A zinc-based plated steel sheet

Abstract

The application discloses a zinc-based plated steel sheet, which comprises at least a substrate layer (1), an oxidation layer (2) adjacent to the substrate layer (1) and a zinc-based plated layer (4) adjacent to the oxidation layer (2), the oxidation layer (2) comprises grain boundary silicon oxide and / or intracrystalline silicon oxide, the thickness of the oxidation layer (2) is 3-10 microns, and the mass fraction of the grain boundary silicon oxide in the oxidation layer (2) is greater than or equal to 4%. The zinc-based plated steel sheet is provided with the oxidation layer, and the oxidation layer has the grain boundary silicon oxide and / or the intracrystalline silicon oxide, that is, the silicon oxide can be enriched in the oxidation layer, and the silicon oxide can block the penetration of liquid zinc into the substrate layer to a certain extent, so that the technical problem of liquid metal embrittlement crack defects can be solved to a certain extent.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of plated steel sheets, and particularly relates to a zinc-based plated steel sheet. BACKGROUND

[0002] In order to achieve the necessary mechanical properties and surface properties of the steel sheet, some chemical elements or surface treatment are inevitably added, but some chemical elements will affect the welding performance of the steel sheet. For example, a zinc-based plated layer can be formed on the surface of the steel sheet to prevent surface oxidation and decarburization during heating, and subsequent shot peening process is not required, and sacrificial anode protection can also be provided to improve the corrosion resistance after painting.

[0003] However, during the welding process, especially during the resistance welding process, the zinc-based plated layer with a low melting point melts at a relatively high welding temperature, and under the action of mechanical tensile stress generated by electrode pressure or thermal stress generated by thermal expansion and contraction of the steel sheet, the molten zinc penetrates into the grain boundary of the zinc-based plated steel sheet base material, causing the grain boundary to become brittle and cracking, causing the zinc-based plated steel sheet to produce liquid metal embrittlement (LME) crack defects caused by liquid zinc, which seriously restricts the application of the zinc-based plated steel sheet.

[0004] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0005] The present application aims to at least be able to solve the technical problem that the zinc-based plated steel sheet is prone to produce liquid metal embrittlement crack defects during the welding process. To this end, the present application provides a zinc-based plated steel sheet.

[0006] The zinc-based plated steel sheet provided by the embodiments of the present application at least includes a substrate layer, an oxidation layer adjacent to the substrate layer, and a zinc-based plated layer adjacent to the oxidation layer, and the oxidation layer includes grain boundary silicon oxide and / or intragranular silicon oxide.

[0007] In some embodiments, the thickness of the oxidation layer is 3-10 μm.

[0008] In some embodiments, the mass fraction of the grain boundary silicon oxide in the oxidation layer is greater than or equal to 4%.

[0009] In some embodiments, the mass fraction of the grain boundary silicon oxide in the oxidation layer is 5.0%-6.4%.

[0010] In some embodiments, the mass fraction of intragranular silicon oxide in the oxidation layer is greater than or equal to 1%, and the ratio of the mass fraction of intragranular silicon oxide in the oxidation layer to the mass fraction of grain boundary silicon oxide in the oxidation layer is less than 1:2.

[0011] In some embodiments, the mass fraction of intragranular silicon oxide in the oxidation layer is 1.0-2.0%.

[0012] In some embodiments, further comprising an inhibition layer abutting between the oxidation layer and the zinc-based plating layer, the thickness of the inhibition layer being less than or equal to 2 μm.

[0013] In some embodiments, the inhibition layer at least comprises iron and zinc.

[0014] In some embodiments, the inhibition layer further comprises aluminum.

[0015] In some embodiments, the zinc-based plating layer comprises a pure zinc plating layer and / or a zinc alloy plating layer, the zinc alloy plating layer comprising zinc, the zinc alloy plating layer further comprising at least one of iron, aluminum, magnesium, and nickel, the contents of iron, aluminum, magnesium, nickel, and zinc in the zinc alloy plating layer being as follows in terms of mass fraction:

[0016] the content of iron being 0.0-15.0%;

[0017] the content of aluminum being 0.0-60.0%;

[0018] the content of magnesium being 0.0-4.0%;

[0019] the content of nickel being 0.0-20.0%; and,

[0020] the content of zinc being the balance.

[0021] In some embodiments, the contents of iron, aluminum, magnesium, nickel, and zinc in the zinc alloy plating layer are as follows in terms of mass fraction:

[0022] the content of iron being 5.0-15.0%;

[0023] the content of aluminum being 1.0-60.0%;

[0024] the content of magnesium being 0.5-4.0%;

[0025] the content of nickel being 8.0-20.0%; and,

[0026] the balance of zinc and inevitable impurities.

[0027] In some embodiments, the substrate layer includes iron, carbon, manganese, and silicon, and further includes at least one of aluminum, chromium, molybdenum, niobium, titanium, and boron; the iron, carbon, manganese, silicon, aluminum, chromium, molybdenum, niobium, titanium, and boron included in the substrate layer are present in the following amounts by mass fraction:

[0028] carbon is present in an amount of 0.05% to 1.00%;

[0029] manganese is present in an amount of 1.20% to 3.00%;

[0030] silicon is present in an amount of 0.10% to 3.00%;

[0031] aluminum is present in an amount of 0.00 to 1.00%;

[0032] chromium is present in an amount of 0.00 to 0.60%;

[0033] molybdenum is present in an amount of 0.00 to 0.60%;

[0034] niobium is present in an amount of 0.00 to 0.10%

[0035] titanium is present in an amount of 0.00 to 0.10%;

[0036] boron is present in an amount of 0.0000 to 0.0025%; and,

[0037] the balance of iron and unavoidable impurities.

