CN113528950B - Preparation method of hot-dip galvanized high-strength steel with good welding performance - Google Patents

Abstract

The embodiment of the present invention discloses a hot-dip galvanized high-strength steel with good welding performance and a preparation method thereof. The method includes: smelting and continuous casting using the chemical composition of the hot-dip galvanizing high-strength steel with good welding performance. , to obtain a continuous casting slab; heating the continuous casting slab before rolling or/and rough rolling, finishing rolling, cooling after rolling, and coiling to obtain a hot-rolled product; pickling and cooling the hot-rolled product Rolling, annealing, hot-dip galvanizing, heat treatment and skin-passing treatment to obtain the hot-dip galvanized high-strength steel with good welding performance; wherein, the temperature of the heat treatment is 70-400° C., and the time of the heat-treatment is 10-60 minutes, so that the The heat treatment is carried out in an atmosphere with a mass fraction of 1-3% hydrogen. The content of diffusible hydrogen in the hot-dip galvanized high-strength steel is less than or equal to 0.2ppm by adjusting the composition and the matching process, so that the hydrogen diffused during welding will not cause cracks to the material, thereby ensuring the welding performance of the material.

Description

A kind of preparation method of hot-dip galvanized high-strength steel with good welding performance

technical field

The embodiments of the present invention relate to the technical field of steel preparation, in particular to a hot-dip galvanized high-strength steel with good welding performance and a preparation method thereof.

Background technique

In recent years, the application of high-strength steel in the body has been increasing year by year with the increasing requirements for crash safety and lightweight in the automotive industry. As high-strength steel is used not only in structural parts, but also in other parts such as body panels, it needs to have better ductility on the basis of higher tensile strength.

Reference document 1: The patent application with the application number "201610542806.2" discloses a 1000MPa grade low-carbon hot-dip galvanized dual-phase steel and a preparation method thereof, belonging to the technical field of high-strength automotive steel, and the weight percentage composition is: C: 0.05-0.10 %, Si: 0.20-0.60%, Mn: 1.40-1.90%, Cr: 0.20-0.70%, Mo: 0.20-0.50%, Al: 0.02-0.06%, Ti: 0.020-0.050%, Nb: 0.010-0.040% , B: 0.0010 ~ 0.0030%, P≤0.015%, S≤0.005%, N≤0.006%, the balance is Fe and inevitable impurities. The yield strength is 630-700MPa, the tensile strength is 1010-1050MPa, and the elongation is 11-14%. Although the above-mentioned high-strength steel can achieve a strength of more than 1000 MPa through the composition system and manufacturing process, it also brings some negative effects. Due to the need to use hydrogen as a reducing atmosphere during the annealing process, a part of the hydrogen will enter the steel structure, and due to the subsequent galvanizing process, it is difficult to release the hydrogen from the steel plate. In the subsequent welding process of automobile parts, cracks will occur due to the release of hydrogen, which will affect the performance of the material.

Therefore, how to solve the problem of the deterioration of the welding performance of the galvanized high-strength steel sheet due to the release of hydrogen in the prior art has become an urgent technical problem to be solved.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present invention is to provide a hot-dip galvanized high-strength steel with good welding performance and a preparation method thereof. The prepared hot-dip galvanized high-strength steel has no cracks in the nugget after welding and has good welding performance.

In order to achieve the above purpose, the embodiment of the present invention provides a hot-dip galvanized high-strength steel with good welding performance, and the chemical composition of the steel is calculated as: C: 0.10-0.30%, Si: 1-2.5%, Mn in terms of mass fraction. : 1.8-2.3%, P: ≤ 0.01%, S: ≤ 0.01%, Al: 0.01-0.5%, N: 0.1-0.6%, and the rest are Fe and inevitable impurities.

Further, the chemical composition of the steel in terms of mass fraction is: C: 0.10-0.30%, Si: 1-2.5%, Mn: 1.8-2.3%, P: ≤ 0.01%, S: ≤ 0.01%, Al: 0.01-0.5%, N: 0.1-0.6%, alloying elements 0.005-0.5%, the alloying elements include at least one of Ti, Nb, V, Zr, Mo, Cr, Cu and Ni, and the rest are Fe and inevitable impurities.

