Coated steel, manufacturing method therefor, steel part, manufacturing method therefor and use thereof

Abstract

A coated steel. The coated steel comprises: a steel substrate; a nickel-containing alloy layer arranged on the surface of the steel substrate; and a zinc-rich layer arranged on the nickel-containing alloy layer. In mass percent of the nickel-containing alloy layer, the nickel-containing alloy layer comprises 0.1%-4% of Al, 0.2%-5% of Ni, 20%-70% of Fe, 0.01-1.5% of Mn, and the balance being Zn and inevitable impurities. In mass percent of the zinc-rich layer, the zinc-rich layer comprises 0-10% of Fe and 88-100% of Zn. The zinc-rich layer further comprises Al.

Description

Coated steel and method for manufacturing same, steel part and method for manufacturing and using same Cross-reference to related applications

[0001] This application claims priority to Chinese patent application No. 202411327666.8, filed on September 23, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure relates to steel products, and in particular to coating techniques for steel products. BACKGROUND

[0003] In recent years, improving the passive safety of the vehicle body and reducing the weight of the vehicle to achieve energy saving and consumption reduction have been the main development trend of the automotive industry. Among them, hot stamping forming is a common way to achieve high strengthening of the vehicle body steel, to improve passive safety while achieving lightweight. It is a way to achieve high strength of the product by combining heat treatment and high-temperature forming quenching. Hot stamping forming technology takes advantage of the easy forming and no springback characteristics at high temperature and the quenching cooling of the die to well solve the problems of easy cracking, wrinkling and serious springback in cold forming. Commonly used hot stamping forming products mainly include front and rear door left and right anti-collision rods (beams), front and rear bumpers, A-pillar reinforcement plates, B-pillar reinforcement plates, C-pillar reinforcement plates, mid-plate channels and roof reinforcement beams, etc. safety structural parts. For some parts with special application requirements, the purpose is to prepare parts with high performance combinations of high tensile strength, high plasticity and good corrosion resistance. The demand for this type of high performance combination is significant in the process of lightweighting in the new energy vehicle industry. This high performance combination can be obtained in particular by using steel parts with high mechanical properties, the microstructure of which is martensite-bainite / ferrite or martensite-bainite structure.

[0004] A conventional non-coated hot stamping steel sheet generates a large amount of surface oxide scale during heating, which reduces the service life of a die, and also requires periodic cleaning of the die, thus reducing production efficiency. Preparing a coating on the surface of a hot stamping steel sheet can prevent the generation of oxide scale and decarburization on the surface of the hot stamping steel sheet, and also improve the corrosion resistance of the hot stamping steel sheet. GI (Dip Galvanized Steel, hot-dip galvanized steel) coating technology is one of the main coating technologies currently applied to hot stamping steel sheets. A hot stamping steel sheet to which GI coating technology is applied not only prevents surface oxidation and decarburization during heating, but also provides sacrificial anode protection, thus improving the corrosion resistance after painting. The production methods of a zinc-coated hot stamping steel sheet mainly include direct hot stamping and indirect hot stamping. For a direct hot stamping process, in the direct hot stamping process of a press hardening steel having a zinc coating, the high temperature during hot stamping causes partial liquefaction of Zn elements, which intrudes into the austenite grain boundaries at high temperature. Hot stamping parts made of a hot-dip galvanized steel sheet are prone to microcracks of about 10 μm to 100 μm, or even macrocracks, which cause the failure of the parts. SUMMARY

[0005] The technical problem of the hot-dip galvanized steel sheet being prone to cracks is solved by using one or more embodiments of the present disclosure.

[0006] In a first aspect, a coated steel according to some embodiments of the present disclosure includes: a steel substrate; a nickel-containing alloy layer disposed on a surface of the steel substrate; and a zinc-rich layer disposed on the nickel-containing alloy layer, wherein the nickel-containing alloy layer includes, in mass percent of the nickel-containing alloy layer, 0.1% to 4% Al, 0.2% to 5% Ni, 20% to 60% Fe, and 0.1% to 1.5% Mn, with the balance being Zn and unavoidable impurities; and the zinc-rich layer includes, in mass percent of the zinc-rich layer, 0% to 10% Fe, 88% to 100% Zn, and 0% to 0.2% Al.

[0007] In a second aspect, a method of manufacturing a coated steel according to some embodiments of the present disclosure includes: providing a steel substrate; plating nickel on a surface of the steel substrate to form a nickel coating, thereby obtaining a nickel-plated substrate; and annealing the nickel-plated substrate and plating zinc on the nickel-plated substrate to form a zinc-rich layer, thereby obtaining the coated steel.

[0008] In a third aspect, a steel part according to some embodiments of the present disclosure includes: a steel substrate; a zinc-iron alloy layer disposed on a surface of the steel substrate; and a zinc-nickel-iron alloy layer disposed on the zinc-iron alloy layer, wherein a main phase of the zinc-iron alloy layer is α-Fe(Zn), and a main phase of the zinc-nickel-iron alloy layer is a nickel-containing Γ-(Fe3Zn10 )。

[0009] In a fourth aspect, a method for manufacturing a steel product according to some embodiments of the present disclosure includes the steps of: providing the plated steel according to the first aspect, or providing the plated steel manufactured by the method for manufacturing a plated steel according to the second aspect; and heating the plated steel to a temperature above the Ac1 temperature of the steel base, reducing the temperature of the plated steel heated to a temperature above the Ac1 temperature of the steel base to a hot stamping forming temperature, and performing a hot stamping process and a quenching process on the plated steel with the reduced temperature to obtain the steel product.

[0010] In a fifth aspect, the steel product according to some embodiments of the present disclosure is applied to a hot stamping steel product for vehicles. BRIEF DESCRIPTION OF DRAWINGS

[0011] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the disclosure.

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the related art, the accompanying drawings needed to be used in the embodiments or the related art description will be briefly introduced. Obviously, those skilled in the art can obtain other drawings from these drawings without any creative effort.

[0013] FIG. 1 shows a flowchart of a method for manufacturing a plated steel according to some embodiments of the present disclosure;

[0014] FIG. 2 shows a flowchart of a method for manufacturing a steel product according to some embodiments of the present disclosure;

[0015] FIG. 3 shows a flowchart of heating the plated steel to a temperature above the Ac1 temperature of the steel base in FIG. 2;

[0016] FIG. 4 shows an element depth distribution diagram of a plated steel according to Embodiment 3 of the present disclosure;

[0017] FIG. 5 shows an electron probe analysis diagram of a steel product according to Embodiment 3 of the present disclosure;

[0018] FIG. 6 shows an electron probe analysis diagram of a steel product according to Comparative Example 3 of the present disclosure;

[0019] FIG. 7 shows a phase diagram of a zinc-iron alloy with different amounts of added Ni element according to the present disclosure;

[0020] FIG. 8 shows a scanning electron microscope image of a thin slice sample of a steel product according to Embodiment 3 and Comparative Example 2 of the present disclosure;

[0021] FIG. 9 shows a transmission electron microscope picture of a flake sample made of a steel piece according to Embodiment 3 of the present disclosure. DETAILED DESCRIPTION

[0022] To make the objects, technical solutions, and advantages of the embodiments of the present disclosure clearer, the following will be combined with the accompanying drawings for the embodiments of the present disclosure to make a clear and complete description of the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are some but not all of the embodiments of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present disclosure.

