High-strength weather-resistant bainite wire rod and preparation method thereof

Abstract

The embodiment of the invention discloses a high-strength weather-resistant bainite wire rod and a preparation method thereof, relates to the technical field of wire rod production, and can effectively improve the strength and weather resistance of the wire rod. The high-strength weather-resistant bainite wire rod comprises the following components in percentage by mass: 0.10 to 0.25 percent of C, 0.20 to 0.50 percent of Mn, 0.20 to 0.50 percent of Si, 2.00 to 2.80 percent of Cr, 0.15 to 0.40 percent of Ni, 0.15 to 0.40 percent of Cu, 0.02 to 0.04 percent of Al, less than or equal to 0.06 percent of Nb, less than or equal to 0.20 percent of Mo, less than or equal to 0.03 percent of P and the balance of Fe. The condition that Cr / (0.54 Mo + 1.5 Al) is greater than or equal to 1.5 is met, and the balance is Fe and inevitable impurities. The method is suitable for production and manufacturing scenes of wire rods or wire rods.

Description

Technical Field

[0001] The present application relates to the technical field of wire production, and in particular to a high-strength weather-resistant bainite wire rod and a preparation method thereof. Background Art

[0002] At present, the structure of industrial wire rods for cold drawing is solidified and its performance is difficult to break through. Its matrix structure is generally ferrite, pearlite + ferrite, and full pearlite, while bainite and martensite are often regarded as "abnormal structures" that are harmful to drawing and are strictly controlled.

[0003] However, on the one hand, although ferrite wire has certain weather resistance, its strength is far from enough and cannot be widely used in major projects such as bridges and buildings. For example, Chinese patent CN116770167B discloses a high-strength weather-resistant wire rod and production method for photovoltaic support rods. By optimizing the design composition and controlled cooling process, the strength and weather resistance of the wire rod are improved. However, its structure is mainly ferrite, and the tensile strength of the produced wire rod is lower than 600MPa, which cannot meet the production requirements of high-strength steel strands.

[0004] On the other hand, for full pearlite wire, the strength is high, and the wire strength after drawing can be more than 1860MPa, and can even reach 2300MPa. It is widely used in major projects such as bridges and large buildings, and high-end equipment such as automobiles and high-speed railways. However, its weather resistance and corrosion resistance are insufficient. For flexible photovoltaic brackets, prestressed steel wires for bridge cables, steel wire ropes, and other complex environments that require certain weather resistance and corrosion resistance, the wires often need to be galvanized. Among them, my country's annual demand for steel wire ropes reaches 6 million tons, and about 1 / 3 of the steel wire ropes need to be galvanized. Due to the particularity of the galvanizing process, the galvanizing process often reduces the tensile strength of the steel wire by about 100MPa, so the steel wire is required to have higher strength and plastic toughness. In addition, the galvanizing process also greatly increases the production cost of the enterprise, generally increasing by several thousand yuan per ton, and also increases carbon emissions during the production process.

[0005] Therefore, it is urgent to break through the existing system composition of industrial wire rods and develop a new type of high-strength and weather-resistant wire rod, so as to achieve performance breakthroughs and cost reduction for wire rods used in complex environments. At present, the production of domestic wire rods is still mainly carried out through the Stelmore air-cooling line, but with the continuous improvement of the performance requirements of wire rods, for some high-carbon wire rods, the Stelmore air-cooling line has gradually failed to meet its production requirements. Therefore, many domestic steel mills began to seek the upgrading and development of equipment. Among them, Anshan Iron and Steel, Xingcheng Special Steel and others have developed online water bath technology, which greatly improved the cooling rate during the controlled cooling process; Qinggang, Jigang and other steel mills have developed offline salt bath technology. Qinggang has also developed online salt bath technology to achieve online isothermal phase transformation of wire rods. Domestic advanced online / offline isothermal heat treatment technology and equipment for wire rods provide a basis for the development of high-strength and weather-resistant bainite wire rods.

