Steel alloy, galvanized steel and preparation method thereof

Abstract

The invention relates to a steel alloy, galvanized steel and a preparation method thereof. The steel alloy comprises the following element components in percentage by mass: 0.87 wt% to 0.95 wt% of C, 0.70 wt% to 0.80 wt% of Mn, 0.27 wt% to 0.37 wt% of Si, 0.25 wt% to 0.35 wt% of Cr, 0.12 wt% to 0.15 wt% of Nb, 0.015 wt% to 0.035 wt% of Al, 0 to 0.0050 wt% of N, and the balance of Fe and inevitable impurities. According to the steel alloy, all the element components in a specific proportion cooperate with one another, and the steel alloy good in high-temperature resistance is obtained; before and after hot-dip galvanizing, the tensile strength, the bending performance and the torsion performance of the steel alloy are slightly changed, the problem of performance degradation of a traditional high-strength steel wire in the hot-dip galvanizing process can be effectively solved, and powerful support is provided for application of steel such as the high-strength steel wire in the high-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of alloys, and in particular to a steel alloy, galvanized steel and a preparation method thereof. Background Art

[0002] In the modern industrial field, high-strength steel wire and other steel products have attracted much attention due to their excellent mechanical properties and wide application prospects. However, traditional high-strength steel wire and other steel products often face the problem of significant performance degradation when undergoing hot-dip galvanizing, with tensile strength reduced by more than 50MPa and torsional and bending properties sharply reduced.

[0003] In order to overcome this technical difficulty, it is particularly important to develop a high-strength steel wire that can maintain stable performance during the hot-dip galvanizing process. Summary of the invention

[0004] Based on this, it is necessary to provide a steel alloy with good high temperature resistance, which has less loss of tensile strength, bending performance and torsional performance after hot-dip galvanizing; further, provide a method for preparing the above-mentioned steel alloy; and a method for preparing galvanized steel and galvanized steel.

[0005] In a first aspect of the present application, a steel alloy is provided, comprising the following elemental components, measured in percentage by mass: C 0.87wt%~0.95wt%, Mn 0.70wt%~0.80wt%, Si 0.27wt%~0.37wt%, Cr 0.25wt%~0.35wt%, Nb 0.12wt%~0.15wt%, Al 0.015wt%~0.035wt%, N 0~0.0050wt%, and the balance being Fe and unavoidable impurities.

[0006] The above steel alloy is obtained by the mutual cooperation of various element components in a specific ratio. Under the condition of hot-dip galvanizing at 450℃~500℃, the structural organization of the steel alloy is not easily destroyed. Before and after hot-dip galvanizing, the tensile strength, bending performance and torsional performance of the steel alloy change little, which can effectively solve the performance attenuation problem of traditional high-strength steel wire during hot-dip galvanizing, and provide strong support for the application of high-strength steel wire in high-temperature environment.

[0007] In some embodiments, the steel alloy contains a pearlite structure.

[0008] In some embodiments, the maximum size of pearlite clusters in the cross section of the steel alloy is 2 μm to 3.5 μm.

[0009] In some embodiments, in the pearlite cluster, the spacing between two adjacent pearlite lamellae is 0.1 μm to 0.18 μm.

[0010] In some embodiments, the steel alloy is a wire, and the diameter of the steel alloy is ≤20 mm.

[0011] The second aspect of the present application provides a method for preparing the steel alloy according to the first aspect, comprising the following steps:

[0012] configuring raw materials according to the elemental composition of the steel alloy;

[0013] The raw materials are sequentially subjected to smelting, refining, continuous casting and hot rolling processes.

[0014] In some embodiments, the following steps are also included:

[0015] The wire rod obtained by the hot rolling process is subjected to a drawing process; the drawing process speed is 3m / s~5m / s.

[0016] A third aspect of the present application provides a galvanized steel comprising the steel alloy described in the first aspect and a zinc coating provided on at least a portion of the surface of the steel alloy.

[0017] The third aspect of the present application provides a method for preparing galvanized steel of the third aspect, comprising the following steps: immersing the steel alloy in liquid zinc.