[0023] Unless otherwise specifically defined, the terms used herein are understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as generally understood by a person of ordinary skill in the art to which the present disclosure belongs. If there is a conflict, the present specification takes precedence.

[0024] Unless otherwise specifically stated, the various raw materials, reagents, instruments, and equipment used in the present disclosure can be purchased from the market or can be prepared by existing methods.

[0025] It should be noted that in the following embodiments of the present disclosure, the plating layer refers to a structural layer in the plating steel or steel piece other than the steel base body, and can refer to any one or several of the nickel-containing alloy layer, the zinc-rich layer, the nickel plating layer, the zinc-iron alloy layer, and the iron-zinc-nickel alloy layer in different cases.

[0026] In view of the technical problem that the hot-dip galvanized steel sheet in the related art is prone to cracks, according to some embodiments of the present disclosure, the general idea for solving the above technical problem is as follows:

[0027] In a first aspect, a plating steel according to some embodiments of the present disclosure includes:

[0028] a steel base body;

[0029] a nickel-containing alloy layer arranged on the surface of the steel base body; and

[0030] a zinc-rich layer arranged on the nickel-containing alloy layer;

[0031] wherein the nickel-containing alloy layer includes 0.1% to 4% of Al, 0.2% to 5% of Ni, 20% to 60% of Fe, and 0.1% to 1.5% of Mn, with the balance being Zn and unavoidable impurities, in terms of mass percentage of the nickel-containing alloy layer.

[0032] The zinc-rich layer includes 0-10% Fe, 88-100% Zn, and 0-0.2% Al in terms of mass percentage of the zinc-rich layer.

[0033] In some embodiments of the present disclosure, the presence of the nickel-containing alloy layer between the zinc-rich layer and the steel substrate of the plated steel can make the plated steel less likely to crack during the hot stamping forming process. In addition, the melting point of the nickel-containing alloy layer is relatively high, reaching more than 800°C, which is conducive to avoiding the risk of liquid zinc induced substrate grain boundary cracking during the forming process due to zinc melting during the further heat treatment of the plated steel including hot stamping forming, thereby reducing the crack propagation depth.

[0034] The present disclosure further theoretically analyzes the melting point of the nickel-containing alloy layer. By using Pandat software to calculate the phase diagram under a specific composition, the obtained phase diagram is shown in FIG. 7. FIG. 7 shows that when the addition amount of Ni element is less than 2%, the melting point of the alloy containing 40% Zn and 60% Fe can be significantly improved.

[0035] In some embodiments of the present disclosure, the total thickness of the nickel-containing alloy layer and the zinc-rich layer is 5-20 μm.

[0036] In some embodiments of the present disclosure, the thickness of the nickel-containing alloy layer is 1-8 μm.

[0037] In some embodiments of the present disclosure, the thickness of the zinc-rich layer is 4-18 μm.

[0038] As an example, the total thickness of the nickel-containing alloy layer and the zinc-rich layer can be 5 μm, 10 μm, 15 μm, or 20 μm.

[0039] As an example, the thickness of the nickel-containing alloy layer can be 1 μm, 2 μm, 4 μm, 6 μm, or 8 μm.

[0040] As an example, the thickness of the zinc-rich layer can be 4 μm, 8 μm, 10 μm, 14 μm, or 18 μm.

[0041] In some embodiments of the present disclosure, the content of Al in the nickel-containing alloy layer and the zinc-rich layer is 0.4-0.6% in terms of percentage of the total mass of the nickel-containing alloy layer and the zinc-rich layer.

[0042] As an example, the content of Al in the nickel-containing alloy layer and the zinc-rich layer can be 0.4%, 0.45%, 0.5%, 0.55%, or 0.6%.

[0043] In some embodiments of the present disclosure, the steel base body includes, in mass percentage of the steel base body, 0.05% to 0.4% of C, 0.8% to 2.5% of Mn, 0 to 0.4% of Si, 0 to 0.5% of Al, 0.1% to 0.3% of Cr, 0 to 0.2% of Mo, 0 to 0.4% of Ni, 0.001% to 0.005% of B, and 0 to 0.01% of N.

[0044] It is easily understood that, in addition to the above elements, the steel base body can also include harmful elements such as P, S, O, and unavoidable impurities, and the content of the above elements should be reduced as much as possible, and the content of P is generally controlled to be below 0.02%, the content of S is controlled to be below 0.005%, and the content of O is controlled to be below 0.003%.

[0045] The effects of the above elements are as follows:

[0046] C: C is a relatively effective and inexpensive solid solution strengthening element, which can effectively ensure the strength of the steel base body during hot stamping forming operation. However, too high content of C is not conducive to obtaining the toughness and plasticity of the steel base body, and too high strength of the steel base body cannot effectively satisfy the effect of collision energy absorption, and too high strength of the steel base body is not conducive to the welding performance with other parts when the steel base body is applied to safety components. If the content of C is too low, it is also not conducive to forming sufficient strengthening effect to make the steel base body obtain stable and sufficient content of high dislocation type martensite, bainite and other strengthening phases.

[0047] Mn: Mn is used to increase the austenite region and reduce the austenitizing temperature, and improve the hardenability. Too high content of Mn will also affect the toughness of the steel base body.

[0048] Cr: Cr can significantly increase the hardenability of the steel base body and reduce the surface oxidation phenomenon, which is conducive to obtaining a steel base body with high surface quality. However, Cr is a strong carbide forming element, which promotes the formation of bainite, and therefore the content thereof should not be too high.

[0049] Mo: Molybdenum can improve the hardenability of the steel base body, and its effect is stronger than that of chromium but slightly weaker than that of manganese. Molybdenum has solid solution strengthening effect on ferrite, and can also improve the stability of carbides, which is conducive to controlling the size of precipitates, thereby improving the precipitation strengthening effect of the steel base body and improving the hydrogen brittleness resistance. However, when the content of molybdenum is relatively high, the deformation resistance of the steel base body to hot stamping forming is increased, which is not conducive to hot stamping forming.

[0050] Ni: Nickel can improve the strength of the steel base body while maintaining good plasticity and toughness, and reduce the ductile-brittle transition temperature, which is conducive to the use of the part at a lower temperature.

[0051] N: N can form compounds with Al, Ti, Nb, V and other elements, thereby refining the grain and reducing the hydrogen-induced delayed fracture sensitivity, but also can segregate at the grain boundary and reduce the grain boundary strength. Therefore, the content of N should not be too high.

[0052] Si: Si is a ferrite forming element. When the hot stamping steel is heated to the austenite (γ) region and kept, Si atoms are dissolved in ferrite. The dissolution of Si in ferrite increases the activity of C atoms, promotes the diffusion of C atoms in ferrite, and increases the carbon content in the surrounding austenite. With the increase of carbon content in austenite, its stability also increases. Too high Si content will increase the brittleness of the steel matrix.

[0053] Al: Al can improve the plasticity of the steel matrix, increase the driving force of austenite to bainite transformation, accelerate the formation of bainite, significantly increase the activity of C atoms in ferrite, and inhibit the formation of cementite. Too high content of Al will increase the difficulty of continuous casting.

[0054] In some embodiments of the present disclosure, the total mass percentage of Cr, Mo and Ni in the steel matrix is 0.11% to 0.45%.

[0055] In some embodiments of the present disclosure, the total mass percentage of Al and Si in the steel matrix is 0.3% to 0.6%.

