TWI711718B - Method for manufacturing hot-dipped galvanized steel sheet - Google Patents

Abstract

A hot-dipped galvanized steel sheet and a method for manufacturing the same are described. In this method, a cold rolled steel sheet is prepared, in which the cold rolled steel sheet includes carbon with a weight percentage from 0.05% to 0.65%, manganese with a weight percentage from 4.0% to8.0%, aluminum with a weight percentage from 1.0% to 4.0%, silicon with a weight percentage from 0.1% to 2.0%, insignificant impurities, and balance iron. A continuous annealing step is performed on the cold rolled steel sheet to obtain an annealed steel sheet. A hot dip galvanizing step is performed to dip the annealed steel sheet in a zinc bath, so as to obtain a zinc-coated steel sheet, in which the zinc bath includes aluminum with a weight percentage from 3.0% to 10.0%. An alloying treatment is performed on the zinc-coated steel sheet to obtain the hot-dipped galvanized steel sheet.

Description

Manufacturing method of hot-dip galvanized steel sheet

The embodiment of the present invention relates to a steel sheet manufacturing technology, and particularly relates to a hot-dip galvanized steel sheet and a manufacturing method thereof.

Because of its high strength and high elongation, hot-dip galvanized steel sheets are generally used in the manufacture of automobile bodies, which can effectively reduce the weight of the car body and improve the fuel efficiency of automobiles. The high-strength hot-dip galvanized steel sheets currently used in the manufacture of automobile bodies are mainly dual-phase steels with strength grades of 780MPa to 1180MPa, with an elongation of about 10% to 20%. In addition, some auto parts use phase transformation induced plasticity steel with a strength grade of 780MPa, which has a better elongation than dual-phase steel, up to 25%.

However, the poor hot-dip galvanizing properties of high-strength bidirectional steel containing manganese (Mn), silicon (Si), and aluminum (Al) and transformation-induced plasticity steel are a major problem in steel production. Japan's Nippon Steel & Sumikin Co., Ltd. proposed a technical proposal for manganese-silicon high-strength steel. This technical scheme has made the following specifications for the composition of steel with good galvanizing properties: 3-([Si]+[Mn]/10+[Al]/3)-12.5*([Al] _Zn -[Mn] _Zn )≧0 where [Si], [Mn], and [Al] are the alloy content of silicon, manganese, and aluminum in the steel respectively, [Al] _Zn and [Mn] _Zn are the content of aluminum and manganese in the coating, respectively Alloy content. For example, under this specification, when the coating does not contain manganese, the content of silicon in steel containing 2.0wt% manganese must be limited to 1.0wt% or less. In addition, this technical solution limits the content of manganese to less than 3.0wt%.

Nippon Steel & Sumikin Co., Ltd. then put forward another technical proposal, in which the composition range of hot-dip galvanized high-strength steel is 0.075wt%~0.400wt% carbon (C), 0.01wt%~2.00wt% silicon, 0.80wt% wt%~3.50wt% manganese and 0.001wt%~2.00wt% aluminum, and the tensile strength of this hot-dip galvanized high-strength steel is higher than 900MPa. The feature of this hot-dip galvanized high-strength steel is that the steel contains more than 3.0% high-carbon residual austenitic iron, and the grain size is small (<2μm). This technical solution uses the method of oxidation first and then reduction in the annealing process to avoid the generation of selective oxides. In addition, a small amount of tensile stress (5MPa~100MPa) and small roll diameter (800mm) bending are applied before the steel strip enters the zinc tank to destroy the continuous pure iron reduction layer generated on the surface and avoid the pure iron reduction layer to cause the galvanized layer to be formed.时 stripped.

Nippon Steel & Sumitomo Metal Co., Ltd. later also proposed two technical solutions, which aimed at steels containing 0.02wt%~0.2wt% carbon and 0.15wt%~2.5wt% manganese before hot-dip galvanizing the steel sheet surface. Apply a layer of electroplated nickel pretreatment.

