Method for producing high-forming hot-dip galvanized IF steel with low energy consumption

Abstract

The invention relates to a method for producing high-forming hot-dip galvanized IF steel with low energy consumption, and belongs to the technical field of steel manufacturing. The method comprises the steps that a plate blank with set chemical components is obtained, and the set chemical components comprise low-content Ti; the plate blank is sequentially subjected to first heating, rolling and coiling, and a hot-rolled coil with coarse TiC particles is obtained; the hot-rolled coil is sequentially subjected to acid pickling and cold rolling, and the following parameters of cold rolling are controlled: the total reduction rate, the first-pass reduction rate and the second-pass reduction rate, so that the nucleation driving force of cold-rolled grain recrystallization of cold rolling is improved, and a cold hard coil is obtained; the cold hard roll is annealed, so that the cold-rolled grains grow up; the annealing comprises secondary heating, soaking and cooling; the annealed cold hard coil is galvanized, and a hot-dip coil is obtained; and the hot-dip roll is subjected to finishing, the finishing elongation is controlled, and the high-forming hot-dip galvanized IF steel is obtained.

Description

Technical Field

[0001] The present application relates to the technical field of steel manufacturing, and in particular to a method for producing high-formability hot-dip galvanized IF steel with low energy consumption. Background Art

[0002] IF steel (interstitial-free steel) has shown unparalleled application advantages in the automotive manufacturing industry, especially in automotive panels and inner panel parts with high forming requirements, such as side panels, door inner panels and other key structural parts, due to its excellent elongation after fracture and plastic strain ratio. This steel can maintain excellent ductility and formability when subjected to complex deformation, thus ensuring high-precision manufacturing and long-term reliability of automotive parts. With the rapid development of the modern automotive industry, consumers have increasing requirements for corrosion resistance and lightweighting of automotive products. Corrosion resistance is essential to extend the service life of the car and maintain the beauty of the car body, while lightweighting is a key way to improve fuel efficiency and reduce carbon emissions. In this context, thin-gauge hot-dip galvanized IF steel has become an ideal choice to meet market demand because of its high strength, high corrosion resistance and good forming performance. Faced with the growing market demand for thin-gauge hot-dip galvanized IF steel, steel mills are facing unprecedented challenges and opportunities. How to achieve stable production at a lower cost while ensuring product quality has become the core issue for improving the profitability of steel mills. This requires steel mills to not only strictly control the chemical composition of raw materials during the production process to ensure the basic performance of IF steel, but also to optimize processes and innovate technologies in key links such as hot rolling, cold rolling, annealing and hot-dip galvanizing.

[0003] The cold-rolled IF steel sheet with fine and uniform grains produced in the prior art CN115627331A lacks a coating on its surface, resulting in insufficient corrosion resistance and failure to meet the growing market demand. The prior art CN109234614B prepares hot-dip galvanized IF steel. In the hot-dip galvanizing horizontal furnace annealing process step, the annealing temperature is 860-895°C, which is relatively high, resulting in high energy consumption and carbon emissions. Summary of the invention

[0004] The present application provides a method for producing high-formability hot-dip galvanized IF steel with low energy consumption, so as to solve the following technical problem: how to produce high-formability hot-dip galvanized IF steel with low energy consumption.

[0005] The present application embodiment provides a method for producing high-formability hot-dip galvanized IF steel with low energy consumption, the method comprising:

[0006] Obtaining a slab having a set chemical composition, wherein the set chemical composition includes a low content of Ti;

[0007] The slab is subjected to first heating, rolling and coiling in sequence to obtain a hot-rolled coil having coarse TiC particles;

[0008] The hot-rolled coil is pickled and cold-rolled in sequence, and the following parameters of the cold rolling are controlled: total reduction rate, first-pass reduction rate, and second-pass reduction rate, so as to increase the nucleation driving force of cold-rolled grain recrystallization in the cold rolling to obtain a chilled coil;

[0009] Annealing the chilled coil to grow the cold-rolled grains; the annealing includes: second heating, soaking and cooling;

[0010] Galvanizing the annealed chilled coil to obtain a hot dipped coil;

[0011] The hot dip coil is skin-passed and the skin-pass elongation is controlled to obtain high-formability hot dip galvanized IF steel.