[0018] In some embodiments, the temperature of the liquid zinc is 440°C to 500°C. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present invention, the present invention is described more comprehensively below. And preferred embodiments of the present invention are given. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0021] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0022] The weight of the relevant components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also indicate the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the description of the embodiments of the present invention, it is within the scope disclosed in the description of the embodiments of the present invention. Specifically, the weight described in the description of the embodiments of the present invention may be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0023] In one embodiment of the present application, a steel alloy is provided, which includes the following element components, measured in percentage by mass: C 0.87wt%~0.95wt%, Mn 0.70wt%~0.80wt%, Si 0.27wt%~0.37wt%, Cr 0.25wt%~0.35wt%, Nb 0.12wt%~0.15wt%, Al 0.015wt%~0.035wt%, N 0~0.0050wt%, and the balance is Fe and unavoidable impurities.

[0024] The above steel alloy is obtained by the mutual cooperation of various element components in a specific ratio. Under the condition of hot-dip galvanizing at 450℃~500℃, the structural organization of the steel alloy is not easily destroyed. Before and after hot-dip galvanizing, the tensile strength, bending performance and torsional performance of the steel alloy change little, which can effectively solve the performance attenuation problem of traditional high-strength steel wire and other steel materials during hot-dip galvanizing, and provide strong support for the application of high-strength steel wire and other steel materials in high temperature environment.

[0025] Specifically, C is the main solid solution strengthening element of the steel alloy. Controlling the mass percentage of C within the range of 0.87wt% to 0.95wt% can enable the steel material to obtain higher strength and good work hardening specificity while maintaining a certain toughness. As an example, in the above steel alloy, the mass percentage of C can be 0.87wt%, 0.88wt%, 0.89wt%, 0.91wt%, 0.92wt%, 0.93wt%, 0.94wt% or 0.95wt%. Further, the mass percentage of C can be a range value consisting of any two of the above point values ​​as end values.

[0026] Controlling the mass percentage of Mn to 0.70wt%~0.80wt% can improve the strength and hardenability of the steel alloy, promote the formation of pearlite, and further improve the strength performance of the steel alloy. As an example, the mass percentage of Mn in the steel alloy can be 0.70wt%, 0.71wt%, 0.72wt%, 0.73wt%, 0.74wt%, 0.75wt%, 0.76wt%, 0.77wt%, 0.78wt%, 0.79wt% or 0.80wt%. Further, the mass percentage of Mn can be a range value consisting of any two of the above point values ​​as end values.

[0027] Si is a good deoxidizer in steel alloy components, and can also cooperate with other components to improve the strength and heat resistance of steel alloys. As an example, the mass percentage of Si can be 0.27wt%, 0.28wt%, 0.29wt%, 0.30wt%, 0.31wt%, 0.32wt%, 0.33wt%, 0.34wt%, 0.35wt%, 0.36wt% or 0.37wt%. Further, the mass percentage of Si can be a range value consisting of any two of the above point values ​​as end values.

[0028] Cr can enhance the corrosion resistance of the steel alloy, and help to form a stable alloy phase, and improve the high temperature resistance of the steel alloy. As an example, the mass percentage of Cr can be 0.25wt%, 0.26wt%, 0.27wt%, 0.28wt%, 0.29wt%, 0.30wt%, 0.31wt%, 0.32wt%, 0.33wt%, 0.34wt% or 0.35wt%. Further, the mass percentage of Cr can be a range value consisting of any two of the above point values ​​as end values.

[0029] Adding a sufficient amount of Nb to the steel alloy component, Nb can form compounds such as NbC with C, so as to achieve grain refinement, precipitation strengthening and other methods to significantly improve the strength and toughness of the steel alloy; further, controlling the Nb content to 0.12wt%~0.15wt%, the NbC compound formed by Nb and C can further refine the pearlite grains, reduce the formation of coarse pearlite, reduce the pearlite interlamellar spacing, improve the organizational stability, and thus achieve the strength retention ability of the steel under high temperature conditions. As an example, the mass percentage of Nb can be 0.12wt%, 0.121wt%, 0.125wt%, 0.126wt%, 0.127wt%, 0.128wt%, 0.129wt%, 0.13wt%, 0.135wt%, 0.14wt%, 0.145wt% or 0.15wt%. Further, the mass percentage of Nb can be a range value consisting of any two of the above point values ​​as end values.

