A high-strength weather-resistant bolt wire rod with nickel saving, bolt and manufacturing method thereof

Abstract

This invention discloses a nickel-saving, high-strength, weather-resistant bolt wire rod containing Fe and unavoidable impurity elements, and further containing the following chemical elements in the following mass percentages: C: 0.15-0.25%, Si: 0.01-2.0%, Mn: 0.3-2.2%, Cr: 2.5-4.5%, Ni: 0.01-0.1%, Cu: 0.2-0.6%, Al: 0.001-0.1%, Ti: 0.01-0.5%; and the mass percentages of Cr and C satisfy: Cr / C > 10; the nickel-saving, high-strength, weather-resistant bolt wire rod does not contain V. Accordingly, this invention also discloses a bolt made from the above-mentioned nickel-saving, high-strength, weather-resistant bolt wire rod after at least a quenching and tempering treatment. Meanwhile, the present invention also discloses a method for manufacturing the above-mentioned bolt, which specifically includes the following steps: (1) smelting and casting; (2) heating; (3) rolling; (4) cooling: after rolling, cooling to below 900°C at a cooling rate of 4-5°C / s, and then continuing to cool to room temperature at a cooling rate of 0.3-0.5°C / s.

Description

Technical Field

[0001] This invention relates to a wire rod, a bolt, and a method for manufacturing the same, and more particularly to a wire rod, a bolt, and a method for manufacturing the same for high-strength weather-resistant bolts. Background Technology

[0002] As is well known, weathering steel is a low-alloy high-strength steel that achieves excellent corrosion resistance in the atmosphere by adding small amounts of alloying elements. It has been widely used in bridge structures, transmission towers, photovoltaic supports, and other fields. When trace elements such as phosphorus, copper, chromium, and nickel are added to the steel, an amorphous spinel oxide layer of about 50μm to 100μm thick is formed between the rust layer and the substrate. This oxide layer is dense and has good adhesion to the base metal, preventing oxygen and water in the atmosphere from penetrating into the steel substrate, slowing down the progression of rust into the steel material, and improving the atmospheric corrosion resistance of the steel material.

[0003] Currently, weathering steel typically exhibits atmospheric corrosion resistance 2 to 8 times that of ordinary carbon steel, and its corrosion resistance becomes more pronounced the longer it is used. In addition to its excellent weather resistance, weathering steel also possesses superior mechanical and weldability properties.

[0004] Weathering steel costs about 5% more to manufacture than ordinary steel, but the cost of painting and protecting ordinary steel is three times the difference in manufacturing cost. Considering that repainting during the service life is more expensive than the initial painting, it is generally believed that, in terms of total cost over the entire lifespan, the cost of a weathering steel bridge is far lower than that of an ordinary steel bridge. Studies estimate that after 60 years, the cost of an ordinary steel bridge will be about 1.5 times that of a weathering steel bridge, and after 100 years, it will be more than twice. Therefore, considering the total cost over the entire lifespan, weathering steel bridges demonstrate better economic efficiency.

[0005] In practical applications, weathering steel is often used to manufacture bolts to extend their service life. Bolt corrosion is a very common phenomenon, causing significant resource waste, and as crucial connecting components, bolt corrosion can seriously compromise structural safety.

[0006] To delay and control bolt corrosion, prevent bolt material degradation and deterioration, and ensure bolt reliability, safety, and service life, surface anti-corrosion treatment is typically required to improve bolt corrosion resistance. Surface anti-corrosion treatment involves applying a protective layer to the metal surface to isolate the metal from corrosive environments, thereby preventing or inhibiting the corrosion process.

[0007] In current steel structures such as buildings, bridges, and transmission towers, high-strength bolts are primarily used for connection. These bolts generally employ coating methods, such as hot-dip galvanizing, electroplating, and mechanical plating, to achieve corrosion protection. However, high-strength bolts have a large preload torque and significant friction between the threads. The coating itself cannot withstand this high friction, and it is often damaged during bolt preload. This results in a thinner coating, and in severe cases, even exposes the bolt's base material to the service environment, reducing its corrosion resistance.