The technical solution proposed by Nippon Steel & Sumikin Co., Ltd. is basically for the first generation of advanced high-strength steel (manganese + silicon + aluminum <5wt%). South Korea’s Pohang Iron and Steel Co., Ltd. proposed a new type of steel for high strength and high elongation Technical solutions for ingredients and processes. In this technical solution, the composition of the steel includes 0.2wt%~1.5wt% carbon, 10wt%~25wt% manganese, 0.01wt%~3.0wt% aluminum, 0.005wt%~2.0wt% silicon, <0.03 wt% phosphorus (P), <0.03wt% sulfur (S), and <0.040wt% nitrogen (N). The process of this technical solution includes the use of steel billet reheating temperature (SRT) of 1050℃~1300℃, finishing temperature (FT) of 850℃~950℃, and coil temperature (CT) of ≦700℃. The rolled plate and the cold rolled plate produced by the above process are then subjected to electro-galvanized or hot-dip galvanized surface treatment to obtain a steel plate.

Yonsei University in South Korea proposed a technology for high-strength and high-elongation steels with 1.0wt%~1.4wt% carbon, 5.0wt%~9.0wt% manganese, and 2.0wt%~8.0wt% chromium Program. This technical solution and the above-mentioned Pohang Iron and Steel Company's technical solution are both the second-generation and third-generation advanced high-strength steels with a full-scale iron structure and a manganese content higher than 5wt%. This technical solution uses a twin crystal induced plasticity (TWIP) mechanism to provide a high work hardening rate, and the Product of Strength and Elongation can reach more than 30 GPa%. The above-mentioned Pohang Steel's technical solution has a strong plastic product of up to 50 GPa%.

Japan JFE Steel Co., Ltd. proposes cold rolling for 0.06wt%~0.4wt% carbon, 1.0wt%~5.0wt% manganese, 0.05wt%~2.5wt% silicon, and 0.05wt%~2.5wt% aluminum Technical solution with hot-dip galvanized steel. The feature of this technical solution is the addition of elements such as nickel (Ni), copper (Cu), antimony (Sb), boron (B), and titanium (Ti), as well as rapid cooling to the toughened iron zone after annealing to obtain rich Contains the structure of small austenitic iron. The strength of the steel produced by this technical solution is higher than 780MPa, extending The rate is higher than 24%, and the strong plastic product is higher than 25GPa%. However, this technical solution does not specify the zinc bath composition of hot-dip galvanizing. Japan JFE Steel Co., Ltd. also proposes a hot-dip galvanizing process for steels with similar composition in this technical solution, which mainly utilizes high-speed heating (>7℃/s) and low dew point (<-45℃) in the heating zone. To suppress the enrichment of manganese and silicon on the surface.

South Korea’s Pohang Iron and Steel Company later put forward a technical proposal for 0.03wt%~0.35wt% carbon, 3.5wt%~10.0wt% manganese, 0.5wt%~3.0wt% silicon, and 0.15wt%~1.5 Cold rolled and hot dip galvanized steel with wt% aluminum. This technical solution uses hot-rolled sheet annealing to promote the enrichment of manganese in austenitic iron. The strength of the produced steel is higher than 1000MPa and the elongation is higher than 25%. However, this technical solution does not specify the galvanizing conditions.

Kobe Steel Co., Ltd. (Kobe Steel) also proposed a technical solution. For high-strength steel with a manganese content of 2wt% to 4wt% and a silicon content of less than 2wt%, the method of first oxidation and then reduction is used to form the secondary surface of the steel. The inner oxide layer overcomes the problems of hot-dip galvanizing and alloying.

According to the above technical solution, the current development of the third-generation high-strength steel is still focused on the composition and manufacturing process of the steel sheet, while the hot-dip galvanizing process has not yet been discussed.

Therefore, one of the objectives of the present invention is to provide a hot-dip galvanized steel sheet and its manufacturing method, which controls the content of silicon + aluminum + manganese between 5 wt% and 12 wt%, so as to ensure that the steel can be processed after the final heat treatment. Still retain more than 20% of the residual austenitic iron. In the subsequent processing and forming, the residual Voss Tiantie will induce the phase transformation of the scattered iron of the hemp and iron due to the strain, which can make the steel have high elongation and high strength.