[0030] Al is also a deoxidizer, and controlling the content of Al in the steel alloy helps to improve the corrosion resistance of the steel alloy. As an example, the mass percentage of Al can be 0.015wt%, 0.016wt%, 0.017wt%, 0.018wt%, 0.019wt%, 0.020wt%, 0.021wt%, 0.022wt%, 0.025wt%, 0.026wt%, 0.027wt%, 0.028wt%, 0.029wt%, 0.030wt%, 0.031wt%, 0.032wt%, 0.033wt%, 0.034wt% or 0.035wt%. Further, the mass percentage of Al can be a range value consisting of any two of the above point values ​​as end values.

[0031] The N element is an inevitable harmful element in the steel alloy composition. The mass percentage of the N element is controlled to be 0~0.005wt% to reduce the formation of harmful phases in the structural organization of the steel alloy and maintain the purity and performance stability of the steel alloy.

[0032] In some embodiments, the steel alloy includes the following element components, measured by mass percentage: C 0.87wt%~0.93wt%, Mn 0.70wt%~0.80wt%, Si 0.30wt%~0.37wt%, Cr 0.25wt%~0.30wt%, Nb 0.12wt%~0.15wt%, Al 0.02wt%~0.035wt%, N 0~0.0050wt%, and the balance is Fe and unavoidable impurities.

[0033] In some embodiments, the element composition of the steel alloy further includes 0-0.015 wt % of P. Controlling the content of the P element reduces the problem of reduced toughness of the steel alloy due to excessively high P content.

[0034] In some embodiments, the element composition of the steel alloy further includes 0-0.010 wt% S. The content of the S element is controlled to prevent the grain structure of the steel alloy from being destroyed under high temperature conditions due to excessive S content, thereby reducing the high temperature resistance. At the same time, it can further ensure that the steel alloy has good corrosion resistance.

[0035] In some embodiments, the steel alloy is in the form of a profile.

[0036] In some embodiments, the steel alloy may be a wire, a plate, a tube, etc. Preferably, the steel alloy is a wire, i.e., a steel wire.

[0037] In some embodiments, the diameter of the steel alloy is ≤ 20 mm. As an example, the diameter of the steel alloy can be 20 mm, 18 mm, 16 mm, 15 mm, 14 mm, 13 mm, 12 mm, 11 mm, 10 mm, 8 mm, 5 mm, 4 mm, 3 mm, 2 mm or 1 mm. Further, the diameter of the steel alloy can be any other value less than 15 mm. Preferably, the diameter of the steel alloy is 1 mm to 15 mm.

[0038] In some embodiments, the steel alloy contains a pearlite structure.

[0039] In some embodiments, the maximum size of the pearlite cluster on the cross section of the steel alloy is 2 μm to 3.5 μm. As an example, the maximum size of the pearlite cluster on the cross section of the steel alloy can be 2 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm, 3.2 μm, 3.4 μm or 3.5 μm. Further, the maximum size of the pearlite cluster on the cross section of the steel alloy can be a range value consisting of any two of the above point values ​​as end values. The maximum size of the pearlite cluster within the above range can make the steel have excellent performance stability and uniform microstructure. The smaller the maximum size of the pearlite cluster, the better the size uniformity of the pearlite cluster, and the more conducive to improving the performance stability of the steel.

[0040] In some embodiments, in a pearlite cluster, the pearlite lamella spacing between two adjacent layers is 0.1 μm to 0.18 μm. As an example, the pearlite lamella spacing between two adjacent layers can be 0.1 μm, 0.12 μm, 0.13 μm, 0.14 μm, 0.15 μm, 0.16 μm, 0.17 μm or 0.18 μm. Further, the pearlite lamella spacing between two adjacent layers can be a range value consisting of any two of the above point values ​​as end values. Preferably, the pearlite lamella spacing between two adjacent layers can be 0.12 μm to 0.15 μm. Smaller pearlite clusters and finer lamella spacing generally give the material higher strength and hardness. This is because when the pearlite in the fine lamellar layer is subjected to external force, the mutual obstruction between the lamellar layers is stronger and can effectively resist deformation; even in a high temperature environment, the structural organization of the pearlite is not easy to change, thereby improving the stability of the steel under high temperature conditions; after the steel wire is hot-dip galvanized at high temperature, its mechanical strength will not be significantly reduced, thereby improving the stability of the mechanical properties of steel wire and other steels.

[0041] In one embodiment of the present application, a method for preparing the above steel alloy is provided, comprising the following steps:

[0042] Configure the raw materials according to the elemental composition of the steel alloy;

[0043] The raw materials are sequentially subjected to smelting, refining, continuous casting and hot rolling processes.