[0038] In some embodiments, the iron, carbon, manganese, silicon, aluminum, chromium, molybdenum, niobium, titanium, and boron included in the substrate layer are present in the following amounts by mass fraction:

[0039] carbon is present in an amount of 0.05% to 1.00%;

[0040] manganese is present in an amount of 1.20% to 3.00%;

[0041] silicon is present in an amount of 0.10% to 3.00%;

[0042] aluminum is present in an amount of 0.02% to 1.00%;

[0043] chromium is present in an amount of 0.10% to 0.60%;

[0044] molybdenum is present in an amount of 0.05% to 0.60%;

[0045] niobium is present in an amount of 0.01% to 0.10%

[0046] titanium is present in an amount of 0.01% to 0.10%;

[0047] boron is present in an amount of 0.0001% to 0.0025%; and,

[0048] The remaining iron and unavoidable impurities.

[0049] In some embodiments, the microstructure of the substrate layer comprises retained austenite.

[0050] In some embodiments, the microstructure of the substrate layer includes ferrite, and the microstructure of the substrate layer also includes at least one of pearlite, bainite and martensite.

[0051] The embodiments of this application have at least the following beneficial effects:

[0052] The aforementioned zinc-based coated steel sheet, by having an oxide layer in the zinc-based coated steel sheet, and the oxide layer having grain boundary silicon oxide and / or intragranular silicon oxide, that is, silicon oxide can be enriched in the oxide layer, and the silicon oxide can, to a certain extent, block liquid zinc from penetrating into the substrate layer, thereby solving the technical problem of liquid metal embrittlement crack defects to a certain extent. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 A schematic diagram of the cross-section of the zinc-based coated steel sheet of Embodiment 3 of this disclosure is shown;

[0055] Figure 2 A micrograph of the cross-section of the zinc-based coated steel sheet of Embodiment 3 of this disclosure is shown;

[0056] Figure 3 A micrograph of a portion of the oxide layer in the zinc-based coated steel sheet of Embodiment 3 of this disclosure is shown;

[0057] Figure 4 A schematic diagram showing the distribution of the inhibition layer iron in the zinc-based coated steel sheet of Embodiment 3 of this disclosure is shown;

[0058] Figure 5 A schematic diagram showing the distribution of the inhibition layer aluminum in the zinc-based coated steel sheet of Embodiment 3 of this disclosure is shown;

[0059] Figure 6 A micrograph of the zinc-based coated steel sheet of Embodiment 3 of this disclosure is shown;

[0060] Figure 7 A micrograph of the cross-section near the zinc-based coating on a zinc-based coated steel sheet, Comparative Example 1 of this disclosure, is shown.

[0061] Figure 8 A microstructure photograph of a cross section near a zinc-based plated layer of the Comparative Example 2 zinc-based plated steel sheet of the present disclosure is shown;

[0062] Figure 9 A microstructure photograph of a local portion of an oxide layer in the Comparative Example 2 zinc-based plated steel sheet of the present disclosure is shown;

[0063] Figure 10 A partial schematic view of a cross section edge portion of the Example 3 welded joint of the present disclosure is shown;

[0064] Figure 11 A partial schematic view of a cross section edge portion of the Comparative Example 1 welded joint of the present disclosure is shown;

[0065] Figure 12 A partial schematic view of a cross section edge portion of the Comparative Example 2 welded joint of the present disclosure is shown.

[0066] Reference Signs:

[0067] 1, base plate layer; 2, oxide layer; 3, suppression layer; 4, zinc-based plated layer. DETAILED DESCRIPTION

[0068] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0069] Steel sheets have extremely wide application ranges. For example, in the automobile manufacturing industry, automobile lightweighting is an effective method for reducing automobile fuel consumption rate and achieving automobile carbon emission reduction targets.

[0070] In order to achieve the automobile lightweighting target while meeting the requirements of automobile safety regulations, the application and development of steel sheets in automobile bodies have attracted high attention in the industry. For example, in order to ensure normal use of automobiles in corrosive environments, a zinc-based plated layer can be formed on the surface of a steel sheet by galvanizing the surface of the steel sheet, so as to improve the corrosion resistance of the steel sheet through the zinc-based plated layer.

[0071] In the process of using steel plates to prepare the body of an automobile, a welding process can be used for assembly, and resistance spot welding is a welding process commonly used in the assembly process of automobile bodies. However, a high temperature is generated in the process of resistance spot welding, and zinc with a low melting point in the zinc-based coating melts at high temperature. Under the action of mechanical tensile stress generated by electrode pressure or thermal stress generated by thermal expansion and contraction of the steel plate, the molten liquid zinc penetrates into the grain boundary of the zinc-based coating steel plate base material, causing the grain boundary to become brittle and cracking, causing the zinc-based coating steel plate to have a liquid metal embrittlement (LME) crack defect caused by liquid zinc, which seriously restricts the application of the zinc-based coating steel plate.

