HOT-DIPPED ALUMINUM-ZINC OR HOT-DIPPED ZINC-ALUMINUM-MAGNESIUM MULTIPHASE STEEL HAVING YIELD STRENGTH OF GREATER THAN OR EQUAL TO 450 MPA AND RAPID HEAT-TREATMENT HOT PLATING MANUFACTURING METHOD THEREFOR
The present invention belongs to the field of rapid heat-treatment technology for materials, and specifically relates to a hot-dipped aluminum-zinc or zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa and a manufacturing method therefor. The application of hot-dipped steel plates has developed from architecture to high-level industries such as household appliances. Therefore, higher requirements have been put forward for the quality of hot-dipped steel plates, including internal quality and surface quality. Hot-dip steel plates are required to have better corrosion resistance, higher strength, better surface quality, bright and diverse colors, and lower costs. High strength hot-dipped aluminum-zinc and zinc-aluminum-magnesium products have good corrosion resistance, mechanical properties, forming performance, heat reflection performance, and surface darkening resistance, and they are increasingly widely used in the fields of architecture and household appliances. Currently, the domestic products of hot-dipped aluminum-zinc and zinc-aluminum-magnesium with high yield strength and tensile strength have low elongation due to the limitations of process equipment, which greatly affects the application range of the products. The strength of products with better elongation can't meet the current demand for high strength. Chinese Patent Application 200710093976.8 disclosed “Hot-dipped Aluminum-zinc Steel Plate for Deep Drawing And Production Method Therefor”, which uses IF steel as the substrate to produce hot-dipped aluminum-zinc products. The steel is ultra-low carbon steel as the C content thereof is ≤0.01%. The steel has a yield strength of 140-220 MPa, a tensile strength of 260-350 MPa, and an elongation ≥30%. Although the steel plate has good tensile properties and forming performance, the strength level thereof is not enough, which greatly affects its applicability. Chinese Patent Application 201710323599.6 discloses “A Hot-dipped Aluminum-Zinc Steel Plate Having Yield Strength Grade Of 550 MPa And Manufacturing Method Therefor”. The substrate comprises the following components: C: 0.05-0.06%, Si: 0-0.05%, Mn: 1.0-1.2%, P: 0-0.015%, Nb: 0.061-0.08%. The metallographic structure thereof is fibrous ferrite-cementite and fine niobium carbide precipitates. The elongation after fracture is 10-18%. The microstructure of the hot-dipped aluminum-zinc steel plate proposed in this patent has adverse effects on forming, with low elongation as well as high production costs due to the addition of more Nb. Chinese Patent Application 201710994660.X discloses “550 MPa Grade Structural Hot-dipped Aluminum-zinc Steel Plate And Preparation Method Therefor”. The steel comprises the following components: C: 0.02-0.07%, Si≤0.03%, Mn: 0.15-0.30%, P≤0.020%, Si≤0.020%, Nb: 0.015-0.030%, Als: 0.020-0.070%. Cold rolling is performed using a low cold rolling reduction rate of 55-60%. It has a yield strength of 550 MPa or more, a tensile strength of 560 MPa, and an elongation of about 10%. The steel plate proposed in this patent has the problem of low elongation and high yield strength, which will influence the subsequent processing. Chinese Patent CN102363857B disclosed “A Production Method For Structural Color Coated Sheet Having Yield Strength of 550 MPa”, wherein Ti and Nb are at most 0.05% and 0.045% respectively; its yield strength Rp0.2reaches 550-600 MPa, the tensile strength Rmis 560-610 MPa, and the elongation after fracture A80 mm is ≥6%. Strengthening is mainly done by low-temperature annealing to keep most of the un-recrystallized banded structure to increase the strength, but the plasticity is poor, which also affects the forming. Chinese Patent CN100529141C discloses “A Full Hard Aluminum-zinc Plated Steel Plate And Production Method Therefor”. The method proposes to prepare a steel plate with a yield strength of 600 MPa and more, an elongation at break ≤7%, a total Ti and Nb content of 0.15-0.100%. The annealing temperature is controlled between 630-710° C. to obtain a full hard steel plate. However, the elongation of the steel plate obtained by this method is too low to effectively meet the current processing requirements for forming performance. Chinese Patent Application CN104060165A discloses “A Hot-dipped Aluminum-zinc Alloy Steel Plate”. The steel comprises the following components: C: 0.04-0.12%, Mn: 0.2-0.6%, P: 0.02-0.1%, S≤0.015%, Ti: 0.01-0.05%, Al: 0.02-0.07%, Si≤0.05%. Rolling process is performed with a hot-rolling finish-rolling entry temperature of 950-1100° C., a finishing rolling temperature of 820-900° C., a coiling temperature of 600-700° C., and a cold rolling total reduction rate of 50-80%. Continuous annealing is performed with an annealing temperature of 680-820° C. For the hot-dip aluminum-zinc plating process, the invention adopts a trace titanium-treatment resulting in limited strength levels and significant fluctuations in strength, which makes it difficult for stable production. Chinese Patent Application CN105063484A discloses “High Elongation Hot-dipped Aluminum-zinc And Color Coated Steel Plate Having Yield Strength 500MP level And Manufacturing Method Therefor”. The steel comprises the following chemical components, in percentage by weight: C: 0.07-0.15%, Si: 0.02-0.15%, Mn: 1.3-1.8%, S≤0.01%, N≤0.004%, Ti≤0.15%, Nb≤0.050%, the balance being Fe and other unavoidable impurities. In addition, the following conditions also need to be met: (C+Mn/6)≥0.3%; when no Ti is contained, Nb meets 0.01%≤(Nb−0.22C−1.1N)≤0.05%; when no Nb is contained, Ti meets 0.5≤Ti/C≤1.5; and when Ti and Nb are added in a compound mode, 0.04%≤(Ti+Nb)≤0.2%. According to the invention, the obtained hot-dipped aluminum-zinc and color coated steel plate has a yield strength ≥450 MPa, a tensile strength ≥500 MPa and an elongation ≥14%. The steel plates also have good strength, toughness and corrosion resistance. The production method therefor has a low cost and a high yield. The steel plate can be used for steel structure buildings such as roofs and walls, and electrical equipment such as household appliances. Conventional processes are used in the invention for production, while rapid heat-treatment processes are not involved. The relevant patents of hot-dipped zinc-aluminum-magnesium mainly focus on the process and composition of the plating layer. For example, Chinese Patent Application CN103361588A discloses “Production Method Of Low Magnesium And Low Aluminum Zinc-Aluminum-Magnesium Plating Steel Plate And Plating Steel Plate Thereof”. The method shows that the steel plate is immersed in molten zinc after annealing at a plating bath temperature of zinc alloy melting point plus 40-200° C. for a plating time of 2-10 seconds with an immersing temperature of the steel plate of the plating bath temperature to (the plating bath temperature+50° C.). The cooling rate after plating is 10-50° C./s. The chemical components of the bath comprise Al: 1.0-2.4%, Mg: 1.0-2.0%, and Al/Mg≥1. Chinese Patent Application CN106811686A discloses “High Strength Zinc-aluminum-magnesium Plating Steel Plate With Good Surface Quality And Manufacturing method Therefor”. The steel plate comprises the following chemical components: C: 0.09-0.18%, Si: 0.40-1.60%, Mn: 0.80-2.10%, S: 0.001-0.008%, and may further comprises Cr: 0.01-0.60%, and/or Mo: 0.01-0.30%. The chemical components of the plating layer comprise Al: 1-14%, Mg: 1.0-5.0%, the balance being Zn and other unavoidable impurities. Although this patent proposes a method for producing a high-strength zinc-aluminum-magnesium plating steel plate, the production cost is high. Besides, high Si content tends to cause surface quality problems, high yield strength and low elongation, which may affect subsequent processing and forming. In summary, current hot-dipped aluminum-zinc and zinc-aluminum-magnesium products have problems such as high cost, bad surface quality, poor matching of strength or elongation, resulting in poor subsequent processing and forming performance, as well as low wind uplift resistance. The purpose of the present invention is to provide a hot-dipped aluminum-zinc or zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa and a rapid heat-treatment hot plating manufacturing method therefor. The obtained hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a yield strength ≥450 MPa, a tensile strength ≥500 MPa and an elongation ≥14%. The steel also has good wind uplift resistance, high corrosion resistance, strength, and extensibility. The steel can be used for