[0056] In some embodiments of the present disclosure, the steel matrix further includes 0.05% to 0.1% of C and 1.5% to 2% of Mn, or,

[0057] 0.15% to 0.25% of C and 1.6% to 2.5% of Mn, or,

[0058] 0.25% to 0.4% of C and 0.8% to 1.5% of Mn, in terms of mass percentage of the steel matrix.

[0059] By limiting the content range of C and Mn in the steel matrix, the steel matrix can meet the hardenability requirements, and the hardenability of the steel matrix will not be too high to cause the decrease of plasticity.

[0060] In some embodiments of the present disclosure, the steel matrix further includes any at least two or more of Ti, Nb and V, in terms of mass percentage of the steel matrix.

[0061] It is easy to understand that Nb, Ti and V can combine with C and N to form precipitates, which can be mainly used to refine austenite grains and improve the effect of precipitation strengthening, thereby improving the toughness and hydrogen embrittlement resistance of the hot stamping part of the plated steel.

[0062] In some embodiments of the present disclosure, when the steel substrate comprises Ti, the mass percentage of Ti in the steel substrate is 0.01% to 0.1%;

[0063] When the steel substrate comprises Nb, the mass percentage of Nb in the steel substrate is 0.01% to 0.06%;

[0064] When the steel substrate comprises V, the mass percentage of V in the steel substrate is 0.01% to 0.10%.

[0065] In some embodiments of the present disclosure, the contents of Ti, Nb and V satisfy the following relationship:

[0066] 0.05%≤(N Ti +3N Nb +2N V )<0.4%,

[0067] wherein N Ti is the mass percentage of Ti in the steel substrate, N Nb is the mass percentage of Nb in the steel substrate, and N V is the mass percentage of V in the steel substrate.

[0068] It is easy to understand that Nb has a better effect of refining grains but is more expensive, the size of the precipitates of V is smaller, and Ti is inexpensive. In the hot stamping process of the steel substrate of the present disclosure, a certain amount of NbC, VC, and / or TiN, VC and / or (V, Ti, Nb)(C, N) complex carbides are precipitated, and the precipitation of the complex carbides is beneficial to reducing the size of the precipitates and improving the stability, and the second phase particles effectively pin the austenite grains, which will refine the original austenite grains. For the condition of 0.05%≤(N Ti +3N Nb +2N V )<0.4%, the coefficient of Nb is larger, followed by V, and Ti is smaller, and a better ratio can be achieved.

[0069] The inventors have found through in-depth research that when (N Ti +3N Nb +2N V ) is greater than 0.4%, it can lead to the coarsening of the precipitated phase, which is not conducive to obtaining nanoscale dispersed distribution of the precipitated phase. In addition, when (N Ti +3N Nb +2N VWhen the content of the precipitated phase is less than 0.05%, the precipitation strengthening effect is not obviously improved, and the precipitated phase is not enough to obtain the effects of precipitation strengthening and fine-grain strengthening. In addition, the number of H traps formed by the precipitated phase is also insufficient, which is not conducive to the use of the product.

[0070] In some embodiments of the present disclosure, the contents of Ti, Nb and V satisfy the following relationship:

[0071] [N Ti / 2(N Nb +N V )]≤1.

[0072] For the condition [N Ti / 2(N Nb +N V )]≤1, after [N Ti / 2(N Nb +N V )]>1, a large amount of Nb and V will adhere to the surface of coarse Ti precipitates, resulting in a reduction in the addition effect of Nb and V. Therefore, [N Ti / 2(N Nb +N V )]≤1 is set.

[0073] In a second aspect, a method for preparing the plated steel according to some embodiments of the present disclosure includes the following steps, as shown in FIG. 1:

[0074] S11: providing a steel substrate;

[0075] S12: plating nickel on the surface of the steel substrate to form a nickel plating layer, thereby obtaining a nickel-plated substrate; and

[0076] S13: annealing the nickel-plated substrate and plating zinc to form a zinc-rich layer, thereby obtaining the plated steel.

[0077] The oxidation resistance of nickel is much higher than that of steel material. In the present disclosure, a nickel plating layer is formed on the surface of the steel material, so that no oxide is formed on the surface of the nickel plating layer during the zinc plating process. The nickel plating layer formed by the pre-plating of nickel can effectively prevent the enrichment of Si and Mn elements on the surface of the steel material during the annealing process, avoid the direct contact between the steel material and the zinc liquid, and prevent the elements such as silicon and manganese in the steel material from entering the zinc liquid. In this way, the surface quality and appearance of the plated steel can be improved, and a nickel-containing alloy layer and a zinc-rich layer with excellent performance can be obtained. Meanwhile, the nickel plating layer formed by the pre-plating of nickel forms a nickel-containing alloy layer on the surface of the steel material during the zinc plating process. The nickel-containing alloy layer can include Fe, Ni, Zn and other elements. The nickel-containing alloy layer can effectively improve the bonding force between the zinc-rich layer and the steel material. Meanwhile, the melting point of the nickel-containing alloy layer is as high as 800°C or higher. This is beneficial to avoiding the risk of the liquid zinc induced cracking of the substrate grain boundary during the forming process caused by the melting of zinc during the further heat treatment of the plated steel, including hot stamping forming, so as to reduce the crack propagation depth.

[0078] In some embodiments of the present disclosure, the plated steel prepared by the preparation method of the plated steel can be the plated steel disclosed in the first aspect of the present disclosure.

[0079] In some embodiments of the present disclosure, the temperature of the annealing is 720-880°C.

[0080] For example, the temperature of the annealing can be 720°C, 760°C, 800°C, 840°C or 880°C.

[0081] In some embodiments of the present disclosure, the nickel plating is performed by electroplating.

[0082] In some embodiments of the present disclosure, the amount of the nickel plating on the surface of the steel material is 300 mg / side / m 2 -1500 mg / side / m 2 .

[0083] In some embodiments of the present disclosure, the zinc plating method is hot dip plating, and the zinc melt used for the hot dip plating contains aluminum.

[0084] The zinc melt used for the hot dip plating contains aluminum, so that the zinc-rich layer on the surface of the plated steel also contains aluminum. During the further heat treatment of the plated steel, including hot stamping forming, aluminum oxide can be formed on the surface of the plated steel, and the evaporation loss of Zn elements can be reduced.

[0085] In some embodiments of the present disclosure, the temperature of the hot dip plating is 400-460°C.

[0086] In some embodiments of the present disclosure, the duration of the hot dip plating is 3-20 s.

[0087] In some embodiments of the present disclosure, the content of aluminum in the zinc melt is 0.25% to 0.35% in terms of mass percentage of the zinc melt.

[0088] As an example, the temperature of hot-dip plating can be 400℃, 420℃, 440℃, 460℃.

[0089] As an example, the duration of hot-dip plating can be 3s, 6s, 10s, 15s, 20s.

[0090] It is easy to understand that the temperature of hot-dip plating, the duration of hot-dip plating, and the content of aluminum in the zinc melt will ultimately affect the content of aluminum in the plating layer (zinc-rich layer) on the surface of the plated steel.

[0091] When the content of aluminum in the zinc melt is less than 0.25%, it will lead to excessive reaction of iron and zinc affecting the surface quality, and at the same time, it cannot effectively inhibit the mutual diffusion of iron and zinc during heating, resulting in too high iron oxide on the surface of the plated steel and too low Zn content in the plating layer (zinc-rich layer), which will further affect the corrosion resistance of the plated steel; when the content of aluminum in the zinc solution is higher than 0.35%, the diffusion of iron and zinc during heating will be excessively inhibited, which cannot improve the melting point of the plating layer (nickel-containing alloy layer) on the surface of the plated steel, resulting in serious problems of base grain boundary cracking during liquid zinc induced forming, and at the same time, it will increase the content of aluminum oxide on the surface of the plated steel, resulting in reduced adhesion of the plated steel surface, which is not conducive to subsequent coating film process.