Another object of the present invention is to provide a hot-dip galvanized steel sheet and a method for manufacturing the same. The high-strength steel sheet is galvanized in a zinc bath with an aluminum content of more than 3wt%, and then alloyed at an appropriate temperature. By chemical treatment, it is possible to obtain a hot-dip galvanized alloy coating with excellent plating properties and adhesion.

According to the above objective of the present invention, a method for manufacturing hot-dip galvanized steel sheet is proposed. In this method, a cold rolled steel sheet is prepared, wherein the cold rolled steel sheet contains 0.05wt% to 0.65wt% carbon, 4.0wt% to 8.0wt% manganese, 1.0wt% to 4.0wt% aluminum, and 0.1wt% to 2.0wt% silicon, unavoidable impurities, and a balanced amount of iron. The cold-rolled steel sheet is subjected to a continuous annealing step to obtain an annealed steel sheet. The annealed steel sheet is immersed in a zinc bath to perform a hot-dip galvanizing step to obtain a galvanized steel sheet, wherein the zinc bath contains 3.0wt% to 10.0wt% aluminum. The galvanized steel sheet is alloyed to obtain a hot-dip galvanized steel sheet.

According to an embodiment of the present invention, the above-mentioned preparing the cold-rolled steel sheet includes preparing a steel billet; performing a hot rolling process on the steel billet to obtain a hot-rolled steel sheet; performing a coil heat treatment on the hot-rolled steel sheet to obtain a hot-rolled steel coil; and The hot-rolled steel coil undergoes a cold-rolling process to obtain cold-rolled steel sheets.

According to an embodiment of the present invention, after the aforementioned coil heat treatment, the microstructure of the hot-rolled steel coil contains more than 20% austenitic iron, and the rest of the microstructure is fat iron.

According to an embodiment of the present invention, performing the cold rolling process includes controlling the thickness reduction rate of about 20% to about 70%.

According to an embodiment of the present invention, the above-mentioned continuous annealing step includes controlling: the soaking temperature is about 600°C to about 750°C; the annealing time is about 20 seconds to about 300 seconds; and the dew point of the heating zone and the soaking zone is about -40°C to about 0°C.

According to an embodiment of the present invention, between the continuous annealing step and the hot-dip galvanizing step, the method for manufacturing the hot-dip galvanized steel sheet further includes cooling the annealed steel sheet to a cooling rate of about 3°C to about 50°C About 400°C to about 550°C.

According to an embodiment of the present invention, the temperature of the aforementioned zinc bath is about 440° C. to about 500° C., and the hot-dip galvanizing step is performed for about 2 seconds to about 10 seconds.

According to an embodiment of the present invention, the temperature of the aforementioned alloying treatment is controlled below about 600° C., and the alloying treatment is performed for about 20 seconds.

According to an embodiment of the present invention, the aforementioned cold rolled steel sheet further contains nickel (Ni), and the total content of nickel and manganese is 5wt% to 8.0wt%.

According to an embodiment of the present invention, the total content of aluminum and silicon is less than 4wt%, and the total content of manganese, aluminum, and silicon is higher than 5wt% and less than 12wt%.

According to an embodiment of the present invention, the above-mentioned cold rolled steel sheet further contains titanium, vanadium (V), niobium (Nb), phosphorus, and copper, and the contents of titanium, vanadium, niobium, phosphorus, and copper are all less than 0.1wt%, And the total content of titanium, vanadium, niobium, phosphorus, and copper is less than 0.3wt%.

According to the above-mentioned object of the present invention, a hot-dip galvanized steel sheet is provided, which is produced by the method for manufacturing a hot-dip galvanized steel sheet described in any of the above embodiments. The surface of the hot-dip galvanized steel sheet includes an alloyed coating, and the alloyed coating is composed of FeAl/FeZn ₁₀ (δ phase)/FeZn ₇ (Γ phase).

According to an embodiment of the present invention, the thickness of the aforementioned FeZn ₇ (Γ phase) is less than about 1 μm, and the volume fraction of FeZn ₁₀ (δ phase) in the alloyed coating is greater than about 80%.

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In order to make the above and other objects, features, advantages and embodiments of the present invention more comprehensible, the description of the accompanying drawings is as follows: [Figure 1] shows a hot dip galvanizing according to one embodiment of the present invention Flow chart of the manufacturing method of steel sheet.