[0072] To solve the problem that the zinc-based coating steel plate of the present disclosure is prone to cause a liquid metal embrittlement crack defect under the action of liquid zinc, the present disclosure provides a zinc-based coating steel plate, as shown in Figure 1 The structure of the cross section of the zinc-based coating steel plate of some embodiments of the present disclosure is shown, which at least includes a base plate layer, an oxidation layer adjacent to the base plate layer, and a zinc-based coating layer adjacent to the oxidation layer. The oxidation layer includes grain boundary silicon oxide and / or intragranular silicon oxide.

[0073] It should be noted that in the disclosure, silicon and the chemical symbol Si are commonly used and have the same meaning.

[0074] In some embodiments of the present disclosure, the zinc-based coating steel plate is provided with an oxidation layer, and the oxidation layer has grain boundary silicon oxide and / or intragranular silicon oxide, that is, the silicon oxide can be enriched in the oxidation layer. The silicon oxide can block the penetration of liquid zinc into the base plate layer to a certain extent, thereby solving the technical problem of the liquid metal embrittlement crack defect to a certain extent.

[0075] In the welding process, the grain boundary silicon oxide and / or intragranular silicon oxide in the oxidation layer can block the penetration of liquid zinc into the base plate layer, and can avoid the occurrence of the liquid metal embrittlement crack defect caused by liquid zinc to a certain extent.

[0076] In some embodiments, as shown in Figure 2 and Figure 3 , the microstructure photograph of the cross section of the zinc-based coating steel plate of Embodiment 3 of the present disclosure is shown, Figure 2 the microstructure photograph of the local oxidation layer in the zinc-based coating steel plate of Embodiment 3 of the present disclosure is shown. From Figure 3 and Figure 2 , it can be seen that the oxidation layer is adjacent to the base plate layer and is located on the surface of the base plate layer. Figure 3

[0077] ​In some embodiments, the oxidation layer can only include grain boundary silicon oxide; in some other embodiments, the oxidation layer can only include intragranular silicon oxide; in some other embodiments, the oxidation layer can include both grain boundary silicon oxide and intragranular silicon oxide.

[0078] In some embodiments, the silicon oxide can be selected from any one or more of SiO, SiO2, Si2O6.

[0079] As an optional embodiment, the thickness of the oxidation layer is 3 μm to 10 μm.

[0080] In some embodiments, by controlling the thickness of the oxidation layer to be 3 μm to 10 μm, the penetration of liquid zinc into the substrate layer can be effectively prevented, thus the occurrence of LME cracks can be effectively inhibited, and the material properties of the substrate layer will not be significantly affected.

[0081] In some embodiments, if the thickness of the oxidation layer is too large, the material properties of the substrate layer will be affected to some extent; if the thickness of the oxidation layer is too small, the inhibition effect of the oxidation layer on LME cracks will be affected to some extent. Optionally, the thickness of the oxidation layer can be any value within the range of 3 μm to 10 μm, such as 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0082] As an optional embodiment, the mass fraction of the grain boundary silicon oxide in the oxidation layer is greater than or equal to 4%.

[0083] In some embodiments, by making the mass fraction of the grain boundary silicon oxide in the oxidation layer greater than or equal to 4%, the silicon oxide can be positioned along the grain boundaries to block the penetration channels of liquid zinc and inhibit the penetration of liquid zinc into the substrate layer. If the content of the grain boundary silicon oxide in the oxidation layer is too low, it will be difficult to effectively block the penetration channels of liquid zinc to some extent, and the penetration effect of liquid zinc will be reduced.

[0084] In some embodiments, optionally, the mass fraction of the grain boundary silicon oxide in the oxidation layer can be 4%, 4.5%, 5%, 5.5%, 6%, etc.

[0085] As an optional embodiment, the mass fraction of the grain boundary silicon oxide in the oxidation layer is 5.0% to 6.4%.

[0086] As an optional embodiment, the mass fraction of the intragranular silicon oxide in the oxidation layer is greater than or equal to 1%, and the ratio of the mass fraction of the intragranular silicon oxide in the oxidation layer to the mass fraction of the grain boundary silicon oxide in the oxidation layer is less than 1:2.

[0087] In some embodiments, by controlling the mass fraction of intragranular silicon oxide in the oxidation layer, the mass fraction of intragranular silicon oxide in the oxidation layer is greater than or equal to 1%, and the ratio of the mass fraction of intragranular silicon oxide in the oxidation layer to the mass fraction of intergranular silicon oxide in the oxidation layer is less than 1:2, the intragranular silicon oxide can reduce the wettability of liquid zinc, so as to inhibit the infiltration of liquid zinc into the substrate layer. If the mass fraction of intragranular silicon oxide in the oxidation layer is too low, the effect of intragranular silicon oxide in reducing the wettability of liquid zinc is poor, and the effect of inhibiting the infiltration of liquid zinc into the substrate layer is not obvious. If the ratio of the mass fraction of intragranular silicon oxide in the oxidation layer to the mass fraction of intergranular silicon oxide in the oxidation layer is too large, the preparation effect of the zinc-based plated layer will be affected to some extent under the action of intragranular silicon oxide reducing the wettability of liquid zinc, the quality of the zinc-based plated layer will be affected, and the zinc-based plated layer will have the risk of surface dezincification.