[0008] Furthermore, surface coating methods require maintenance every 3-5 years and recoating every 10-15 years. This maintenance not only increases costs but also poses health hazards and environmental pollution. Moreover, some coating processes introduce hydrogen sources into the bolts, increasing their hydrogen embrittlement sensitivity, especially for high-strength bolts, and potentially leading to delayed fracture and other safety risks. Therefore, there is an urgent need to develop a high-strength, weather-resistant steel for bolts that can be used without coating.

[0009] Based on this, and to meet current market demands, this invention aims to develop a new nickel-saving, high-strength, weather-resistant bolt wire rod. By adding only a small amount of Ni and combining it with an optimized wire rod rolling process, the formation of copper-rich phases can be effectively suppressed, resulting in excellent performance. This nickel-saving, high-strength, weather-resistant bolt wire rod can achieve a strength grade of 8.8-10.9 and possesses strong weather resistance. Bolts made from it can be made without painting, which is of great significance to the development of the bolt industry. Summary of the Invention

[0010] One of the objectives of this invention is to provide a nickel-saving, high-strength, weather-resistant bolt wire rod. This nickel-saving, high-strength, weather-resistant bolt wire rod only requires the addition of a small amount of Ni to achieve both high strength and strong weather resistance. Its strength level reaches the requirements of 8.8-10.9, and its atmospheric corrosion resistance meets the requirements for no coating or plating.

[0011] To achieve the above objectives, the present invention provides a nickel-saving, high-strength, weather-resistant bolt wire rod, which contains Fe and unavoidable impurities, and also contains the following chemical elements in the following mass percentages: C: 0.15-0.25%, Si: 0.01-2.0%, Mn: 0.3-2.2%, Cr: 2.5-4.5%, Ni: 0.01-0.1%, Cu: 0.2-0.6%, Al: 0.001-0.1%, Ti: 0.01-0.5%; Furthermore, the mass percentage content of Cr and C satisfies the following condition: Cr / C > 10; The nickel-saving high-strength weather-resistant bolt wire rods do not contain V.

[0012] Furthermore, in the nickel-saving high-strength weather-resistant bolt wire rod described in this invention, the mass percentage content of each chemical element is as follows: C: 0.15-0.25%, Si: 0.01-2.0%, Mn: 0.3-2.2%, Cr: 2.5-4.5%, Ni: 0.01-0.1%, Cu: 0.2-0.6%, Al: 0.001-0.1%, Ti: 0.01-0.5%, with the balance being Fe and other unavoidable impurities; Furthermore, the mass percentage of Cr and C satisfies the condition: Cr / C > 10.

[0013] The design principles of each chemical element in the nickel-saving high-strength weather-resistant bolt wire rod of the present invention are as follows: C: In the nickel-saving high-strength weather-resistant bolt wire rod described in this invention, C is an important element for forming fine, dispersed carbides after quenching and tempering, playing a crucial role in improving the strength of the steel. However, it should be noted that the C content in the steel should not be too high, as excessive C content will affect the material's atmospheric corrosion resistance. Therefore, to ensure that the material of this invention achieves good strength and atmospheric corrosion resistance, the C content in the steel needs to be controlled within a reasonable range. In this invention, the mass percentage of C is specifically controlled between 0.15% and 0.25%.

[0014] Si: In the nickel-saving high-strength weather-resistant bolt wire rod of the present invention, Si has a high solid solubility in steel. Adding an appropriate amount of Si to steel can effectively increase the volume fraction of ferrite in the steel and refine the grains, thereby improving the toughness of the steel. Therefore, in order to give full play to the beneficial effects of Si, the mass percentage of Si in the nickel-saving high-strength weather-resistant bolt wire rod of the present invention is controlled between 0.01% and 2.0%.