In view of the fact that there have not been too many discussions and achievements on the hot-dip galvanizing process of the third-generation high-strength steel in the prior art, the embodiment of the present invention proposes a hot-dip galvanized steel sheet and a manufacturing method thereof, which combines silicon + The content of aluminum + manganese is controlled between 5wt%~12wt%, so as to obtain the dual phase structure of fertilizer grain iron and austenitic iron of more than 20%, and the average particle size of fertilizer grain iron and austenitic iron is less than 1μm, and Cold rolled steel sheet with mechanical properties with tensile strength higher than 1000MPa and elongation higher than 20% can be produced. Then hot-dip galvanizing the cold-rolled steel sheet in a zinc bath with an aluminum content of 3wt% or more can form a dense Fe ₃ Al ₁₃ phase galvanized layer at the interface between the steel and the galvanized layer, which can be obtained after alloying heat treatment Hot-dip galvanized alloy coating with uniform surface and excellent adhesion.

Please refer to FIG. 1, which shows a flow chart of a method for manufacturing a hot-dip galvanized steel sheet according to an embodiment of the present invention. When manufacturing hot-dip galvanized steel sheets, step 100 may be performed first to prepare cold-rolled steel sheets. The cold rolled steel sheet may, for example, contain carbon, manganese, aluminum, silicon, unavoidable impurities, and a balanced amount of iron. In some embodiments, the total content of manganese, aluminum, and silicon in the composition of the cold-rolled steel sheet may be higher than 5wt% and lower than 12wt%, so as to ensure that the steel can obtain more than 20% residual austin after the final heat treatment. iron. Since the austenitic iron phase requires more solid solution carbon, if too much carbide is precipitated, the solid solution carbon will be insufficient, which will make the austenitic iron unstable and difficult to retain at room temperature. Aluminum and silicon can be used as elements that inhibit the precipitation of carbides and regulate the superimposition energy of steel. However, the excessive content of aluminum and silicon may generate undesired phases in the steel structure, such as the ferrite phase. Therefore, in some cases, the total content of aluminum and silicon in the cold rolled steel sheet is controlled to be less than 4wt%. In some exemplary examples, the cold rolled steel sheet may contain 0.05wt% to 0.65wt% carbon, 4.0wt% to 8.0wt% manganese, 1.0wt% to 4.0wt% aluminum, and 0.1wt% to 2.0wt% silicon , Inevitable impurities, and the balance of iron.

In some embodiments, nickel can be added to the cold rolled steel sheet as a stabilizing element of austenitic iron. The total content of nickel and manganese may be, for example, 5.0 wt% to 8.0 wt%. When the total content of nickel and manganese is less than 5.0wt%, the austenitic iron phase in the cold-rolled steel sheet may not reach 20%, and the steel sheet cannot obtain the required elongation. In some examples, the cold rolled steel sheet can be further added with titanium, vanadium, niobium, phosphorus, and copper as solid solution and precipitation strengthening elements, wherein the contents of titanium, vanadium, niobium, phosphorus, and copper are all less than 0.1wt%, and The total content of titanium, vanadium, niobium, phosphorus, and copper is less than 0.3wt%.

Please continue to refer to FIG. 1, in some embodiments, when preparing the cold-rolled steel sheet, step 102 may be performed first to prepare the steel blank. For example, a continuous casting process can be used to produce steel blanks. Next, step 104 may be performed to perform a hot rolling process on the steel blank to obtain a hot rolled steel sheet. Next, step 106 may be performed to perform a coil heat treatment on the hot-rolled steel sheet, and the hot-rolled steel sheet is coiled into a hot-rolled steel coil. In some cases, the microstructure of the hot-rolled steel coil contains more than 20% austenitic iron, and the remaining part of the microstructure of the hot-rolled steel coil is fat iron. After the coil heat treatment of the hot-rolled steel sheet is completed, step 108 may be performed to perform a cold-rolling process on the hot-rolled steel coil to obtain the cold-rolled steel sheet. For example, performing the cold rolling process includes controlling the thickness reduction rate from about 20% to about 70%. In some exemplary cases, the hot-rolled steel coil may be pickled first after the heat treatment of the coil and before the cold-rolling process to remove the oxide layer on the surface of the hot-rolled steel sheet.

