High-performance spring steel bar for commercial vehicle stabilizer bar and manufacturing method

Abstract

The steel comprises the following chemical components in percentage by mass: 0.40 to 0.55 percent of C, 0.80 to 1.20 percent of Si, 0.80 to 1.60 percent of Mn, 0.90 to 1.25 percent of Cr, less than or equal to 0.020 percent of P, less than or equal to 0.015 percent of S, less than or equal to 0.15 percent of Cu, less than or equal to 0.08 percent of V and less than or equal to 0.20 percent of Nb, 0.0005 to 0.0050 percent of B, 0.015 to 0.025 percent of N, less than or equal to 0.15 percent of Ni, less than or equal to 0.05 percent of Mo, 0.04 to 0.10 percent of Ti, less than or equal to 0.001 percent of Ca, less than or equal to 0.0008 percent of [O] and the balance of Fe and inevitable impurity elements. After heat treatment, the tensile strength of the steel is 1800 MPa or above, the yield strength is 1620 MPa or above, the ductility is 10% or above, the area reduction rate is 40% or above, and the yield ratio is 0.90 or above; and the boundary dimension precision is that the dimension precision of phi 45 to phi 60 is less than or equal to + / -0.05 mm, and the surface has no defect. According to the invention, key procedures are optimized, researched and controlled, so that the high-performance spring steel for the stabilizer bar of the commercial vehicle has ultrahigh purity, high strength and high yield ratio, and is superior to the existing spring steel for the stabilizer bar of the commercial vehicle.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of special steel smelting, and particularly relates to a high-performance spring steel bar for a commercial vehicle stabilizer bar and a manufacturing method. BACKGROUND

[0002] In recent years, the development degree of the technology level of the automobile industry is gradually improved, the automobile industry enters a high-speed development stage, however, the environmental and energy problems are also increasingly serious. Light weight technology has become the key to improving the market competitiveness of various automobile enterprises, and low energy consumption, safety and light weight of automobiles have become a hot issue in the field of automobile research.

[0003] The automobile stabilizer bar is one of the important auxiliary elastic elements in the automobile suspension system, and is mainly used for reducing the lateral inclination of the automobile when turning at high speed, and improving the stability and smoothness of the automobile, and preventing excessive roll. The manufacturing material is mostly medium-carbon alloy steel, which is quenched and tempered at medium temperature to obtain tempered troostite, and the hardness is about 45 HRC, so as to obtain high strength and certain toughness. With the requirements of energy saving and environmental protection and automobile light weight, the automobile stabilizer bar also requires light weight, so the automobile stabilizer bar is also developing towards high-performance stabilizer bar.

[0004] The latest data released by the China Automobile Industry Association shows that in 2022, China's automobile production and sales completed 27,021,000 and 26,844,000 respectively, with a year-on-year increase of 3.4% and 2.1%, showing a sustained growth trend. The total amount of automobile production and sales in China has ranked first in the world for 14 consecutive years. The demand for high-performance stabilizer bar steel also shows an increasing trend year by year. The existing commercial vehicle stabilizer bar steel is mostly 50CrVA spring steel, and is basically ordered according to GB / T 1222, and its performance after oil quenching at 850 DEG C and tempering at 500 DEG C is that the tensile strength is greater than or equal to 1275Mpa, the elongation is greater than or equal to 10%, and the area reduction is greater than or equal to 40%.

[0005] In order to meet the demand of automobile light weight, the performance of the material is required to be high: such as improving the tensile strength of the material under the premise of ensuring plasticity; in order to achieve high tensile strength, the inclusions in the steel need to be reduced as much as possible; the surface quality of the steel is good, etc. The ordinary spring steel cannot meet the requirements of the high-performance stabilizer bar of the commercial vehicle. Based on the current production status of the stabilizer bar rod for commercial vehicles and the commercial, it is an urgent technical problem for the technical personnel in the field to produce an economical high-performance stabilizer bar steel for commercial vehicles.