[0044] In some embodiments, the initial rolling temperature of the hot rolling treatment is 900°C to 1200°C. The initial rolling temperature of the hot rolling treatment refers to the temperature of the billet to be hot rolled, that is, when the billet temperature reaches 900°C to 1200°C, the billet is started to be rolled. As an example, the initial rolling temperature of the hot rolling treatment can be 900°C, 920°C, 950°C, 980°C, 1000°C, 1050°C, 1100°C, 1150°C or 1200°C. Further, the initial rolling temperature of the hot rolling treatment can be a range value consisting of any two of the above point values ​​as end values. Preferably, the initial rolling temperature of the hot rolling treatment is 950°C to 1000°C.

[0045] In some embodiments, after hot rolling treatment, a wire rod with a diameter of 10 mm to 20 mm can be obtained.

[0046] In some embodiments, the tensile strength of the wire rod obtained after hot rolling treatment is 1300 MPa~1450 MPa.

[0047] In some embodiments, the cross-sectional reduction rate of the wire rod obtained after hot rolling treatment is 40%~45%.

[0048] In some embodiments, the wire rod obtained after hot rolling has an elongation at break of 10% to 16%.

[0049] In some embodiments, the preparation method further comprises: performing a first drawing process on the wire rod obtained by the hot rolling process; the speed of the first drawing process is 3m / s to 5m / s. Performing the first drawing process on the wire rod obtained by the hot rolling process can not only obtain a steel wire with a smaller diameter, but also dislocation strengthening, grain refinement, work hardening, etc. occur during the drawing process, thereby significantly improving the tensile strength of the steel wire.

[0050] In some embodiments, the first drawing process is performed at room temperature. Specifically, it can be performed at 15°C to 40°C. As an example, the first drawing process can be performed at 15°C, 20°C, 25°C, 30°C, 35°C or 40°C. Further, the first drawing process can be performed within a range value consisting of any two of the above point values ​​as end values.

[0051] In some embodiments, after the first drawing process, a first steel wire with a diameter of 5 mm to 9 mm can be obtained.

[0052] In some embodiments, the tensile strength of the first steel wire obtained after the first drawing process is 2000 MPa~2500 MPa.

[0053] In some embodiments, before the first drawing treatment is performed on the wire rod obtained by the hot rolling treatment, the surface treatment steps of pickling and phosphating the wire rod obtained by the hot rolling treatment are also included, wherein the specific process conditions of pickling and phosphating are conventional process conditions in the art.

[0054] In some embodiments, the preparation method further comprises the step of subjecting the first steel wire to lead bath quenching and then subjecting the first steel wire to a second drawing treatment.

[0055] In some embodiments, the speed of the second drawing process is 4 m / s to 7 m / s.

[0056] In some embodiments, the second drawing process is performed at room temperature. Specifically, it can be performed at 15°C to 40°C. As an example, the second drawing process can be performed at 15°C, 20°C, 25°C, 30°C, 35°C or 40°C. Further, the second drawing process can be performed within a range of values ​​formed by using any two of the above point values ​​as end values.

[0057] In some embodiments, after the second drawing process, a second steel wire with a diameter of 1 mm to 4 mm can be obtained.

[0058] In some embodiments, the tensile strength of the second steel wire obtained after the second drawing process is 1700MPa~2000MPa.

[0059] In some embodiments, the step of lead bath quenching comprises:

[0060] Firstly, the first steel wire is heated to 890±30°C; then, the heated first steel wire is immersed in a lead bath of 550°C to 620°C for 40s to 60s.

[0061] In some embodiments, the first steel wire after the first drawing process may be subjected to lead bath quenching and the second drawing process repeatedly to obtain steel wires with different diameters.

[0062] In one embodiment of the present application, a galvanized steel is provided, which includes the above-mentioned steel alloy and a zinc coating provided on at least a portion of the surface of the steel alloy.

[0063] In some embodiments, in galvanized steel, the zinc coating may be provided on the entire surface of the steel alloy or on a portion of the surface thereof.

[0064] In one embodiment of the present application, a method for preparing galvanized steel is provided, comprising the following steps:

[0065] The steel alloy is immersed in liquid zinc.

[0066] In some embodiments, the temperature of the liquid zinc is 440°C to 460°C.