steel structure buildings such as roofs and walls, and electrical equipment such as household appliances. To achieve the above object, the present invention provides the following technical solutions. A hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa comprises the following components, in percentage by weight: 0.06-0.12% of C, 0.05-0.30% of Si, 1.0-1.8% of Mn, P≤0.015%, S≤0.015%, such as ≤0.012%, N≤0.04%, Cr≤0.50%, such as 0.25-0.50% or ≤0.40%, and further comprises one or both of Ti or Nb, with 0-0.045% (such as 0-0.035%) of Nb and 0-0.045% (such as 0-0.035%) of Ti, the balance being Fe and other unavoidable impurities; in addition, the following conditions also need to be met: In some embodiments, the content of C is 0.06-0.10% or 0.075-0.12%. In some embodiments, the content of Mn is 1.0-1.6% or 1.2-1.8%. In some embodiments, Si≤0.012%. In some embodiments, the content of Cr is ≤0.40%, or 0.25-0.5%. In some embodiments, the content of Nb is 0-0.035%. In some embodiments, the content of Ti is 0-0.035%. In some embodiments, 0.25≤(C+Mn/6)≤0.35. In some embodiments, 0.30≤(C+Mn/6)≤0.40. In some embodiments, when no Nb is contained, Ti meets 0.3≤Ti/C≤0.5, or meets 0.4≤Ti/C≤0.6. In some embodiments, when both Ti and Nb are contained, 0.03%≤(Ti+Nb)≤0.06%, or 0.05%≤(Ti+Nb)≤0.07%. Preferably, the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to the present invention is obtained by the following process:
Preferably, the content of C is 0.06-0.08% or 0.08-0.10%. Preferably, the content of Si is 0.15-0.30%. Preferably, the content of Mn is 1.0-1.3% or 1.2-1.6%. Preferably, the whole process of the continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium takes a time of 22-80.5 s, such as 22-80 s or 23-66 s. Preferably, in step 2), the hot rolling tapping temperature is 1180-1220° C. Preferably, in step 2), the hot rolling finishing temperature is 850-880° C., such as 850-870° C. or 860-880° C. Preferably, in step 2), the coiling temperature is 550-620° C. or 570-620° C. Preferably, in step 2), the laminar flow front section rapid cooling rate is 100-120° C./s. Preferably, in step 3), the cold rolling cumulative reduction rate is 60-70%. Preferably, in step 4), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s. Preferably, in step 4), when two-stage rapid heating is used in the rapid heating, the heating is performed from room temperature to 550-620° C. or 550-625° C. at a heating rate of 30-300° C./s in the first stage, and from 550-620° C. or 550-625° C. to 760-840° C. or 770-850° C. at a heating rate of 50-300° C./s in the second stage. According to the present invention, the microstructure of the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel is a multiphase structure comprising at least three types of structures selected from ferrite, martensite, bainite, micron-scale precipitated carbides, and ribbon grains. The size of the micron-scale precipitated carbide is generally 0.1-1 micron. According to the present invention, the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a yield strength ≥450 MPa, a tensile strength ≥500 MPa, and an elongation ≥14%. According to the present invention, the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a surface of homogenous silver white spangle, with the spangle size controlled within 0.1-6.0 mm. In some embodiments, according to the present invention, the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength ≥450 MPa comprises the following components, in percentage by weight: 0.06-0.10% of C, 0.05-0.30% of Si, 1.0-1.6% of Mn, P≤0.015%, S≤0.015%, N≤0.04%, such as ≤0.005% or 0.0005-0.005%, Cr≤0.40%, such as 0.05-0.40%, and further comprises one or both of Ti or Nb, with 0-0.035% of Nb and 0-0.035% of Ti, the balance being Fe and other unavoidable impurities; in addition, the following conditions also need to be met: 0.25≤(C+Mn/6)≤0.35; Mn/S≥150; when no Ti is contained, Nb meets 0.01%≤(Nb−0.22C−1.1N)≤0.03%; when no Nb is contained, Ti meets 0.3≤Ti/C≤0.5; and when both Ti and Nb are contained, 0.03%≤(Ti+Nb)≤0.06%. Preferably, in the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel, the content of C is 0.06-0.08%; preferably, the content of Si is 0.15-0.30%; preferably, the content of Mn is 1.0-1.3%; Preferably, the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a yield strength ≥450 MPa, a tensile strength 500 MPa and an elongation ≥20%; preferably, the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a yield strength of 450-515 MPa, such as 450-540 MPa, a tensile strength of 510-590 MPa, such as 510-580 MPa, an elongation of 20-26.5%, such as 21-26%. Preferably, the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel is obtained by the following process:
Preferably, the whole process of the continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium in step d) takes a time of 23-66.5 s, such as 23-66 s. Preferably, in step b), the hot rolling tapping temperature is 1180-1220° C. Preferably, in step b), the hot rolling finishing temperature is 850-870° C. Preferably, in step b), the coiling temperature is 550-620° C. Preferably, in step b), the laminar flow front section rapid cooling rate is 100-120° C./s. Preferably, in step c), the cold rolling cumulative reduction rate is 60-70%. Preferably, in step d), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s. Preferably, in step d), when two-stage heating is used in the rapid heating, the heating is performed from room temperature to 550-625° C. at a heating rate of 30-300° C./s in the first stage, and from 550-625° C. to 760-840° C. at a heating rate of 50-300° C./s in the second stage. In some embodiments, according to the present invention, the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa comprises the following components, in percentage by weight: 0.075-0.12% of C, 0.05-0.30% of Si, 1.2-1.8% of Mn, P≤0.015%, S≤0.012%, N≤0.04%, such as ≤0.01% or 0.001-0.01%, 0.25-0.50% of Cr, and further comprises one or both of Ti or Nb, with 0-0.045% of Nb and 0-0.045% of Ti, the balance being Fe and other unavoidable impurities; in addition, the following conditions also need to be met: 0.30≤(C+Mn/6)≤0.40; Mn/S≥150; when no Ti is contained, Nb meets 0.01%≤(Nb−0.22C−1.1N)≤0.03%; when no Nb is contained, Ti meets 0.4≤Ti/C≤0.6; and when both Ti and Nb are contained, 0.05%≤(Ti+Nb)≤0.07%. The hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa has a yield strength ≥550 MPa. Preferably, in the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa, the content of C is 0.08-0.10%; preferably, the content of Si is 0.15-0.30%; and preferably, the content of Mn is 1.2-1.6%. Preferably, the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a yield strength ≥550 MPa, a tensile strength ≥600 MPa and an elongation ≥14%. Preferably, the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a yield strength of 550-625 MPa, such as 550-615 MPa, a tensile strength of 615-700 MPa, an elongation of 14-17.5%, such as 14-17%. Preferably, the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel is obtained by the following process:
Preferably, the whole process of the continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium in step D) takes a time of 22-80.5 s, such as 22-80 s. Preferably, in step B), the hot rolling tapping temperature is 1180-1220° C. Preferably, in step B), the hot rolling finishing temperature is 860-880° C. Preferably, in step B), the coiling temperature is 570-620° C. Preferably, in step B), the laminar flow front section rapid cooling rate is 100-120° C./s. Preferably, in step C), the cold rolling cumulative reduction rate is 60-70%. Preferably, in step D), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s. Preferably, in step D), when two-stage heating is used in the rapid heating, the heating is performed from room temperature to 550-620° C. at a heating rate of 30-300° C./s in the first stage, and from 550-620° C. to 770-850° C. at a heating rate of 50-300° C./s in the second stage. Carbon (C): Carbon is the most common strengthening element in steel, which increases the strength of steel and decreases the plasticity of steel. Therefore, the carbon content should not be excessive. The carbon content has a significant impact on the mechanical properties of steel. As the carbon content increases, the number of pearlite will increase, which greatly improves the strength and hardness of the steel while greatly decreases the plasticity and toughness thereof. If the carbon content is too high, there will be significant network carbides present in the steel. The presence of network carbides will significantly reduce the strength, plasticity, and toughness of the steel. The strengthening effect caused by the increase of carbon content in the