[0006] There are some patents that provide a kind of high toughness spring steel, such as: patent document 1 application number CN 105821311 discloses "a kind of high toughness spring steel and its preparation method", especially relates to a kind of high toughness spring steel and its preparation method.The chemical composition of the spring steel is as follows: C: 0.53%~0.68%, Si: 1.24%~1.56%, Mn: 1.50%~2.00%, P: 0.006~0.008%, S: 0.002~0.005%, Cr: 0.89%~0.96%, Ti: 0.05~0.07%, Al: 0.08~0.10%, Cu: 0~0.15%, Ni: 1.21~1.26%, Nb: 0.45~0.60%, O: 0~0.006%, H: 0~0.00020%, Mo: 0.23~0.25%, rare earth elements: 0.23~0.25%, the balance is Fe and inevitable impurities;The spring steel has good elasticity, is suitable for normal work in load environment, has high yield strength and long service life for manufacturing spring material.The tensile strength can be guaranteed above 1920MPa, the surface shrinkage is above 40%, and the elongation is above 10%, which can greatly meet the requirements of commercial vehicle stabilizer bar, but due to the addition of Ni, Mo, high content of Nb and rare earth elements in this steel, the production cost of this steel is high, and the content of P and S needs to be controlled at a low level, which increases the production cost and makes the surface quality control of the material difficult, so it is not suitable for mass production.Patent document 2 application number CN 106834907 B discloses "ultra-high strength spring steel for valve spring", especially relates to an ultra-high strength spring steel for valve spring.The ultra-high strength spring steel for valve spring in vehicle engine is based on 100% by weight of ultra-high strength spring steel, which comprises 0.5-0.7% by weight of carbon (C), 1.3-2.3% of silicon (Si), 0.6-1.2% of manganese (Mn), 0.6-1.2% of chromium (Cr), 0.1-0.5% of molybdenum (Mo), 0.05-0.8% of nickel (Ni), 0.05-0.5% of vanadium (V), 0.05-0.5% of niobium (Nb), 0.05-0.3% of titanium (Ti), 0.001-0.01% of boron (B), 0.01-0.52% of tungsten (W), 0.3% or less (excluding 0%) of copper (Cu), 0.3% or less (excluding 0%) of aluminum (Al), 0.03% or less (excluding 0%) of nitrogen (N), 0.003% or less (excluding 0%) of oxygen (O), and the balance of Fe and other inevitable impurities.The ultra-high strength spring steel has a tensile strength of 3000MPa or more.This patent only provides a way to improve the strength of valve spring steel, but does not provide a way to improve the toughness. SUMMARY

[0007] The technical problem solved by the present application is to provide a high-performance spring steel bar for a commercial vehicle stabilizer bar and a manufacturing method.

[0008] The technical solution adopted by the present application to solve the above problems is: a high-performance spring steel bar for a commercial vehicle stabilizer bar, the chemical composition of the steel bar is as follows in terms of mass percentage: C: 0.40-0.55%, Si: 0.80-1.20%, Mn: 0.80-1.60%, Cr: 0.90-1.25%, P: ≤0.020%, S: ≤0.015%, Cu: ≤0.15%, 0.08%≤V+Nb≤0.20%, B: 0.0005-0.0050, N: 0.015%-0.025%, Ni: ≤0.15%, Mo: ≤0.05%, Ti: 0.04-0.10%, Ca: ≤0.001%, [O]≤0.0008%, the balance being Fe and unavoidable impurities.

[0009] The tensile strength of the steel bar after heat treatment is above 1800MPa, the yield strength is above 1620MPa, the elongation is above 10%, the area reduction is above 40%, and the yield strength ratio is above 0.90.

[0010] The dimensional accuracy of the steel bar is: φ45-φ60 dimensional accuracy ≤±0.05mm.

[0011] The non-metallic inclusions of the steel bar are:

[0012] The surface is defect-free and the surface roughness is not more than Ra1.6.

[0013] The main role of the alloy composition and the specific explanation of the content setting are as follows: C content requirement: C is the main strengthening element. Carbon dissolved in steel forms interstitial solid solution, which plays a solid solution strengthening role. When it forms carbide with strong carbide, it plays a precipitation strengthening role. Therefore, the strength, hardness, plasticity and toughness of carbon spring steel, decarburization tendency, microstructure are greatly influenced, and carbon is also the most intense element affecting the ballistic performance. The C content of the present application is 0.35-0.55%.