[0067] In some embodiments, the steel alloy is immersed in the liquid zinc for a period of 30 seconds to 180 seconds.

[0068] In some embodiments, the liquid zinc may be pure zinc metal liquid or zinc alloy liquid.

[0069] In some embodiments, the zinc alloy liquid may be a zinc-aluminum alloy liquid.

[0070] In order to make the purpose, technical solutions and advantages of the present invention more concise and clear, the present invention is described with the following specific embodiments, but the present invention is by no means limited to these embodiments. The embodiments described below are only preferred embodiments of the present invention, which can be used to describe the present invention and cannot be understood as limiting the scope of the present invention. It should be pointed out that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0071] In order to better illustrate the present invention, the present invention is further described below in conjunction with the embodiments. The following are specific embodiments.

[0072] Example 1

[0073] S1. Prepare the steel alloy according to the element composition in Table 1.

[0074] S2. Molten steel is obtained by smelting molten iron and scrap steel; wherein the mass percentage of S in the molten iron is ≤0.035Wt; the end point of converter tapping requires that C in the molten steel is ≥0.20Wt% and P is ≤0.020Wt; when tapping, appropriate amounts of ferrosilicon, ferromanganese, ferroaluminum and low-N carbon powder raw materials are added according to the element composition ratio in Table 1.

[0075] S3, LF refining: the LF furnace is powered on for 20 minutes, the total argon blowing time is 40 minutes, and the soft blowing time is 10 minutes; the carbon composition is adjusted with carbon wire; ferroniobium, ferrovanadium and ferrotitanium are added as needed.

[0076] S4. Continuous casting: After LF refining is completed, the molten steel is poured into the casting equipment and the casting is protected throughout the process. During the casting process, a crystallizer and an end-stage electromagnetic stirring are used. The crystallizer electromagnetic stirring current is 360 (A) / frequency 12 (Hz), and the end-stage electromagnetic stirring current is 150 (A) / frequency 5 (Hz) to obtain a cast billet.

[0077] S5. Rolling: The ingot is heated to 980±20° C. in a heating furnace, and then hot-rolled on a high-speed wire rolling production line to obtain a cylindrical wire rod with a diameter of 13 mm.

[0078] S6. Pickling of wire rod: Place the wire rod in pickling solution for pickling, and then wash with water to remove the surface oxide scale and residual acid on the surface; the pickling solution uses 15% dilute sulfuric acid, the pickling temperature is 65°C, and the pickling time is 20 minutes.

[0079] S7. Wire rod phosphating: After pickling, the wire rod is placed in a phosphating solution for phosphating, and then washed again to remove the residual phosphating solution on the surface; then potassium dichromate solution is used for passivation to further improve the corrosion resistance of the phosphating film. Finally, drying treatment is performed to make the phosphating film on the surface of the workpiece more stable.

[0080] S8. Prepare a steel wire with a diameter of 5 mm:

[0081] (1) Wire rod drawing: a portion of the wire rod after phosphating treatment is placed in a drawing machine for drawing to obtain a steel wire with a diameter of 5 mm; wherein the drawing speed is 5 m / s.

[0082] (2) Galvanizing of steel wire surface: immerse a steel wire with a diameter of 5 mm in pure zinc liquid at 450±5°C for 45±5 seconds to obtain galvanized steel wire.

[0083] S9. Prepare a steel wire with a diameter of 3.85 mm

[0084] (1) Wire rod drawing: The other part of the wire rod after phosphating treatment is placed in a drawing machine for drawing to obtain a steel wire with a diameter of 7.3 mm; wherein the drawing speed is 3 m / s.

[0085] (2) Lead bath quenching: Heat the hot drawn steel wire obtained in step (1) to 890±20°C; then immerse the heated steel wire in a lead bath at 570±20°C for 40s to 60s. Then air cool to room temperature.

[0086] (3) Secondary drawing: The steel wire after lead bath quenching is placed in the drawing machine again for a second drawing to obtain a steel wire with a diameter of 3.85 mm; wherein the drawing speed is 7 m / s.

[0087] (4) Galvanizing of steel wire surface: immerse a steel wire with a diameter of 3.85 mm in pure zinc liquid at 450±5°C for 35±5 seconds to obtain a galvanized steel wire.