steel may also be significantly reduced, resulting in deteriorated welding and forming process performance of the steel. Thus, the carbon content should be minimized as much as possible while ensuring the strength. As a result, in the present invention, the C content is controlled within 0.06-0.12%. Silicon (Si): Silicon forms solid solution in ferrite or austenite, thereby enhancing the yield strength and tensile strength of steel. Moreover, silicon, a beneficial element in alloy steel, may increase the cold work deformation hardening rate of steel. In addition, there is a significant enrichment phenomenon of silicon on the intergranular fracture surface of silicon manganese steel. The segregation of silicon at grain boundaries may alleviate the distribution of carbon and phosphorus along grain boundaries, thereby improving the embrittlement state of grain boundaries. Silicon may enhance the strength, hardness, and wear resistance of steel without significantly reducing its plasticity. Silicon has a strong ability to deoxygenate and is commonly used as a deoxidizer in steelmaking. Silicon may also increase the fluidity of molten steel, so it is generally contained in steel. However, when the silicon content in the steel is too high, the plasticity and toughness thereof may significantly decrease. Excessive silicon content may form oxide scale defects on the surface and seriously affect the surface wetting behavior of strip steel during hot plating. Therefore, in the present invention, the Si content is controlled between 0.05-0.30%. Manganese (Mn): Manganese, as a typical austenite stabilizing element, may significantly increases the hardenability of steel and reduces the critical cooling rate for the formation of bainite and martensite, thereby effectively decreasing the cooling rate of the rapid cooling stage during the annealing process, which is beneficial for obtaining bainite or martensite structure. Mn is a cheap element that stabilizes austenite and strengthens alloys. Manganese decreases the γ−α phase transition temperature mainly through solid solution strengthening, so as to promote grain refinement, thereby changing the microstructure after phase transition. Manganese, as a γ phase region expanding element, may lower the critical points of A3and Al. However, high manganese content (>2.0%) may not only delays the transformation of pearlite, but also delays the transformation of bainite, making the “process window” smaller and the bainite zone shifted to the right, thereby increasing the sensitivity of steel to process conditions, which is not conducive to stable batch production. Low manganese content tends to cause pearlite transformation, making it difficult to form a sufficient amount of bainite in the structure. The strength of the material is simply represented as carbon equivalent through the statistical analysis of a large amount of experimental data, therefore the present invention requires 0.25≤(C+Mn/6)≤0.40. In addition, Mn can be infinitely miscible in steel, and Mn mainly plays a solid solution strengthening effect. Due to a certain residual amount of S element in the molten steel, S element has negative effects such as increasing the hot brittleness of the slab and deteriorating the mechanical properties of the steel. In order to reduce the negative effects of S, the Mn/S ratio in the steel plate is increased so that Mn/S is ≥150, so as to effectively reduce the negative effects of S. Therefore, in the present invention, the manganese content is limited within 1.0-1.8%. Chromium (Cr): The role of chromium in multiphase steel is mainly reflected in its ability to increase the stability of austenite and the hardenability of steel. These two opposite effects together affect and constrain the volume fraction of martensite in chromium containing steel. At lower cooling rates, chromium mainly affects the stability of undercooling austenite; at higher cooling rates, chromium mainly affects the volume fraction of austenite. The addition of chromium on the one hand plays a role in solid solution strengthening, on the other hand, it can change the morphology and distribution of martensite by changing the phase transformation temperature of the steel, thereby increasing the strength and plasticity of the steel. However, chromium is the most effective element in delaying bainite transformation. Its effect on delaying bainite transformation is much greater than that on delaying pearlite transformation. Thus, chromium should be added to the steel in an appropriate amount. Therefore, in the present invention, the chromium content is limited within 0.50%. Titanium (Ti): Titanium is a strong carbide-forming element. Adding trace amount of titanium to steel is beneficial for fixing N in the steel. The formed TiN may prevent excessive growth of austenite grains during slab heating, thereby achieving the goal of refining the original austenite grains. Titanium in steel may also react with carbon and sulfur to form compounds such as TiC, TiS, and Ti4C2S2, which exist in the form of inclusions and second phase particles. These carbon nitride precipitates of titanium may prevent grain growth in the heat affected zone during welding, thereby improving the welding performance of the finished steel plate, meanwhile playing a role in precipitation strengthening in steel. When Ti is added alone, the composition is designed to be 0.3≤Ti/C≤0.6, which makes a large amount of special carbide TiC forming as a good dispersion strengthening reinforcement. Nb: Nb may significantly increase the recrystallization temperature of steel and achieve grain refinement. During the hot rolling process, the strain-induced precipitation of niobium carbides may hinder the recovery and recrystallization of deformed austenite. After controlled rolling and cooling the microstructure of deformed austenite, fine phase transformation products are obtained. Meanwhile, during the annealing process, fine precipitates of niobium carbonitride may play a role in precipitation strengthening. Therefore, niobium should be added to the steel in a small amount. When no Ti is contained, in order to ensure that Nb element can achieve better precipitation strengthening effect, while avoid adding too much Nb element to deteriorate the precipitation effect, it is necessary to meet the requirement of 0.01%≤(Nb−0.22C−1.1N)≤0.03% for Nb in the absence of Ti. When microalloy element Ti and Nb are added in a compound mode in the present invention, fine precipitates with strengthening effects such as Nb (C, N), TiC, TiN, (Ti, Nb) (C, N) may be formed to strengthen the matrix. The presence thereof in form of carbides, nitrides, and carbonitrides may prevent the growth of austenite grains and increase the coarsening temperature of steel. The dispersed small particles of carbides and nitrides may fix the austenite grain boundaries to hinder the migration of austenite grain boundaries, thereby increasing the recrystallization temperature of austenite so as to expand the unrecrystallized zone. i.e. prevent the growth of austenite grains. Adding trace amount of Nb and Ti to steel may, on the one hand, reduce carbon equivalent content while increasing the strength to improve the welding performance of the steel, on the other hand, fix impure substances such as oxygen, nitrogen, sulfur to improve the weldability of steel. When Ti and Nb are added in a compound mode, 0.03%≤(Ti+Nb)≤0.07% is controlled to ensure the best strengthening effect. A rapid heat-treatment hot plating manufacturing method for the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to the present invention comprises the following steps:
Preferably, the whole process of the continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium takes a time of 22-80 s, such as 23-66 s. Preferably, in step 2), the hot rolling tapping temperature is 1180-1220° C. Preferably, in step 2), the hot rolling finishing temperature is 850-870° C. or 860-880° C. Preferably, in step 2), the coiling temperature is 550-620° C. or 570-620° C. Preferably, in step 2), the laminar flow front section rapid cooling rate is 100-120° C./s. Preferably, in step 3), the cold rolling cumulative reduction rate is 60-70%. Preferably, in step 4), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s. Preferably, in the step 4), when two-stage heating is used in the rapid heating, heating is performed from room temperature to 550-625° C., such as 550-620° C., at a heating rate of 30-300° C./s in the first stage; and from 550-625° C., such as 550-620° C., to 750-840° C. at a heating rate of 50-300° C./s in the second stage. Preferably, in the soaking process of step 4), after heating the strip steel or steel plate to the target temperature of austenite and ferrite two-phase area, the temperature is kept constant for soaking. Preferably, in the soaking process of step 4), the strip steel or steel plate is subjected to a small increase in temperature or a small decrease in temperature during the soaking time period with the temperature not exceeding 850° C. after the temperature increase and not falling below 750° C. after the temperature decrease. Preferably, the soaking time period is 10-20 s. In some embodiments, the method comprises the steps of:
Preferably, the whole process of the continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium in step d) takes a time of 23-66 s. Preferably, in step d), the hot rolling tapping temperature is 1180-1220° C. Preferably, in step b), the hot rolling finishing temperature is 850-870° C. Preferably, in step b), the coiling temperature is 550-620° C. Preferably, in step b), the laminar flow front section rapid cooling rate is 100-120° C./s. Preferably, in step c), the cold rolling cumulative reduction rate is 60-70%. Preferably, in step d), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s. Preferably, in step d), when two-stage heating is used in the rapid heating, the heating is performed from room temperature to 550-625° C. at a heating rate of 30-300° C./s in the first stage, and from 550-625° C. to 750-840° C. at a heating rate of 50-300° C./s in the second stage. Preferably, in the soaking process of step d), after heating the strip steel or steel plate to the target temperature of austenite and ferrite two-phase area, the temperature is kept constant for soaking. Preferably, in the soaking process of step d), the strip steel or steel plate is subjected to a small increase in temperature or a small decrease in temperature during the soaking time period with the temperature not exceeding 840° C. after the temperature increase and not falling below 750° C. after the temperature decrease. Preferably, the soaking time period is 10-20 s. In some embodiment, the method for manufacturing the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 550 MPa described herein comprises the following steps:
Preferably, the whole process of the continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium in step D) takes a time of 22-80 s. Preferably, in step B), the hot rolling tapping temperature is 1180-1220° C. Preferably, in step B), the hot rolling finishing temperature is 860-880° C. Preferably, in step B), the coiling temperature is 570-620° C. Preferably, in step B), the laminar flow front section rapid cooling rate is 100-120° C./s. Preferably, in step C), the cold rolling cumulative reduction rate is 60-70%. Preferably, in step D), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s. Preferably, in step D), when two-stage heating is used in the rapid heating, the heating is performed from room temperature to 550-620° C. at a heating rate of 30-300° C./s in the first stage, and from 550-620° C. to 770-850° C. at a heating rate of 50-300° C./s in the second stage. Preferably, in the soaking process of step D), after heating the strip steel or steel plate to the target temperature of austenite and ferrite two-phase area, the temperature is kept constant for soaking. Preferably, in the soaking process of step D), the strip steel or steel plate is subjected to a small increase in temperature or a small decrease in temperature during the soaking time period with the temperature not exceeding 850° C. after the temperature increase and not falling below 770° C. after the temperature decrease. Preferably, the soaking time period is 10-20 s. In the manufacturing method of the present invention, direct fire rapid heating, short-term heat preservation, and rapid cooling method are used to achieve rapid heat-treatment, refine the structure, and improve strength and elongation. According to the present invention, due to the significant increase in heating rate and the shortening of soaking time, the residence time of the hot-dipped zinc substrate material at high temperatures is significantly shortened. Therefore, the surface enrichment of high-strength steel alloy elements is reduced, the platability is enhanced and the surface quality is improved. In addition, the shortening of the length of furnace units (at least one-third shorter than traditional continuous annealing furnaces) and the reduction of furnace rollers significantly reduce the probability of surface defects such as furnace roller marks, pits, and scratches, and improve the surface quality of the products. The present invention adopts direct fire heating to increase the heating rate and shorten the heat preservation time to 1-20 s, thereby inhibiting the grain growth, achieving rapid heat treatment and refining grains. Due to the addition of alloys, high-strength low alloy steel is quite sensitive to annealing temperature, so the temperature and heat preservation time of each stage of the annealing should be strictly controlled. During the annealing process of hot-dipping aluminum-zinc and zinc-aluminum-magnesium, fine precipitates hinder the pinning of dislocations and the migration of subgrain boundaries, inhibit the growth of recrystallized grains, refine the grains, and improve the yield strength and tensile strength of the steel, thereby strengthening the material and maintaining good plasticity. After plating, cold aerosol spray method is used for rapid cooling to refine grains and obtain strengthening phases. Aerosol cooling is the process of adding fine droplets of water to the protective gas of spray cooling, which is jetted onto the surface of the strip steel at a certain angle and jet velocity, allowing greatly improvement in the heat exchange efficiency on the strip steel surface. In the manufacturing method of the present invention, direct fire rapid heating, short-term heat preservation, and rapid cooling method are used to achieve rapid heat-treatment, refine the structure, and improve strength and elongation. After plating, cold spray or aerosol cooling method is used to refine grains and obtain strengthening phases. Under the premise of controlling the cold rolling reduction rate between 60% and 80% with appropriate components and hot-rolling process, only by maintaining suitable cold rolling reduction can an ideal metallographic structure be obtained. Due to the little deformation energy storage at lower cold rolling reduction, recrystallization is less likely to occur during subsequent annealing. Therefore, a little cold rolled structure in an appropriate amount can be retained to increase the strength. A greater reduction rate of 60-80% can be used to accelerate recrystallization and improve plasticity. After testing, the hot-dipped aluminum-zinc or zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa of the present invention has a yield strength of 450-615 MPa, a tensile strength of 510-700 MPa, and an elongation of 14-26%. The hot-dipped aluminum-zinc or zinc-aluminum-magnesium substrate has a multiphase structure comprising at least three types of structures selected from ferrite, martensite, bainite, ribbon grains, and micron-scale precipitated carbides. The present invention precisely formulates the components with controlling: 0.25≤(C+Mn/6)≤0.40; Mn/S≥150; when no Ti is contained, Nb meets 0.01%≤(Nb−0.22C−1.1N)≤0.03%; when no Nb is contained, Ti meets 0.3≤Ti/C≤0.6; when both Ti and Nb are contained, 0.03%≤(Ti+Nb)≤0.07%, combined with a rapid heat treatment process, results in products with high strength and good plasticity. Compared to traditional hot-dipped aluminum-zinc or zinc-aluminum-magnesium high-strength steel, it has better strength, toughness, forming performance, and a significant competitive advantage in the market. Meanwhile, due to the significant increase in heating rate and the shortening of soaking time, the residence time of the hot-dip galvanized substrate material at high temperatures is significantly shortened. Therefore, the surface enrichment of high-strength steel alloy elements is reduced, the platability is enhanced and the surface quality is improved. The shortening of the length of furnace units (at least one-third shorter than traditional continuous annealing furnaces) and the reduction of furnace rollers significantly reduce the probability of surface defects such as furnace roller marks, pits, and scratches, and improve the surface quality of the products. The present invention does not require equipment modification and has a simple manufacturing process. According to the present invention, the hot-dipped aluminum-zinc or zinc-aluminum-magnesium products with high corrosion resistance, heat resistance, and excellent strength and toughness can be produced. In