[0014] Si content requirements: Si not only has a solid solution strengthening effect, but also changes the number, size, and morphology of carbides precipitated during tempering, improving the tempering stability of the steel, thereby also benefiting the strength and hardness. Si also helps improve the resistance to elastic degradation. According to relevant reports, the effect of Si increases with its content within the range of 0.29-2.26%. However, higher Si contents can promote decarburization, graphitization, and grain coarsening during heating of the steel. The Si content of the present invention is 0.80-1.20%.

[0015] Mn content requirements: Mn can significantly improve hardenability, improve heat treatment performance, strengthen the matrix and refine pearlite, thereby increasing the strength and hardness of steel. At the same time, manganese alloys are cheap and readily available. The Mn content of the present invention is 0.80-1.60%.

[0016] Cr content requirement: Cr can significantly improve the hardenability of steel. It is a carbide-forming element, which increases the activation energy of steel diffusion in steel and can reduce the decarburization tendency of steel. The Cr content of the present invention is 0.90-1.25%.

[0017] P content requirement: P easily causes high-temperature temper brittleness of the material. At the same time, since P is an inevitable impurity element in steel, it can only be reduced as much as possible during the production process. The P content of the present invention is ≤0.020%.

[0018] S content requirement: S will reduce the toughness of steel and easily cause hot brittleness of steel. Commercial vehicle stabilizer bars do not have chip cutting processes, so it is desirable to reduce S as much as possible. The S content of the present invention is ≤0.020%.

[0019] Boron content requirements: Boron contributes most to hardenability, reducing the amount of alloying elements added and lowering costs. Boron also improves the steel's resistance to spring loss. Excessive B content can easily lead to segregation and the formation of borides, which seriously deteriorates the toughness of spring steel. The B content in this invention is 0.0005-0.0035%.

[0020] Ti Content Requirements: Boron is a relatively active element with a strong affinity for oxygen and nitrogen. Titanium is added during smelting to protect boron from oxidation and nitridation after solidification, thereby ensuring its stable contribution to hardenability. Generally, adding at least 0.04% Ti to the steel will ensure this. Excessive Ti additions can easily form TiN, which can lead to sharp inclusions and affect fatigue life. Therefore, the Ti content in this invention is set at 0.04-0.010%.

[0021] Ni content requirement: Ni is the formation element of carbide. Ni exists in the form of solid solution in steel, which can improve the strength and improve the hardenability of steel. At the same time, Ni can reduce the Ar3 transformation temperature, make the ferrite grain fine, and can make the pearlite interlamellar spacing decrease, which is beneficial to improve the plasticity and toughness of the steel. But because Ni is a precious metal, it is expensive, and for economic consideration, the steel grade does not consider adding Ni, only for the inevitable Ni in the molten steel in the scrap or alloy in the smelting process, the Ni content of the present application is ≤0.15%.

[0022] Mo content requirement: Mo can improve the hardenability, overcome the temper brittleness, improve the heat treatment performance, fatigue performance, etc. But because of high price, poor economy, Mo is cancelled in the present application, which improves the cost competitiveness of the invented steel grade. But because Mo cannot be avoided in the raw materials in the smelting process, the Mo in the present application is ≤0.05%.

[0023] V, Nb content requirement: V and Nb are strong carbide forming elements. When they generate fine and dispersed MC type carbide, they can produce strong precipitation strengthening effect, and also can pin the austenite, inhibit the growth of austenite grain during heating, and improve the strength, elastic reduction resistance, etc. of the steel material through grain refinement. If the addition amount is too low, the effect is not obvious. If the addition amount is too large, it is easy to segregate on the grain boundary, and the toughness decreases. At the same time, the price of V and Nb alloy is relatively high, and the addition amount is too large, which affects the cost. Therefore, the present patent is 0.10%≤V+Nb≤0.20%.

[0024] N content requirement: N is a very strong austenite forming and stabilizing element. N can have strong affinity with Nb and V elements, and can form stable interstitial phases. Nitride and carbide can be mutually dissolved to form carbonitride. These compounds can effectively prevent austenite coarsening, prevent grain growth, and improve the toughness of the material. The N content of the present application is 0.15% to 0.25%.

[0025] Ca content requirement: adding a certain amount of Ca in the steel can prevent the Al2O3 in the steel from forming a mass in the water gap, ensuring smooth pouring of the molten steel, and also can change the inclusions. But the increase of Ca element will lead to the number and size of large size point-shaped oxides in the steel, which will make the fatigue performance of the steel worse. A certain amount of Ca is added in the steel in the present application, and the content is ≤0.001%.