[0012] Optionally, the temperature of the second heating is 760°C to 790°C, and the heating rate of the second heating is 5°C / s to 7°C / s.

[0013] Optionally, the temperature of the equalization is 765° C. to 795° C., and the time of the equalization is 100 s to 150 s.

[0014] Optionally, the total reduction rate is 81% to 85%, the first reduction rate is 30% to 35%, and the second reduction rate is 25% to 30%.

[0015] Optionally, the finishing elongation is 1.1% to 1.5%.

[0016] Optionally, the galvanizing temperature is 440°C to 480°C.

[0017] Optionally, the temperature of the first heating is 1200° C. to 1250° C., and the insulation time of the first heating is 110 min to 170 min.

[0018] Optionally, the final rolling temperature is 900°C to 950°C.

[0019] Optionally, the coiling temperature is 710°C to 750°C.

[0020] Optionally, the acid concentration of the pickling acid solution is 41 g / L to 55 g / L, the temperature of the pickling acid solution is 78° C. to 84° C., and the pickling speed is 120 m / min to 200 m / min.

[0021] Optionally, the set chemical composition includes, by mass fraction: C≤0.002%, Mn: 0.1%~0.25%, Si≤0.05%, Al: 0.02%~0.06%, P≤0.02%, S≤0.015%, Ti: 0.02%~0.04%, and matrix element Fe.

[0022] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0023] The embodiment of the present application provides a method for producing high-formability hot-dip galvanized IF steel with low energy consumption, the method comprising: obtaining a slab with a set chemical composition, the set chemical composition comprising a low content of Ti; sequentially performing first heating, rolling and coiling on the slab to obtain a hot-rolled coil with coarse TiC particles; sequentially performing pickling and cold rolling on the hot-rolled coil, and controlling the following parameters of the cold rolling: total reduction rate, first pass reduction rate and second pass reduction rate to increase the nucleation driving force of cold-rolled grain recrystallization of the cold-rolled coil to obtain a cold-hardened coil; annealing the cold-hardened coil to make the cold-rolled grain grow; the annealing comprises: second heating, soaking and cooling; galvanizing the annealed cold-hardened coil to obtain a hot-dip coil; performing skin pass on the hot-dip coil, and controlling the skin pass elongation to obtain a high-formability hot-dip galvanized IF steel. By adopting a low Ti content, the excellent performance of IF steel is maintained on the basis of reducing production costs. Coarse TiC particles are obtained by high-temperature coiling. These particles can serve as nucleation points for grains during annealing to promote the recrystallization process. The recrystallization nucleation driving force is increased by large cold rolling reduction and rapid heating during annealing, and the plastic strain ratio (forming ability) is increased by combining long-term heat preservation to allow grain growth. The embodiment of the present application can achieve the production of high-forming ability IF steel through a lower annealing temperature, achieving energy saving and carbon reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 A schematic flow chart of a method for producing high-formability hot-dip galvanized IF steel with low energy consumption provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0028] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical 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 range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range; in addition, whenever a numerical range is indicated in this document, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0029] In this document, the terms including "including" and "including" mean "including but not limited to". 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 these entities or operations. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "plurality" means two or more; "at least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items; for example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts" such as parts by weight and parts by mass indicate the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the weight ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond to the proportional numbers in the proportional formula in the order of description, that is, the weight of substance A: the weight of substance B: the weight of substance C = 1:2:3.

[0030] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0031] Figure 1 A schematic flow chart of a method for producing high-formability hot-dip galvanized IF steel with low energy consumption provided in an embodiment of the present application.

[0032] like Figure 1 As shown, the embodiment of the present application provides a method for producing high-formability hot-dip galvanized IF steel with low energy consumption, comprising:

[0033] S1. Obtaining a slab with a set chemical composition, wherein the set chemical composition includes a low content of Ti;

[0034] In some embodiments, the set chemical composition includes, by mass fraction: C≤0.002%, Mn: 0.1%-0.25%, Si≤0.05%, Al: 0.02%-0.06%, P≤0.02%, S≤0.015%, Ti: 0.02%-0.04%, and matrix element Fe.

