow cooling section arranged in sequence, and the temperature of the soaking section and the outlet temperature of the slow cooling section are controlled; the strip steel is JAC980YL with a thickness of 2.0 mm and a width of 1100 mm, the temperature of the soaking section is 760 ℃, the outlet temperature of the slow cooling section is 660 ℃, the running speed of the strip steel is 65 m / min, the volume concentration of hydrogen in the furnace is 7%, the temperature difference of the cross section of the strip steel in the furnace is 25 ℃, and the cooling rate of the slow cooling section is 8 ℃ / s;
[0093] carrying out hot galvanizing on the annealed plate using a zinc-aluminum plating solution containing a set aluminum content to obtain a galvanized plate; the dew point temperature of the furnace nose of the hot galvanizing is -60 ℃, and the set aluminum content is 0.14 wt%;
[0094] The galvanized plate is blown and scraped using an air knife, and the distance between the edge baffle of the air knife and the galvanized plate and the height of the air knife are controlled; the air knife is cooled using nitrogen, the distance between the edge baffle of the air knife and the galvanized plate is 4mm, and the height of the air knife is 400mm;
[0095] The galvanized plate after being blown and scraped is alloyed, and the temperature of alloying is controlled to obtain the alloyed galvanized plate; the temperature of the alloying furnace is 560℃, and the residence time is 37s.
[0096] The degree of pulverization of the alloyed galvanized plate of Examples 1-3 and Comparative Examples 1-2 is tested, and the test results are shown in Table 1.
[0097] Table 1 test results
[0098] Serial number Degree of pulverization (edge, middle, edge) Example 1 6 mm, 6 mm, 6 mm Example 2 7 mm, 7 mm, 7 mm Example 3 5 mm, 5 mm, 5 mm Comparative Example 1 9 mm, 8 mm, 7 mm Comparative Example 2 10 mm, 7 mm, 11 mm
[0099] As shown in Table 1, the degree of pulverization of the alloyed galvanized plate prepared by Examples 1-3 is ≤7mm and uniform, which improves the alloying uniformity of the 980MPa-grade ultra-high strength steel with improved tensile strength. Comparative Examples 1-2 do not fully meet the technical solutions of the present application, and the degree of pulverization is high and uneven.
[0100] The one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:
[0101] (1) By optimizing the key process parameters such as soaking temperature, slow cooling temperature, furnace dew point, zinc liquid aluminum content, air knife cooling medium and alloying temperature, combined with the precise control of the degree of pulverization, the stable regulation and control of the JAC980YL alloying degree is realized;
[0102] (2) The problems of uneven alloying, excessive pulverization and stamping dezincification caused by process parameter fluctuations in the prior art are solved, the mechanical properties and surface quality of the product are significantly improved, and the strict requirements of high-end automobile steel are met.
[0103] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.
Claims
1. A method for controlling alloying of ultra-high-strength steel with a tensile strength of 980 MPa, the method comprising: The steel strip is subjected to segmented continuous annealing to obtain an annealed plate; wherein the segmented continuous annealing includes sequentially arranged soaking sections and slow cooling sections, and the temperature of the soaking sections and the outlet temperature of the slow cooling sections are controlled; Hot-dip the annealed sheet using a zinc-aluminum plating solution containing a set aluminum content to obtain a galvanized sheet; Using an air knife to blow and scrape the galvanized sheet, and controlling the distance between the edge baffle of the air knife and the galvanized sheet, as well as the height of the air knife; The galvanized sheet after scraping is alloyed, and the alloying temperature is controlled to obtain an alloyed galvanized sheet.
2. The method according to claim 1, characterized in that The temperature of the soaking section is 760° C. to 800° C.; and / or, The outlet temperature of the slow cooling section is 660°C to 700°C.
3. The method according to claim 2, characterized in that The cooling rate of the slow cooling section is ≤10°C / s.
4. The method according to claim 1, wherein The aluminum content is set to be 0.12 wt% to 0.16 wt%.
5. The method according to claim 1, wherein The distance between the edge baffle of the air knife and the galvanized sheet is ≤5mm; and / or, The height of the air knife is 200 mm to 350 mm.
6. The method according to claim 1 or 5, characterized in that The cooling medium of the air knife includes nitrogen.
7. The method according to claim 1, characterized in that The alloying temperature is 500°C to 540°C.
8. The method according to claim 1, characterized in that The running speed of the continuously annealed steel strip is ≤80 m / min.
9. The method according to claim 1, characterized in that The dew point temperature of the hot-dip furnace nose is <-40°C.
10. The method according to claim 1, characterized in that The temperature difference of the strip cross section in the continuous annealing furnace is ≤15°C.