[0026] Cu content requirement: Cu is not a special added element, it is present as a residual element, or as some non-essential added element, the molten steel smelting process with raw materials inevitably exist Cu and other elements, Cu content is higher, it will improve the strength, at the same time will deteriorate the plasticity and toughness of steel, at the same time Cu is easy to cause the surface crack of steel. Therefore, the upper limit of their content is limited, Cu: ≤0.015%.

[0027] O content requirement: O mainly exists in the form of Al2O3, MnO, CaO, SiO2 and other inclusions in steel, after a large number of research, the size and quantity of oxide inclusions in steel significantly deteriorate the fatigue life of steel, therefore, the upper limit is regulated to be 0.0008%.

[0028] The application further provides a high-performance spring steel bar for commercial vehicle stabilizer and a manufacturing method, the process mainly includes: Converter or electric arc furnace smelting- refining- RH or VD vacuum degassing- continuous casting- continuous casting billet hot delivery- heating- breakdown (flame cleaning)- intermediate billet flaw detection- heating- continuous rolling- sawing- cold stacking- softening annealing- straightening- car + fine straightening + abrasive belt polishing- surface and internal flaw detection- packaging- warehousing. Among them: Molten steel smelting: the smelting raw materials must pass through KR molten iron pretreatment, converter or electric arc furnace smelting, LF refining, RH or VD furnace vacuum degassing in turn.

[0029] KR molten iron pretreatment: the molten iron must be subjected to KR molten iron pretreatment, the content of harmful elements S and P is preliminarily reduced, and clean molten iron is obtained, and the molten iron pretreatment can also reduce the addition amount of subsequent smelting slagging agent, shorten the smelting time and improve the production efficiency.

[0030] Converter or electric arc furnace preliminary smelting: mainly to reduce the content of C, further remove the content of P and S elements, the end point C of the tapping process is controlled below 0.10%, and Si iron is used for pre-deoxidization. The converter or electric furnace adopts slag blocking plug, post-furnace slagging and other control technologies, and adds clean scrap steel, strictly controls the content of residual elements in the scrap steel, and strictly controls the content of residual harmful elements in the molten steel.

[0031] LF refining furnace: in addition to accurately controlling the content of each element, and accelerating the transfer of substances between molten steel and refining slag by blowing inert gas in the steel, non-metallic inclusions can be fully floated and removed, and at the same time, in order to reduce the influence of brittle inclusions on the fatigue life of stabilizer, the inclusions are subjected to denaturation treatment.

[0032] RH or VD furnace: the molten steel must be vacuum degassed, and the furnace must reach sufficient vacuum degree and maintain sufficient circulation processing time to further remove harmful gas and non-metallic inclusions in the molten steel, improve the purity of the molten steel, the maximum vacuum degree is ≤1.5 mbar, the high vacuum time is ≥15 min, after breaking the vacuum, argon soft blowing stirring is used, the soft blowing time is ≥25 min, on the one hand to ensure the gas content in the molten steel, on the other hand to fully ensure the floating and removal of inclusions.

[0033] Continuous casting: argon protection is used for the whole process to prevent secondary pollution and oxidation of the molten steel; large section 300mm×300mm and above are used for continuous casting, electromagnetic stirring, tundish induction heating and light pressing down are used to reduce the superheat of the molten steel and improve the segregation of the casting blank. The pouring superheat ΔT is ≤25℃, the light pressing down amount is 8mm-12mm, the pouring speed is 0.60-0.80m / min; the steel flow ratio to water is 0.5-0.7L / kg, the ladle residual steel amount is not less than 5 tons; end electromagnetic stirring is used, through the above various control technologies, the center segregation of the steel is further improved, the uniformity of the steel organization is improved, and the center porosity is not higher than C1.0 level.

[0034] Blooming: the continuous casting blank is sent to a heating furnace in a neutral or weak oxidizing atmosphere for heating, and then is rolled by a blooming mill to form a square intermediate blank with a size of 200mm×200mm-300mm×300mm. The heating temperature is controlled at 1200-1240℃, and the total heating time is not less than 5 hours, on the one hand to ensure full austenitization of the blank, on the other hand to ensure that elements such as Nb, V, N and C are fully and uniformly dissolved in the austenite phase, to prepare for uniform precipitation in the subsequent cooling process and effectively control the grain refinement. At the same time, in order to eliminate the surface decarburization of the intermediate blank, flame cleaning is used during the blooming process.