[0006] Based on this, it is necessary to develop a new type of high-strength weather-resistant wire rod and production method, so that the wire rod not only has high strength and plasticity, but also has good weather resistance, thereby being able to effectively solve the problems of insufficient corrosion resistance of existing pearlite wire rods and realize the integration of wire rod structure and function and greening. Summary of the invention

[0007] In view of this, the present application provides a high-strength weather-resistant bainite wire rod and a preparation method thereof, which can effectively improve the strength and weather resistance of the wire rod.

[0008] In a first aspect, an embodiment of the present application provides a high-strength weather-resistant bainite wire rod, comprising the following components by mass percentage: C: 0.10~0.25%, Mn: 0.20~0.50%, Si: 0.20~0.50%, Cr: 2.00~2.80%, Ni: 0.15~0.40%, Cu: 0.15~0.40%, Al: 0.02~0.04%, Nb≤0.06%, Mo≤0.20%, P≤0.03%; S≤0.03%, and satisfies: Cr / (0.54Mo+1.5Al)≥1.5, and the rest are Fe and unavoidable impurities.

[0009] In a specific embodiment, the high-strength weather-resistant bainite wire rod comprises the following components by mass percentage: C: 0.12~0.20%, Mn: 0.20~0.30%, Si: 0.20~0.30%, Cr: 2.00~2.60%, Ni: 0.20~0.35%, Cu: 0.20~0.35%, Nb: 0.02~0.04%, Mo: 0.05~0.15%, Al: 0.02~0.03%.

[0010] In a specific embodiment, the tensile strength of the high-strength weather-resistant bainite wire rod is above 1100 MPa; and / or the cross-sectional shrinkage rate of the high-strength weather-resistant bainite wire rod is above 45%; and / or the tensile strength of the high-strength weather-resistant bainite wire rod after drawing is above 1900 MPa; and / or the weather resistance index of the high-strength weather-resistant bainite wire rod is above 7.5.

[0011] In a specific embodiment, the microstructure of the high-strength weather-resistant bainite wire rod comprises bainite and martensite, wherein the content of the bainite is greater than 90%.

[0012] In a second aspect, the embodiments of the present application further provide a method for preparing a high-strength weather-resistant bainite wire rod, which is used to prepare any of the high-strength weather-resistant bainite wire rods described in the embodiments of the present application, and the method for preparing the high-strength weather-resistant bainite wire rod comprises the following steps: S1. Smelting and refining the raw materials, and continuously casting them by a continuous casting machine to obtain a steel billet; wherein the raw materials include the following components by mass percentage: C: 0.10-0.25%, Mn: 0.20-0.50%, Si: 0.20-0.50%, Cr: 2.00-2.80%, Ni: 0.15-0.40%, Cu: 0.15-0.40%, Al: 0.02-0.04%, Nb≤0.06%, Mo≤0.20%, P≤0.03%; S≤0.03%, and satisfying: Cr / (0.54Mo+1.5Al)≥1.5, and the rest is Fe and unavoidable impurities; S2, sending the steel billet into a heating furnace for heating; S3, dephosphorizing the heated steel billet; S4, the steel billet after dephosphorization is subjected to wire rolling by rough rolling, intermediate rolling and finishing rolling mills, and then subjected to wire laying by a wire laying machine to produce an initial wire rod; S5. Isothermally heat treating the initial wire rod to obtain the high-strength weather-resistant bainite wire rod.

[0013] In a specific embodiment, in the step S1, the casting speed of the continuous casting machine is 1.0-1.8 m / min.

[0014] In a specific embodiment, in the step S4, the temperature of the steel billet before the rough rolling is controlled at 950°C-1050°C, and the temperature before the finish rolling is controlled at 850°C-950°C.

[0015] In a specific embodiment, in the step S4, the spinning temperature is controlled at 860°C to 950°C.