[0088] In some embodiments, the mass fraction of intragranular silicon oxide in the oxidation layer can be 1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, and 2%, etc. The ratio of the mass fraction of intragranular silicon oxide in the oxidation layer to the mass fraction of intergranular silicon oxide in the oxidation layer can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, and 1:5, etc.

[0089] As an optional implementation, the mass fraction of intragranular silicon oxide in the oxidation layer is 1.0-2.0%.

[0090] In some embodiments, the content of intergranular silicon oxide and intergranular silicon oxide in the oxidation layer can be detected by a scanning electron microscope (SEM) with an EDS energy spectrometer. For example, after detection, Figure 3 As shown, the mass fraction of intergranular silicon oxide in the oxidation layer is 5.0%-6.4%, and the mass fraction of intragranular silicon oxide in the oxidation layer is 1.0%-2.0%.

[0091] It should be noted that in the embodiments of the present disclosure, the mass fraction of intergranular silicon oxide refers to the total mass of intergranular silicon oxide in the oxidation layer accounting for the percentage of the overall mass of the oxidation layer, and the mass fraction of intragranular silicon oxide refers to the total mass of intragranular silicon oxide in the oxidation layer accounting for the percentage of the overall mass of the oxidation layer.

[0092] As an optional implementation, the zinc-based plated steel sheet further comprises an inhibition layer adjacent to the oxidation layer and the zinc-based plated layer, and the thickness of the inhibition layer is less than or equal to 2 μm.

[0093] In some embodiments, the zinc-based plated steel sheet further comprises an inhibition layer between the oxidation layer and the zinc-based plated layer, and the thickness of the inhibition layer is controlled to be less than or equal to 2 μm. The inhibition layer can inhibit the generation of liquid metal embrittlement crack defects, without increasing the manufacturing difficulty and manufacturing cost. In addition, the thickness of the inhibition layer does not need to be too large. If the thickness of the inhibition layer is too large, the manufacturing difficulty and manufacturing cost of the zinc-based plated steel sheet will be increased to some extent, and the inhibition effect on the liquid metal embrittlement crack defects will not be significantly increased.

[0094] In some embodiments, the thickness of the inhibition layer can be less than or equal to 2 μm, such as 2 μm, 1.8 μm, 1.6 μm, and 1.4 μm.

[0095] As an optional implementation, the inhibition layer comprises at least iron and zinc. Optionally, the inhibition layer further comprises aluminum.

[0096] In some embodiments, the iron and aluminum in the inhibition layer can form an iron-aluminum (Fe-Al) compound, which can hinder the alloying reaction between the zinc-based plated layer and the substrate layer, so as to inhibit the generation of liquid metal embrittlement crack defects.

[0097] In some embodiments, the distribution of elements in the inhibition layer can be detected by an electron probe, as shown in FIGS. 1-3. Figure 4 and Figure 5 FIG. 1 shows a schematic diagram of the distribution of iron in the inhibition layer of the zinc-based plated steel sheet according to an embodiment of the present disclosure, Figure 4 FIG. 2 shows a schematic diagram of the distribution of aluminum in the inhibition layer of the zinc-based plated steel sheet according to an embodiment of the present disclosure, and Figure 5 FIG. 3 shows a schematic diagram of the distribution of magnesium in the inhibition layer of the zinc-based plated steel sheet according to an embodiment of the present disclosure.

[0098] As an optional implementation, the zinc-based plated layer comprises a pure zinc plated layer and / or a zinc alloy plated layer, the zinc alloy plated layer comprises zinc, and the zinc alloy plated layer further comprises at least one of iron, aluminum, magnesium, and nickel. The content of iron, aluminum, magnesium, nickel, and zinc in the zinc alloy plated layer is as follows in terms of mass fraction:

[0099] the content of iron is 0.0-15.0%;

[0100] the content of aluminum is 0.0-60.0%;

[0101] the content of magnesium is 0.0-4.0%;

[0102] the content of nickel is 0.0-20.0%; and

[0103] the content of zinc is the balance.

[0104] In some embodiments, the zinc-based coating mainly functions to protect the steel plate from corrosion, so as to ensure that the equipment using the zinc-based coated steel plate can be normally used in a corrosive environment. For example, to ensure that the automobile can be normally used in a corrosive environment with a certain humidity, and to ensure the service life of the automobile.

[0105] In some embodiments, the zinc-based coating can be formed by annealing galvanizing of pure zinc.

[0106] In some embodiments, the zinc-based coating can be formed by annealing galvanizing of an alloy containing zinc. That is, in the zinc alloy coating, in addition to zinc, at least one of iron, aluminum, magnesium and nickel can also be contained.

[0107] In some embodiments, the zinc-based coating can also simultaneously include a pure zinc coating and a zinc alloy coating.

[0108] In some embodiments, the thickness of the zinc-based coating can be 5 μm to 15 μm, for example, the thickness of the zinc-based coating can be 5 μm, 6 μm, 7 μm, 9 μm, 11 μm, 12 μm, 13 μm, 14 μm and 15 μm, etc.