[0088] Embodiment 2~7

[0089] The preparation methods of Examples 2 to 7 are basically the same as those of Example 1, except that the elemental composition of the steel alloy is different; specifically, the elemental composition of the steel alloy prepared in Examples 2 to 7 is shown in Table 1.

[0090] Comparative Examples 1 to 4

[0091] The preparation methods of Comparative Examples 1 to 4 are basically the same as those of Example 1, except that the elemental composition of the steel alloy is different; specifically, the elemental composition of the steel alloy prepared in Comparative Examples 1 to 4 is shown in Table 1.

[0092] The elemental compositions of the steel alloys prepared in various embodiments and comparative examples are shown in Table 1.

[0093] Table 1

[0094]

[0095] Performance Testing

[0096] The tensile strength, cross-sectional shrinkage and elongation after fracture of the wire rods with a diameter of 13 mm prepared in each embodiment and comparative example were tested according to the method specified in GB / T228.1-2021.

[0097] The tensile strength of the steel wires with a diameter of 5 mm before and after galvanizing and 0.385 mm before and after galvanizing prepared in each embodiment and comparative example was tested according to the method specified in GB / T 228.1-2021.

[0098] The cross-sections of the embodiments and comparative examples were observed by scanning electron microscope and metallographic analysis was performed.

[0099] The bending properties of the steel wires with a diameter of 5 mm before and after galvanizing and 0.385 mm before and after galvanizing prepared in accordance with the method specified in GB / T 232-2024 in each embodiment and comparative example were tested, and the number of bending times when breakage occurred was recorded.

[0100] The torsional properties of the steel wires with a diameter of 5 mm before and after galvanizing and 0.385 mm before and after galvanizing prepared in accordance with the method specified in GB / T 239.1-2023 in each embodiment and comparative example were tested, and the number of twistings when fracture occurred was recorded.

[0101] The test data of tensile strength, cross-sectional shrinkage and elongation after fracture of the wire rods prepared in each embodiment and comparative example are shown in Table 2.

[0102] The data of the maximum size of pearlite clusters and the pearlite lamella spacing in the cross section of the wire rod prepared in each embodiment and comparative example are shown in Table 3.

[0103] The tensile strength, bending properties and torsional properties of the steel wires with a diameter of 5 mm before and after galvanizing prepared in various embodiments and comparative examples are shown in Table 4.

[0104] The tensile strength, bending properties and torsional properties of the steel wires with a diameter of 3.85 mm prepared in various embodiments and comparative examples before and after galvanizing are shown in Table 5.

[0105] Table 2

[0106]

[0107] Table 3

[0108]

[0109] Table 4

[0110]

[0111] Note: The change in the table is the performance data after galvanizing minus the performance data before galvanizing. A negative change indicates that the corresponding performance decreases after galvanizing; a positive change indicates that the corresponding performance is improved after galvanizing.

[0112] Table 5

[0113]

[0114] It can be seen from the data in Tables 1 to 5 that the wire rods with a diameter of 13 mm prepared by the technical solution of the present application in Examples 1 to 7 have good mechanical properties, wherein the tensile strength reaches 1332MPa~1359MPa, the cross-sectional shrinkage rate reaches 42%~45, and the elongation after fracture reaches 12%~14%. The performance change value of the steel wire with a diameter of 5 mm prepared in Examples 1 to 7 before and after galvanizing is small, wherein the tensile strength is only reduced within 10MPa, and the bending and torsion are basically unchanged. The performance change value of the steel wire with a diameter of 3.85 mm before and after galvanizing is small, wherein the tensile strength is only reduced within 14MPa, and the bending and torsion are basically unchanged. Combined with Table 2, the wire rods with a diameter of 13 mm prepared in Examples 1 to 7 contain pearlite, and the maximum size of the pearlite cluster is 2.10μm~3.29μm, and the pearlite interlamellar spacing is 0.121μm~0.147μm. It can be seen that the pearlite clusters in the steels prepared in Examples 1 to 7 are smaller and the interlamellar spacing is smaller, which is more conducive to maintaining the performance stability of the steel wire before and after hot-dip galvanizing.