addition, the plating layer of steel according to the present invention is uniform, dense, and of appropriate thickness, which can be widely applied in industries such as architecture and household appliances, expanding a wide range of fields for the application of hot-dipped aluminum-zinc, zinc-aluminum-magnesium, and color-coated products. The present invention will be further described below in conjunction with examples and figures. The examples are implemented on the premise of the technical solution of the present invention and provide detailed implementations and specific operation processes. But the protection scope of the present invention is not limited to the following examples. In examples, the yield strength, tensile strength, and elongation were tested in accordance with the “GB/T228.1-2010 Metallic materials—Tensile testing—Part 1: Method of test at room temperature”, using the P7 specimen for testing along the transverse direction. Table 1 shows the composition of the test steel in the example. Table 2 shows the specific parameters of the one-stage rapid heating process in the example. Table 3 shows the specific parameters of the two-stage rapid heating process in the example. Table 4 shows the mechanical properties of the steel plate obtained by the process according to Table 2 from the test steel of the example. Table 5 shows the mechanical properties of the steel plate obtained by the process according to Table 3 from the test steel of the example. It can be found from the example, the product of the present invention has a yield strength of 450-510 MPa, a tensile strength of 510-580 MPa, and an elongation of 21-26%. Through precise composition ratio and rapid heat-treatment process, high-strength and high elongation hot-dipped aluminum-zinc or zinc-aluminum-magnesium products are obtained, which own a significant market competitive advantage. Table 6 shows the composition of the test steel in the example. Table 7 shows the specific parameters of the one-stage rapid heating process in the example. Table 8 shows the specific parameters of the two-stage rapid heating process in the example. Table 9 shows the mechanical properties of the steel plate obtained by the process according to Table 7 from the test steel of the example. Table 10 shows the mechanical properties of the steel plate obtained by the process according to Table 8 from the test steel of the example. It can be found from the example, the product of the present invention has a yield strength of 550-615 MPa, a tensile strength of 615-700 MPa, and an elongation of 14-17%. Through precise composition ratio and rapid heat-treatment process, high-strength and high elongation hot-dipped aluminum-zinc or zinc-aluminum-magnesium products are obtained, which own a significant market competitive advantage. As can be seen from A hot-dipped aluminum-zinc or zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa and a rapid heat-treatment hot plating manufacturing method therefor. The steel comprises the following components, in percentage by weight: 0.06-0.12% of C, 0.05-0.30% of Si, 1.0-1.8% of Mn, P≤0.015%, S≤0.015%, N≤0.04%, Cr≤0.50%, and further comprises one or both of Ti or Nb, with 0-0.045% of Nb and 0-0.045% of Ti, the balance being Fe and other unavoidable impurities. In addition, the following conditions also need to be met: 0.25≤(C+Mn/6)≤0.40; Mn/S≥150; when no Ti is contained, Nb meets 0.01%≤(Nb−0.22C−1.1N)≤0.03%; when no Nb is contained, Ti meets 0.3≤Ti/C≤0.6; and when Ti and Nb are added in a compound mode, 0.03%≤(Ti+Nb)≤0.07%. According to the present invention, the obtained hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium steel plate has a yield strength ≥450 MPa, a tensile strength ≥500 MPa and an elongation ≥14%, and also has good strength, toughness and corrosion resistance. The production method therefor has a low cost and a high yield. The steel plate can be used for steel structure buildings such as roofs and walls, and used in household appliances, photovoltaic industries, etc. 1. A hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa comprises the following components, in percentage by weight: 0.06-0.12% of C, 0.05-0.30% of Si, 1.0-1.8% of Mn, P≤0.015%, S≤0.015%, or S≤0.012%, N≤0.04%, Cr≤0.50%, or Cr 0.25-0.50% or ≤0.40%, and further comprises one or both of Ti or Nb, with 0-0.045% or 0-0.035% of Nb, and 0-0.045% or 0-0.035% of Ti, the balance being Fe and other unavoidable impurities; in addition, the following conditions also need to be met:
when no Ti is contained, Nb meets 0.01%≤(Nb−0.22C−1.1N)≤0.03%; when no Nb is contained, Ti meets 0.3≤Ti/C≤0.6; when both Ti and Nb are contained, 0.03%≤(Ti+Nb)≤0.07%. 2. The hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to the content of C is 0.06-0.10%, 0.06-0.08%, 0.075-0.12%, or 0.08-0.10%; and/or the content of Si is 0.15-0.30%; and/or the content of Mn is 1.0-1.6%, 1.0-1.3%, 1.2-1.8%, or 1.2-1.6%; and/or the Si is ≤0.012%; and/or the content of Cr≤0.40%, or is 0.25-0.5%; and/or the content of Nb is 0-0.035%; and/or the content of Ti is 0-0.035%. 3. The hot-dipped aluminum-zinc or zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to 4. The hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a microstructure of multiphase structure comprising at least three types of structures selected from ferrite, martensite, bainite, micron-scale precipitated carbides, and ribbon grains; and/or the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a yield strength ≥450 MPa, a tensile strength ≥500 MPa, and an elongation ≥14%; and/or the hot-dipped aluminum-zinc or hot-dipped zin c-aluminum-magnesium multiphase steel has a surface of homogenous silver white spangle, with the spangle size of 0.1-6.0 mm. 5.-6. (canceled) 7. The hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to 0.0005-0.005%, Cr≤0.40%, or Cr: 0.05-0.40%, and further comprises one or both of Ti or Nb, with 0-0.035% of Nb and 0-0.035% of Ti, the balance being Fe and other unavoidable impurities; in addition, the following conditions also need to be met: 0.25≤(C+Mn/6)≤0.35; Mn/S≥150; when no Ti is contained, Nb meets 0.01%≤(Nb−0.22C−1.1N)≤0.03%; when no Nb is contained, Ti meets 0.3≤Ti/C≤0.5; and when both Ti and Nb are contained, 0.03%≤(Ti+Nb)≤0.06%. 8. The hot-dipped aluminum-zinc or zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to a) Smelting and casting smelting and casting the above-mentioned chemical components into slabs; b) Hot rolling and cooling the hot rolling tapping temperature: 1150-1250° C., the hot rolling finishing temperature: 830-890° C., the coiling temperature: 520-650° C.; after rolling, using laminar flow cooling with a laminar flow front section rapid cooling rate of 80-120° C./s; c) Pickling and cold rolling after cooling, pickling the surface of strip steel to clean the mill scale, the cold rolling cumulative reduction rate being 60-80%; d) Continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium performing continuous annealing in the non-oxidation continuous annealing aluminum-zinc plating or zinc-aluminum-magnesium plating furnace; the annealing treatment sequentially including a heating section, a soaking section, and a pre-plating cooling section; wherein, one-stage or two-stage heating is used in the heating section; when one-stage rapid heating is used, the heating rate is 30-300° C./s; when two-stage rapid heating is used, the heating is performed from room temperature to 550-625° C. at a heating rate of 10-300° C./s in the first stage, and from 550-625° C. to 750-840° C. at a heating rate of 30-300° C./s in the second stage; afterwards, performing soaking at a soaking temperature of 750-840° C. for a soaking time of 1-20 s; then cooling to 550-600° C. at a cooling rate of 30-150° C./s; performing hot-dipping aluminum-zinc or hot-dipping zinc-aluminum-magnesium; after hot-dipping aluminum-zinc, cooling to room temperature at a cooling rate of 30-200° C./s to obtain hot-dipped aluminum-zinc AZ products; or after hot-dipping zinc-aluminum-magnesium, cooling to room temperature at a cooling rate of 30-180° C./s to obtain hot-dipped zinc-aluminum-magnesium AM products; e) Finishing and straightening the temper rolling rate: 0.25%±0.2, the straightening rate: 0.2%±0.2. 9. The hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to the whole process of the continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium in step d) takes a time of 23-66.5 s, or 23-66 s; and/or in step b), the hot rolling tapping temperature is 1180-1220° C.; and/or in step b), the hot rolling finishing temperature is 850-870° C.; and/or in step b), the coiling temperature is 550-620° C.; and/or in step b), the laminar flow front section rapid cooling rate is 100-120° C./s; and/or in step c), the cold rolling cumulative reduction rate is 60-70%; and/or in step d), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s; and/or in step d), when two-stage heating is used in the rapid heating, the heating is performed from room temperature to 550-625° C. at a heating rate of 30-300° C./s in the first stage, and from 550-625° C. to 760-840° C. at a heating rate of 50-300° C./s in the second stage. 