[0016] In a specific embodiment, during the isothermal heat treatment, the phase transition temperature of austenite to bainite in the initial wire rod is controlled at 350-480° C., and the time of the isothermal heat treatment is less than or equal to 10 minutes.

[0017] In a specific embodiment, the isothermal heat treatment comprises at least one of the following: an online water bath, an online salt bath, an offline salt bath, and an offline lead bath.

[0018] The embodiments of the present application provide a high-strength weather-resistant bainite wire rod and a preparation method thereof, wherein the high-strength weather-resistant bainite wire rod comprises the following components in mass percentage: C: 0.10~0.25%, Mn: 0.20~0.50%, Si: 0.20~0.50%, Cr: 2.00~2.80%, Ni: 0.15~0.40%, Cu: 0.15~0.40%, Al: 0.02~0.04%, Nb≤0.06%, Mo≤0.20%, P≤0.03%; S≤0.03%, and satisfies: Cr / (0.54Mo+1.5Al)≥1.5, and the rest are Fe and unavoidable impurities, which can effectively improve the strength and weather resistance of the wire rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is a schematic diagram of the microstructure of the high-strength weather-resistant bainite wire rod obtained in Experimental Example 1 in the embodiments of the present application under a scanning electron microscope; Figure 2 This is a schematic diagram of the microstructure of the high-strength weather-resistant bainite wire rod obtained in Experimental Example 2 in the embodiments of the present application under a scanning electron microscope; Figure 3 This is a schematic diagram of the microstructure of the high-strength weather-resistant bainite wire rod obtained in Experimental Example 3 in the embodiments of the present application under a scanning electron microscope; Figure 4 This is a schematic diagram of the microstructure of the high-strength weather-resistant bainite wire rod obtained in Experimental Example 4 in the embodiments of the present application under a scanning electron microscope; Figure 5 This is a schematic diagram of the microstructure of the high-strength weather-resistant bainite wire rod obtained in Experimental Example 5 in the embodiments of the present application under a scanning electron microscope; Figure 6 This is a schematic diagram of the microstructure of the high-strength weather-resistant bainite wire rod obtained in Experimental Example 6 in the embodiments of the present application under a scanning electron microscope; Figure 7 This is a schematic diagram of the microstructure of the high-strength weather-resistant bainite wire rod obtained in Experimental Example 7 in the embodiments of the present application under a scanning electron microscope; Figure 8 This is a schematic diagram of the microstructure of the high-strength weather-resistant bainite wire rod obtained in Experimental Example 8 in the embodiments of the present application under a scanning electron microscope; Fig. 9 A schematic diagram of the microstructure of a high-strength weather-resistant bainite wire rod obtained in Experimental Example 9 in the embodiments of the present application is obtained by scanning electron microscopy; Fig.10 A schematic diagram of a tensile curve of a high-strength weather-resistant bainite wire rod prepared in Experimental Example 1 in the embodiments of the present application; Fig.11 This is a schematic diagram of the tensile curve of the high-strength weather-resistant bainite wire rod after drawing obtained in Experimental Example 1 in the embodiments of the present application; Fig.12 This is a scanning electron microscope schematic diagram of the microstructure of the high-strength weather-resistant bainite wire rod after drawing obtained in Experimental Example 1 in the embodiments of the present application. DETAILED DESCRIPTION

[0021] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0022] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0023] At present, the structure of industrial wire rods for cold drawing is solidified and its performance is difficult to break through. For example, although ferrite wire has certain weather resistance, its strength is far from enough; and although full pearlite wire has high strength, its weather resistance and corrosion resistance are insufficient, making it difficult to apply to complex environments. In order to solve the above problems, in the first aspect, an embodiment of the present application provides a high-strength weather-resistant bainite wire rod, which includes the following components in mass percentage: C: 0.10~0.25%, Mn: 0.20~0.50%, Si: 0.20~0.50%, Cr: 2.00~2.80%, Ni: 0.15~0.40%, Cu: 0.15~0.40%, Al: 0.02~0.04%, Nb≤0.06%, Mo≤0.20%, P≤0.03%; S≤0.03%, and satisfies: Cr / (0.54Mo+1.5Al)≥1.5, and the rest are Fe and unavoidable impurities.

