Wire rod and production method thereof and method for producing automobile solid stabilizer bar using the same

Abstract

The present invention relates to the technical field of automobile stabilizer bar production, specifically a wire rod and a production method, as well as a method for producing solid automobile stabilizer bars using the wire rod. The wire rod comprises the following chemical components by weight: C: 0.51% to 0.58%, Si: 0.15% to 0.38%, Mn: 0.7% to 1.1%, P: ≤0.020%, S: ≤0.015%, Cr: 0.7% to 1.1%, with the remainder being Fe and unavoidable impurities. The resulting solid stabilizer bar has the advantages of a simple processing flow, low manufacturing cost, stable product performance, high product strength and fatigue life. Compared with solid stabilizer bars made from rods, the structure and properties are more uniform and stable, while the yield rate is high. The present invention utilizes a cost-effective alloy combination design, combined with a controlled rolling and controlled cooling process, to ultimately achieve a metallographic structure composed of pearlite and proeutectoid ferrite. Appropriate control of the ratio of the two contents can achieve an optimal balance of strength, ductility, toughness, and hardness. The present invention utilizes a residual heat quenching process, saving energy and reducing processing costs.

Description

Technical Field

[0001] The invention relates to the technical field of automobile stabilizer bar production, in particular to a wire rod and a production method thereof, and a method for producing an automobile solid stabilizer bar by using the wire rod. Background Art

[0002] A lateral stabilizer bar, also known as an anti-roll bar, is an auxiliary elastic element in a vehicle's suspension. It increases roll stiffness, reduces lateral tilt, prevents lateral rollover, and improves ride comfort, thereby enhancing stability and ride safety. Made of spring steel, the lateral stabilizer bar is U-shaped and placed horizontally at the front and rear ends of the vehicle. When the vehicle pitches up and down and the body rolls, the stabilizer bar twists and deforms. The resulting rebound force acts as a resistance to roll, thereby stabilizing the vehicle's shape. Similarly, when the vehicle corners, the centrifugal force causes the stabilizer bar to twist. The rebound force generated by this twisting bar acts to suppress roll. Vehicles equipped with lateral stabilizers are more stable and comfortable, significantly reducing the chance of rollover. Statistics show that vehicles equipped with lateral stabilizers on rough roads and sharp turns have a 60% to 80% lower rollover probability. Therefore, the stabilizer bar is a crucial safety component in the vehicle suspension system.

[0003] In recent years, in order to reduce the weight of vehicles, hollow stabilizer bars have been used more and more. However, the blanks of hollow stabilizer bars are generally made by curling and welding the plates or directly rolling them into tubes. The plates need to be welded after curling, and the welding quality must be very high, otherwise there will be a risk of cracking. The direct tube rolling process is complicated, and the specifications of the stabilizer bars are basically around 20 to 40 mm. Such small specifications require large-size hot-rolled seamless steel pipes to be subsequently drawn. The intermediate drawing also requires several annealing steps, which has high production costs and complicated processes.

[0004] Chinese patent publication number CN109423580B discloses a "steel tube for a hollow automotive stabilizer bar and its manufacturing method." This manufacturing method requires coil welding, which places extremely high demands on welding quality, is difficult to produce, and has high processing costs. Chinese patent publication number CN113265581A discloses a "steel tube for a stabilizer bar and its manufacturing method." This method uses hot-rolled steel tubes, drawn, annealed, and then subjected to forming heat treatment after reaching the required size. The process is complex and the annealing processing cost is high. Chinese patent publication number CN102782172B discloses a "solid stabilizer bar, steel material for a solid stabilizer bar, and a method for manufacturing a solid stabilizer bar." Although this method reduces costs, its strength is not high. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the present invention provides a wire rod and a production method and a method for producing a solid stabilizer bar for an automobile using the same. The wire rod is used as the raw material for the stabilizer bar. The solid stabilizer bar produced has the advantages of high yield rate, simple processing flow, low manufacturing cost, stable product performance, high product strength and fatigue life, and can well meet the requirements of automobile use.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A wire rod for a solid stabilizer bar of an automobile, comprising the following chemical components in percentage by weight:

[0008] C: 0.51% to 0.58%, Si: 0.15% to 0.38%, Mn: 0.7% to 1.1%, P: ≤ 0.020%, S: ≤ 0.015%, Cr: 0.7% to 1.1%, and the balance is Fe and unavoidable impurities.