10. The hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to 11. The hot-dipped aluminum-zinc or zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to A) Smelting and casting smelting and casting the above-mentioned chemical components into slabs; B) Hot rolling and cooling The hot rolling tapping temperature: 1170-1250° C., the hot rolling finishing temperature: 845-890° C. or 850-890° C., the coiling temperature: 550-680° C.; after rolling, using laminar flow cooling with a laminar flow front section rapid cooling rate of 80-120° C./s; C) Pickling and cold rolling after cooling, pickling the surface of strip steel to clean the mill scale, the cold rolling cumulative reduction rate being 60-80%; D) Continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium performing continuous annealing in the non-oxidation continuous annealing aluminum-zinc plating or zinc-aluminum-magnesium plating furnace; the annealing treatment sequentially including a heating section, a soaking section, and a pre-plating cooling section; wherein, one-stage or two-stage heating is used in the heating section; when one-stage rapid heating is used, the heating rate is 30-300° C./s; when two-stage rapid heating is used, the heating is performed from room temperature to 550-620° C. at a heating rate of 10-300° C./s in the first stage, and from 550-620° C. to 770-850° C. at a heating rate of 30-300° C./s in the second stage; afterwards, performing soaking at a soaking temperature of 770-850° C. for a soaking time of 1-20 s; then rapidly cooling to 550-600° C. at a cooling rate of 30-150° C./s; performing hot-dipping aluminum-zinc or hot-dipping zinc-aluminum-magnesium; after hot-dipping aluminum-zinc, cooling to room temperature at a cooling rate of 30-200° C./s to obtain hot-dipped aluminum-zinc AZ products; or after hot-dipping zinc-aluminum-magnesium, cooling to room temperature at a cooling rate of 30-180° C./s to obtain hot-dipped zinc-aluminum-magnesium AM products; 5) Finishing and straightening the temper rolling rate: 0.25%±0.2, the straightening rate: 0.2%±0.2. 12. The hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to the whole process of the continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium in step d) takes a time of 22-80.5 s, or 22-80 s; and/or in step B), the hot rolling tapping temperature is 1180-1220° C.; and/or in step B), the hot rolling finishing temperature is 860-880° C.; and/or in step B), the coiling temperature is 570-620° C.; and/or in step B), the laminar flow front section rapid cooling rate is 100-120° C./s; and/or in step C), the cold rolling cumulative reduction rate is 60-70%; and/or in step D), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s; and/or in step d), when two-stage heating is used in the rapid heating, the heating is performed from room temperature to 550-620° C. at a heating rate of 30-300° C./s in the first stage, and from 550-620° C. to 770-850° C. at a heating rate of 50-300° C./s in the second stage. 13. A rapid heat-treatment hot plating manufacturing method for the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to 1) Smelting and casting smelting and casting the above-mentioned chemical components into slabs; 2) Hot rolling and cooling the hot rolling tapping temperature: 1150-1250° C., the hot rolling finishing temperature: 830-890° C., the coiling temperature: 520-680° C.; after rolling, using laminar flow cooling with a laminar flow cooling front section rapid cooling rate of 80-120° C./s; 3) Pickling and cold rolling after cooling, pickling the surface of strip steel to clean the mill scale, the cold rolling cumulative reduction rate being 60-80%; 4) Continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium a. Continuous annealing performing continuous annealing in the non-oxidation continuous annealing aluminum-zinc plating or zinc-aluminum-magnesium plating furnace; the annealing treatment sequentially including a heating section, a soaking section, and a pre-plating cooling section; wherein, one-stage or two-stage heating is used in the heating section; when one-stage rapid heating is used, the heating rate is 30-300° C./s; when two-stage rapid heating is used, heating is performed from room temperature to 550-625° C. at a heating rate of 10-300° C./s in the first stage, and from 550-625° C. to 750-850° C. at a heating rate of 30-300° C./s in the second stage; afterwards, performing soaking at a soaking temperature of 750-850° C. for a soaking time of 1-20 s; then rapidly cooling to 550-600° C. at a cooling rate of 30-150° C./s; b. Hot-dipping aluminum-zinc or hot-dipping zinc-aluminum-magnesium after annealing, performing hot-dipping aluminum-zinc at a temperature of 550-600° C.; then rapidly cooling from 550-600° C. to room temperature at a cooling rate of 30-200° C./s to obtain hot-dipped aluminum-zinc AZ products; or after annealing, performing hot-dipping zinc-aluminum-magnesium at a temperature of 550-600° C.; then rapidly cooling from 550-600° C. to room temperature at a cooling rate of 30-180° C./s to obtain hot-dipped zinc-aluminum-magnesium AM products; 5) Finishing and straightening the temper rolling rate: 0.25%±0.2, the straightening rate: 0.2%±0.2. 14. The method according to the whole process of the continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium takes a time of 22-80 s, or 23-66 s; and/or in step 2), the hot rolling tapping temperature is 1180-1220° C.; and/or in step 2), the hot rolling finishing temperature is 850-870° C. or 860-880° C.; and/or in step 2), the coiling temperature is 550-620° C. or 570-620° C.; and/or in step 2), the laminar flow front section rapid cooling rate is 100-120° C./s; and/or in step 3), the cold rolling cumulative reduction rate is 60-70%; and/or in step 4), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s; and/or in step 4), when two-stage heating is used in the rapid heating, heating is performed from room temperature to 550-625° C. or 550-620° C., at a heating rate of 30-300° C./s in the first stage; and from 550-625° C. or 550-620° C., to 750-840° C. at a heating rate of 50-300° C./s in the second stage; and/or in the soaking process of step 4), after heating the strip steel or steel plate to the target temperature of austenite and ferrite two-phase area, the temperature is kept constant for soaking; and/or in the soaking process of step 4), the strip steel or steel plate is subjected to a small increase in temperature or a small decrease in temperature during the soaking time period with the temperature not exceeding 850° C. after the temperature increase and not falling below 750° C. after the temperature decrease; and/or the soaking time period is 10-20 s. 15. The method according to a) Smelting and casting smelting and casting the above-mentioned chemical components into slabs; b) Hot rolling and cooling the hot rolling tapping temperature: 1150-1250° C., the hot rolling finishing temperature: 830-890° C., the coiling temperature: 520-650° C.; after rolling, using laminar flow cooling with a laminar flow front section rapid cooling rate of 80-120° C./s; c) Pickling and cold rolling after cooling, pickling the surface of strip steel to clean the mill scale, the cold rolling cumulative reduction rate being 60-80%; d) Continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium a. Continuous annealing performing continuous annealing in the non-oxidation continuous annealing aluminum-zinc plating or zinc-aluminum-magnesium plating furnace; the annealing treatment sequentially including a heating section, a soaking section, and a pre-plating cooling section; wherein, one-stage or two-stage heating is used in the heating section; when one-stage rapid heating is used, the heating rate is 30-300° C./s; when two-stage rapid heating is used, heating is performed from room temperature to 550-625° C. at a heating rate of 10-300° C./s in the first stage, and from 550-625° C. to 750-840° C. at a heating rate of 30-300° C./s in the second stage; afterwards, performing soaking at a soaking temperature of 750-840° C. for a soaking time of 1-20 s; then rapidly cooling to 550-600° C. at a cooling rate of 30-150° C./s; b. Hot-dipping and cooling after annealing, performing hot-dipping aluminum-zinc at a temperature of 550-600° C.; then rapidly cooling from 550-600° C. to room temperature at a cooling rate of 30-200° C./s to obtain hot-dipped aluminum-zinc AZ products; or after annealing, performing hot-dipping zinc-aluminum-magnesium at a temperature of 550-600° C.; then rapidly cooling from 550-600° C. to room temperature at a cooling rate of 30-180° C./s to obtain hot-dipped zinc-aluminum-magnesium AM products; e) Finishing and straightening the temper rolling rate: 0.25%±0.2, the straightening rate: 0.2%±0.2. 