[0115] The steel material of Comparative Example 1 does not contain Nb element. The maximum size of pearlite clusters on the cross section of the wire rod with a diameter of 13 mm prepared therefrom reaches 5.37 μm, and the spacing between pearlite lamellae reaches 0.267 μm. The pearlite clusters are much larger than the pearlite clusters of Examples 1 to 7, and the spacing between pearlite lamellae is also larger than that of Examples 1 to 7. As a result, the tensile strength, bending performance and torsional performance of the steel wire with a diameter of 5 mm and the steel wire with a diameter of 3.85 mm prepared in Comparative Example 1 are significantly reduced before and after hot-dip galvanizing. The high temperature stability of the steel material of Comparative Example 1 is inferior to that of Examples 1 to 7.

[0116] In the steel materials of Comparative Examples 2-3, trace amounts of Nb and niobium, vanadium and titanium are added respectively, and the maximum size of the pearlite clusters on the cross section of the wire rod with a diameter of 13 mm prepared therefrom reaches 6.37 μm, and the spacing between the pearlite lamellae reaches 0.305 μm, which is much larger than the pearlite clusters of Examples 1-7, and the spacing between the pearlite lamellae is also larger than that of Examples 1-7. As a result, the tensile strength, bending performance and torsional performance of the steel wire with a diameter of 5 mm and the steel wire with a diameter of 3.85 mm prepared in Comparative Examples 2-3 are significantly reduced before and after hot-dip galvanizing. The high temperature stability of the steel material of Comparative Example 1 is not as good as that of Examples 1-7.

[0117] Comparative Example 4 increases the manganese content on the basis of the embodiment. The maximum size of the pearlite clusters and the spacing between the pearlite lamellae on the cross section of the wire rod with a diameter of 13 mm prepared by the comparative example 4 are not significantly different from those of embodiments 1 to 7, and the strength is significantly increased, but the cross-sectional shrinkage rate and cross-sectional extension are decreased. The bending performance and torsion performance of the steel wire with a diameter of 5 mm and the steel wire with a diameter of 3.85 mm prepared in comparative example 4 before and after hot-dip galvanizing are significantly lower than those of embodiments 1 to 7; the tensile strength, bending and torsion of the steel wire with a diameter of 5 mm and the steel wire with a diameter of 3.85 mm prepared in comparative example 4 are basically unchanged before and after hot-dip galvanizing. The high temperature stability of the steel in comparative example 1 is not as good as that in embodiments 1 to 7. It can be seen that the pearlite clusters in the steel prepared in comparative example 4 are smaller and the spacing between the lamellae is small, which is more conducive to maintaining the performance stability of the steel wire before and after hot-dip galvanizing; after the manganese content is increased, the plasticity of the wire rod and the processed steel wire is not as good as that of embodiments 1 to 7.

[0118] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0119] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A steel alloy, characterized in that Calculated by mass percentage, it includes the following elemental components: C 0.87wt%~0.95wt%, Mn 0.70wt%~0.80wt%, Si 0.27wt%~0.37wt%, Cr 0.25wt%~0.35wt%, Nb 0.12wt%~0.15wt%, Al 0.015wt%~0.035wt%, N 0~0.0050wt%, and the balance is Fe and inevitable impurities.

2. The steel alloy according to claim 1, characterized in that The steel alloy contains a pearlite structure.

3. The steel alloy according to claim 2, characterized in that The maximum size of pearlite clusters in the cross section of the steel alloy is 2 μm to 3.5 μm.

4. The steel alloy according to claim 2, characterized in that In the pearlite cluster, the distance between two adjacent pearlite lamellae is 0.1 μm to 0.18 μm.

5. The steel alloy according to any one of claims 1 to 4, characterized in that: The steel alloy is a wire, and the diameter of the steel alloy is ≤20 mm.

6. The method for preparing a steel alloy according to any one of claims 1 to 5, characterized in that: The steps include: configuring raw materials according to the elemental composition of the steel alloy; The raw materials are sequentially subjected to smelting, refining, continuous casting and hot rolling processes.

7. The method for preparing a steel alloy according to claim 6, characterized in that: The following steps are also included: The wire rod obtained by the hot rolling process is subjected to a drawing process; the drawing process speed is 3 mm / s to 5 mm / s.

8. A galvanized steel, characterized in that: The invention comprises the steel alloy according to any one of claims 1 to 5 and a zinc coating provided on at least a part of the surface of the steel alloy.

9. The method for preparing galvanized steel according to claim 8, characterized in that: The method comprises the following steps: immersing the steel alloy in liquid zinc.

10. The preparation method according to claim 9, characterized in that: The temperature of the liquid zinc is 440°C to 500°C.

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