After the manufacture of the cold-rolled steel sheet is completed, step 110 may be performed to perform a continuous annealing step on the cold-rolled steel sheet to obtain an annealed steel sheet. In some examples, when the cold-rolled steel sheet is subjected to a continuous annealing step, the cold-rolled steel sheet can be performed at a uniform temperature of about 600°C to about 750°C, and the annealing time is about 20 seconds to about 300 seconds, and heating The dew point of the zone and the soaking zone is controlled at about -40°C to about 0°C. In addition, when performing continuous annealing, the hydrogen content in the annealing atmosphere may be higher than 5%. After continuous annealing, the annealed steel sheet has a dual phase structure of fat grain iron and more than 20% austenitic iron. The average particle size of ferrite iron and austenitic iron is less than 1μm, so the dual phase structure below the average particle size can provide the high strength required by steel. The residual austenitic iron will induce the phase transformation of the fluffy iron scattered iron due to strain during the subsequent processing and forming, which can make the steel have high elongation and high strength. because Therefore, the annealed steel sheet may have mechanical properties with a tensile strength higher than 1000 MPa and an elongation higher than 20%.

Then, in some examples, step 120 may be optionally performed to perform a cooling step on the annealed steel sheet, and the temperature of the annealed steel sheet is reduced to about 400°C to about 550°C at a cooling rate of about 3°C to about 50°C.

After the cooling of the annealed steel sheet is completed, step 130 may be performed to immerse the annealed steel sheet in a zinc bath to perform a hot dip galvanizing step to obtain a galvanized steel sheet. In some embodiments, the zinc bath includes 3.0 wt% to 10.0 wt% aluminum. When the aluminum content in the zinc bath is less than 3.0wt%, the coating effect of zinc is not good; and when it is greater than 10wt%, the proportion of iron and zinc in the coating is low, which is not the purpose of the hot-dip galvanizing step. In addition, the temperature of the zinc bath may be, for example, about 440° C. to about 500° C., and the hot-dip galvanizing step of annealing the steel sheet may be performed for about 2 seconds to about 10 seconds. The galvanized steel sheet can mainly include steel and a galvanized layer coated on the surface of the steel. In some exemplary cases, the hot-dip galvanizing step can form a dense Fe ₄ Al ₁₃ phase galvanized layer at the interface.

The inventor found that when the hydrogen content in the annealing atmosphere of continuous annealing is higher than 5% and the dew point is between -40°C and 0°C, a dense oxide layer with a thickness of more than 100nm will be formed on the surface of the steel. The layer is mainly composed of manganese monoxide (MnO) and a small amount of oxides containing aluminum and silicon. The dense oxide layer can increase the aluminum content in the zinc bath to more than 3wt%, and the manganese monoxide in the dense oxide layer can be reduced and removed by the thermite reduction reaction, thereby making the Fe ₄ Al ₁₃ intermetallic compound available in The formation of the iron-zinc interface can greatly improve the wettability of the zinc liquid on the steel surface.

After the hot-dip galvanizing step is completed, step 140 may be performed to perform alloying treatment on the galvanized steel sheet to obtain a hot-dip galvanized steel sheet. In some examples, during the alloying treatment, the temperature may be controlled below about 600° C., and the alloying treatment may be performed for about 20 seconds. After the alloying treatment, the surface of the hot-dip galvanized steel sheet contains an alloyed coating. For example, this alloyed coating can be composed of FeAl/FeZn ₁₀ (δ phase)/FeZn ₇ (Γ phase), where FeZn ₇ (Γ phase) is closest to the steel, FeAl is the outermost, and FeZn ₁₀ (δ phase) It is between FeZn ₇ (Γ phase) and FeAl. In some exemplary examples, the thickness of FeZn ₇ (Γ phase) in the alloyed coating is less than about 1 μm, and the volume fraction of FeZn ₁₀ (δ phase) in the alloyed coating is greater than about 80%.