[0015] Mn: In the nickel-saving high-strength weather-resistant bolt wire rod of the present invention, Mn has a strong solid solution strengthening effect and is also an important toughening element. Adding an appropriate amount of Mn to steel can significantly reduce the phase transformation temperature of the steel and refine the microstructure of the steel. Based on this, considering the beneficial effects of Mn, the mass percentage of Mn in the nickel-saving high-strength weather-resistant bolt wire rod of the present invention is controlled between 0.3% and 2.2%.

[0016] Cr: In the nickel-saving, high-strength, weather-resistant bolt wire rod described in this invention, the presence of Cr significantly accelerates the development of electrochemical corrosion products towards a thermodynamically stable state. In rust layer analysis, Cr can significantly accelerate (Fe... X H Y O ZThe transformation process from α-FeOOH to γ-FeOOH promotes the formation of spinel compounds; simultaneously, Cr in steel can partially replace Fe to form ferrochromium hydroxide Cr. X Fe 1-X OOH, thus giving the α-FeOOH rust layer cation selectivity and preventing Cl... - SO4 2- It penetrates into the substrate surface, giving the rust layer a protective effect. Therefore, in order to maximize the beneficial effects of Cr and ensure a significant improvement in the atmospheric corrosion resistance of steel, the mass percentage of Cr in the nickel-saving high-strength weather-resistant bolt wire rod described in this invention is controlled between 2.5% and 4.5%.

[0017] Of course, it should be noted that Cr will inevitably combine with C to form precipitated Cr phase. 23 C6, precipitated phase Cr 23 C6 does not improve the weather resistance of steel. Therefore, in this invention, while controlling the mass percentage content of a single chemical element, it is also necessary to further control the Cr and C content in the steel to meet the requirement that Cr / C > 10, so as to ensure that there is enough Cr in the steel to improve weather resistance.

[0018] Ni: In the nickel-saving high-strength weather-resistant bolt wire rod of the present invention, Ni can significantly improve the corrosion resistance of steel and effectively inhibit the formation of copper-rich phase, thereby preventing Cu hot brittleness. However, it should be noted that the Ni content in the steel should not be too high. Excessive Ni content will increase the adhesion of oxide scale during the heating process of the steel billet and increase the difficulty of pickling and descaling. Pressing into the steel will form wire rod defects on the surface. In addition, excessive Ni content in the steel will also increase the cost of the material. Therefore, in the nickel-saving high-strength weather-resistant bolt wire rod of the present invention, in order to effectively improve the corrosion resistance of the material, the mass percentage of Ni is specifically controlled between 0.01% and 0.1%.

[0019] Cu: In the nickel-saving high-strength weather-resistant bolt wire rod described in this invention, among all alloying elements, Cu has the most significant impact on the material's weather resistance. Adding an appropriate amount of Cu to steel can effectively delay the anodic dissolution of Fe or reduce the electronic conductivity of the rust layer, thus slowing down the rate at which electrons flow to the cathode region. Simultaneously, Cu in steel can also combine to form small amounts of insoluble copper oxyhydroxide, such as Cu₄(SO₄)(OH)₂ and Cu₄(SO₄)(OH)₄. These compounds can precipitate within the pores of the rust layer and enhance the barrier effect of the corrosion product film. However, it should be noted that the Cu content in the steel should not be too high, as excessive Cu can lead to hot brittleness and increase production difficulty. Therefore, to maximize the beneficial effects of Cu, the mass percentage of Cu in the nickel-saving high-strength weather-resistant bolt wire rod described in this invention is controlled between 0.2% and 0.6%.

[0020] Al: In the nickel-saving high-strength weather-resistant bolt wire rod described in this invention, Al is a deoxidizer added to the steel, which can play a deoxidizing role. In this invention, the mass percentage of Al element is controlled between 0.001-0.1%, which is beneficial to refine the grains and improve the strength and toughness of the steel.