[0092] In some embodiments of the present disclosure, the steel material substrate involved in the preparation method of the plated steel comprises 0.05% to 0.4% of C, 0.8% to 2.5% of Mn, 0 to 0.4% of Si, 0 to 0.5% of Al, 0.1% to 0.3% of Cr, 0 to 0.2% of Mo, 0 to 0.4% of Ni, 0.0001% to 0.005% of B, and 0 to 0.01% of N in terms of mass percentage of the steel material substrate.

[0093] In some embodiments of the present disclosure, the steel material substrate involved in the preparation method of the plated steel is the same as the steel material substrate in the plated steel disclosed in any one of the embodiments of the first aspect of the present disclosure, and the optional implementation manners thereof can be referred to the content disclosed in the first aspect, which will not be described here.

[0094] In a third aspect, a steel piece according to some embodiments of the present disclosure, the steel piece comprises:

[0095] a steel material substrate;

[0096] a zinc-iron alloy layer arranged on the surface of the steel material substrate;

[0097] a zinc-iron-nickel alloy layer arranged on the zinc-iron alloy layer,

[0098] The main phase of the zinc-iron alloy layer is α-Fe(Zn), and the main phase of the iron-zinc-nickel alloy layer is Γ-(Fe3Zn) containing nickel. 10 )。

[0099] In some embodiments of the present disclosure, the zinc-iron alloy layer and the iron-zinc-nickel alloy layer include 30% to 70% of Fe, 30% to 70% of Zn, 0 to 0.5% of Al, and 0.01% to 1% of Ni, in terms of the total mass percentage of the zinc-iron alloy layer and the iron-zinc-nickel alloy layer.

[0100] In some embodiments of the present disclosure, the zinc-iron alloy layer includes 15% to 65% of Zn and 0 to 0.5% of Al, in terms of the mass percentage of the zinc-iron alloy layer, and the balance is Fe and inevitable impurities.

[0101] In some embodiments of the present disclosure, the iron-zinc-nickel alloy layer includes 65% to 85% of Zn and 0.2% to 2% of Ni, in terms of the mass percentage of the iron-zinc-nickel alloy layer, and the balance is Fe and inevitable impurities.

[0102] In some embodiments of the present disclosure, the steel piece satisfies the following condition: 0.01 < p < 1,

[0103] wherein p is a value obtained by dividing the volume of the main phase of the iron-zinc-nickel alloy layer by the volume of the main phase of the zinc-iron alloy layer.

[0104] The value of p can be inferred from the results of scanning electron microscope observation or X-ray microanalysis.

[0105] When p < 0.01, the zinc content of the plated layer (zinc-iron alloy layer and iron-zinc-nickel alloy layer) on the surface of the steel piece is too low, and the corrosion resistance is insufficient; when p > 1, it indicates that there may be insufficient heating during the process of heating the plated steel to above the Ac1 temperature of the steel substrate, and therefore the phenomenon of insufficient austenitization of the steel substrate may occur when p > 1.

[0106] As an example, the structure and the volume of the metal phase of the plated layer in the plated steel and the steel piece can be observed using a scanning electron microscope (SEM) or an electron probe X-ray microanalyser (EPMA).

[0107] In some embodiments of the present disclosure, in the grain boundaries of α-Fe(Zn), the proportion of the number of grain boundaries enriched with Zn elements is not higher than 60%.

[0108] The enrichment of Zn elements in the grain boundaries may reduce the strength of the grain boundaries. The phenomenon of enrichment of Zn elements in the grain boundaries can be effectively reduced by preheating the plated steel to reduce the problem of Zn liquefaction.

[0109] The enrichment of Zn element in the grain boundary can be determined by transmission electron microscopy and EDS (Energy Dispersive Spectroscopy) scanning.

[0110] As an example, the element enrichment of the grain boundary can be determined by EDS (Energy Dispersive Spectroscopy) plane scanning.

[0111] In some embodiments of the present disclosure, the total thickness of the zinc-iron alloy layer and the iron-zinc-nickel alloy layer is 10 μm to 40 μm.

[0112] As an example, the total thickness of the zinc-iron alloy layer and the iron-zinc-nickel alloy layer can be 10 μm, 20 μm, 30 μm, or 40 μm.

[0113] In some embodiments of the present disclosure, the steel substrate involved in the steel piece comprises 0.05% to 0.4% of C, 0.8% to 2.5% of Mn, 0 to 0.4% of Si, 0 to 0.5% of Al, 0.1% to 0.3% of Cr, 0 to 0.2% of Mo, 0 to 0.4% of Ni, 0.0001% to 0.005% of B, and 0 to 0.01% of N, in terms of mass percentage of the steel substrate.

[0114] In some embodiments of the present disclosure, the steel substrate in the steel piece can be the same as the steel substrate in the plated steel disclosed in any of the embodiments of the first aspect of the present disclosure, and the optional implementation thereof can refer to the content disclosed in the first aspect, which will not be described herein again.

[0115] S21: providing the plated steel disclosed in any of the embodiments of the first aspect, or providing the plated steel prepared by the preparation method of the plated steel disclosed in any of the embodiments of the second aspect;

[0116] S22: heating the plated steel to above the Ac1 temperature of the steel substrate, reducing the temperature of the plated steel heated to above the Ac1 temperature of the steel substrate to a hot stamping forming temperature, and performing hot stamping forming treatment and quenching treatment on the plated steel with the temperature reduced to the hot stamping forming temperature to obtain a steel piece.

[0117] In the process of heating the plated steel to above the Ac1 temperature of the steel substrate and reducing the temperature of the plated steel heated to above the Ac1 temperature of the steel substrate to a hot forming temperature in step S22, an iron-zinc-nickel alloy layer will be formed on the surface of the plated steel, and the main phase of the iron-zinc-nickel alloy layer is Γ-(Fe3Zn 10) alloy, the Ni in the Ni-containing alloy layer of the plated steel will combine with the Zn in the Zn-rich layer and enrich into the Γ-(Fe3Zn 10 ) alloy layer, which will make the structure of the iron-zinc-nickel alloy layer containing Γ-(Fe3Zn 10 ) more stable, so as to make the iron-zinc-nickel alloy layer have excellent corrosion resistance, and finally realize the improvement of the corrosion resistance of the steel part.

[0118] In addition, in the process of heating the plated steel to above the Ac1 temperature of the steel base body, and reducing the temperature of the plated steel heated to above the Ac1 temperature of the steel base body to the hot forming temperature, it is also a heat treatment process for the steel base body itself. Through this heat treatment process, the heat treatment of the steel base body and the heat treatment of the plated layer on the surface of the plated steel can be realized at the same time, and the process flow is simplified.

[0119] In some embodiments of the present disclosure, the plated steel is heated to above the Ac1 temperature of the steel base body, as shown in FIG. 3, including the following steps:

[0120] S221: preheating the plated steel;

[0121] S222: austenitizing the plated steel in a first stage heating;

[0122] S223: austenitizing the plated steel in a second stage heating;

[0123] Preheating temperature is not higher than the temperature of the second stage austenitizing heating, and the temperature of the second stage austenitizing heating is not higher than the temperature of the first stage austenitizing heating.