[0109] In some embodiments, when the zinc-based coating is a pure zinc coating, an inhibition layer can be arranged between the pure zinc coating and the oxidation layer, so as to hinder the alloying reaction between the pure zinc coating and the iron matrix (the oxidation layer and / or the substrate layer can be regarded as the iron matrix) at high temperature, so as to inhibit the generation of liquid metal embrittlement crack defects.

[0110] As an optional embodiment, the content of iron, aluminum, magnesium, nickel and zinc contained in the zinc alloy coating is as follows in terms of mass fraction:

[0111] The content of iron is 5.0% to 15.0%;

[0112] The content of aluminum is 1.0% to 60.0%;

[0113] The content of magnesium is 0.5% to 4.0%;

[0114] The content of nickel is 8.0% to 20.0%; and

[0115] The balance is zinc and unavoidable impurities.

[0116] As an optional embodiment, the substrate layer includes iron, carbon, manganese and silicon, and further includes at least one of aluminum, chromium, molybdenum, niobium, titanium and boron; the content of iron, carbon, manganese, silicon, aluminum, chromium, molybdenum, niobium, titanium and boron contained in the substrate layer is as follows in terms of mass fraction:

[0117] The content of carbon is 0.05% to 1.00%;

[0118] manganese in an amount of 1.20% to 3.00%;

[0119] silicon in an amount of 0.10% to 3.00%;

[0120] aluminum in an amount of 0.00 to 1.00%;

[0121] chromium in an amount of 0.00 to 0.60%;

[0122] molybdenum in an amount of 0.00 to 0.60%;

[0123] niobium in an amount of 0.00 to 0.10%

[0124] titanium in an amount of 0.00 to 0.10%;

[0125] boron in an amount of 0.0000 to 0.0025%; and,

[0126] the balance of iron and inevitable impurities.

[0127] In some embodiments, the substrate layer includes the following components in mass fractions:

[0128] carbon in an amount of 0.15% to 0.25%;

[0129] manganese in an amount of 1.70% to 2.80%;

[0130] silicon in an amount of 1.0% to 2.00%; and,

[0131] the balance of iron and inevitable impurities.

[0132] As an optional embodiment, the substrate layer includes iron, carbon, manganese, silicon, aluminum, chromium, molybdenum, niobium, titanium, and boron in the following amounts in mass fractions:

[0133] carbon in an amount of 0.05% to 1.00%;

[0134] manganese in an amount of 1.20% to 3.00%;

[0135] silicon in an amount of 0.10% to 3.00%;

[0136] aluminum in an amount of 0.02% to 1.00%;

[0137] chromium in an amount of 0.10% to 0.60%;

[0138] molybdenum in an amount of 0.05% to 0.60%;

[0139] niobium in an amount of 0.01% to 0.10%

[0140] The titanium content is 0.01% to 0.10%;

[0141] The boron content is 0.0001% to 0.0025%; and,

[0142] The remaining iron and unavoidable impurities.

[0143] As an alternative implementation, the microstructure of the substrate layer includes retained austenite.

[0144] In some embodiments, the residual austenite in the substrate layer can be transformed into martensite during deformation to increase the plasticity of the substrate layer and enable it to meet the elongation requirements.

[0145] As an alternative implementation, the microstructure of the substrate layer includes ferrite, and the microstructure of the substrate layer also includes at least one of pearlite, bainite and martensite.

[0146] In some embodiments, ferrite in the substrate layer can increase the plasticity of the substrate so that it meets the elongation requirements.

[0147] In some embodiments, pearlite, bainite, and martensite in the substrate layer can increase the strength of the substrate layer to meet the strength requirements.

[0148] In some embodiments of this disclosure, the tensile strength of zinc-based coated steel sheets can reach over 500 MPa.

[0149] Optionally, the zinc-based coated steel sheet can have a tensile strength of over 800 MPa, a yield strength of over 600 MPa, and an elongation (A80) of over 15%, so that the strength and elongation of the zinc-based coated steel sheet can meet the requirements of the automotive structural parts used.

[0150] For example, please see Figure 6 As shown, Figure 6 A micrograph of the zinc-based coated steel sheet of Example 3 of this disclosure is shown. After testing, it can be seen that the zinc-based coated steel sheet of Example 3 has a yield strength ≥650MPa, a tensile strength ≥1000MPa, and an elongation A80 ≥16%.

[0151] It should be noted that the high temperature mentioned in the embodiments of this disclosure refers to the temperature at which zinc can be melted and the temperature range above the temperature at which zinc can be melted.

[0152] Based on the same inventive concept, this disclosure also proposes a method for preparing the above-mentioned zinc-based coated steel sheet, the method comprising the following steps:

[0153] The cold hard plate is sequentially subjected to continuous annealing treatment and galvanizing treatment to obtain a zinc-based plated steel plate, wherein the continuous annealing treatment comprises a pre-oxidation section, a heating section and a soaking section.

[0154] In some embodiments, the continuous annealing treatment can form an oxidation layer on the surface of the substrate layer, and at the same time, the surface state of the oxidation layer can be improved, so that a zinc-based plated layer with good adhesion can be obtained in subsequent galvanizing treatment.