[0021] Ti: In the nickel-saving high-strength weather-resistant bolt wire rod described in this invention, Ti can inhibit the growth of austenite grains in the slab during the thermal process, thereby improving the toughness of the steel. Therefore, to maximize the beneficial effects of Ti, the mass percentage of Ti is controlled between 0.01% and 0.5% in this invention.

[0022] Furthermore, in the nickel-saving high-strength weather-resistant bolt wire rod described in this invention, among the unavoidable impurities, P≤0.012% and S≤0.005%.

[0023] In the nickel-saving high-strength weather-resistant bolt wire rod described in this invention, both P and S elements are impurity elements in steel. Under the condition that technical conditions permit, in order to obtain steel with better performance and higher quality, the content of impurity elements in steel should be reduced as much as possible.

[0024] S and P: In this invention, the presence of impurity element S will worsen the atmospheric corrosion resistance of steel and lead to hot brittleness. While P can improve the atmospheric corrosion resistance of steel, excessively high P content will significantly reduce the toughness and plasticity of the steel and lead to cold brittleness. Therefore, except for special requirements, the content of P and S elements in steel should be reduced as much as possible. This invention uses extremely low S and P contents, specifically controlling the mass percentage of P element to P≤0.012% and the mass percentage of S element to S≤0.005%.

[0025] Furthermore, in the nickel-saving high-strength weather-resistant bolt wire rod described in this invention, its microstructure is ferrite + pearlite + bainite.

[0026] Furthermore, in the nickel-saving high-strength weather-resistant bolt wire rod described in this invention, its weather resistance index I ≥ 9, where I = 26.01 × Cu + 3.88 × Ni + 1.20 × Cr + 1.49 × Si + 17.28 × P - 7.29 × Cu × Ni - 9.10 × Ni × P - 33.39 × Cu 2 Substitute the values ​​of the chemical elements in the formula into the values ​​preceding the percentage sign.

[0027] In the above technical solution of the present invention, while controlling the mass percentage content of a single chemical element, the present invention can further control the element ratio in the steel. Based on the chemical composition of the above nickel-saving high-strength weather-resistant bolt wire rod, the Legault-Leckie empirical formula is used to predict its weather resistance index I≥9.

[0028] It should be noted that for steel, the higher the I value, the higher the atmospheric corrosion resistance of the steel. Generally speaking, materials with a weather resistance index I > 6 have very good atmospheric corrosion resistance.

[0029] Furthermore, in the nickel-saving high-strength weather-resistant bolt wire rod described in this invention, its yield strength is ≥900MPa, tensile strength is ≥1000MPa, elongation is ≥8%, and reduction of area is ≥15%.

[0030] In addition, another objective of the present invention is to disclose a bolt made from the above-mentioned nickel-saving high-strength weather-resistant bolt wire rod. The bolt made from the nickel-saving high-strength weather-resistant bolt wire rod not only has high strength, but also excellent atmospheric corrosion resistance. It can be applied to bridge structures, transmission towers, photovoltaic supports and other fields without painting, and has good application prospects.

[0031] To achieve the above objectives, the present invention proposes a bolt, which is made from the nickel-saving high-strength weather-resistant bolt wire rod of the present invention after at least quenching and tempering treatment. The bolt has a yield strength ≥720MPa, tensile strength ≥870MPa, elongation ≥15%, and reduction of area ≥55%.

[0032] In the above technical solution of the present invention, the finished nickel-saving high-strength weather-resistant bolt wire rod prepared by the present invention can be further processed by downstream users in the specific bolt manufacturing process by pickling, phosphating, drawing, cold heading, quenching and tempering, thread rolling and other processes to produce high-strength and high-weather-resistant bolts.

[0033] In some implementations, the specific heat treatment process adopted by downstream users can be: quenching temperature of 850℃-930℃, holding for 80 minutes followed by oil quenching; tempering temperature of 420-600℃, holding for 1 hour followed by air cooling.