[0035] The positive effect of limiting the mass fraction of C to ≤ 0.002% is that C is a solid solution strengthening element of steel. The strength of steel increases with the increase of the mass fraction of C. High strength is not conducive to the forming of IF steel. Therefore, the mass fraction of C is limited to ≤ 0.002%. For example, the mass fraction of C can be 0.001%, 0.0012%, 0.0014%, 0.0016%, 0.0018%, 0.0020%, etc.

[0036] The positive effect of limiting the mass fraction of Mn to 0.1% to 0.25% is that Mn is also a strengthening element of steel. Limiting the mass fraction of Mn to 0.1% to 0.25% can ensure the tensile strength and forming ability of steel. For example, the mass fraction of Mn can be 0.1%, 0.13%, 0.15%, 0.17%, 0.19%, 0.21%, 0.23%, 0.25%, etc.

[0037] Positive effect of limiting the mass fraction of Si to ≤ 0.05%: When the mass fraction of Si is higher than 0.05%, red rust that is difficult to clean will appear on the surface of the hot-rolled steel strip, thereby affecting the surface quality of the galvanized steel. For example, the mass fraction of Si can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, etc.

[0038] Positive effects of limiting the mass fraction of Al to 0.02% to 0.06%: Al is used for deoxidation during the molten steel refining process, and a small amount of Al is present in the embodiments of the present application. The mass fraction of Al above 0.06% increases the viscosity of the molten steel and makes continuous casting production difficult. For example, the mass fraction of Al can be 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, etc.

[0039] The positive effect of limiting the mass fraction of P to ≤ 0.02% is that in order to control costs, the refining process does not need to make too strict requirements on P, but the upper limit still needs to be controlled. If the mass fraction of P is higher than 0.02%, the strength of the strip will increase and the formability will be affected. For example, the mass fraction of P can be 0.005%, 0.01%, 0.012%, 0.014%, 0.016%, 0.018%, 0.02%, etc.

[0040] The positive effect of limiting the mass fraction of S to ≤ 0.015% is that in order to control costs, the refining process does not need to have too strict requirements on S, but the upper limit still needs to be controlled. S with a mass fraction higher than 0.015% will form inclusions with Ti, reducing the plasticity and strength of the strip. For example, the mass fraction of S can be 0.005%, 0.008%, 0.011%, 0.013%, 0.015%, etc.

[0041] The positive effect of limiting the mass fraction of Ti to 0.02-0.04% is as follows: Ti plays an important role in IF steel. It can form TiC and TiN with interstitial atoms C, N, etc. in the steel, play the role of fixing interstitial atoms, form a pure ferrite matrix, and improve the formability of steel. The mass fraction of Ti is higher than 0.04%, which is costly and wasteful. For example, the mass fraction of Ti can be 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, etc.

[0042] Fe is a matrix element. The specific content / content range of Fe can be obtained by the upper and lower limit formula of the component, that is:

[0043] The sum of the percentages of the contents of each component in a composition should be equal to 100%, and the content ranges of several components should meet the following conditions: the upper limit value of a component + the lower limit value of other components ≤ 100; the lower limit value of a component + the upper limit value of other components ≥ 100.

[0044] Preferably, the mass fraction of C is ≤0.0018%, the mass fraction of Mn is 0.1%-0.2%, the mass fraction of Si is ≤0.03%, the mass fraction of Al is 0.02%-0.05%, the mass fraction of P is ≤0.015%, the mass fraction of S is ≤0.01%, and the mass fraction of Ti is 0.03%.

[0045] S2, sequentially performing first heating, rolling and coiling on the slab to obtain a hot-rolled coil having coarse TiC particles;

[0046] In some embodiments, the temperature of the first heating is 1200° C. to 1250° C., and the insulation time of the first heating is 110 min to 170 min.