[0024] The high strength in this application refers to a tensile strength of 1100 MPa or more.

[0025] Carbon (C) is the most important element in steel and the most effective element for improving the strength of steel. Increasing the carbon content within a certain range can greatly improve the strength of steel: theoretically, for every 0.1% increase in the mass fraction of carbon in high-carbon steel, its tensile strength increases by about 30-40 MPa. When the carbon content is high, austenite is more stable and atomic diffusion is difficult, which will slow down the transformation rate of bainite and inhibit the growth of bainite. Therefore, the mass percentage of C in this embodiment is controlled at C: 0.10-0.25%.

[0026] Manganese (Mn) elements can form fine carbide or nitride precipitations with other alloying elements (such as Nb, V, Ti), and these precipitations are dispersed in the bainite structure, play a pinning role on dislocations, and further improve the strength of the steel. The Mn element can refine the bainite structure, thereby improving the toughness of the steel. However, as the Mn element increases, the bainite transformation temperature will be reduced and the bainite phase transition time will be prolonged. Therefore, the mass percentage of the Mn element in this embodiment is controlled at Mn: 0.20~0.50%.

[0027] Silicon (Si) elements can work synergistically with other alloying elements (such as Mn, Cr, etc.) to improve the strength of steel. For example, when used together with Mn, Si can enhance the solid solution strengthening effect of Mn. At the same time, Si can prevent the accumulation of impurity elements at the grain boundaries, purify the grain boundaries, and improve the bonding strength of the grain boundaries, thereby maintaining the toughness of the steel during the tempering process. However, a higher Si element will delay the bainite transformation, so the mass percentage of the Si element in this embodiment is controlled at Si: 0.20~0.50%.

[0028] Chromium (Cr) element has a solid solution strengthening effect in bainitic steel. For every 1% increase in Cr content, the yield strength of bainitic steel can be increased by 40~60MPa, and Cr element can help to refine the bainite structure. In addition, the addition of Cr element can improve the weather resistance of bainitic steel. During the bainite transformation process, Cr combines with carbon element, which slows down the diffusion rate of carbon in austenite. At the same time, the segregation of Cr atoms at the austenite grain boundary will also hinder the nucleation of bainitic ferrite, thereby extending the bainite transformation incubation period and reducing the pearlite transformation temperature. Therefore, the mass percentage of Cr element in this embodiment is controlled at Cr: 2.00~2.80%.

[0029] Nickel (Ni) element can be used as a heterogeneous nucleation core in the bainitic steel process, thereby increasing the nucleation rate. The addition of nickel element can effectively improve the morphology of bainitic steel and improve the strength of bainitic steel through the solid solution strengthening mechanism. In addition, nickel element can improve the corrosion resistance of bainitic steel. In a corrosive environment, nickel can form a dense oxide film on the surface of steel. However, since nickel element is expensive, excessive addition will lead to higher cost of bainitic steel. Therefore, the mass percentage of Ni element in this embodiment is controlled at Ni: 0.15~0.40%.

[0030] During the cooling process of copper (Cu) element in bainitic steel, copper atoms will precipitate in the form of fine dispersed particles, which can effectively hinder the movement of dislocations and play a certain role in dispersion strengthening. Copper element affects the nucleation and growth process of bainite, promotes the formation of crystal nuclei and refines the bainite structure during the bainite transformation process. In addition, copper element can form a dense protective film on the surface of bainitic steel, increasing the weather resistance of bainitic steel. Therefore, the mass percentage of Cu element in this embodiment is controlled at Cu: 0.15~0.40%.