Further, the metallographic structure of the steel matrix is calculated by volume fraction: 10-30% ferrite, 40%-80% martensite, ≤10% bainite and 4-20% residual Austenite.

Further, the grain size of the ferrite is 3 μm to 6 μm, the grain size of the martensite is 1 μm to 4 μm, the grain size of the bainite is 0.7 μm to 3.6 μm, and the residual The grain size of austenite is 0.6 μm to 1.8 μm.

The embodiment of the present invention also provides a preparation method of the hot-dip galvanized high-strength steel with good welding performance, the preparation method comprising:

Using the chemical composition of the hot-dip galvanized high-strength steel with good weldability, through smelting and continuous casting, continuous casting slabs are obtained;

The continuous casting slab is heated or/and rough rolled before rolling, followed by finish rolling, cooled after rolling and coiled to obtain a hot rolled product;

The hot-rolled finished product is pickled, cold-rolled, annealed, hot-dip galvanized, heat-treated and smoothed to obtain the hot-dip galvanized high-strength steel with good welding performance; wherein, the heat treatment temperature is 70-400° C., The time of the heat treatment is 10-60 minutes, and the heat treatment is performed in an atmosphere with a mass fraction of 1-3% hydrogen.

Further, the temperature of the heating before rolling is 1100-1300° C., and the heating time before rolling is ≥180 min.

Further, the outlet temperature of the finishing rolling is 800-950°C.

Further, the temperature of the coiling is 450-700°C.

Further, the cold rolling reduction ratio is 20% to 50%.

Further, the annealing includes a heating section, a cooling section and an aging section in sequence, wherein, the heating section is kept at 820-900°C for 5-25s; Cool to 400-550°C at a rate of ~10°C/s; the aging section is kept at 400-550°C for ≥8s; the annealing is performed in an atmosphere with a mass fraction of 2%-10% hydrogen.

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

The embodiment of the present invention provides a hot-dip galvanized high-strength steel with good welding performance. The chemical composition of the steel is calculated as: C: 0.10-0.30%, Si: 1-2.5%, Mn: 1.8-2.3 %, P: ≤ 0.01%, S: ≤ 0.01%, Al: 0.01-0.5%, N: 0.1-0.6%, and the rest are Fe and inevitable impurities; The diffusible hydrogen content in high strength steel is less than or equal to 0.2ppm. When the diffusible hydrogen content is less than or equal to 0.2ppm, the hydrogen diffused during welding will not cause cracks to the material, thereby ensuring the welding performance of the material.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments. Obviously, the drawings in the following description are some implementations of the embodiments of the present invention. For example, for those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

Fig. 1 is the metallographic structure diagram of the hot-dip galvanized high-strength steel with good weldability prepared in Example 1 of the present invention;

2 is a picture of no cracks after welding of the hot-dip galvanized high-strength steel with good weldability prepared in Example 1 of the present invention;

Figure 3 is a picture of cracks after welding of the hot-dip galvanized high-strength steel prepared in Comparative Example 1;

FIG. 4 is a flow chart of a method for preparing a hot-dip galvanized high-strength steel with good weldability provided by an embodiment of the present invention.

Detailed ways

Hereinafter, the embodiments of the present invention will be described in detail with reference to specific implementation manners and examples, and the advantages and various effects of the embodiments of the present invention will be more clearly presented thereby. Those skilled in the art should understand that these specific implementation manners and examples are used to illustrate the embodiments of the present invention, but not to limit the embodiments of the present invention.

Throughout the specification, unless specifically stated otherwise, terms used herein are to be understood as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this invention belong. In case of conflict, the present specification takes precedence.

Unless otherwise specified, various raw materials, reagents, instruments and equipment, etc. used in the embodiments of the present invention can be purchased from the market or can be obtained by existing methods.

The technical solutions of the embodiments of the present application are to solve the above-mentioned technical problems, and the general idea is as follows:

According to a typical embodiment of the embodiment of the present invention, a hot-dip galvanized high-strength steel with good welding performance is provided, and the chemical composition of the steel is calculated as: C: 0.10-0.30%, Si: 1-2.5 %, Mn: 1.8-2.3%, P: ≤ 0.01%, S: ≤ 0.01%, Al: 0.01-0.5%, N: 0.1-0.6%, and the rest are Fe and inevitable impurities.