[0047] The alloying element Ti in the steel needs to be fully dissolved into the steel matrix at a certain temperature. Setting the temperature of the first heating to 1200℃~1250℃ can ensure that alloying elements such as Ti are effectively dissolved into the steel matrix, thereby playing a positive role in the performance of the steel. Exemplarily, the temperature of the first heating can be 1200℃, 1210℃, 1220℃, 1230℃, 1240℃, 1250℃, etc. The length of the holding time directly affects the degree of solid solution of the alloying elements in the steel. If the holding time is too short, the alloying elements may not be fully dissolved; if the holding time is too long, it may cause excessive grain growth of the steel. Therefore, setting the holding time to 110min~170min can ensure that the alloying elements are uniformly dissolved in the steel while avoiding excessive grain growth. Exemplarily, the holding time of the first heating can be 110min, 120min, 130min, 140min, 150min, 160min, 170min, etc.

[0048] In some embodiments, the final rolling temperature of the rolling is 900°C to 950°C.

[0049] The positive effect of limiting the final rolling temperature of rolling to 900°C to 950°C is to avoid rolling in the two-phase region, which has an adverse effect on the performance. For example, the final rolling temperature can be 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, etc.

[0050] In some embodiments, the coiling temperature is 710°C to 750°C.

[0051] The positive effect of limiting the coiling temperature to 710°C to 750°C is to increase the grain size of the original structure and improve the plastic strain ratio of the final product. For example, the coiling temperature can be 710°C, 720°C, 730°C, 740°C, 750°C, etc.

[0052] S3, sequentially pickling and cold rolling the hot-rolled coil, and controlling the following parameters of the cold rolling: total reduction rate, first-pass reduction rate, and second-pass reduction rate, so as to increase the nucleation driving force of cold-rolled grain recrystallization during the cold rolling to obtain a chilled coil;

[0053] In some embodiments, the acid solution concentration of the pickling is 41 g / L to 55 g / L, the acid solution temperature of the pickling is 78° C. to 84° C., and the pickling speed is 120 m / min to 200 m / min.

[0054] The acid concentration of 41g / L to 55g / L can ensure that the iron oxide and rust on the surface of the steel are effectively removed, providing a clean surface for the subsequent galvanizing operation. If the concentration is lower than 41g / L, the pickling effect is poor and it is difficult to completely remove the rust; if the concentration is higher than 41g / L, it may cause excessive corrosion on the surface of the steel, affecting the adhesion and quality of the galvanized layer. Exemplarily, the acid concentration can be 41g / L, 43g / L, 45g / L, 47g / L, 49g / L, 51g / L, 53g / L, 55g / L, etc. The chemical reaction rate during the pickling process is closely related to the temperature. In the acid temperature range of 78°C to 84°C, the chemical reaction rate is moderate, which can ensure that the iron oxide and rust on the surface of the steel are effectively removed. If the temperature is lower than 78°C, the chemical reaction rate is slow and the pickling effect is poor; if the temperature is higher than 84°C, the chemical reaction may be too intense, causing excessive corrosion to the surface of the steel. Exemplarily, the acid solution temperature can be 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, etc. The pickling speed of 120m / min to 200m / min can ensure that the steel surface stays in the acid solution for a sufficient time to effectively remove iron oxide and rust. A speed lower than 120m / min may result in a long pickling time and increase production costs; a speed higher than 200m / min may cause the steel surface to fail to fully contact the acid solution, affecting the pickling effect. Exemplarily, the pickling speed can be 120m / min, 140m / min, 160m / min, 180m / min, 200m / min, etc. The acid used in the embodiment of the present application is hydrochloric acid.

[0055] In some embodiments, the total reduction ratio is 81% to 85%, the first reduction ratio is 30% to 35%, and the second reduction ratio is 25% to 30%.

[0056] In some embodiments, the cold rolling is performed in five passes.

[0057] The total reduction rate refers to the total thickness reduction ratio of steel during the cold rolling process. The first-pass reduction rate is the first reduction rate in the cold rolling process, which directly affects the reduction effect of subsequent passes and the organizational structure of the steel. The second-pass reduction rate is the second reduction rate in the cold rolling process, which further improves the organizational structure of the steel and improves the uniformity of material performance.