[0034] Accordingly, another object of the present invention is to provide a method for manufacturing the above-mentioned nickel-saving high-strength weather-resistant bolt wire rod, which is convenient and simple to implement, and can effectively prepare the nickel-saving high-strength weather-resistant bolt wire rod of the present invention.

[0035] To achieve the above objectives, the present invention proposes a method for manufacturing the aforementioned nickel-saving high-strength weather-resistant bolt wire rod, comprising the following steps: (1) Smelting and casting; (2) Heating; (3) Rolling; (4) Cooling: After rolling, cool to below 900℃ at a cooling rate of 4~5℃ / s, and then continue to cool to room temperature at a cooling rate of 0.3~0.5℃ / s.

[0036] Furthermore, in the manufacturing method described in this invention, in step (2), the heating temperature is controlled to be 1050~1100℃.

[0037] In the manufacturing method designed in this invention, after obtaining molten steel by smelting according to the chemical composition designed in this invention, the molten steel can be cast into steel ingots or billets under protective conditions after being cooled.

[0038] Accordingly, the obtained steel ingots or billets require further heating, rolling, and cooling processes. It is important to note that the temperature of the billet must be strictly controlled during rolling to avoid excessive heating that could lead to the precipitation of copper-rich phases. Therefore, the specific process control can be as follows: before rolling, the heating temperature of the billet should be controlled at 1050~1100℃; after rolling, it should be cooled to below 900℃ at a cooling rate of 4~5℃ / s, and then cooled to room temperature at a cooling rate of 0.3~0.5℃ / s, thereby obtaining the nickel-saving high-strength weather-resistant bolt wire rod described in this invention.

[0039] Compared with the prior art, the nickel-saving high-strength weather-resistant bolt wire rod, bolt, and manufacturing method of the present invention have the following advantages and beneficial effects: This invention develops a novel nickel-saving, high-strength, weather-resistant bolt wire rod. Through reasonable composition matching and process design, it achieves high strength and excellent weather resistance by adding a small amount of Ni without adding V. Its strength level meets the requirements of 8.8-10.9, and its atmospheric corrosion resistance (weather resistance index I ≥ 9) satisfies the requirement of no coating. This nickel-saving, high-strength, weather-resistant bolt wire rod has a yield strength ≥ 900 MPa, tensile strength ≥ 1000 MPa, elongation ≥ 8%, and reduction of area ≥ 15%.

[0040] Based on the present invention, nickel-saving high-strength weather-resistant bolt wire rods can be processed into high-performance bolts by downstream users through processes such as pickling, phosphating, drawing, cold heading, quenching and tempering, and thread rolling. The prepared bolts have a yield strength ≥720MPa, tensile strength ≥870MPa, elongation ≥15%, and reduction of area ≥55%, which can effectively meet the application requirements.

[0041] Bolts made from this nickel-saving, high-strength, weather-resistant wire rod not only have high strength but also excellent atmospheric corrosion resistance. They can be used without coating in bridge structures, transmission towers, photovoltaic supports, and other fields, which is of great significance to the development of the bolt industry and has good application prospects. Detailed Implementation

[0042] The following will further explain and illustrate the nickel-saving high-strength weather-resistant bolt wire rod, bolt, and manufacturing method of the present invention with reference to specific embodiments. However, this explanation and illustration do not constitute an improper limitation on the technical solution of the present invention.

[0043] Examples 1-6 Table 1-1 lists the mass percentage of each chemical element designed for the nickel-saving high-strength weather-resistant bolt wire rods of Examples 1-6.

[0044] Table 1-1. (wt%, balance is Fe and other unavoidable impurities other than P and S) Table 1-2 lists the content relationships of some chemical elements in the nickel-saving high-strength weather-resistant bolt wire rods of Examples 1-6.