The present application forms a hot-dip galvanized high-strength steel with good weldability of the above chemical composition by optimizing the composition elements, based on the following principles:

(1) the control principle is as follows in the chemical composition design of the embodiment of the present invention:

C element is the most important solid solution strengthening element and austenite stabilizing element in dual-phase steel. By adjusting the content of C element, the steel material can obtain sufficient martensite content during the cooling process to ensure the strength and obtain a certain amount of retained austenite to improve formability.

Si element is also a strengthening element, which helps to expand the two-phase region and dissolves in ferrite for strengthening effect. At the same time, Si can effectively inhibit the decomposition of retained austenite and the precipitation of carbides. However, too much Si element will adversely affect the welding performance and surface quality, so the present invention controls the Si content to 1-2.5%.

Mn element is also an important element for solid solution strengthening and stabilizing austenite. Mn element can prevent the transformation of austenite to pearlite during the cooling process, thereby improving the hardenability of the material and ensuring the problem of participating in austenite. However, if the Mn element is too high, it will have a negative impact on the processability of the material, so the Mn content in the present invention is controlled at 1.8-2.3%.

The P element is a harmful element of the material, and segregation at the grain boundary will cause the grain boundary strength to decrease and deteriorate the mechanical properties of the material. Therefore, the content of the P element in the present invention is controlled below 0.01%.

S element is also a harmful element, and if the content is too high in the material, it will combine with Mn to produce MnS, which will affect the hole expansion and corrosion resistance of the material. Therefore, the content of S element in the present invention is controlled below 0.01%.

Al element can promote the formation of ferrite, and at the same time effectively inhibit the decomposition of retained austenite and carbide precipitation, but too high content of Al element will cause problems such as non-metallic inclusions in the production process, so the content of Al needs to be similar to the effect The Si element is synergistically controlled within a suitable range. The Al content of the present invention needs to be controlled at 0.01-0.5%.

N element can combine with solid solution aluminum to form AlN and prevent the growth of austenite grains when the material is heated, resulting in an intrinsically fine-grained steel. Considering that too much N content will lead to aging phenomenon, the present invention controls the N content to 0.1-0.6%.

As an optional embodiment, the steel further includes 0.005% to 0.5% of alloy elements, and the alloy elements include at least one of Ti, Nb, V, Zr, Mo, Cr, Cu and Ni;

Ti, Nb, V, Zr, Mo, Cr, Cu, Ni and other alloying elements can improve the hardenability of austenite, so as to obtain a sufficient amount of martensite to ensure the strength. For example, as a microalloying element, Ti can be combined with C The formation of TiC nano-precipitation phase plays the role of grain refinement and precipitation strengthening, and has a significant effect on improving the structure and improving the yield strength. But at the same time, the content of alloying elements is too much, which is not conducive to the formation of retained austenite, and will lead to a significant increase in cost, so the content of alloying elements is controlled at 0.005% to 0.5%.

As an optional embodiment, the metallographic structure of the steel matrix, in terms of volume fraction, is: 10-30% ferrite, 40-80% martensite, ≤10% bainite and 4 to 20% retained austenite. The grain size of the ferrite is 3 μm to 6 μm, the grain size of the martensite is 1 μm to 4 μm, the grain size of the bainite is 0.7 μm to 3.6 μm, and the retained austenite has a grain size of 0.7 μm to 3.6 μm. The grain size of the bulk is 0.6 μm to 1.8 μm.

The embodiment of the present invention further improves the performance through precise control of the microstructure: martensite provides sufficient strength for the material, but if the martensite is too high, the forming ability of the material will be significantly reduced, so the martensite content Set to 40 to 80%. Ferrite is the soft matrix of the material, and during plastic deformation, geometric compatibility is ensured by getting the right amount of ferrite around it and having additional deformation around it. The retained austenite can enhance the forming ability of the material, but when the retained austenite is less than 4%, the elongation cannot be significantly improved due to the transformation-induced plasticity effect during deformation, and if the content is too high, the alloy content must be greatly increased, resulting in Costs rise and formability is wasted.