Since the Fe ₄ Al ₁₃ intermetallic compound formed at the iron-zinc interface during the hot-dip galvanizing step can greatly improve the wettability of the zinc liquid on the steel surface, the alloying coating has a good coating effect after the alloying treatment, and The alloyed coating has excellent adhesion. In some examples, the density of unplated dots with a thickness of the alloyed coating layer greater than 0.5 mm is lower than 1 dot/100 mm ² . In addition, after the alloying treatment, the tensile strength of the hot-dip galvanized steel sheet can be higher than 1000MPa, the total elongation is higher than 20%, and the strong plastic product is higher than 25GPa%.

The following uses a number of embodiments and comparative examples to more specifically describe the technical content and effects of the above-mentioned embodiments of the present invention, but they are not intended to limit the present invention.

The steel composition of Comparative Example 1 contained 1.5wt% manganese, 1.2wt% silicon, and 0.15wt% carbon, and the steel composition of several examples contained 5.7wt% manganese, 1.6wt% aluminum, 1.6wt% silicon, and 0.16wt% carbon. Comparative example 1 and these several examples of steel after hot rolling and cold rolling process, compare Example 1 was annealed at 800°C, while the examples were annealed at 700°C, 725°C, and 750°C, respectively, and were subjected to tensile tests after cooling at 3°C/s, 20°C/s, and 50°C/s. . The test results show that the tensile strength of the steel sheet of Comparative Example 1 is only 815 MPa, the uniform elongation is 25%, the total elongation is 30%, and the strong plastic product is 24 GPa%. The mechanical properties of Comparative Example 1 are better than those of general first-generation advanced high-strength steels. The tensile strengths of the steel sheets in these examples are all over 1000 MPa, and the highest tensile strength of the steel sheets in these examples can reach 1300 MPa. The total elongation of the steel sheets in these examples can be at least 22% and the total elongation is the highest. It can reach 34%, so the strong plastic product of the steel sheets of these examples is 29 GPa% to 37 GPa%, which are far better than Comparative Example 1.

The steel composition of Comparative Example 2 contained 5.7wt% manganese, 1.6wt% aluminum, 1.6wt% silicon, and 0.16wt% carbon. The steel of Comparative Example 2 was subjected to hot rolling process and cold rolling process, annealed at 800° C., and then subjected to a hot dip galvanizing process in a zinc bath with an aluminum content of 0.2 wt%, and then subjected to an alloying treatment at 500° C. Comparative Example 2 The surface of the hot-dip galvanized steel sheet after the alloying treatment has a lot of unplated spots, and after the alloy coating is removed by pickling, it shows that the interface between iron and zinc cannot form a uniformly distributed iron-aluminum intermetallic layer , This means that the adhesion of the coating is poor.

The steel composition of another embodiment also includes 5.7% by weight manganese, 1.6% by weight aluminum, 1.6% by weight silicon, and 0.16% by weight carbon. After hot rolling and cold rolling, the steel of this embodiment is annealed at 800°C, and then subjected to a hot-dip galvanizing process in a zinc bath with an aluminum content of 4.5wt% to 10wt%, and then alloyed at 500°C . The surface structure of the alloyed hot-dip galvanized steel sheet of this embodiment is complete and there are no unplated spots, and the alloy plating layer is pickled and removed, showing that there is a difference between iron and zinc A uniformly distributed iron-aluminum intermetallic layer is formed at the interface, which means that the adhesion of the coating is excellent.

It can be seen from the above-mentioned embodiments that one of the advantages of the present invention is that the embodiment of the present invention controls the content of silicon + aluminum + manganese to be between 5 wt% and 12 wt%, so as to ensure that the steel can still retain 20% after the final heat treatment. More than% of residual austenitic iron. In the subsequent processing and forming, the residual austenitic iron will induce the phase transformation of the hemp iron scattered iron due to the strain, which can make the steel have high elongation and high strength.

It can be seen from the above-mentioned embodiments that another advantage of the present invention is that the embodiment of the present invention is to perform galvanizing operations on high-strength steel sheets in a zinc bath with an aluminum content of more than 3wt%, and then alloying them at an appropriate temperature By this treatment, it is possible to obtain a hot-dip galvanized alloy plating layer with excellent plating properties and adhesion.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in this technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to those defined by the attached patent application scope.