[0124] In the process of preheating the plated steel in step S221, the preheating temperature can be lower than the liquefaction temperature of zinc, so that sufficient iron, nickel and other elements can diffuse into the plated layer (iron-zinc-nickel alloy layer) on the surface of the plated steel, thereby improving the melting point. The temperature of the second stage austenitizing heating is not higher than the temperature of the first stage austenitizing heating. A higher first stage austenitizing temperature range is conducive to quickly completing austenitizing, shortening the holding time and saving energy. A lower second stage austenitizing temperature range is conducive to reducing the furnace temperature and shortening the time consumption of reducing the temperature of the plated steel to the hot forming temperature.

[0125] In some embodiments of the present disclosure, the thickness of the steel substrate is 0.7mm-1.4mm, the preheating temperature is 600-860℃, the preheating time is 60-200s, the first-stage austenitizing heating temperature is 880-950℃, and the second-stage austenitizing heating temperature is 850-900℃; or, the thickness of the steel substrate is 1.4-3mm, the preheating temperature is 700-880℃, the preheating time is 80-220s, the first-stage austenitizing heating temperature is 890-960℃, and the second-stage austenitizing heating temperature is 840-890℃.

[0126] It is easy to understand that the present disclosure sets different heating temperatures for steel substrates of different thicknesses, so that the steel substrate can be fully austenitized.

[0127] In some embodiments of the present disclosure, the thickness of the steel substrate is 0.7-1mm, and the total time of the first-stage austenitizing heating and the second-stage austenitizing heating is 80-200s; or,

[0128] The thickness of the steel substrate is 1-1.4mm, and the total time of the first-stage austenitizing heating and the second-stage austenitizing heating is 120-300s; or,

[0129] The thickness of the steel substrate is 1.4-2mm, and the total time of the first-stage austenitizing heating and the second-stage austenitizing heating is 100-280s; or,

[0130] The thickness of the steel substrate is 2-3mm, and the total time of the first-stage austenitizing heating and the second-stage austenitizing heating is 160-360s.

[0131] It is easy to understand that, on the premise that the present disclosure sets different heating temperatures for steel substrates of different thicknesses, the present disclosure further subdivides the thickness of the steel substrate and sets different heating times for different thicknesses, so that the steel substrate can be fully austenitized.

[0132] In some embodiments of the present disclosure, at least the preheating is performed in an atmosphere with an oxygen volume fraction of 2-20% during the preheating, the first-stage austenitizing heating, and the second-stage austenitizing heating.

[0133] It is easy to understand that, in the above atmosphere, heat treatment can form oxides such as ZnO and AlO on the surface of the plated steel, reducing the evaporation loss of Zn elements.

[0134] For example, the oxygen volume fraction of the atmosphere can be 2%, 4%, 8%, 15%, or 20%.

[0135] The beneficial effect of the oxygen volume fraction of 2% to 20% in the atmosphere is that oxides such as ZnO and AlO can be formed to reduce the evaporation loss of Zn element, and the amount of the formed oxides will not be excessive to cause additional surface treatment cost.

[0136] In some embodiments of the present disclosure, the temperature for hot stamping forming is 500℃ to 740℃.

[0137] In some embodiments of the present disclosure, the temperature of the plated steel is reduced to the temperature for hot stamping forming, and the duration of the temperature reduction of the plated steel is 5s to 16s.

[0138] It is easy to understand that the temperature for hot stamping forming of the galvanized steel sheet is usually below 700℃. Due to the presence of the high melting point metal Ni, the temperature for hot stamping forming can be extended to 740℃ in the present disclosure.

[0139] It is easy to understand that the temperature for hot stamping forming that is too low will cause the forming resistance of the steel substrate to increase, and even cause the steel part to crack; the temperature for hot stamping forming that is too high will cause the Zn to melt and induce the base grain boundary to crack during the forming process.

[0140] As an example, the temperature of the plated steel is reduced to the temperature for hot stamping forming, and the method for reducing the temperature can be at least one of air jet cooling, water mist cooling, and water solution cooling.

[0141] It is easy to understand that the duration of the temperature reduction treatment of the plated steel is 5s to 16s, which can ensure that the temperature of the plated steel can be reduced to the temperature for hot stamping forming, and the duration of the temperature reduction treatment will not be too long to affect the efficiency.

[0142] In some embodiments of the present disclosure, the steel substrate in the preparation method of the steel part comprises, in percentage by mass of the steel substrate, 0.05% to 0.4% of C, 0.8% to 2.5% of Mn, 0 to 0.4% of Si, 0 to 0.5% of Al, 0.1% to 0.3% of Cr, 0 to 0.2% of Mo, 0 to 0.4% of Ni, 0.0001% to 0.005% of B, and 0 to 0.01% of N.

[0143] In some embodiments of the present disclosure, the steel substrate involved in the preparation method of the steel part can be the same as the steel substrate in the plated steel disclosed in any one of the embodiments of the first aspect, and the optional implementation manner thereof can be referred to the content disclosed in the first aspect, which will not be described herein again.

[0144] In some embodiments of the present disclosure, the hot stamping steel part for vehicles can be any one of a front door left and right bumper bar, a front door left and right bumper bar beam, a rear door left and right bumper bar, a rear door left and right bumper bar beam, a front bumper, a rear bumper, an A-pillar reinforcement plate, a B-pillar reinforcement plate, a C-pillar reinforcement plate, a panel tunnel, a roof reinforcement beam, a new energy vehicle battery package shell, and an automobile door sill safety structure.

[0145] The present disclosure will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present disclosure and are not used to limit the scope of the present disclosure. The experimental methods in the following examples without specific conditions are generally determined according to the industry standards. If there is no corresponding industry standard, the general international standards, conventional conditions, or the conditions suggested by the manufacturer are followed.

[0146] Example 1

[0147] First, the present embodiment discloses a steel base material with the element composition shown in Table 1. The steel base material is a cold hard steel strip, which is prepared by smelting, casting, hot rolling, and pickling and cold rolling processes.

[0148] The present embodiment prepares a steel part based on the above steel base material, and the preparation method of the steel part includes the following steps:

[0149] Sa: pretreatment before nickel plating of the steel base material, which can include alkaline solution degreasing, water cleaning, electrolytic degreasing, pickling, and water cleaning to remove grease, residual iron, and other impurities on the surface of the steel base material, so that the surface of the steel base material (strip steel) remains clean;

[0150] Sb: after the pretreatment is completed, the steel base material is subjected to electroplating on both sides to obtain a nickel-plated base material with nickel plating on both sides, wherein the weight of the electroplated nickel is shown in Table 2;

[0151] Sc: after the nickel-plated base material is subjected to continuous annealing treatment, hot dip plating is performed in a zinc melt containing aluminum, and after the hot dip plating, a nickel-containing alloy layer and a zinc-rich layer are formed on the surface of the steel base material to obtain a plated steel, wherein the temperature and time of the continuous annealing, the temperature and time of the hot dip plating, the content of aluminum in the zinc melt, the thickness of the nickel-containing alloy layer and the zinc-rich layer, the total content of each element and aluminum in the nickel-containing alloy layer and the zinc-rich layer are shown in Table 2, and the element composition of the nickel-containing alloy layer and the zinc-rich layer is shown in Table 3;

[0152] Sd: The plated steel is preheated, heated in the first stage of austenitization, heated in the second stage of austenitization, then the plated steel is subjected to hot stamping forming treatment and quenching treatment to obtain a steel part, the steel part comprises a steel base, a zinc-iron alloy layer formed on the surface of the steel base, and a zinc-nickel-iron alloy layer formed on the surface of the zinc-iron alloy layer, wherein the thickness of the steel base, the temperature and time of preheating, the temperature and time of the first stage of austenitization, the temperature and time of the second stage of austenitization, the temperature of hot stamping treatment, the thickness of the surface plated layer (zinc-nickel-iron alloy layer and zinc-nickel-iron alloy layer) of the steel part, and the p value (p is a value obtained by dividing the volume of the main phase of the zinc-nickel-iron alloy layer by the volume of the main phase of the zinc-iron alloy layer) of the steel part are shown in Table 4, and the elemental composition of the zinc-iron alloy layer and the zinc-nickel-iron alloy layer is shown in Table 5.