According to another typical embodiment of the embodiment of the present invention, a preparation method of the hot-dip galvanized high-strength steel with good welding performance is provided, as shown in FIG. 4 , the preparation method includes:

S1, adopt the chemical composition of described hot-dip galvanized high-strength steel with good weldability to obtain continuous casting slab through smelting and continuous casting;

S2, heating the continuous casting slab before rolling or/and rough rolling, finishing rolling, cooling and coiling after rolling, to obtain a hot-rolled product;

The continuous casting slab can be subjected to rough rolling after heating, or the continuous casting slab can be directly subjected to rough rolling;

The heating temperature before rolling is 1100-1300° C., and the heating time before rolling is ≥180 min. The above-mentioned heating temperature of 1100-1300° C. is selected mainly to prevent the thickening of the precipitation of the billet, which has an adverse effect on the subsequent structure formation. If the heating temperature is too high or too low, it will easily cause adverse effects on the tissue;

The outlet temperature of the finish rolling is 800-950°C. Selecting the finishing rolling temperature can make the material structure more uniform and ensure the performance. If the outlet temperature of the finishing rolling is too high or too low, it is easy to adversely affect the uniformity of the structure;

The temperature of the coiling is 450 to 700°C. The coiling temperature is chosen to ensure uniformity of the tissue and final properties to meet requirements. If the coiling temperature is too high or too low, it will easily cause adverse effects on the uniformity of the tissue;

S3, subjecting the hot-rolled finished product to pickling, cold-rolling, annealing, hot-dip galvanizing, heat treatment and skin-passing to obtain the hot-dip galvanized high-strength steel with good welding performance; wherein, the temperature of the heat treatment is 70-400 °C ℃, the time of the heat treatment is 10-60 min, and the heat treatment is performed in an atmosphere with a mass fraction of 1-3% hydrogen.

The cold rolling reduction ratio is controlled at 20-50%. This limit is to ensure a uniform steel structure and to ensure the integrity of the surface structure. If the cold rolling reduction ratio is lower than 20% or higher than 50%, it will easily cause adverse effects on the uniformity of the structure;

The annealing process after the cold rolling mainly includes a heating section, a cooling section and an aging section. The temperature of the heating section is 820-900℃, the heating time is 5-25s, the aging section is 400-550℃, and the aging section time is ≥8s. The hydrogen content in the annealing furnace is 2% to 10%. Selecting the heating section temperature of 820-900°C and the heating time of 5-25s can make the steel structure more uniform and ensure the formation of necessary martensite, retained austenite and bainite. After the cooling section, bainite and retained austenite are formed under the condition that the aging section is 400-550 °C and the aging section time is ≥8s, and the hydrogen in part of the steel is removed at the same time. From the perspective of manufacturing cost, the aging period should not be too long, but extending the aging period will not affect the organization. The hydrogen content in the annealing furnace is limited to 2 to 10%. Setting the hydrogen atmosphere above 2% mainly considers the required reducing atmosphere, while controlling the hydrogen below 10% can prevent excess hydrogen from entering the steel material, and ensure that the residual hydrogen content in the subsequent process can be controlled at a lower level. s level.

In the hot-dip galvanizing process, the temperature before entering the zinc pot is limited to 400-550°C, and the temperature below 550°C can ensure the retention of retained austenite, and at the same time, selecting more than 400°C can avoid the temperature of the zinc pot being too low and causing the zinc liquid to advance in advance. solidification. If it is higher than 550 ℃, it is difficult to retain retained austenite, and if it is lower than 400 ℃, it is easy to cause the zinc liquid to solidify in advance.

The temperature of the heat treatment is 70-400 DEG C, the time is 10-60 min, and the hydrogen content in the heat-treatment furnace is 1-3%. The hydrogen content can suppress the increase of hydrogen in the steel under the condition that the reducing atmosphere is ensured, and at the heat treatment temperature, the hydrogen entered in the steel in the previous process can be slowly released. If the hydrogen content is less than 1%, a sufficient reducing atmosphere cannot be provided, which affects the quality of the indicator; if the hydrogen content is higher than 3%, the internal hydrogen cannot be fully released due to the high external hydrogen content;

The limited heat treatment temperature and time can ensure the release time of hydrogen, and the equilibrium of hydrogen entry and permeation can be reached in about 1h at most. If the heat treatment temperature is less than 70°C and the time is less than 10min, it is not conducive to the diffusion of hydrogen; if the heat treatment temperature is greater than 400°C, the hydrogen diffused for more than 60min will easily cause cracks to the material;