[0045] Table 1-2. Content Relationship of Some Chemical Elements in Nickel-Saving High-Strength Weather-Resistant Bolt Wire Rods Note: In Table 1-2 above, Cr and C in the formula "Cr / C" are substituted with the mass percentage of the corresponding chemical elements; and I = 26.01×Cu + 3.88×Ni + 1.20×Cr + 1.49×Si + 17.28×P - 7.29×Cu×Ni - 9.10×Ni×P - 33.39×Cu 2 Furthermore, each chemical element in the formula is replaced with the value preceding the percentage sign of its corresponding mass percentage content.

[0046] In this invention, the nickel-saving high-strength weather-resistant bolt wire rods of Examples 1-6 are all specifically prepared using the following steps: (1) Smelting and casting according to the chemical composition shown in Table 1-1 and Table 1-2: Smelting according to the design composition, and casting into 142mm×142mm square billets under protective conditions after the molten steel is calmed.

[0047] (2) Heating: The 142mm×142mm square billet is fed into a heating furnace for heating, and the heating temperature is controlled at 1050~1100℃.

[0048] (3) Rolling.

[0049] (4) Cooling: After rolling, cool to below 900℃ at a cooling rate of 4~5℃ / s, and then continue to cool to room temperature at a cooling rate of 0.3~0.5℃ / s to obtain the corresponding φ10~26mm nickel-saving high-strength weather-resistant bolt wire rod.

[0050] In this invention, six heats of steel were prepared by smelting according to the chemical compositions designed in Tables 1-1 and 1-2, namely Examples 1-6. The chemical element composition and related process design of the nickel-saving high-strength weather-resistant bolt wire rods of Examples 1-6 all meet the design specifications of this invention.

[0051] Table 2 lists the specific process parameters for the nickel-saving high-strength weather-resistant bolt wire rods of Examples 1-6 in the above process steps.

[0052] Table 2. Rolling process parameters for nickel-saving high-strength weather-resistant bolt wire rods Samples of the nickel-saving high-strength weather-resistant bolt wire rods from Examples 1-6 were taken and observed. The inventors observed that the microstructure of the nickel-saving high-strength weather-resistant bolt wire rods from Examples 1-6 was ferrite + pearlite + bainite.

[0053] Accordingly, after completing the above observations and analyses, the nickel-saving high-strength weather-resistant bolt wire rods of the finished products 1-6 can be sampled again, and relevant mechanical property tests can be performed on the wire rod samples of each embodiment. The mechanical property test results are listed in Table 3.

[0054] The relevant mechanical property testing methods are as follows: Tensile test: Under room temperature conditions, according to GBT228-2002 Metallic Materials Room Temperature Tensile Test Method, the yield strength, tensile strength, elongation and reduction of area of ​​the nickel-saving high-strength weather-resistant bolt wire rods of Examples 1-6 were tested.

[0055] Table 3 lists the mechanical property test results of the nickel-saving high-strength weather-resistant bolt wire rods obtained in Examples 1-6.

[0056] Table 3. Mechanical properties of nickel-saving high-strength weather-resistant bolt wire rod As shown in Table 3, and in conjunction with Tables 1-2, it can be seen that the nickel-saving high-strength weather-resistant bolt wire rods of Examples 1-6 of this invention possess excellent corrosion resistance (weather resistance index I between 9.3 and 11.4) while also exhibiting high strength. The atmospheric corrosion resistance of the nickel-saving high-strength weather-resistant bolt wire rods of Examples 1-6 meets the requirements for coating-free operation.

[0057] In this invention, the mechanical properties of the nickel-saving high-strength weather-resistant bolt wire rods of Examples 1-6 are as follows: their yield strength R p0.2 Tensile strength R is between 909-990 MPa. m Between 1020-1100 MPa, the elongation A is between 8-11%, and the reduction of area is between 15-18%.

[0058] Accordingly, to further illustrate that the nickel-saving high-strength weather-resistant bolt wire rod prepared by the present invention can be further used to produce bolts with excellent performance, downstream users can further perform pickling, phosphating, drawing, cold heading, quenching and tempering, thread rolling, and other processes on the nickel-saving high-strength weather-resistant bolt wire rods of the present invention to further process them into high-strength weather-resistant bolts with excellent performance.