[0009] The reasons for adopting the above ingredients and their weight percentages in the present invention are described in detail below:

[0010] C:

[0011] In the present invention, the stabilizer rod's strength is enhanced by the addition of carbon. Carbon effectively increases the strength of steel through the formation of carbides. Furthermore, carbon is low-cost, allowing for higher finished product strength with minimal addition of alloying elements. However, excessive carbon content can affect the material's cold working properties, making it susceptible to cracking during cold working. This also impacts the steel's toughness, which in turn affects its fatigue properties, and can also cause severe material segregation. Therefore, in the present invention, the carbon content is controlled within a range of 0.51% to 0.58%.

[0012] Si:

[0013] Silicon (Si) is a reducing agent and deoxidizer in steelmaking, primarily dissolving in the ferrite phase to strengthen the steel. Increasing the Si content helps increase the material's elastic limit and improves the strength of stabilizer bar steel. However, excessive Si content can reduce the steel's plasticity and increase decarburization sensitivity. Therefore, the Si content in this invention is controlled to be between 0.15% and 0.38%.

[0014] Mn:

[0015] Manganese is an austenite-stabilizing and strengthening element that improves hardenability. It is also a good deoxidizer and desulfurizer, improving the workability and hardenability of steel. However, excessive Mn content will coarsen the steel's grains, reducing its ductility and toughness. Therefore, the Mn content is controlled between 0.70% and 1.00%.

[0016] S, P:

[0017] Sulfur easily forms MnS inclusions with manganese in steel. Phosphorus is generally considered a harmful element and tends to segregate at grain boundaries, reducing steel toughness, increasing intergranular fracture tendency, and negatively impacting fatigue performance. Therefore, the P content should be controlled below 0.020%, and the S content below 0.015%.

[0018] Cr:

[0019] Cr has a strengthening effect and can improve the strength, hardness and wear resistance of steel and can improve the hardenability of spring steel. In the present invention, the Cr element content is controlled at 0.70% to 1.00%.

[0020] The production method of the above-mentioned wire rod for automobile solid stabilizer bar comprises the following specific steps:

[0021] 1. Smelting: Conventional converter smelting + refining outside the furnace, plus VD vacuum degassing process. The vacuum degassing time is greater than 30 minutes to ensure sufficient removal of gas.

[0022] 2. Continuous rolling: The size of the blank after rolling is 160mm×160mm using a secondary annealing process, and local grinding is performed. The continuous rolling heating temperature is 1150~1250℃.

[0023] 3. Heating: The wire heating temperature is 1000-1070℃, and the heating time is 1.5-2h. To ensure the surface quality of the wire rod, the descaling pressure is 18-22MPa.

[0024] 4. Rolling: The finishing rolling temperature is 850-900℃, the double module temperature is 850-900℃, and the wire rod extrusion temperature is controlled at 850-880℃.

[0025] 5. Wire rod cooling: After spinning, the wire rod is air-cooled on an air-cooled roller at a cooling rate of 4 to 6°C / s.

[0026] A method for producing a solid automotive stabilizer bar using the wire rod comprises the following specific steps:

[0027] 1. Preparation of bright silver material: Wire rod is drawn and ground into straight bars. The process is as follows: wire rod - drawing - winding - straightening - cutting - polishing - flaw detection - bundling. Cut lengths range from 1000 to 6000 mm, with a single-side grinding depth of 50 to 100 microns to effectively remove decarburization and surface defects.

[0028] 2. Thermoforming: After the ends are flattened and punched, the thermoforming process is carried out. The ends are heated to 750-800℃ for flattening and punching. Medium frequency induction heating is used at a temperature of 950-1050℃, followed by hot bending.

[0029] 3. Quenching and tempering: adopt residual heat quenching process, quenching temperature 840 ~ 880 ℃, quenching medium is oil, quenching time 3 ~ 8 minutes, quenching oil temperature 90 ℃, tempering heating temperature 460 ~ 500 ℃, tempering holding time 50 ~ 60 minutes.