To sum up, the hot-dip galvanized high-strength steel with good welding performance prepared in the embodiment of the present invention is adjusted to make the diffusible hydrogen content in the hot-dip galvanized high-strength steel ≤ 0.2 ppm by adjusting the composition and process. When the diffusible hydrogen content is less than or equal to 0.2ppm, the hydrogen diffused during welding will not cause cracks to the material, thereby ensuring the welding performance of the material; the prepared hot-dip galvanized high-strength steel with good welding performance has mechanical performance parameters as follows: The tensile strength is greater than 980MPa, the yield strength is greater than 700MPa, and the elongation with a gauge length of 80mm is greater than or equal to 12%.

A hot-dip galvanized high-strength steel with good welding performance and a preparation method thereof of the present application will be described in detail below with reference to the embodiments, comparative examples and experimental data.

S1. The molten steel is smelted in a converter, and the continuous casting slab is obtained by continuous casting; the actual chemical composition is shown in Table 1;

Table 1 - Chemical composition of hot-dip galvanized high-strength steel for each group (wt%)

Element C Si Mn P S Al N Nb Cr Mo Ti Example 1 0.17 1.66 2.06 0.005 0.002 0.43 - - - - Example 2 0.18 1.33 2.11 0.005 0.002 0.25 0.18 - - - - Example 3 0.19 1.57 2.02 0.007 0.003 0.34 0.32 0.031 - - - Example 4 0.21 1.61 2.14 0.006 0.003 0.27 - 0.21 - - Example 5 0.19 1.67 2.04 0.005 0.002 0.44 0.54 - - 0.11 - Example 6 0.22 2.23 1.87 0.007 0.002 0.34 0.13 - - - 0.031 Example 7 1.51 2.22 0.009 0.004 0.26 0.24 0.031 0.27 0.031 Comparative Example 1 0.17 1.66 2.06 0.005 0.002 0.43 - - - - Comparative Example 2 0.17 1.66 2.06 0.005 0.002 0.43 - - - - Comparative Example 3 0.08 0.2 2.3 0.005 0.005 0.6 - - 0.7 0.3 0.04 Comparative Example 4 0.085 0.0 1.7 0.012 0.002 0.04 0.004 0.02 0.42 0.35 0.03

S2. After the casting billet is obtained by conventional technology, hot rolling is carried out. The method of direct hot rolling of the casting billet can also be used. It is 450～700 ℃. After the hot-rolled coil is subjected to a conventional pickling procedure, cold rolling is performed, and the reduction ratio of the cold rolling procedure is controlled at 20-50%. The annealing process after cold rolling is mainly a heating section, a cooling section, and an aging section. The heating section temperature is 820-900°C, the heating time is 5-25s, the aging section is 400-550°C, and the aging section time is ≥8s. The hydrogen content in the annealing furnace is 2%-10%. The annealed steel sheet enters the hot-dip galvanizing process, and the temperature before entering the zinc pot is limited to 400-550 °C. After the galvanizing is cooled, subsequent heat treatment is performed, the heat treatment temperature is 70-400° C., the time is 10 minutes-1 hour, and the hydrogen content in the heat treatment furnace is 1-3%. The details are shown in Table 2.

Table 2 - Process Parameters

The finished product samples were tested for mechanical properties. The steel samples were evaluated after the surface zinc layer was removed. The surface hydrogen content was replaced by using argon gas in a quartz tube, and the amount of hydrogen released was determined by a gas chromatograph. The evaluation method of welding performance is to use a DC resistance spot welder to connect two steel plates, and control the current intensity to make the nugget diameter reach about 4 mm. After the welding material was placed for 24 hours, the nugget cross-section was observed for cracks by SEM. The results are shown in Table 3.