[0035] Finished product rolling: high-precision three-roll KOCKS or PSM rolling mill is used for accurate control of the finished product size, and the size accuracy can reach: φ50~55 size accuracy ≤±0.20mm. High-pressure water descaling treatment is required before rolling, the rolling start temperature is not more than 950℃, the finish rolling temperature is 680-720℃, and after rolling, the rolling mill is cooled on the cooling bed, a heat preservation cover is added on the cooling bed to ensure that the organization after rolling off line is F+P, the actual grain is ≥7 level, high-precision three-roll KOCKS or PSM finishing rolling mill is used for finished product rolling, compared with the traditional two-roll rolling mill, the size accuracy is greatly improved.

[0036] Softening annealing: continuous annealing furnace with protective atmosphere is used for softening annealing, the annealing process adopts 650-710℃ for 4h or more and then slow cooling, the hardness after annealing is not more than 240HBW.

[0037] Silver bright processing: after annealing, the steel is straightened by two-roll or multi-roll straightening machine, and then is processed by high-efficiency car skin machine, two-roll fine straightening and abrasive belt polishing to remove the surface oxide layer, surface defects and decarburized layer of the rolled material, and at the same time, the material surface decarburization is defect-free, the surface roughness is below RZ12.5, and the size precision is controlled within H9 level.

[0038] Compared with the prior art, the application has the advantages that: The application realizes the synergistic effect of fine-grain strengthening and precipitation strengthening by optimizing the basic element ratio of C, Si, Mn, Cr and the like, introducing the micro-alloying combination of V, Nb and N (0.08%≤V+Nb≤0.20%, N: 0.015%~0.025%), and adding a small amount of B (0.0005%~0.0050%). Compared with the prior art (such as the patent document 1 relying on high Ni, Mo and rare earth elements), the application significantly reduces the cost while ensuring that the tensile strength is greater than or equal to 1800 MPa by reducing the use of expensive elements.

[0039] The application strictly limits the impurity elements such as P, S and O (such as O≤0.0008%), and combines the Ca treatment inclusion modification technology to greatly improve the purity and fatigue life of the steel, and solves the pain points of traditional spring steel, such as many inclusions and poor surface quality.

[0040] The application realizes high purity and defect-free delivery (no surface damage and decarburization) of the steel through the production process of two-fired materials, flame cleaning, silver bright processing and the like.

[0041] The application controls 0.08%≤V+Nb≤0.20%, 1.8≤(V+Nb) / N≤3, high-temperature heating 1200~1240℃ and the like to ensure that the elements such as Nb, V, N and C are fully and uniformly dissolved in the austenite phase. Low-temperature rolling is adopted during finished product rolling, which can control the decarburization of the rolled material and prevent grain growth.

[0042] The application adopts 690~710℃ annealing to ensure that the hardness of the steel is uniform and the hardness is controlled below 240HBW, which prepares conditions for later car skin processing.

[0043] In summary: the tensile strength of the steel after heat treatment is greater than 1800 MPa, the yield strength is greater than 1620 MPa, the elongation is greater than 10%, the area reduction is greater than 40%, and the yield strength ratio is greater than 0.90. The size precision of the steel: the size precision of φ45~φ60 is ≤±0.05mm, and the surface roughness is not more than Ra1.6.

[0044] The high-performance spring steel bar for commercial vehicle stabilizer bars has the advantages of high strength, high yield strength ratio, low inclusion content, low oxygen content, small composition segregation, high dimensional accuracy, etc. DETAILED DESCRIPTION

[0045] The technical solutions of the present application will be described in more detail in combination with the preferred embodiments of the present application. However, these embodiments are only used to describe the preferred embodiments of the present application, and cannot impose any limitation on the scope of the present application.

[0046] The manufacturing process of the high-performance spring steel bar for commercial vehicle stabilizer bars in the embodiment of the present application is a specific production process, which is hot metal pretreatment, converter or electric arc furnace smelting, LF refining, RH or VD furnace vacuum degassing, large-section continuous casting CCM large billet, intermediate billet opening, intermediate billet rolling into finished product, annealing, silver bright processing, finishing, and warehousing.