[0153] In addition, it should be noted that the sum of the content of each element in Table 1, Table 3 and Table 5 does not reach 100%, which is because other unavoidable impurities are contained, such as Mn and Si elements diffused from the steel base.

[0154] Example 2

[0155] The difference between this example and Example 1 is shown in Table 1, Table 2, Table 3, Table 4 and Table 5. In addition to the data shown in Table 1, Table 2, Table 3, Table 4 and Table 5, the other operating modes and conditions of this example and Example 1 are exactly the same.

[0156] Example 3

[0157] The difference between this example and Example 1 is shown in Table 1, Table 2, Table 3, Table 4 and Table 5. In addition to the data shown in Table 1, Table 2, Table 3, Table 4 and Table 5, the other operating modes and conditions of this example and Example 1 are exactly the same.

[0158] In addition, the element depth distribution of the plated steel and the steel part obtained in this example is tested and analyzed by GDS850A glow spectrum, and the element depth distribution diagram obtained is shown in Figure 4. Figure 4(a) is the element depth distribution in the surface plated layer of the plated steel, and Figure 4(b) is the element depth distribution in the surface plated layer of the steel part. The elemental composition of the zinc-iron alloy layer and the zinc-nickel-iron alloy layer can be calculated from Figure 4, and the specific results are shown in Table 5.

[0159] Example 4

[0160] The difference between this example and Example 1 is shown in Table 1, Table 2, Table 3, Table 4 and Table 5. In addition to the data shown in Table 1, Table 2, Table 3, Table 4 and Table 5, the other operating modes and conditions of this example and Example 1 are exactly the same.

[0161] Example 5

[0162] The difference between this example and Example 1 is found in Tables 1, 2, 3, 4, and 5. Except for the data shown in Tables 1, 2, 3, 4, and 5, the other operation modes and conditions of this example are exactly the same as those of Example 1.

[0163] Example 6

[0164] The difference between this example and Example 1 is found in Tables 1, 2, 3, 4, and 5. Except for the data shown in Tables 1, 2, 3, 4, and 5, the other operation modes and conditions of this example are exactly the same as those of Example 1.

[0165] Comparative Example 1

[0166] The difference between this example and Example 1 is found in Tables 1, 2, 3, 4, and 5. Except for the data shown in Tables 1, 2, 3, 4, and 5, the difference between this example and Example 1 is that this example does not include Step Sb, but directly performs the continuous annealing and hot-dip plating treatment in Step Sc on the steel substrate that has been subjected to Step Sa.

[0167] Comparative Example 2

[0168] The difference between this example and Example 1 is found in Tables 1, 2, 3, 4, and 5. Except for the data shown in Tables 1, 2, 3, 4, and 5, the difference between this example and Example 1 is that this example does not include Step Sb, but directly performs the continuous annealing and hot-dip plating treatment in Step Sc on the steel substrate that has been subjected to Step Sa.

[0169] Comparative Example 3

[0170] The difference between this example and Example 1 is found in Tables 1, 2, 3, 4, and 5. Except for the data shown in Tables 1, 2, 3, 4, and 5, the difference between this example and Example 1 is that this example does not include Step Sb, but directly performs the continuous annealing and hot-dip plating treatment in Step Sc on the steel substrate that has been subjected to Step Sa.

[0171] Comparative Example 4

[0172] The difference between this example and Example 1 is found in Tables 1, 2, 3, 4, and 5. Except for the data shown in Tables 1, 2, 3, 4, and 5, the difference between this example and Example 1 is that this example does not include Step Sb, but directly performs the continuous annealing and hot-dip plating treatment in Step Sc on the steel substrate that has been subjected to Step Sa.

[0173] Table 1 Element composition of steel substrate in each example and comparative example

[0174] Table 1 (continued)

[0175] Table 2 Process parameters and product parameters involved in step Sb and step Sc in each of the examples and the comparative examples

[0176] Table 3 Element composition of the nickel-containing alloy layer and the zinc-rich layer

[0177] Table 4 Process parameters and product parameters involved in step Sd in each of the examples and the comparative examples

[0178] Table 5 Element composition of the zinc-iron alloy layer and the iron-zinc-nickel alloy layer

[0179] Table 5 (continued)

[0180] Related experiments and effect data:

[0181] The steel parts obtained in Examples 1-6 and Comparative Examples 1-3 were subjected to mechanical property testing, and the yield strength, tensile strength and elongation at break data were obtained, and the testing results are shown in Table 6; the martensite volume fraction, ferrite volume fraction and bainite volume fraction of the steel matrix in the steel parts obtained in Examples 1-6 and Comparative Examples 1-3 were analyzed by XRD (X-Ray Diffraction), and the analysis results are shown in Table 6; whether the steel parts meet the corrosion resistance requirements of automobile manufacturers was tested according to ISO 11997-1 cycle B, and the results are shown in Table 6; the surface crack depth of the steel parts obtained in Examples 1-6 and Comparative Examples 1-3 was observed by SEM (Scanning Electron Microscope), and the results are shown in Table 6.

[0182] Table 6 Testing and analysis results of the steel parts obtained in Examples 1-6 and Comparative Examples 1-3

[0183] Based on the comprehensive analysis of Tables 1, 4 and 6, the following conclusions can be drawn:

[0184] The steel matrix of Comparative Example 1 does not contain Nb and V elements, and the C, Cr and other elements do not meet the required range of the present disclosure, which results in the yield strength of the steel part of Comparative Example 1 being less than 350 MPa.

[0185] The steel matrix of Comparative Example 3 does not contain Nb and V elements, and the elongation of the obtained steel part is less than 4%.

[0186] The plated steel of Comparative Examples 1 to 4 cannot withstand higher preheating temperature, austenite first stage heating temperature, austenite second stage heating temperature, and hot stamping temperature because of no nickel-containing plating layer, resulting in liquefaction of zinc under high heat environment and inducing cracks in the steel substrate. The crack depth of Comparative Examples 1 to 4 is generally higher than that of the Examples.

[0187] The Al content in the zinc melt of Comparative Examples 1, 2, and 3 is low, resulting in excessive reaction of iron and zinc, and simultaneously, the mutual diffusion of iron and zinc during heating cannot be effectively inhibited, resulting in too high iron oxide on the surface of the plated steel and too low Zn content in the nickel-containing alloy layer, affecting the corrosion resistance, and failing to meet the corrosion resistance requirement.