[0059] It should be noted that, in this invention, the inventor designed the following heat treatment process for downstream users: quenching temperature 850℃-930℃, holding temperature for 80 minutes followed by oil quenching; tempering temperature 420-600℃, holding temperature for 1 hour followed by air cooling.

[0060] Accordingly, for the high-strength weather-resistant bolts prepared in Examples 1-6, the inventors conducted mechanical property tests on each bolt, and the test results are listed in Table 4 below. When conducting mechanical property tests on the high-strength weather-resistant bolts prepared in Examples 1-6, the inventors used the same tensile testing method as described in Table 3 above, and will not repeat it here.

[0061] Table 4 lists the mechanical properties of the high-strength weather-resistant bolts prepared in Examples 1-6.

[0062] Table 4. Mechanical properties of nickel-saving high-strength weather-resistant bolts As shown in Table 4 above, the bolts prepared in Examples 1-6 also have excellent mechanical properties, namely high strength. Their weather resistance can be inherited from the nickel-saving high-strength weather-resistant bolt wire rods of Examples 1-6, which will not be elaborated here.

[0063] In this invention, the bolts prepared according to Examples 1-6 have a yield strength Rp0.2 between 767-1062 MPa, a tensile strength Rm between 903-1143 MPa, an elongation A between 15-19%, and a reduction of area Z between 61-68%. They have excellent mechanical properties, with a strength grade of 8.8-10.9, and can be applied without painting in fields such as bridge structures, transmission towers, and photovoltaic supports, showing good application prospects.

[0064] It should be noted that the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0065] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A bolt, which is made from a nickel-saving, high-strength, weather-resistant bolt wire rod that has undergone at least a quenching and tempering treatment, characterized in that, The mass percentage of each chemical element in the nickel-saving high-strength weather-resistant bolt wire rod is as follows: C: 0.15-0.25%, Si: 0.01-2.0%, Mn: 0.3-2.2%, Cr: 2.5-4.5%, Ni: 0.01-0.1%, Cu: 0.2-0.6%, Al: 0.001-0.1%, Ti: 0.01-0.5%; the balance is Fe and other unavoidable impurities; and the mass percentage of Cr and C satisfies: Cr / C > 10; The bolt has a yield strength ≥720MPa, tensile strength ≥870MPa, elongation ≥15%, and reduction of area ≥55%.

2. The bolt as described in claim 1, characterized in that, The unavoidable impurities in the nickel-saving high-strength weather-resistant bolt wire rod are P≤0.012% and S≤0.005%.

3. The bolt as described in claim 1, characterized in that, The microstructure of the nickel-saving high-strength weather-resistant bolt wire rod is ferrite + pearlite + bainite.

4. The bolt as claimed in claim 1, characterized in that, The weathering resistance index I of the nickel-saving high-strength weather-resistant bolt wire rod is ≥9, where I = 26.01×Cu + 3.88×Ni + 1.20×Cr + 1.49×Si + 17.28×P - 7.29×Cu×Ni - 9.10×Ni×P - 33.39×Cu 2 Substitute the values ​​of each chemical element in the formula into the values ​​preceding the percentage sign.

5. The bolt as claimed in claim 1, characterized in that, The nickel-saving high-strength weather-resistant bolt wire rod has a yield strength ≥900MPa, tensile strength ≥1000MPa, elongation ≥8%, and reduction of area ≥15%.

6. The bolt as described in any one of claims 1-5, characterized in that, The nickel-saving high-strength weather-resistant bolt wire rod is manufactured using the following steps: (1) Smelting and casting; (2) Heating; (3) Rolling; (4) Cooling: After rolling, cool to below 900℃ at a cooling rate of 4~5℃ / s, and then continue to cool to room temperature at a cooling rate of 0.3~0.5℃ / s.

7. The bolt as claimed in claim 6, characterized in that, In step (2), the heating temperature is controlled to be 1050~1100℃.

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