[0047] Specifically, before smelting, the hot metal must be subjected to KR hot metal pretreatment, and the molten steel is smelted by a converter or an electric furnace. In addition to adding high-quality hot metal, a certain amount of clean scrap steel and high-quality raw and auxiliary materials are also added to ensure that the end point C of tapping is controlled at about 0.10% and the tapping temperature is above 1600℃; during LF refining, high-quality refractory materials and high-performance precise synthetic slag are added according to the target composition; during vacuum degassing, sufficient vacuum degree and sufficient circulation processing time are maintained; during continuous casting, protective casting is adopted throughout the whole process, and the technologies of tundish induction heating, light press-down, and electromagnetic stirring are adopted, and low superheat casting is adopted, with the superheat controlled at ≤25℃; the intermediate billet is opened, the heating temperature is controlled at 1200-1240℃, the total heating time is not less than 5 hours, the opening rolling temperature is 1130±10℃, and the final rolling temperature is controlled at 850-950℃; after rolling, the intermediate billet should be cooled in the pit, and the cooling time is not less than 60 hours; then, the intermediate billet is heated and rolled, the opening billet temperature is ensured to be not more than 950℃, the bar is rolled to the target size, the final rolling temperature is 680-720℃, and after rolling, the bar is covered with a heat preservation cover when it is placed on the cooling bed; after slow cooling, the bar must be subjected to straightening, annealing, wagon, precise straightening, surface quality and internal quality flaw detection, and the silver bright bar finished product is obtained after passing the quality inspection.

[0048] The chemical composition (wt%) of the high-performance stabilizer bar for commercial vehicles in each embodiment is shown in Table 1 and Table 2.

[0049] Table 1

[0050] Table 2

[0051] The non-metallic inclusions (grade) of the high-performance stabilizer bar for commercial vehicles in each embodiment are shown in Table 3. Table 3

[0052] The round bar steel material of the embodiments 1-3 of the present application is processed into a sample and subjected to heat treatment: quenching: 900±20 DEG C, oil quenching; tempering 400±30 DEG C, and the longitudinal mechanical property data of the sample are shown in Table 4 Table 4

[0053] The austenite grain size of the high-performance stabilizer bar steel material for commercial vehicles according to the embodiments of the present application Table 5

[0054] The macroscopic inspection data (grade) of the high-performance stabilizer bar steel material for commercial vehicles according to the embodiments of the present application Table 6

[0055] In summary, the high-performance stabilizer bar steel material for commercial vehicles produced by the process of vacuum degassing + continuous casting + blooming + continuous rolling + annealing + straightening + wheeling + precision straightening + flaw detection has the following advantages: the harmful non-metallic inclusions are effectively removed in each process of molten iron pretreatment, high-quality raw and auxiliary materials, high-performance precision smelting slag, vacuum degassing, and protective pouring, thereby ensuring high purity of the steel material; the micro-alloying elements such as V, Nb and N content are added to improve the performance of the steel material; the large-section size continuous casting billet, two-fire rolling process, and high-temperature diffusion process before rolling are adopted to improve the uniformity of the steel material, thereby finally obtaining the steel material with high purity and high uniformity of the structure; and the annealing, wheeling, precision straightening, and abrasive belt polishing are adopted to ensure that the steel material has no defects on the surface and improve the fatigue life of the stabilizer bar.

[0056] Although the preferred embodiments of the present application have been described in detail above, it should be understood that various modifications and changes can be made by those skilled in the art without departing from the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A high-performance spring steel bar for commercial vehicle stabilizer bar, characterized in that The chemical composition of the rod is as follows by mass percentage: C: 0.40-0.55%, Si: 0.80-1.20%, Mn: 0.80-1.60%, Cr: 0.90-1.25%, P: ≤0.020%, S: ≤0.015%, Cu: ≤0.15%, 0.08%≤V+Nb≤ 0.20%, B: 0.0005-0.0050%, N: 0.015%-0.025%, Ni: ≤0.15%, Mo: ≤0.05%, Ti: 0.04-0.10%, Ca: ≤0.001%, [O] ≤0.0008%, and the balance is Fe and unavoidable impurity elements.