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Claims (12)

A method for manufacturing a hot-dip galvanized steel sheet includes: preparing a cold-rolled steel sheet, wherein the cold-rolled steel sheet contains: 0.05wt% to 0.65wt% carbon; 4.0wt% to 8.0wt% manganese; 1.0wt% to 4.0wt% aluminum; 0.1wt% to 2.0wt% silicon; unavoidable impurities; and iron in balance; perform a continuous annealing step on the cold rolled steel sheet to obtain an annealed steel sheet; the annealed steel sheet Immersing in a zinc bath to perform a hot-dip galvanizing step to obtain a galvanized steel sheet, wherein the zinc bath contains 3.0wt% to 10.0wt% aluminum; and performing an alloying treatment on the galvanized steel sheet, The hot-dip galvanized steel sheet is obtained, wherein one surface of the hot-dip galvanized steel sheet includes an alloyed coating, and the alloyed coating is composed of FeAl/FeZn ₁₀ (δ phase)/FeZn ₇ (Γ phase). For example, the method for manufacturing hot-dip galvanized steel sheet in the first item of the patent application, wherein preparing the cold-rolled steel sheet includes: preparing a steel blank; performing a hot rolling process on the steel blank to obtain a hot-rolled steel sheet; The hot-rolled steel sheet undergoes a coil heat treatment to obtain a hot-rolled steel coil; and A cold rolling process is performed on the hot rolled steel coil to obtain the cold rolled steel sheet. For example, the method for manufacturing hot-dip galvanized steel sheet in the second item of the scope of patent application, wherein after the heat treatment of the coil, a microstructure of the hot-rolled steel coil contains more than 20% austenitic iron, and the microstructure The rest is fat iron. For example, the method for manufacturing hot-dip galvanized steel sheet in the second item of the scope of patent application, wherein the cold rolling process includes controlling a thickness reduction rate of 20% to 70%. For example, the method for manufacturing a hot-dip galvanized steel sheet in the scope of the patent application, wherein performing the continuous annealing step includes controlling: a uniform temperature of 600°C to 750°C; an annealing time of 20 seconds to 300 seconds; and The dew point of one of the heating zone and a soaking zone is -40°C to 0°C. For example, the method for manufacturing hot-dip galvanized steel sheet in the fifth item of the scope of patent application, between the continuous annealing step and the hot-dip galvanizing step, further includes cooling the annealed steel sheet at a cooling rate of 3°C to 50°C To 400°C to 550°C. For example, the method for manufacturing hot-dip galvanized steel sheet in the sixth item of the scope of patent application, wherein the temperature of the zinc bath is 440°C to 500°C, and the hot-dip galvanizing step is performed for 2 seconds to 10 seconds. For example, the method for manufacturing hot-dip galvanized steel sheet in the first item of the scope of patent application, wherein the temperature of the alloying treatment is controlled below 600°C, and the alloying treatment is performed for 20 seconds. For example, the method for manufacturing hot-dip galvanized steel sheet in the first patent application, wherein the cold-rolled steel sheet further contains nickel, and the total content of the nickel and the manganese is 5wt% to 8.0wt%. For example, the method for manufacturing hot-dip galvanized steel sheet in the first item of the patent application, wherein the total content of the aluminum and the silicon is less than 4wt%, and the total content of the manganese, the aluminum, and the silicon is higher than 5wt% and low于12wt%. For example, the method for manufacturing hot-dip galvanized steel sheet in the first item of the patent application, wherein the cold-rolled steel sheet further contains titanium, vanadium, niobium, phosphorus, and copper, and each of the titanium, vanadium, niobium, phosphorus, The content with the copper is less than 0.1 wt%, and the total content of the titanium, the vanadium, the niobium, the phosphorus, and the copper is less than 0.3 wt%. For example, the method for manufacturing hot-dip galvanized steel sheet in the first item of the patent application, wherein the thickness of the FeZn ₇ (Γ phase) is less than 1 μm, and the volume fraction of the FeZn ₁₀ (δ phase) in the alloyed coating is greater than 80 %.

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