[0155] As an optional implementation, before the cold hard plate is subjected to the continuous annealing treatment, the following step can be further included:

[0156] The smelting step, the continuous casting step, the hot rolling step, the pickling step and the cold rolling step are performed to obtain the cold hard plate.

[0157] As an optional implementation, the continuous annealing treatment can further include a cooling section after the soaking section.

[0158] As an optional implementation, the dew point temperature of the pre-oxidation section is 0-20℃.

[0159] In some embodiments, by controlling the dew point temperature of the pre-oxidation section, the dew point temperature of the pre-oxidation section is in the range of 0-20℃, the surface of the substrate layer can form an iron oxide layer, and at the same time, the silicon is oxidized and enriched in the grain boundary and intracrystalline near the surface of the substrate layer, so as to form an oxidation layer near the surface of the substrate layer, thus the oxidation layer can be regarded as a part of the substrate layer adjacent to the surface.

[0160] In some embodiments, if the dew point temperature of the pre-oxidation section is too high, the silicon layer enriched near the surface of the substrate layer will thicken to a certain extent, that is, the oxidation layer formed after the heating section and the soaking section will thicken, which will affect the mechanical properties of the zinc-based plated steel plate and have an adverse effect on the mechanical properties of the zinc-based plated steel plate; if the dew point temperature of the pre-oxidation section is too low, the formation of the iron oxide layer on the surface of the substrate layer in the pre-oxidation section will be affected to a certain extent, which will be not conducive to the formation of the inhibition layer in the later stage.

[0161] In some embodiments, the dew point temperature of the pre-oxidation section can be 0℃, 4℃, 8℃, 12℃, 16℃, 20℃, etc.; alternatively, the dew point temperature of the pre-oxidation section can be 5-10℃.

[0162] As an optional implementation, the dew point temperature of the heating section is -32℃ to -25℃, and the dew point temperature of the soaking section is -32℃ to -25℃.

[0163] In some embodiments, by controlling the dew point temperature of the heating section and the soaking section, the dew point temperature of the heating section and the soaking section are both in the range of -32℃ to -25℃, the iron oxide formed on the surface of the substrate layer can be reduced, a thin iron reduction layer is formed on the surface of the substrate layer, and thus the iron reduction layer can be regarded as a part of the substrate layer located on the surface. The iron reduction layer can improve the platability of the surface of the substrate layer to improve the adhesion of the zinc-based plating layer. At the same time, in the heating section and the soaking section, as the oxygenophilic element, the silicon enriched in the grain boundary and the intracrystalline of the surface of the substrate layer will continue to be oxidized to form an oxidation layer meeting the content of silicon oxide. In addition, the iron reduction layer on the surface of the substrate layer can form an iron-aluminum compound as an inhibition layer with aluminum in the zinc plating material during zinc plating to ensure the quality of the zinc-based plating layer and improve the adhesion thereof.

[0164] In some embodiments, if the dew point temperature of the heating section or the soaking section is too high, the iron oxide layer formed in the pre-oxidation section cannot be reduced to a certain extent, which may affect the quality of the zinc-based plating layer; if the dew point temperature of the heating section or the soaking section is too low, the oxidation process of silicon in the heating section or the soaking section will be affected to a certain extent, which makes it difficult to form an oxidation layer that can block the invasion of liquid zinc.

[0165] In some embodiments, the dew point temperature of the heating section can be -32℃, -31℃, -29℃, -27℃, -25℃, etc., and the dew point temperature of the soaking section can be -32℃, -31℃, -29℃, -27℃, -25℃, etc.

[0166] The preparation method of the zinc-based plating steel sheet of the embodiments of the present disclosure is based on the above-mentioned zinc-based plating steel sheet, and the structure of the zinc-based plating steel sheet can refer to the above-mentioned embodiments. Since the preparation method of the zinc-based plating steel sheet adopts part or all of the technical solutions of the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, and thus will not be described here.

[0167] The present application will be further described in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods not specified in the following examples are generally determined according to the national standards. If there is no corresponding national standard, the international standard, the conventional condition, or the condition suggested by the manufacturer is used.

[0168] The embodiments of the present disclosure provide a zinc-based plating steel sheet. The zinc-based plating steel sheet includes a substrate layer, an oxidation layer, an inhibition layer, and a zinc-based plating layer in sequence, and the oxidation layer includes grain boundary silicon oxide and / or intracrystalline silicon oxide. The chemical composition of the substrate layer of the zinc-based plating steel sheet is shown in Table 1, and the surface property parameters of the zinc-based plating steel sheet are shown in Table 2.

[0169] Table 1 Chemical composition of the middle substrate layer of the zinc-based plated steel plate

[0170] Serial number Mass fraction of C (%) Mass fraction of Mn (%) Mass fraction of Si (%) Example 1 0.25 2.8 1.0 Example 2 0.15 1.7 2.0 Example 3 0.2 2.0 1.5 Comparative Example 1 0.1 2.2 0.5 Comparative Example 2 0.2 2.0 0.5

[0171] Table 2 Surface property parameters of the zinc-based plated steel plate

[0172]

[0173] In some embodiments, scanning electron microscopy (SEM) can be used in combination with an EDS spectrometer to detect the distribution of grain boundary silicon oxides and intragranular silicon oxides in the zinc-based plated steel plate, Figure 3 A microstructure photograph of a local part of the oxide layer in the zinc-based plated steel plate of Example 3 of the present disclosure is shown, Figure 9 A microstructure photograph of a local part of the oxide layer in the zinc-based plated steel plate of Comparative Example 2 of the present disclosure is shown, and the distribution of grain boundary silicon oxides and intragranular silicon oxides detected for Example 3 and Comparative Example 2 is shown in Table 3.