[0031] Aluminum (Al) element can participate in forming a protective film on the surface of bainitic steel. Aluminum reacts with oxygen in humid air to form an aluminum oxide protective film, which can effectively improve the weather resistance of bainitic steel. However, a high aluminum content will form a large amount of aluminum oxide inclusions in the steel, which seriously affects the mechanical properties of bainitic steel. Therefore, the mass percentage of Al element in this embodiment is controlled to be Al: 0.02~0.04%.

[0032] Niobium (Nb) is a strong carbide-forming element that can form fine carbides in steel and can serve as effective nucleation sites for bainite transformation. During the bainite transformation, the presence of compounds will pin the grain boundaries, thereby refining the bainite structure. However, the cost of niobium is relatively high, and adding excessive niobium to steel will greatly increase the cost. Therefore, the mass percentage of Nb in this embodiment is controlled to be Nb≤0.06%.

[0033] Molybdenum (Mo) element will form carbides in steel, such as Mo2C, etc. These carbides are distributed in bainite in a fine dispersed state, which improves the strength of bainitic steel. Some molybdenum atoms will dissolve in the matrix, playing a certain role in solid solution strengthening. Molybdenum element can effectively refine the bainite structure and improve the plasticity and toughness of bainitic steel. However, a higher content of molybdenum element will delay the bainite transformation and reduce the bainite transformation rate. In addition, since molybdenum is expensive and it is not easy to add more in steel, the mass percentage of Mo element in this embodiment is controlled at Mo≤0.20%.

[0034] Based on the analysis of the properties of the above-mentioned elements, in order to ensure that sufficient bainite can be formed in the microstructure of the high-strength weather-resistant bainite wire rod, and that the structural distribution and mechanical properties of the bainite can achieve the expected effects, this embodiment specifically limits the mass percentage ratio of Cr, Mo, and Al to: Cr / (0.54Mo+1.5Al)≥1.5, so that the final high-strength weather-resistant bainite wire rod meets the strength and weather resistance requirements.

[0035] In order to obtain higher steel performance through a better composition ratio, optionally, in one embodiment of the present application, the high-strength weather-resistant bainite wire rod includes the following components in mass percentage: C: 0.12~0.20%, Mn: 0.20~0.30%, Si: 0.20~0.30%, Cr: 2.00~2.60%, Ni: 0.20~0.35%, Cu: 0.20~0.35%, Nb: 0.02~0.04%, Mo: 0.05~0.15%, Al: 0.02~0.03%.

[0036] Optionally, in one embodiment of the present application, the tensile strength of the high-strength weather-resistant bainite wire rod is above 1100MPa; and / or the cross-sectional shrinkage rate of the high-strength weather-resistant bainite wire rod is above 45%; and / or the tensile strength of the high-strength weather-resistant bainite wire rod after drawing is above 1900MPa; and / or the weathering index of the high-strength weather-resistant bainite wire rod is above 7.5. Weather resistance refers to the durability and resistance to environmental changes of a material, such as the material's ability to resist oxidation and corrosion in different natural environments such as the atmosphere, soil, water, and ocean. The weathering index of this embodiment is obtained according to the calculation formula of GB / T 4171 "Weathering Resistant Structural Steel", and the calculation of the weathering index I can be calculated by the following formula: I=26.01(Cu%)+3.88(Ni%)+1.29(Cr%)+1.49(Si%)+17.28(P%)-7.29(Cu%)(Ni%)-9.10(Ni%)(P%)-33.9(Cu%) 2 Optionally, in one embodiment of the present application, the microstructure of the high-strength weather-resistant bainite wire rod contains bainite and martensite, wherein the content of bainite is more than 90%.

[0037] The high-strength and weather-resistant bainite wire rod provided in the embodiments of the present application includes the following components in mass percentage: C: 0.10~0.25%, Mn: 0.20~0.50%, Si: 0.20~0.50%, Cr: 2.00~2.80%, Ni: 0.15~0.40%, Cu: 0.15~0.40%, Al: 0.02~0.04%, Nb≤0.06%, Mo≤0.20%, P≤0.03%; S≤0.03%, and satisfies: Cr / (0.54Mo+1.5Al)≥1.5, and the rest are Fe and unavoidable impurities, which can effectively improve the strength and weather resistance of the wire rod.