[0188] The steel parts obtained from Example 3 and Comparative Example 3 were analyzed by EPMA (Electron Probe X-ray Micro-Analyzer). The electron probe analysis diagram of the steel part of Example 3 is shown in FIG. 5, and the electron probe analysis diagram of the steel part of Comparative Example 3 is shown in FIG. 6. Among them, FIG. 5(a) is a backscattered image of the plating layer, FIG. 5(b) is a Fe element content distribution diagram, FIG. 5(c) is a Ni element content distribution diagram, and FIG. 5(d) is a Zn element content distribution diagram; FIG. 6(a) is a Fe element content distribution diagram, FIG. 6(b) is a Fe element content distribution diagram, and FIG. 6(c) is a Zn element content distribution diagram. In FIG. 5(a) and FIG. 6(a), the iron-zinc alloy phase α-Fe(Zn) is light gray, and the zinc-rich Γ-Fe3Zn10 phase is light white. In FIG. 5, the Ni element is enriched in the Γ phase, and the content of each element in each phase can be clearly seen from the element distribution diagram.

[0189] The steel parts obtained from Example 3 and Comparative Example 2 were analyzed by EPMA (Electron Probe X-ray Micro-Analyzer). The electron probe analysis diagram of the steel part of Example 3 is shown in FIG. 5, and the electron probe analysis diagram of the steel part of Comparative Example 3 is shown in FIG. 6. Among them, FIG. 5(a) is a backscattered image of the plating layer, FIG. 5(b) is a Fe element content distribution diagram, FIG. 5(c) is a Ni element content distribution diagram, and FIG. 5(d) is a Zn element content distribution diagram; FIG. 6(a) is a Fe element content distribution diagram, FIG. 6(b) is a Fe element content distribution diagram, and FIG. 6(c) is a Zn element content distribution diagram. In FIG. 5(a) and FIG. 6(a), the iron-zinc alloy phase α-Fe(Zn) is light gray, and the zinc-rich Γ-Fe3Zn10 phase is light white. In FIG. 5, the Ni element is enriched in the Γ phase, and the content of each element in each phase can be clearly seen from the element distribution diagram.

[0190] The flake sample of Example 3 above was observed by Transmission Electron Microscope (TEM) (JEM-2100F, JEOL Ltd.) to randomly observe the grain boundaries of the α-Fe(Zn) solid solution adjacent to the interface. The element enrichment of the grain boundaries was determined by EDS (Energy Dispersive Spectroscopy) area scanning. The TEM image obtained is shown in FIG. 9. FIG. 9 shows that the Zn element adjacent to the matrix is enriched at the grain boundaries of the α-Fe(Zn) solid solution. By randomly observing the grain boundaries, the number of grain boundaries with Zn enrichment is less than or equal to 60%.

[0191] The plated steel according to some embodiments of the present disclosure has the following advantages compared to the related art:

[0192] The plated steel according to some embodiments of the present disclosure has the following advantages compared to the related art:

[0193] Various embodiments of the present disclosure can exist in the form of a range; it should be understood that the description in the form of a range is merely for the convenience and brevity, and should not be understood as a hard limit on the scope of the present disclosure; therefore, it should be considered that the described range has 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 described range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0194] In the present disclosure, the orientation words such as "upper" and "lower" are specifically the directions of the drawing surface in the drawings unless otherwise stated. In addition, in the description of the present disclosure, the terms "comprise", "contain" and the like mean "including but not limited to". Moreover, the terms "comprise", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device. Without more limitations, the elements defined by the statement "comprise" do not exclude the presence of other identical elements in the process, method, article or device including the elements. In this paper, the relationship terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. In this paper, the "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the following cases: A exists alone, A and B exist together, and B exists alone. For the association relationship of more than three associated objects described by "and / or", it means that any one of the three associated objects can exist alone, or any at least two of them exist together, for example, for A, and / or B, and / or C, it means that any one of A, B and C exists alone, or any two of them exist together, or all three of them exist together. In this paper, "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 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.

[0195] The above description is only a specific embodiment of the present disclosure, which enables those skilled in the art to understand or implement the present disclosure. Various modifications of these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments shown herein, but will conform to a wider range consistent with the principles and novel features disclosed herein.

Claims

1. A plated steel, comprising: a steel substrate; a nickel-containing alloy layer disposed on a surface of the steel substrate; and a zinc-rich layer disposed on the nickel-containing alloy layer; wherein the nickel-containing alloy layer comprises, in mass percentage of the nickel-containing alloy layer, 0.1%-4% of Al, 0.2%-5% of Ni, 20%-70% of Fe, and 0.01%-1.5% of Mn, with the balance being Zn and unavoidable impurities; the zinc-rich layer comprises, in mass percentage of the zinc-rich layer, 0-10% of Fe, 88%-100% of Zn, and 0-0.2% of Al; the total thickness of the nickel-containing alloy layer and the zinc-rich layer is 5-20μm; and / or the thickness of the nickel-containing alloy layer is 1-8μm; and / or the thickness of the zinc-rich layer is 4-18μm; the total content of Al in the nickel-containing alloy layer and the zinc-rich layer is 0.4%-0.6%, in mass percentage of the total mass of the nickel-containing alloy layer and the zinc-rich layer; the steel substrate comprises, in mass percentage of the steel substrate, 0.05%-0.4% of C, 0.8%-2.5% of Mn, 0-0.4% of Si, 0-0.5% of Al, 0.1%-0.3% of Cr, 0-0.2% of Mo, 0-0.4% of Ni, 0.0001%-0.005% of B, and 0-0.01% of N; the total mass percentage of Cr, Mo, and Ni in the steel substrate is 0.11%-0.45%; and / or the total mass percentage of Al and Si in the steel substrate is 0.3%-0.6%; the steel substrate further comprises, in mass percentage of the steel substrate, 0.05%-0.1% of C and 1.5%-2% of Mn; or the steel substrate further comprises, in mass percentage of the steel substrate, 0.15%-0.25% of C and 1.6%-2.5% of Mn; or the steel substrate further comprises, in mass percentage of the steel substrate, 0.25%-0.4% of C and 0.8%-1.5% of Mn; the steel substrate further comprises any two or more of Ti, Nb, and V; when the steel substrate comprises Ti, the mass percentage of Ti in the steel substrate is 0.01%-0.1%; when the steel substrate comprises Nb, the mass percentage of Nb in the steel substrate is 0.01%-0.06%; and when the steel substrate comprises V, the mass percentage of V in the steel substrate is 0.01%-0.10%. 11.A method for preparing a plated steel, comprising the steps of: providing a steel substrate; plating nickel on a surface of the steel substrate to form a nickel plating layer, thereby obtaining a nickel-plated substrate; and annealing the nickel-plated substrate and plating zinc on the nickel-plated substrate to form a zinc-rich layer, thereby obtaining the plated steel; the annealing is performed at a temperature of 720-880℃; the nickel plating is performed by electroplating; and / or the zinc plating is performed by hot-dip galvanizing. ​ ​ ​ ​ ​ 2. The plated steel of claim 1, wherein, ​ ​ ​ 3. The plated steel of claim 1, wherein, ​ 4. The plated steel of claim 1, wherein, ​ 5. The plated steel of claim 4, wherein, ​ ​ 6. The plated steel of claim 4, wherein, ​ ​ ​ 7. The plated steel of claim 4, wherein, ​ 8. The plated steel of claim 7, wherein, ​ ​ ​ 9. The coated steel of claim 8, wherein, The content of the three elements of Ti, Nb and V satisfies the following relationship: 0.05%≤(N Ti +3N Nb +2N V )<0.4% in terms of the mass percentage of the steel base. wherein N Ti is the mass percentage of Ti in the steel base body, N Nb is the mass percentage of Nb in the steel base body, N V is the mass percentage of V in the steel base body.