[0058] The positive effects of limiting the total cold rolling reduction rate to 81% to 85%, the first pass reduction rate to 30% to 35%, and the second pass reduction rate to 25% to 30% are: increasing the nucleation driving force of cold rolled grain recrystallization, improving the texture in the organization, and improving the uniformity of material performance, so that a higher plastic strain ratio can be obtained without a higher annealing temperature and Ti element content. When the total reduction rate, the first pass reduction rate, and the second pass reduction rate are insufficient, a higher annealing temperature is required to obtain a close plastic strain ratio. Exemplarily, the total reduction rate can be 81%, 82%, 83%, 84%, 85%, etc.

[0059] S4, annealing the chilled coil to grow the cold-rolled grains; the annealing includes: second heating, soaking and cooling;

[0060] Annealing is a metal heat treatment process that involves slowly heating the metal to a certain temperature, keeping it for a sufficient time, and then cooling it at an appropriate rate. The main purpose of this treatment method is to reduce hardness and improve machinability; eliminate residual stress, stabilize size, reduce deformation and crack tendency; refine grains, adjust structure, and eliminate structural defects.

[0061] In some embodiments, the temperature of the second heating is 760° C. to 790° C., and the heating rate of the second heating is 5° C. / s to 7° C. / s.

[0062] The second heating temperature of 760℃~790℃ can promote the recovery recrystallization of the cold-rolled structure, release the deformation energy storage inside the steel, and grow the grains again into equiaxed grains. The formation of equiaxed grains helps to improve the formability and toughness of the steel. Exemplarily, the temperature of the second heating can be 760℃, 765℃, 770℃, 775℃, 780℃, 785℃, 790℃, etc. When the heating rate of the second heating is less than 5℃ / s, the driving force for the nucleation of grain recrystallization is insufficient, and the trend of grain growth is not obvious, resulting in insufficient formability of the steel. In addition, when producing thin and wide specifications, the temperature and heating rate of the second heating are higher than the above range, which is easy to cause buckling defects in the steel during annealing, affecting product quality. Exemplarily, the heating rate of the second heating can be 5℃ / s, 5.5℃ / s, 6℃ / s, 6.5℃ / s, 7℃ / s, etc.

[0063] In some embodiments, the soaking temperature is 765° C. to 795° C., and the soaking time is 100 s to 150 s.

[0064] During the soaking stage, as the soaking temperature and time increase, the equiaxed grains will grow further, further reducing the strength of the steel and further improving the formability. For example, the soaking temperature can be 765°C, 770°C, 775°C, 780°C, 785°C, 790°C, 795°C, etc. The soaking time of 100s to 150s can ensure that the internal structure of the steel is fully recrystallized and the grains grow to a suitable size. A soaking time longer than 150s may cause excessive grain growth and affect the performance of the steel; while a soaking time shorter than 100s may cause insufficient recrystallization of the structure, which also affects the performance. For example, the soaking time can be 100s, 110s, 120s, 130s, 140s, 150s, etc.

[0065] S5, galvanizing the annealed chilled coil to obtain a hot dipped coil;

[0066] In some embodiments, the galvanizing temperature is 440°C to 480°C.

[0067] Galvanizing within this temperature range can ensure the quality of hot-dip galvanizing. Too low or too high a galvanizing temperature will result in a large amount of zinc slag, affecting the uniformity and adhesion of the galvanized layer. A galvanizing temperature lower than 440°C may result in poor bonding between the zinc layer and the steel substrate, resulting in leakage; while a galvanizing temperature higher than 480°C may result in an overly thick zinc layer, a rough surface, or slag point defects. Exemplarily, the galvanizing temperature can be 440°C, 450°C, 460°C, 470°C, 480°C, etc.

[0068] S6. Perform skin pass on the hot dip coil and control the skin pass elongation to obtain high-formability hot dip galvanized IF steel.

[0069] In some embodiments, the smoothing elongation is 1.1% to 1.5%.