[0038] In a second aspect, the embodiments of the present application also provide a method for preparing a high-strength weather-resistant bainite wire rod, which is used to prepare any high-strength weather-resistant bainite wire rod in the embodiments of the present application, and can effectively improve the strength and weather resistance of the wire rod.

[0039] The preparation method of the high-strength weather-resistant bainite wire rod comprises the following steps: S1. Smelting and refining raw materials, and continuously casting them by a continuous casting machine to obtain steel billets; wherein the raw materials include the following components by mass percentage: C: 0.10-0.25%, Mn: 0.20-0.50%, Si: 0.20-0.50%, Cr: 2.00-2.80%, Ni: 0.15-0.40%, Cu: 0.15-0.40%, Al: 0.02-0.04%, Nb≤0.06%, Mo≤0.20%, P≤0.03%; S≤0.03%, and satisfying: Cr / (0.54Mo+1.5Al)≥1.5, and the rest is Fe and unavoidable impurities.

[0040] S2. Send the steel billet into a heating furnace for heating.

[0041] S3, dephosphorizing the heated steel billet. In the dephosphorization process, high-pressure water dephosphorization can be used.

[0042] S4, the steel billet after dephosphorization is rolled into wire rod by rough rolling, intermediate rolling and finishing rolling mill, and then the wire laying machine is used to lay wire to obtain initial wire rod. The steel billet after dephosphorization is rolled by rough rolling, intermediate rolling and finishing rolling mill to obtain wire rod meeting the cross-sectional size requirements, and then the wire laying machine lays wire into coils to obtain initial wire rod for easy collection.

[0043] S5, isothermally heat treating the initial wire rod to obtain high-strength weather-resistant bainite wire rod. The finished products after inspection can be stacked in a heat preservation warehouse, waiting for delivery and transportation. Wire rod usually refers to a small-diameter round steel in a coil, and the diameter of the wire rod is in the range of 5-19 mm, usually 6-9 mm. In this embodiment, the initial wire rod obtained by the spinning machine is further isothermally heat treated to finally obtain high-strength weather-resistant bainite wire rod.

[0044] Optionally, in one embodiment of the present application, in step S1, the billet drawing speed of the continuous casting machine is 1.0~1.8m / min. The billet drawing speed (referred to as the drawing speed) is expressed by the length of the billet drawn per minute by each stream of the continuous casting machine. The drawing speed is one of the important parameters of the continuous casting machine. After the billet section is determined, the drawing speed plays a decisive role in the production capacity of the continuous casting machine. The greater the drawing speed, the greater the production capacity of the continuous casting machine, but it has a certain limit, because the solidification rate of the molten steel limits the thickness of the billet shell when the billet leaves the crystallizer. The higher the drawing speed, the thinner the billet shell, which is prone to excessive deformation or even steel leakage, and at the same time, it will cause looseness and shrinkage inside the billet, causing quality deterioration. Therefore, according to field experimental verification, this embodiment controls the billet drawing speed of the continuous casting machine to 1.0~1.8m / min.

[0045] Optionally, in one embodiment of the present application, in step S4, the temperature of the steel billet before rough rolling is controlled at 950°C to 1050°C, and the temperature before finish rolling is controlled at 850°C to 950°C. Optionally, in one embodiment of the present application, in step S4, the wire laying temperature is controlled at 860°C to 950°C.

[0046] Optionally, in one embodiment of the present application, during the isothermal heat treatment, the phase transition temperature of austenite to bainite in the initial wire rod is controlled at 350-480°C, and the time of the isothermal heat treatment is less than or equal to 10 minutes. The isothermal heat treatment method can ensure that the microstructure of the obtained high-strength weather-resistant bainite wire rod contains more than 90% bainite and a small amount of martensite. Optionally, in one embodiment of the present application, the isothermal heat treatment includes at least one of the following: an online water bath, an online salt bath, an offline salt bath, and an offline lead bath. Through isothermal heat treatment, the metallographic structure inside the initial wire rod can undergo a corresponding transformation, and the strength, hardness, and corrosion resistance can be significantly improved, thereby obtaining a high-strength weather-resistant bainite wire rod.