[0174] Table 3 Distribution of grain boundary silicon oxides and intragranular silicon oxides in the zinc-based plated steel plate

[0175] Oxidation position Spectrum Silicon oxide mass fraction of Example 3 (%) Silicon oxide mass fraction of Comparative Example 2 (%) Grain boundary oxidation spectrum Figure 1 6.4 0.9 Grain boundary oxidation spectrum Figure 2 6.2 0.5 Grain boundary oxidation spectrum Figure 3 5.0 1.4 Grain boundary oxidation spectrum Figure 4 5.1 2.9 In-grain oxidation spectrum Figure 5 2.0 0.6 In-grain oxidation spectrum Figure 6 1.5 0.6 In-grain oxidation spectrum Figure 7 1.0 0.0

[0176] The present disclosure provides a method for preparing a zinc-based plated steel plate, comprising the following steps:

[0177] S11, performing continuous annealing treatment and galvanizing treatment on the cold hard plate to obtain a zinc-based plated high-strength steel plate; wherein the continuous annealing treatment comprises a pre-oxidation section, a heating section, and a soaking section, the dew point temperatures of the pre-oxidation section, the heating section, and the soaking section are shown in Table 4, and the mechanical properties of the obtained zinc-based plated steel plate are shown in Table 5.

[0178] Table 4 Dew point control parameters in the continuous annealing treatment of the zinc-based plated steel plate

[0179] Serial number Pre-oxidation section dew point temperature (°C) Heating section dew point temperature (°C) Soaking section dew point temperature (°C) Example 1 0 -32 -32 Example 2 20 -25 -25 Example 3 10 -29 -29 Comparative Example 1 -10 -40 -40 Comparative Example 2 0 -35 -35

[0180] Table 5 Mechanical properties of the zinc-based plated steel plate

[0181] Serial number Yield strength (MPa) Tensile strength (MPa) Elongation A 80 (%)]] Example 1 600 1000 17 Example 2 760 1000 16 Example 3 700 1000 16.5 Comparative Example 1 650 1000 13 Comparative Example 2 750 1000 17

[0182] To illustrate the effectiveness of the embodiments of the present disclosure in reducing LME cracks caused by resistance spot welding, the occurrence of LME cracks in the resistance spot welded joints of Examples 1-3 and Comparative Examples 1-2 was analyzed. The zinc-based plated steel sheets of Examples 1-3 and Comparative Examples 1-2 were resistance spot welded according to the welding process parameters shown in Table 6 for LME crack testing of zinc-based plated steel sheets. The welding experiment was based on the SEP1220-2 resistance spot welding standard, and the welding current was selected to be the upper limit current near the spatter of each material. The LME crack detection results of the zinc-based plated steel sheets after welding are shown in Table 7.

[0183] Table 6: Welding process parameters for LME crack testing of zinc-based plated steel sheets

[0184] Serial number Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Plate thickness 1.6 mm 1.6 mm 1.6 mm 1.2 mm 1.5 mm Electrode end face diameter 6 mm 6 mm 6 mm 6 mm 6 mm Welding pressure 4.5 kN 4.5 kN 4.5 kN 4.0 kN 4.5 kN Welding current 7.9 kA 7.9 kA 7.9 kA 7.9 kA 7.9 kA Current time 380 ms 380 ms 380 ms 320 ms 380 ms Pressure maintaining time 300 ms 300 ms 300 ms 300 ms 300 ms

[0185] Table 7: LME crack detection results of zinc-based plated steel sheets

[0186] Serial number Whether there is obvious LME crack Example 1 No Example 2 No Example 3 No Comparative Example 1 Yes Comparative Example 2 Yes

[0187] The microstructure photograph of the cross section near the zinc-based coating of the zinc-based plated steel sheet of Comparative Example 1 of the present disclosure is shown in Figure 7 The microstructure photograph of the cross section near the zinc-based coating of the zinc-based plated steel sheet of Comparative Example 2 of the present disclosure is shown in Figure 8 The microstructure photograph of the local oxidation layer in the zinc-based plated steel sheet of Comparative Example 2 of the present disclosure is shown in Figure 7 to Figure 9 The oxidation layers of Comparative Examples 1 and 2 have obvious LME cracks.