[0070] The positive effect of limiting the skin-finishing elongation to 1.1% to 1.5% is that the strip surface obtains appropriate roughness and yield strength. When the skin-finishing elongation is higher than 1.5%, the yield strength increases and the elongation after fracture decreases. When the skin-finishing elongation is lower than 1.1%, the roughness of the strip surface is insufficient, which affects the use of subsequent coating. For example, the skin-finishing elongation can be 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, etc.

[0071] In summary, the embodiments of the present application innovatively provide a method for producing high-formability hot-dip galvanized IF steel with low energy consumption, and the key technical innovations are as follows:

[0072] Low Ti content chemical composition design: The chemical composition design with low Ti content effectively reduces the production cost while maintaining the excellent performance of IF steel.

[0073] High temperature coiling and the formation of coarse TiC particles: Coarse TiC particles are obtained through the high temperature coiling process. These particles can serve as nucleation points for grains in the subsequent annealing process, effectively promoting the recrystallization process, thereby improving the mechanical properties of the steel.

[0074] Optimization of cold rolling and annealing process: Accurately control the total cold rolling reduction rate, the first pass reduction rate and the second pass reduction rate to improve the nucleation driving force of cold rolling grain recrystallization. The annealing process includes the second heating, soaking and cooling. Through rapid heating, long soaking and insulation and appropriate cooling rate, the growth of grains is promoted, thereby improving the plastic strain ratio (forming ability) of steel.

[0075] Annealing temperature control for energy saving and carbon reduction: The embodiment of the present application can realize the production of high-formability IF steel by adopting a lower annealing temperature. This innovation not only reduces energy consumption, but also reduces carbon emissions, which is in line with the current trend of green manufacturing and sustainable development.

[0076] Skin finishing process and elongation control: The hot-dip coils are skin-finished and the skin-finishing elongation is precisely controlled, which further improves the surface quality and formability of the steel.

[0077] The implementation effects and advantages are as follows:

[0078] Low cost and high efficiency: Low-Ti content chemical composition design and optimized production process enable low-cost and high-efficiency production of IF steel.

[0079] High forming ability: Through a series of process optimizations, the forming ability of IF steel has been significantly improved, meeting the needs of high-forming steel in the fields of automobiles, home appliances, construction, etc.

[0080] Energy saving and carbon reduction: The use of lower annealing temperature achieves the goal of energy saving and carbon reduction, which meets the requirements of green manufacturing and sustainable development.

[0081] Therefore, the method for producing high-formability hot-dip galvanized IF steel with low energy consumption provided in the embodiment of the present application achieves the goal of producing high-formability hot-dip galvanized IF steel with low energy consumption and high efficiency by accurately controlling the chemical composition and parameters of each process link. This method not only improves the forming performance and surface quality of the steel, but also reduces the production cost, and has important industrial application value.

[0082] The present application is further described below in conjunction with specific embodiments. The experimental methods in the following embodiments that do not specify specific conditions are usually measured in accordance with national standards / industry standards; if there are no corresponding national standards / industry standards, they are measured in accordance with common international standards, conventional conditions, or conditions recommended by the manufacturer.

[0083] The method for producing high-formability hot-dip galvanized IF steel with low energy consumption provided in the embodiment of the present application comprises:

[0084] Obtaining a slab having a set chemical composition, wherein the set chemical composition includes a low content of Ti;

[0085] The slab is subjected to first heating, rolling and coiling in sequence to obtain a hot-rolled coil having coarse TiC particles;

[0086] The hot-rolled coil is pickled and cold-rolled in sequence, and the following parameters of the cold rolling are controlled: total reduction rate, first-pass reduction rate, and second-pass reduction rate, so as to increase the nucleation driving force of cold-rolled grain recrystallization in the cold rolling to obtain a chilled coil;

[0087] Annealing the chilled coil to grow the cold-rolled grains; the annealing includes: second heating, soaking and cooling;

[0088] Galvanizing the annealed chilled coil to obtain a hot dipped coil;

[0089] The hot dip coil is skin-passed and the skin-pass elongation is controlled to obtain high-formability hot dip galvanized IF steel. The chemical composition (wt%) of the slab is shown in Table 1, and the preparation process parameters of the embodiment and the comparative example are shown in Table 2.