Table 3 Mechanical and welding properties of hot-dip galvanized high-strength steel with good welding properties

It can be seen from the data in Table 3 that:

In Comparative Example 1, the hydrogen content in the heat treatment section is 0, which is less than the range of 1 to 3% in the embodiment of the present invention, and has the disadvantage of poor surface quality;

In Comparative Example 2, the temperature of the heat treatment is 50°C, which is lower than the range of 70 to 400°C in the embodiment of the present invention, but due to the low temperature, hydrogen release cannot be achieved;

In Comparative Example 3, the chemical composition is different from that of Example 1, and the post-galvanizing heat treatment step is not performed, the tensile strength is low, and the nugget has cracks after welding;

In Comparative Example 4, the chemical composition is different from that of Example 1, and the post-galvanizing heat treatment step is not performed, the tensile strength is low, and the nugget has cracks after welding;

The hot-dip galvanized high-strength steel sheet in Examples 1-6 has a yield strength of over 700 MPa, a tensile strength of over 980 MPa, and an elongation of over 12%. At the same time, the diffusible hydrogen content of the steel plate is low, and the nugget has no cracks after welding, which can have good mechanical properties and welding performance at the same time.

Detailed description of Figures 1-3:

In Fig. 1, the metallographic structure of the hot-dip galvanized high-strength steel with good weldability prepared in Example 1 of the present invention includes 10-30% ferrite, 40%-80% martensite, bainite≤10%, Retained austenite 4-20%.

There is no crack in the nugget section after welding of hot-dip galvanized high-strength steel in Example 1 in Fig. 2;

In Fig. 3, there are cracks in the nugget section of the hot-dip galvanized high-strength steel in Comparative Example 1 after welding;

Finally, it should also be noted that the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device comprising a series of elements includes not only those elements, but also Also included are other elements not expressly listed or inherent to such a process, method, article or apparatus.

While preferred embodiments of the embodiments of the present invention have been described, additional changes and modifications to these embodiments may occur to those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the embodiments of the present invention.

Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the embodiments of the present invention and their equivalents, the embodiments of the present invention are also intended to include these modifications and variations.

Claims (4)

1. a preparation method of hot-dip galvanized high-strength steel with good weldability, is characterized in that, described preparation method comprises: The chemical composition of hot-dip galvanized high-strength steel with good welding performance is used for smelting and continuous casting to obtain continuous casting slab. Mn: 1.8～2.3%, P: ≤0.01%, S: ≤0.01%, Al: 0.01～0.5%, N: 0.1～0.6%, the rest are Fe and inevitable impurities; The continuous casting slab is heated or/and rough rolled before rolling, followed by finish rolling, cooled after rolling and coiled to obtain a hot rolled product; The hot-rolled finished product is pickled, cold-rolled, annealed, hot-dip galvanized, heat-treated and smoothed to obtain the hot-dip galvanized high-strength steel with good welding performance; wherein, the heat treatment temperature is 70-400° C., The time of the heat treatment is 10 to 60 minutes, and the heat treatment is carried out in an atmosphere with a mass fraction of 1 to 3% hydrogen; The annealing includes a heating section, a cooling section and an aging section in sequence, wherein, the heating section is kept at 820-900°C for 5-25s; Cooling to 400-550°C at a rate of /s; the aging section is kept at 400-550°C for ≥8s; the annealing is performed in an atmosphere with a mass fraction of 2%-10% hydrogen; The heating temperature before rolling is 1100-1300°C, the heating time before rolling is ≥180min; the exit temperature of the finishing rolling is 800-950°C, the coiling temperature is 450-700°C, and the cooling The rolling reduction rate is 20% to 50%. 2 . The method for preparing a hot-dip galvanized high-strength steel with good weldability according to claim 1 , wherein the chemical composition of the steel in terms of mass fraction is: C: 0.10-0.30%, Si: 1～2.5%, Mn: 1.8～2.3%, P: ≤0.01%, S: ≤0.01%, Al: 0.01～0.5%, N: 0.1～0.6%, alloying elements 0.005%～0.5%, the alloying elements It includes at least one of Ti, Nb, V, Zr, Mo, Cr, Cu and Ni, and the rest are Fe and inevitable impurities. 3. The method for preparing a hot-dip galvanized high-strength steel with good weldability according to claim 1, wherein the metallographic structure of the steel matrix is calculated as: 10-30% ferrite, 40%～80% martensite, ≤10% bainite and 4～20% retained austenite. 4 . The method for preparing a hot-dip galvanized high-strength steel with good weldability according to claim 3 , wherein the ferrite has a grain size of 3 μm to 6 μm, and the martensite has a crystal grain size of 3 μm to 6 μm. 5 . The grain size is 1 μm˜4 μm, the grain size of the bainite is 0.7 μm˜3.6 μm, and the grain size of the retained austenite is 0.6 μm˜1.8 μm.

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