[0047] The high-strength weather-resistant bainite wire rod prepared by the above method has a strength of more than 1100MPa, a cross-sectional shrinkage rate of more than 45%, and a strength of 1900MPa after drawing, which meets the production requirements of 1860MPa grade steel strands and has excellent weather resistance. According to the calculation formula of GB / T4171-2008 "Weather-resistant Structural Steel", its weather resistance index can reach more than 7.5.

[0048] In order to further illustrate the preparation method of high-strength weather-resistant bainite wire rod, this embodiment gives the following specific comparative experiments, wherein Experimental Examples 1-9 are high-strength weather-resistant bainite wire rods prepared by the method of the present application, and the comparative example is a wire rod prepared by 82B high-carbon steel material (carbon content is 0.82%).

[0049]

[0050] In order to further illustrate the performance of the high-strength weather-resistant bainite wire rod prepared in the present application through experimental comparison, experimental examples 1-9 were compared with the comparative example. Experimental examples 1-9 and the comparative example were subjected to isothermal heat treatment at the same temperature, and the wire rods prepared from experimental examples 1-9 and the comparative example were made into 10 mm high metallographic samples by wire cutting. The surfaces of the metallographic samples were ground, mechanically polished, and vibrated polished, and then etched with 4% nitric acid alcohol. Then, the characteristic parameters of the microstructure structure were counted by scanning electron microscopy. The specific results are shown in Table 2, wherein the microstructure of the wire rod prepared from experimental examples 1-9 contains bainite, and the microstructure of the wire rod prepared from the comparative example contains pearlite. The organizational morphology of the wire rod prepared from experimental examples 1-9 is shown in Table 2. Figure 1-9 shown.

[0051]

[0052] The wire rods prepared in Experimental Examples 1-9 and the comparative example were subjected to tensile tests using a hydraulic universal testing machine, and the tensile strength, yield strength and cross-sectional shrinkage of the corresponding wire rods were recorded. The specific results are shown in Table 3. The tensile curve of Experimental Example 1 is shown in Fig.10 shown.

[0053]

[0054] The corresponding weathering index I of the wire rods prepared in Experimental Examples 1-9 and Comparative Example is calculated by the following weathering index formula: I=26.01(Cu%)+3.88(Ni%)+1.29(Cr%)+1.49(Si%)+17.28(P%)-7.29(Cu%)(Ni%)-9.10(Ni%)(P%)-33.9(Cu%) 2 The specific results are shown in Table 4, wherein the wire rods prepared in Experimental Examples 1-9 have excellent weather resistance, while the comparative example obviously does not have weather resistance.

[0055]

[0056] In addition, in this embodiment, taking Experimental Example 1 as an example, the prepared Φ13 mm wire rod is drawn to Φ6.0 mm, and a standard tensile specimen is cut to test the mechanical properties of the steel wire. The specific results are shown in Table 5. The tensile curve is shown in Fig.11 shown.

[0057]

[0058] Taking Experimental Example 1 as an example, a Φ13 mm wire rod was drawn to Φ6.0 mm, and a metallographic sample was cut by a wire cutting device. After the surface of the metallographic sample was ground, mechanically polished, and vibrated, it was etched with 4% nitric acid alcohol. The microstructure is shown in the figure. Fig.12 From the above experimental results, it can be seen that the microstructure and mechanical properties of the high-strength weather-resistant bainite wire rod prepared in this embodiment have achieved the expected effects and meet the use requirements of strength and weather resistance.