[0090] Table 1 Chemical composition of slab (wt%), the rest is Fe and unavoidable impurities

[0091] Group C / ％ Si / % Mn / % P / ％ S / ％ Al / ％ Ti / % Example 1 0.0018 0.036 0.185 0.014 0.012 0.047 0.038 Example 2 0.0019 0.037 0.164 0.015 0.012 0.042 0.034 Example 3 0.0018 0.034 0.155 0.014 0.011 0.041 0.035 Comparative Example 1 0.0018 0.035 0.185 0.014 0.011 0.048 0.033 Comparative Example 2 0.0017 0.038 0.155 0.013 0.013 0.047 0.068

[0092] Table 2 Preparation process parameters of examples and comparative examples

[0093]

[0094] Table 3 Performance of Examples and Comparative Examples

[0095]

[0096]

[0097] The performance of the embodiments and comparative examples are shown in Table 3. As shown in Tables 1 to 3, the hot-dip galvanized IF steel prepared by the method provided in the embodiments of the present application has a tensile strength within 300 MPa, a yield strength within 150 MPa, an elongation greater than 45% at a gauge length of 80 mm, and a plastic strain ratio (R90) greater than 2.8, and has high forming ability.

[0098] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0099] The hot-dip galvanized IF steel produced in the embodiment of the present invention not only has good formability and surface quality, but also achieves the goal of energy saving and carbon reduction.

[0100] The above is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. It will be apparent to those skilled in the art that various modifications to these embodiments are possible, and the general principles defined in the present application 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 in the present application, but will conform to the widest scope consistent with the principles and novel features applied for by the present application.

Claims

1. A method for producing high-formability hot-dip galvanized IF steel with low energy consumption, the method comprising: Obtaining a slab having a set chemical composition, wherein the set chemical composition includes a low content of Ti; The slab is subjected to first heating, rolling and coiling in sequence to obtain a hot-rolled coil having coarse TiC particles; The hot-rolled coil is pickled and cold-rolled in sequence, and the following parameters of the cold rolling are controlled: total reduction rate, first-pass reduction rate, and second-pass reduction rate, so as to increase the nucleation driving force of cold-rolled grain recrystallization in the cold rolling to obtain a chilled coil; Annealing the chilled coil to grow the cold-rolled grains; the annealing includes: second heating, soaking and cooling; Galvanizing the annealed chilled coil to obtain a hot dipped coil; The hot dip coil is skin-passed and the skin-pass elongation is controlled to obtain high-formability hot dip galvanized IF steel.

2. The method according to claim 1, characterized in that The temperature of the second heating is 760° C. to 790° C., and the heating rate of the second heating is 5° C. / s to 7° C. / s.

3. The method according to claim 1, characterized in that The soaking temperature is 765° C. to 795° C., and the soaking time is 100 s to 150 s.

4. The method according to claim 1, characterized in that: The total reduction rate is 81% to 85%, the first pass reduction rate is 30% to 35%, and the second pass reduction rate is 25% to 30%.

5. The method according to claim 1, characterized in that The smoothing elongation is 1.1% to 1.5%.

6. The method according to claim 1, characterized in that The galvanizing temperature is 440°C to 480°C.

7. The method according to claim 1, characterized in that The temperature of the first heating is 1200° C. to 1250° C., and the insulation time of the first heating is 110 min to 170 min.

8. The method according to claim 1, characterized in that The final rolling temperature of the rolling is 900° C. to 950° C.; and / or, The coiling temperature is 710°C to 750°C.

9. The method according to claim 1, characterized in that: The acid solution concentration of the pickling is 41 g / L to 55 g / L, the acid solution temperature of the pickling is 78° C. to 84° C., and the pickling speed is 120 m / min to 200 m / min.

10. The method according to claim 1, characterized in that In terms of mass fraction, the set chemical composition includes: C≤0.002%, Mn: 0.1%-0.25%, Si≤0.05%, Al: 0.02%-0.06%, P≤0.02%, S≤0.015%, Ti: 0.02%-0.04%, and matrix element Fe.

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