[0188] Figure 10 A partial schematic view of the edge of the weld cross section of Example 3 of the present disclosure is shown in Figure 11 A partial schematic view of the edge of the weld cross section of Comparative Example 1 of the present disclosure is shown in Figure 12 A partial schematic view of the edge of the weld cross section of Comparative Example 2 of the present disclosure is shown in Figure 10 to Figure 12 As shown in the above figures, no obvious LME cracks were observed in the edge of the weld cross section of Example 3 of the present disclosure, but obvious LME cracks were observed in the edge of the weld cross section of Comparative Examples 1 and 2. It can be seen that, using a preparation method different from the embodiments of the present disclosure, zinc-based plated steel sheets with an oxidation layer structure different from the embodiments of the present disclosure were prepared, even if the mechanical properties were similar to the embodiments of the present disclosure, but there were obvious LME crack defects, which posed a certain safety hazard.

[0189] Compared with the comparative example, the zinc-based plated steel sheet of the embodiment of the present disclosure is provided with an oxide layer, and the oxide layer has grain boundary silicon oxide and / or intracrystalline silicon oxide, that is, the silicon oxide can be enriched in the oxide layer, and the silicon oxide can block the penetration of liquid zinc into the substrate layer to a certain extent, thereby being able to solve the technical problem of liquid metal embrittlement crack defects to a certain extent.

[0190] During the welding process, the grain boundary silicon oxide and / or intracrystalline silicon oxide in the oxide layer can block the penetration of liquid zinc into the substrate layer, and can avoid the occurrence of liquid metal embrittlement crack defects caused by liquid zinc to a certain extent.

[0191] Meanwhile, the zinc-based plated steel sheet is also provided with an inhibition layer, which can also improve the effect of inhibiting liquid metal embrittlement crack defects to a certain extent.

[0192] Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is only for the convenience and brevity, and should not be understood as a hard limit on the scope of the present application; therefore, it should be considered that the described range has been specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, regardless of the range. In addition, whenever a numerical range is indicated in this text, it refers to any cited number (fraction or integer) within the indicated range.

[0193] In this text, "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural. In this text, "at least one" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or similar expressions mean any combination of these items, including any combination of single item or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0194] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0195] The foregoing detailed description of the application has been presented for purposes of illustration and description. Various modifications and changes can be made to these embodiments without departing from the spirit and scope of the application. It is intended that the scope of the application should not be limited by the particular representative embodiments described above.

Claims

1. A zinc-based plated steel sheet, characterized by, The zinc-based plated steel sheet comprises at least a base plate layer, an oxidation layer adjacent to the base plate layer, and a zinc-based plated layer adjacent to the oxidation layer, the oxidation layer comprising grain boundary silicon oxide and intracrystalline silicon oxide, the thickness of the oxidation layer being 3-10 μm, and the mass fraction of the grain boundary silicon oxide in the oxidation layer being 4.0-8.0%.

2. The zinc-based plated steel sheet according to claim 1, characterized in that, The mass fraction of the grain boundary silicon oxide in the oxidation layer is 5.0-6.4%.

3. The zinc-based plated steel sheet according to claim 1, characterized in that, The mass fraction of the intracrystalline silicon oxide in the oxidation layer is greater than or equal to 1%, and the ratio of the mass fraction of the intracrystalline silicon oxide in the oxidation layer to the mass fraction of the grain boundary silicon oxide in the oxidation layer is less than 1:

2.

4. The zinc-based plated steel sheet according to claim 3, characterized in that, The mass fraction of the intracrystalline silicon oxide in the oxidation layer is 1.0-2.0%.

5. The zinc-based plated steel sheet according to claim 1 or 2, characterized in that, An inhibition layer is further included adjacent to the oxidation layer and the zinc-based plated layer, the thickness of the inhibition layer being less than or equal to 2 μm.

6. The zinc-based plated steel sheet according to claim 5, characterized in that, The inhibition layer comprises at least iron and zinc.

7. The zinc-based plated steel sheet according to claim 5, characterized in that, The inhibition layer further comprises aluminum.

8. The zinc-based coated steel sheet according to any one of claims 1 to 7, characterized in that, The zinc-based plated layer comprises a pure zinc plated layer and / or a zinc alloy plated layer, the zinc alloy plated layer comprising zinc, and the zinc alloy plated layer further comprising at least one of iron, aluminum, magnesium and nickel, the contents of the iron, aluminum, magnesium, nickel and zinc in the zinc alloy plated layer being as follows in terms of mass fraction: the content of iron being 0.0-15.0%; the content of aluminum being 0.0-60.0%; the content of magnesium being 0.0-4.0%; the content of nickel being 0.0-20.0%; and the content of zinc being the balance.

9. The zinc-based plated steel sheet according to claim 8, characterized in that, The base plate layer comprises iron, carbon, manganese and silicon, and further comprises at least one of aluminum, chromium, molybdenum, niobium, titanium and boron; the contents of the iron, carbon, manganese, silicon, aluminum, chromium, molybdenum, niobium, titanium and boron in the base plate layer being as follows in terms of mass fraction: the content of carbon being 0.05%-1.00%; the content of manganese being 1.20%-3.00%; the content of silicon being 0.10%-3.00%; the content of aluminum being 0.00-1.00%; the content of chromium being 0.00-0.60%; the content of molybdenum being 0.00-0.60%; the content of niobium being 0.00-0.10% the content of titanium being 0.00-0.10%; the content of boron being 0.0000-0.0025%; and the balance of iron and inevitable impurities.

10. The zinc-based plated steel sheet according to claim 9, characterized in that, The microstructure of the base plate layer comprises residual austenite.

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