2. The high-performance spring steel bar for a commercial vehicle stabilizer bar according to claim 1, characterized in that: Ni, Cu, Mo, and Ca in the rod are not particularly added elements.

3. The high-performance spring steel bar for a commercial vehicle stabilizer bar according to claim 1, characterized in that: After heat treatment, the tensile strength of the bar is above 1800 MPa, the yield strength is above 1620 MPa, the elongation is above 10%, the area reduction is above 40%, and the yield strength ratio is above 0.

90.

4. The high-performance spring steel bar for a commercial vehicle stabilizer bar according to claim 1, characterized in that: The external dimension accuracy of the bar is: φ45~φ60 dimension accuracy ≤±0.05mm, and the surface roughness does not exceed Ra1.

6.

5. A method for manufacturing a high-performance spring steel bar for a commercial vehicle stabilizer bar according to claim 1, characterized in that: The method mainly includes: Step 1: Smelting Molten steel smelting: the smelting raw materials go through KR molten iron pretreatment, converter or electric arc furnace smelting, LF refining, RH or VD furnace vacuum degassing in sequence; Step 2: Continuous Casting Argon protection is used throughout the pouring process to prevent secondary contamination and oxidation of the molten steel. Continuous casting uses large sections of 300mm×300mm and above, and adopts electromagnetic stirring, tundish induction heating, and soft reduction to reduce the superheat of the molten steel and improve the segregation of the cast strands. Step 3: Open the intermediate billet The continuous casting billet is sent to a heating furnace in a neutral or weakly oxidizing atmosphere for heating, and then rolled into a square intermediate billet of 200mm×200mm-300mm×300mm by a blooming mill; Step 4: Finished product rolling High-pressure water descaling treatment is required before rolling. The starting rolling temperature does not exceed 950℃, and the final rolling temperature is 680-720℃. After rolling, the steel is cooled on a cooling bed with a heat preservation cover to ensure that the structure after rolling off the line is F+P and the actual grain size is ≥7 levels. Step 5: Softening annealing Use a continuous annealing furnace with a protective atmosphere for soft annealing. The annealing process uses 650-710℃ for more than 4 hours and then slowly cools. The hardness after annealing does not exceed 240HBW. Step 6: Silver processing The annealed steel is straightened by a two-roller or multi-roller straightening machine, and then goes through a high-efficiency car skin machine + two-roller fine straightening + belt polishing to remove the surface oxide layer, surface defects and decarburization layer of the rolled material. At the same time, it is ensured that the material surface is decarburized and defect-free before delivery, with surface roughness below Ra1.6 and dimensional accuracy controlled within H9 level.

6. The method for manufacturing a high-performance spring steel bar for a commercial vehicle stabilizer bar according to claim 5, characterized in that: In step 1, the endpoint C of the steel tapping process of the converter or electric arc furnace is controlled below 0.10%, and Si iron is used for pre-deoxidation; LF refining allows the non-metallic inclusions to be fully floated and removed by blowing inert gas into the steel; the maximum vacuum degree of the RH or VD furnace vacuum degassing is ≤1.5mbar, the high vacuum time is ≥15min, and argon soft blowing is used for stirring after breaking the air, and the soft blowing time is ≥25min.

7. The method for manufacturing a high-performance spring steel bar for a commercial vehicle stabilizer bar according to claim 5, characterized in that: In step 2, the pouring superheat △T≤25℃, the light pressure reduction is 8mm~12mm, and the pouring speed is 0.60~0.80m / min; The steel flow water content is 0.5-0.7L / kg, and the remaining steel in the ladle is not less than 5 tons; end electromagnetic stirring is adopted, and the center porosity is not higher than C1.0 level.

8. The method for manufacturing a high-performance spring steel bar for a commercial vehicle stabilizer bar according to claim 5, characterized in that: In step 3, the heating temperature is controlled at 1200-1240°C, the total heating time is not less than 5 hours, and flame cleaning is adopted during the blanking process, with a single-side cleaning depth of 2.0-2.5 mm.

9. The method for manufacturing a high-performance spring steel bar for a commercial vehicle stabilizer bar according to claim 5, characterized in that: In step 4, a high-precision three-roll KOCKS or PSM rolling mill is used to precisely control the size of the finished product. The overall dimensional accuracy can reach: φ50~55 dimensional accuracy ≤±0.20mm.

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