16. The method according to the whole process of the continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium in step d) takes a time of 23-66 s; and/or in step b), the hot rolling tapping temperature is 1180-1220° C.; and/or in step b), the hot rolling finishing temperature is 850-870° C.; and/or in step b), the coiling temperature is 550-620° C.; and/or in step b), the laminar flow front section rapid cooling rate is 100-120° C./s; and/or in step c), the cold rolling cumulative reduction rate is 60-70%; and/or in step d), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s; and/or in step d), when two-stage heating is used in the rapid heating, the heating is performed from room temperature to 550-625° C. at a heating rate of 30-300° C./s in the first stage, and from 550-625° C. to 750-840° C. at a heating rate of 50-300° C./s in the second stage; and/or in the soaking process of step d), the strip steel or steel plate is heated to the target temperature of austenite and ferrite two-phase area; and the temperature is kept constant for soaking; and/or in the soaking process of step d), the strip steel or steel plate is subjected to a small increase in temperature or a small decrease in temperature during the soaking time period with the temperature not exceeding 840° C. after the temperature increase and not falling below 750° C. after the temperature decrease; and/or the soaking time period is 10-20 s. 17. The method according to A) Smelting and casting smelting and casting the above-mentioned chemical components into slabs; B) Hot rolling and cooling the hot rolling tapping temperature: 1170-1250° C., the hot rolling finishing temperature: 850-890° C., the coiling temperature: 550-680° C.; after rolling, using laminar cooling with a laminar cooling front section rapid cooling rate of 80-120° C./s; C) Pickling and cold rolling after cooling, pickling the surface of strip steel to clean the mill scale, the cold rolling cumulative reduction rate being 60-80%; D) Continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium a. Continuous annealing performing continuous annealing in the non-oxidation continuous annealing aluminum-zinc plating or zinc-aluminum-magnesium plating furnace; the annealing treatment sequentially including a heating section, a soaking section, and a pre-plating cooling section; wherein, one-stage or two-stage heating is used in the heating section; when one-stage rapid heating is used, the heating rate is 30-300° C./s; when two-stage rapid heating is used, heating is performed from room temperature to 550-620° C. at a heating rate of 10-300° C./s in the first stage, and from 550-620° C. to 770-850° C. at a heating rate of 30-300° C./s in the second stage; afterwards, performing soaking at a soaking temperature of 770-850° C. for a soaking time of 1-20 s; then rapidly cooling to 550-600° C. at a cooling rate of 30-150° C./s; b. Hot-dipping aluminum-zinc or hot-dipping zinc-aluminum-magnesium after annealing, performing hot-dipping aluminum-zinc at a temperature of 550-600° C.; then rapidly cooling from 550-600° C. to room temperature at a cooling rate of 30-200° C./s to obtain hot-dipped aluminum-zinc AZ products; or after annealing, performing hot-dipping zinc-aluminum-magnesium at a temperature of 550-600° C.; then rapidly cooling from 550-600° C. to room temperature at a cooling rate of 30-180° C./s to obtain hot-dipped zinc-aluminum-magnesium AM products; E) Finishing and straightening the temper rolling rate: 0.25%±0.2, the straightening rate: 0.2%±0.2. 18. The method according to the whole process of the continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium in step D) takes a time of 22-80 s; and/or in step B), the hot rolling tapping temperature is 1180-1220° C.; and/or in step B), the hot rolling finishing temperature is 860-880° C.; and/or in step B), the coiling temperature is 570-620° C.; and/or in step B), the laminar flow front section rapid cooling rate is 100-120° C./s; and/or in step C), the cumulative cold rolling reduction rate is 60-70%; and/or in step D), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s; and/or in step D), when two-stage heating is used in the rapid heating, the heating is performed from room temperature to 550-620° C. at a heating rate of 30-300° C./s in the first stage, and from 550-620° C. to 770-850° C. at a heating rate of 50-300° C./s in the second stage; and/or in the soaking process of step D), the strip steel or steel plate is heated to the target temperature of austenite and ferrite two-phase area; and the temperature is kept constant for soaking; and/or in the soaking process of step D), the strip steel or steel plate is subjected to a small increase in temperature or a small decrease in temperature during the soaking time period with the temperature not exceeding 850° C. after the temperature increase and not falling below 770° C. after the temperature decrease; and/or the soaking time period is 10-20 s. 19. The hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to 1) Smelting and casting smelting and casting the above-mentioned chemical components into slabs; 2) Hot rolling and cooling the hot rolling tapping temperature: 1150-1250° C., the hot rolling finishing temperature: 830-890° C., the coiling temperature: 520-680° C.; after rolling, using laminar flow cooling with a laminar flow front section rapid cooling rate of 80-120° C./s; 3) Pickling and cold rolling after cooling, pickling the surface of strip steel to clean the mill scale, the cold rolling cumulative reduction rate being 60-80%; 4) Continuous annealing, hot-dipping aluminum-zinc, or hot-dipping zinc-aluminum-magnesium performing continuous annealing in the non-oxidation continuous annealing aluminum-zinc plating or zinc-aluminum-magnesium plating furnace; the annealing treatment sequentially including a heating section, a soaking section, and a pre-plating cooling section; wherein, one-stage or two-stage heating is used in the heating section; when one-stage rapid heating is used, the heating rate is 30-300° C./s; when two-stage rapid heating is used, the heating is performed from room temperature to 550-625° C. at a heating rate of 10-300° C./s in the first stage, and from 550-625° C. to 750-850° C. at a heating rate of 30-300° C./s in the second stage; afterwards, performing soaking at a soaking temperature of 750-840° C. for a soaking time of 1-20 s; then rapidly cooling to 550-600° C. at a cooling rate of 30-150° C./s; performing hot-dipping aluminum-zinc or hot-dipping zinc-aluminum-magnesium; after hot-dipping aluminum-zinc, cooling to room temperature at a cooling rate of 30-200° C./s to obtain hot-dipped aluminum-zinc AZ products; or after hot-dipping zinc-aluminum-magnesium, cooling to room temperature at a cooling rate of 30-180° C./s to obtain hot-dipped zinc-aluminum-magnesium AM products; 5) Finishing and straightening the temper rolling rate: 0.25%±0.2, the straightening rate: 0.2%±0.2. 20. The hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to the whole process of continuous annealing, hot-dipping aluminum-zinc or hot-dip zinc-aluminum-magnesium multiphase steel takes a time of 22-80.5 s, 22-80 s or 23-66 s; and/or in the step 2), the hot rolling tapping temperature is 1180-1220° C.; and/or in the step 2), the hot rolling finishing temperature is 850-880° C., 850-870° C. or 860-880° C.; and/or in the step 2), the coiling temperature is 550-620° C. or 570-620° C.; and/or in the step 2), the laminar flow front section rapid cooling rate is 100-120° C./s; and/or in the step 3), the cold rolling cumulative reduction rate is 60-70%; and/or in the step 4), when one-stage heating is used in the rapid heating, the heating rate is 50-300° C./s; and/or in the step 4), when two-stage rapid heating is used in the rapid heating, the heating is performed from room temperature to 550-620° C. or 550-625° C. at a heating rate of 30-300° C./s in the first stage, and from 550-620° C. or 550-625° C. to 760-840° C. or 770-850° C. at a heating rate of 50-300° C./s in the second stage. 21. The hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to in the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel, the content of C is 0.06-0.08%; the content of Si is 0.15-0.30%; and the content of Mn is 1.0-1.3%; or the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a yield strength ≥450 MPa, or 450-515 MPa or 450-540 MPa; a tensile strength ≥500 MPa, or 510-590 MPa or 510-580 MPa; and an elongation ≥20%, or 20-26.5% or 21-26%. 22. The hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel having a yield strength of greater than or equal to 450 MPa according to the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a yield strength ≥550 MPa; and/or in the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel, the content of C is 0.08-0.10%; the content of Si is 0.15-0.30%; the content of Mn is 1.2-1.6%; and/or the hot-dipped aluminum-zinc or hot-dipped zinc-aluminum-magnesium multiphase steel has a yield strength ≥550 MPa, or 550-625 MPa or 550-615 MPa; a tensile strength ≥600 MPa, or 615-700 MPa; and an elongation ≥14%, or 14-17.5% or 14-17%.TECHNICAL FIELD