10. The coated steel of claim 9, wherein, The content of the three elements of Ti, Nb and V also satisfies the following relationship in terms of the mass percentage of the steel base: N Ti / 2(N Nb +N V )≤1. ​ ​ ​ ​ 12. The method of producing a plated steel sheet according to claim 11, wherein, ​ 13. The method of producing a plated steel sheet according to claim 11, wherein ​ The amount of nickel plating is 300 mg / side / m 2 ~ 1500 mg / side / m 2 .

14. The method of producing a plated steel sheet according to claim 11, wherein The galvanizing method is hot-dip galvanizing, and the zinc melt used for the hot-dip galvanizing contains aluminum.

15. The method of producing a plated steel sheet according to claim 14, wherein The temperature of the hot-dip galvanizing is 400-460℃; and / or, The duration of the hot-dip galvanizing is 3-20s; and / or, The mass content of aluminum in the zinc melt is 0.25-0.35% in terms of mass percentage of the zinc melt.

16. The method of producing a plated steel sheet according to claim 11, wherein The steel base body contains 0.05-0.4% of C, 0.8-2.5% of Mn, 0-0.4% of Si, 0-0.5% of Al, 0.1-0.3% of Cr, 0-0.2% of Mo, 0-0.4% of Ni, 0.0001-0.005% of B and 0-0.01% of N in terms of mass percentage of the steel base body.

17. A steel piece, comprising: a steel base body; a zinc-iron alloy layer arranged on the surface of the steel base body; and a zinc-iron-nickel alloy layer arranged on the zinc-iron alloy layer; The zinc-iron alloy layer has a main phase of α-Fe(Zn), and the iron-zinc-nickel alloy layer has a main phase of Γ-(Fe3Zn) containing nickel. 10 ) 18. Steel piece according to claim 17, wherein, the zinc-iron alloy layer and the zinc-iron-nickel alloy layer contain 30-70% of Fe, 30-70% of Zn, 0-0.5% of Al and 0.01-1% of Ni in terms of total mass percentage of the zinc-iron alloy layer and the zinc-iron-nickel alloy layer.

19. Steel piece according to claim 18, wherein, the zinc-iron alloy layer contains 15-65% of Zn, 0-0.5% of Al and the balance of Fe and inevitable impurities in terms of mass percentage of the zinc-iron alloy layer; and / or, the zinc-iron-nickel alloy layer contains 65-85% of Zn, 0.2-2% of Ni and the balance of Fe and inevitable impurities in terms of mass percentage of the zinc-iron-nickel alloy layer.

20. The steel piece according to claim 17, wherein, the steel piece satisfies the condition: 0.01 wherein p is a value obtained by dividing the volume of the main phase of the zinc-iron-nickel alloy layer by the volume of the main phase of the zinc-iron alloy layer.

21. Steel piece according to claim 17, wherein, The number of grain boundaries rich in Zn element in the grain boundaries of the α-Fe(Zn) accounts for no more than 60%.

22. The steel piece according to claim 17, wherein, The total thickness of the zinc-iron alloy layer and the zinc-iron-nickel alloy layer is 10-40μm.

23. The steel piece according to claim 17, wherein, The steel base body contains 0.05-0.4% of C, 0.8-2.5% of Mn, 0-0.4% of Si, 0-0.5% of Al, 0.1-0.3% of Cr, 0-0.2% of Mo, 0-0.4% of Ni, 0.0001-0.005% of B and 0-0.01% of N in terms of mass percentage of the steel base body.

24. A method for preparing a steel piece, comprising the following steps: providing the plated steel as claimed in any one of claims 1-10, or providing the plated steel prepared by the method for preparing a plated steel as claimed in any one of claims 11-16; and heating the plated steel to above the Ac1 temperature of the steel base body, reducing the temperature of the plated steel heated to above the Ac1 temperature of the steel base body to a hot stamping forming temperature, and performing hot stamping forming treatment and quenching treatment on the plated steel whose temperature is reduced to the hot stamping forming temperature to obtain the steel piece.

25. The method of manufacturing a steel piece according to claim 24, wherein, the heating of the plated steel to above the Ac1 temperature of the steel base body comprises the following steps: preheating the plated steel; first-stage austenitizing heating of the plated steel; second-stage austenitizing heating of the plated steel, wherein the preheating temperature is not higher than the second-stage austenitizing heating temperature, and the second-stage austenitizing heating temperature is not higher than the first-stage austenitizing heating temperature.

26. A method of producing a steel piece according to claim 25, wherein, the thickness of the steel substrate is 0.7 mm to 1.4 mm, the preheating temperature is 600°C to 860°C, the preheating time is 60 s to 200 s, the first-stage austenitizing heating temperature is 880°C to 950°C, and the second-stage austenitizing heating temperature is 850°C to 900°C; or the thickness of the steel substrate is 1.4 mm to 3 mm, the preheating temperature is 700°C to 880°C, the preheating time is 80 s to 220 s, the first-stage austenitizing heating temperature is 890°C to 960°C, and the second-stage austenitizing heating temperature is 840°C to 890°C.

27. A method of producing a steel piece according to claim 26, wherein, the thickness of the steel substrate is 0.7 mm to 1 mm, and the total time of the first-stage austenitizing heating and the second-stage austenitizing heating is 80 s to 200 s; or the thickness of the steel substrate is 1 mm to 1.4 mm, and the total time of the first-stage austenitizing heating and the second-stage austenitizing heating is 120 s to 300 s; or the thickness of the steel substrate is 1.4 mm to 2 mm, and the total time of the first-stage austenitizing heating and the second-stage austenitizing heating is 100 s to 280 s; or the thickness of the steel substrate is 2 mm to 3 mm, and the total time of the first-stage austenitizing heating and the second-stage austenitizing heating is 160 s to 360 s.

28. A method of manufacturing a steel piece according to claim 25, wherein, At least the preheating is performed in an atmosphere with an oxygen volume fraction of 2% to 20% among the preheating, the first-stage austenitizing heating, and the second-stage austenitizing heating.

29. A method of manufacturing a steel piece according to claim 24, wherein, the hot stamping forming temperature is 500°C to 740°C; and / or the duration of the temperature reduction of the plated steel to the hot forming temperature is 5 s to 16 s.

30. A method of manufacturing a steel piece according to claim 24, wherein, The steel substrate comprises, by mass percentage of the steel substrate, 0.05% to 0.4% of C, 0.8% to 2.5% of Mn, 0 to 0.4% of Si, 0 to 0.5% of Al, 0.1% to 0.3% of Cr, 0 to 0.2% of Mo, 0 to 0.4% of Ni, 0.0001% to 0.005% of B, and 0 to 0.01% of N.

31. Use of a steel part in a hot stamping steel part for a vehicle.

32. Use of a steel piece according to claim 31, wherein, The hot stamping steel part for a vehicle is any one of a front door left and right bumper beam, a front door left and right bumper beam, a rear door left and right bumper beam, a rear door left and right bumper beam, a front bumper, a rear bumper, an A-pillar reinforcement plate, a B-pillar reinforcement plate, a C-pillar reinforcement plate, a floor tunnel, a roof reinforcement beam, a new energy vehicle battery pack shell, and a vehicle rocker safety structure.

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