[0059] It should be noted that, in this article, relational terms such as first and second, etc. 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 these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0060] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0061] In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0062] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A high-strength weather-resistant bainite wire rod, characterized in that: The following components are included by mass percentage: C: 0.10~0.25%, Mn: 0.20~0.50%, Si: 0.20~0.50%, Cr: 2.00~2.80%, Ni: 0.15~0.40%, Cu: 0.15~0.40%, Al: 0.02~0.04%, Nb≤0.06%, Mo≤0.20%, P≤0.03%; S≤0.03%, and meets the following requirements: Cr / (0.54Mo+1.5Al)≥1.5, and the rest are Fe and unavoidable impurities.

2. The high-strength weather-resistant bainite wire rod according to claim 1, characterized in that: The components by mass percentage are as follows: C: 0.12~0.20%, Mn: 0.20~0.30%, Si: 0.20~0.30%, Cr: 2.00~2.60%, Ni: 0.20~0.35%, Cu: 0.20~0.35%, Nb: 0.02~0.04%, Mo: 0.05~0.15%, Al: 0.02~0.03%.

3. The high-strength weather-resistant bainite wire rod according to claim 1, characterized in that: The tensile strength of the high-strength weather-resistant bainite wire rod is above 1100 MPa; and / or The cross-sectional shrinkage of the high-strength weather-resistant bainite wire rod is greater than 45%; and / or The tensile strength of the high-strength weather-resistant bainite wire rod after drawing is above 1900 MPa; and / or The weather resistance index of the high-strength weather-resistant bainite wire rod is above 7.

5.

4. The high-strength weather-resistant bainite wire rod according to claim 1, characterized in that: The microstructure of the high-strength weather-resistant bainite wire rod comprises bainite and martensite, wherein the content of the bainite is greater than 90%.

5. A method for preparing a high-strength weather-resistant bainite wire rod, for preparing the high-strength weather-resistant bainite wire rod according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Smelting and refining the raw materials, and continuously casting them by a continuous casting machine to obtain a steel billet; wherein the raw materials include the following components by mass percentage: C: 0.10-0.25%, Mn: 0.20-0.50%, Si: 0.20-0.50%, Cr: 2.00-2.80%, Ni: 0.15-0.40%, Cu: 0.15-0.40%, Al: 0.02-0.04%, Nb≤0.06%, Mo≤0.20%, P≤0.03%; S≤0.03%, and satisfying: Cr / (0.54Mo+1.5Al)≥1.5, and the rest is Fe and unavoidable impurities; S2, sending the steel billet into a heating furnace for heating; S3, dephosphorizing the heated steel billet; S4, the steel billet after dephosphorization is subjected to wire rolling by rough rolling, intermediate rolling and finishing rolling mills, and then subjected to wire laying by a wire laying machine to produce an initial wire rod; S5. Isothermally heat treating the initial wire rod to obtain the high-strength weather-resistant bainite wire rod.

6. The method for preparing high-strength weather-resistant bainite wire rod according to claim 5, characterized in that: In the step S1, the casting speed of the continuous casting machine is 1.0-1.8 m / min.

7. The method for preparing high-strength weather-resistant bainite wire rod according to claim 5, characterized in that: In the step S4, the temperature of the steel billet before the rough rolling is controlled at 950°C to 1050°C, and the temperature of the steel billet before the finish rolling is controlled at 850°C to 950°C.

8. The method for preparing high-strength weather-resistant bainite wire rod according to claim 5, characterized in that: In the step S4, the spinning temperature is controlled at 860°C to 950°C.

9. The method for preparing high-strength weather-resistant bainite wire rod according to claim 5, characterized in that: During the isothermal heat treatment, the phase transition temperature of the initial wire rod from austenite to bainite is controlled at 350-480° C., and the time of the isothermal heat treatment is less than or equal to 10 minutes.

10. The method for preparing high-strength weather-resistant bainite wire rod according to claim 5, characterized in that: The isothermal heat treatment comprises at least one of the following: an online water bath, an online salt bath, an offline salt bath, and an offline lead bath.

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