BACKGROUND
SUMMARY
0.25≤(C+Mn/6)≤0.40;
Mn/S≥150;In the Composition of the Steel Designed According to the Present Invention:
Beneficial Effects of the Present Invention
DESCRIPTION OF FIGURES
DETAILED DESCRIPTION
Example I
(unit: mass percentage) Test Steel C Si Mn P S Nb Ti Cr N A 0.07 0.15 1.4 0.010 0.007 / 0.035 0.40 0.0005 B 0.08 0.18 1.6 0.012 0.008 0.018 0.015 0.30 0.002 C 0.10 0.20 1.2 0.014 0.005 0.020 0.010 0.25 0.003 D 0.09 0.30 1.0 0.008 0.006 0.025 0.020 0.15 0.004 E 0.06 0.08 1.5 0.009 0.004 0.030 0.030 0.05 0.0025 F 0.10 0.15 1.1 0.011 0.003 0.035 / 0.38 0.001 Laminar Continuous annealing (one-stage) the whole Hot Hot flow Cold Rapid time for roll- roll- front rolling cool- Cool- rapid ing ing section cumula- Rapid Rapid ing Hot ing heat tap- finish- Coil- rapid tive heat- Soak- Soak- cool- end- dipp- rate treatment, ping ing ing cooling reduc- ing ing ing ing point ing after hot-dipping temp. temp. temp. rate tion rate temp. time rate temp. temp. plating AZ or hot- ° C. ° C. ° C. ° C./s rate % ° C./s ° C. periods ° C./s ° C. ° C. ° C./s dipping AMs Example 1 1150 870 550 80 60 50 820 10 80 550 550 100 34.7 Example 2 1230 860 520 92 80 150 780 15 120 560 560 180 24.9 Example 3 1250 890 600 112 72 250 840 8 30 575 575 200 22.9 Example 4 1170 830 580 120 75 300 800 20 150 585 585 150 27.8 Example 5 1200 850 620 105 65 100 790 5 50 590 590 80 23.8 Example 6 1220 860 650 98 78 30 750 1 100 600 600 30 46.2 Conv. 1230 860 650 75 70 11 770 160 40 585 585 30 251.6 Process 1 Conv. 1230 860 630 62 80 10 790 130 50 590 590 40 225.3 Process 2 Conv. 1250 890 600 72 72 11 810 110 45 597 597 35 203.0 Process 3 Conv. 1270 830 580 50 75 13 830 90 60 598 598 45 169.0 Process 4 Conv. 1200 850 620 75 80 15 845 70 50 586 586 25 152.8 Process 5 Conv. 1220 860 640 55 80 11 770 160 30 585 585 30 253.2 Process 6 Laminar Continuous annealing (two-stage) the whole Hot Hot flow Cold Heat- Temp. Heat- Rapid time for roll- roll- front rolling ing after ing cool- Cool- the rapid ing ing section cumula- rate the rate Rapid ing Hot ing heat tap- finish- Coil- rapid tive of the first of the Soak- Soak- cool- end- dipp- rate treatment, ping ing ing cooling reduc- first stage second ing ing ing point ing after hot-dipping temp. temp. temp. rate tion stage heating stage temp. time rate temp. temp. plating AZ or hot- ° C. ° C. ° C. ° C./s rate % ° C./s ° C. ° C./s ° C. periods ° C./s ° C. ° C. ° C./s dipping AMs Example 7 1150 870 550 80 60 10 550 30 790 1 150 550 550 200 66.3 Example 8 1230 860 520 92 80 30 560 150 750 5 120 560 560 100 31.3 Example 9 1250 890 600 112 72 80 570 250 840 10 100 575 575 150 24.3 Example 10 1180 830 580 120 75 150 600 300 785 12 80 585 585 70 27.1 Example 11 1200 850 620 105 69 300 625 100 820 20 50 590 590 180 31.7 Example 12 1220 880 650 98 65 200 580 50 770 18 30 600 600 30 50.1 Conv. 1260 860 650 75 60 10 150 7 790 130 40 590 590 30 258.4 Process 7 Conv. 1230 860 630 62 80 11 180 6 810 110 50 597 597 40 248.2 Process 8 Conv. 1250 890 600 72 72 13 210 5 830 90 45 598 598 35 250.3 Process 9 Conv. 1270 830 580 50 75 15 250 5 845 70 60 586 586 45 221.2 Process 10 Conv. 1200 850 620 75 80 11 150 8 770 160 50 585 585 25 275.6 Process 11 Conv. 1220 860 640 55 80 10 150 7 790 130 30 600 600 30 260.1 Process 12 1 A Example 1 485 538 23.4 2 B Example 2 505 555 22.2 3 C Example 3 505 565 22.0 4 D Example 4 510 580 21.2 5 E Example 5 470 530 24.8 6 F Example 6 455 515 26.1 7 A Conv. Process 1 423 518 22.0 8 B Conv. Process 2 422 510 23.0 9 C Conv. Process 3 430 515 22.8 10 D Conv. Process 4 418 508 24.6 11 E Conv. Process 5 415 502 24.5 12 F Conv. Process 6 412 492 25.5 1 A Example 7 500 548 23.4 2 B Example 8 505 555 21.2 3 C Example 9 515 575 22.0 4 D Example 10 510 585 20.2 5 E Example 11 480 540 23.8 6 F Example 12 465 525 25.1 7 A Conv. Process 7 433 518 22.0 8 B Conv. Process 8 412 510 23.8 9 C Conv. Process 9 420 525 22.8 10 D Conv. Process 10 408 508 24.2 11 E Conv. Process 11 415 505 24.5 12 F Conv. Process 12 422 512 24.5 Example II
(unit: mass percentage) Steel No. C Si Mn P S Nb Ti Cr N A 0.090 0.15 1.8 0.010 0.012 / 0.045 0.30 0.003 B 0.075 0.18 1.6 0.015 0.010 0.035 0.020 0.35 0.001 C 0.120 0.30 1.5 0.009 0.006 0.025 0.030 0.25 0.009 D 0.105 0.05 1.2 0.008 0.005 0.030 0.025 0.50 0.008 E 0.088 0.08 1.3 0.012 0.008 0.033 0.035 0.40 0.002 F 0.100 0.20 1.4 0.013 0.009 0.045 / 0.35 0.005 Laminar Continuous annealing (one-stage) the whole Hot Hot flow Cold Rapid time for roll- roll- front rolling cool- Cool- the rapid ing ing section cumula- Rapid ing Rapid Hot ing heat tap- finish- Coil- rapid tive heat- Soak- Soak- end- cool- dipp- rate treatment, ping ing ing cooling reduc- ing ing ing point ing ing after hot-dipping temp. temp. temp. rate tion rate temp. time temp. rate temp. plating AZ or hot- Example ° C. ° C. ° C. ° C./s rate % ° C./s ° C. periods ° C. ° C./s ° C. ° C./s dipping AMs Example 1 1220 880 580 80 60 30 790 1 550 80 550 200 32.3 Example 2 1230 860 550 95 80 80 780 5 565 130 565 100 21.6 Example 3 1250 890 600 115 72 200 835 20 570 100 570 150 30.4 Example 4 1170 850 600 120 75 300 785 18 585 150 585 70 30.0 Example 5 1200 845 680 100 79 100 770 15 590 60 590 180 28.7 Example 6 1220 860 650 85 65 50 850 12 600 30 600 30 56.3 Conv. 1220 880 580 75 60 15 845 70 586 40 586 40 145.6 Process 1 Conv. 1230 860 550 62 80 11 770 160 585 50 585 35 248.0 Process 2 Conv. 1250 890 600 72 72 10 790 130 600 45 600 45 224.1 Process 3 Conv. 1170 850 580 50 75 11 810 110 590 60 590 25 208.3 Process 4 Conv. 1200 850 680 75 80 13 830 90 580 50 580 30 176.0 Process 5 Conv. 1220 860 650 55 80 15 845 70 585 30 585 30 152.5 Process 6 Laminar Continuous annealing (two-stage) the whole Hot Hot flow Cold Heat- Temp. Heat- Rapid time for roll- roll- front rolling ing after ing cool- Cool- the rapid ing ing section cumula- rate the rate ing Rapid Hot ing heat tap- finish- Coil- rapid tive of the first of the Soak- Soak- end- cool- dipp- rate treatment, ping ing ing cooling reduc- first stage second ing ing point ing ing after hot-dipping temp. temp. temp. rate tion stage heating stage temp. time temp. rate temp. plating AZ or hot- Example ° C. ° C. ° C. ° C./s rate % ° C./s ° C. ° C./s ° C. periods ° C. ° C./s ° C. ° C./s dipping AMs Example 7 1230 860 550 80 60 200 560 30 790 18 550 30 550 200 39.0 Example 8 1230 860 680 92 80 30 580 80 780 5 560 120 560 100 33.4 Example 9 1250 890 600 112 72 80 570 250 850 10 575 100 575 150 24.4 Example 10 1170 830 580 120 75 120 600 300 770 12 585 150 585 70 26.7 Example 11 1200 850 620 105 80 300 620 100 820 20 590 80 590 180 30.0 Example 12 1220 860 640 98 80 10 550 50 800 1 600 100 600 30 80.3 Conv. 1230 860 550 75 68 15 250 5 845 70 586 40 586 30 229.7 Process 7 Conv. 1230 860 530 62 80 11 150 8 770 160 585 50 585 40 267.1 Process 8 Conv. 1250 890 600 72 72 10 150 7 790 130 600 45 600 35 255.2 Process 9 Conv. 1170 830 580 50 75 11 180 6 810 110 590 60 590 45 245.9 Process 10 Conv. 1200 850 620 75 80 13 210 5 830 90 580 50 580 25 256.0 Process 11 Conv. 1220 860 640 55 80 15 250 5 845 70 585 30 585 30 231.8 Process 12 1 A Example 1 585 638 16.4 2 B Example 2 600 655 15.4 3 C Example 3 570 665 15.0 4 D Example 4 605 660 15.2 5 E Example 5 615 700 14.8 6 F Example 6 565 615 17.1 7 A Conv. Process 1 505 605 15.5 8 B Conv. Process 2 515 610 15.4 9 C Conv. Process 3 491 595 17.0 10 D Conv. Process 4 510 600 15.2 11 E Conv. Process 5 503 585 16.5 12 F Conv. Process 6 515 580 18.8 1 A Example 7 595 638 15.4 2 B Example 8 600 645 15.2 3 C Example 9 580 655 15.0 4 D Example 10 615 670 15.2 5 E Example 11 625 700 14.8 6 F Example 12 595 618 16.1 7 A Conv. Process 7 515 608 16.4 8 B Conv. Process 8 510 605 16.2 9 C Conv. Process 9 500 588 17.0 10 D Conv. Process 10 509 610 15.2 11 E Conv. Process 11 501 595 17.8 12 F Conv. Process 12 515 580 18.1
0.25≤(C+Mn/6)≤0.40;
Mn/S≥150;