[0030] 4. Finishing, shot blasting, flaw detection and spraying.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. This invention uses wire rod as the raw material for producing solid stabilizer bars. Compared with hollow stabilizer bars, the solid stabilizer bars produced have the advantages of simpler processing, lower manufacturing costs, more stable product performance, and higher product strength and fatigue life. Compared with solid stabilizer bars made from bar material, the structure and properties are more uniform and stable, and the yield rate is higher.

[0033] 2. This invention controls the microstructure and properties of the wire rod by adding a certain amount of C, Mn, and Cr, leveraging the solid solution strengthening effect of Mn and the enhanced hardenability of the steel. This, combined with a corresponding unique production process, addresses the challenges of large fluctuations in microstructure and properties, high manufacturing costs, and low fatigue life in stabilizer bar springs. This invention utilizes a cost-effective alloy combination design, coupled with controlled rolling and cooling processes, to achieve a microstructure composed of pearlite and proeutectoid ferrite. Appropriate control of the ratio of these two elements optimizes the balance of strength, ductility, and hardness.

[0034] 3. The present invention adopts waste heat quenching process, which saves energy and reduces processing costs.

[0035] The present invention adopts a residual heat quenching process to avoid the waste of resource costs caused by reheating, and obtains a uniform tempered troostite structure and an unorganized and coarse acicular martensite structure in the core. The heat-treated steel wire has excellent strength and surface shrinkage performance. The obtained stabilizer bar has excellent mechanical properties and fatigue properties, and meets the use requirements of automobile stabilizer bars.

[0036] In summary, the present invention utilizes wire rod as the raw material for the stabilizer bar. The resulting solid stabilizer bar boasts a high yield, a simple processing flow, low manufacturing costs, stable product performance, and high strength and fatigue life, effectively meeting automotive requirements. The decarburized layer on the wire rod is less than 0.8%D (where D is the wire rod diameter), the stabilizer bar has a hardness of over 41 HRC, and a fatigue life exceeding 1.2 million cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is the metallographic organization diagram of the present invention. DETAILED DESCRIPTION

[0038] The present invention discloses a wire rod, a production method, and a method for producing a solid automotive stabilizer bar using the same. Those skilled in the art may refer to the contents herein and appropriately modify the process parameters to achieve the desired results. It is particularly important to note that all similar substitutions and modifications obvious to those skilled in the art are considered encompassed by the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel may readily modify or appropriately alter and combine the methods and applications described herein without departing from the content, spirit, and scope of the present invention to implement and apply the technology of the present invention.

[0039] [Example]

[0040] Each embodiment of the present invention is produced according to the following process, and the specific steps are as follows:

[0041] 1. Wire rod production

[0042] (1) Smelting: Conventional converter smelting + refining outside the furnace, plus VD vacuum degassing process. The vacuum degassing time is greater than 30 minutes to ensure sufficient removal of gas.

[0043] (2) Continuous rolling: The two-fire process is used, and the size of the blank after opening is 160×160mm, and a local grinding process is performed. The continuous rolling heating temperature is 1150~1250℃.

[0044] (3) Heating: Wire heating temperature and time: 1000-1070℃, heating time 1.5-2h. To ensure the surface quality of the wire rod, the descaling pressure is 18-22MPa.

[0045] (4) Rolling temperature: finishing rolling temperature is 850℃~900℃, double module temperature is 850℃~900℃, and wire rod extrusion temperature is controlled at 850℃~880℃;

[0046] (5) Wire rod cooling: After spinning, the wire rod is air-cooled on an air-cooled roller at a cooling rate of 4 to 6 °C / s.

[0047] 2. The process of segmented grinding into silver-bright material

[0048] (6) Silver-bright material production involves offline finishing of wire rods. The wire rods are drawn and ground into straight bars. The process is as follows: wire rod production – drawing – winding – straightening – cutting – polishing – flaw detection – bundling. Cutting lengths range from 1000 to 6000 mm, with a single-side grinding depth of 50-100 microns, effectively removing decarburization and surface defects.

[0049] 3. Solid stabilizer bar production

[0050] The steps are: cutting (silver bright material) → end flattening → end punching → hot forming → quenching → tempering → finishing → shot peening → flaw detection → spraying.

[0051] (7) Thermoforming: After the end is flattened and punched, the thermoforming process is carried out. The end is heated to 750-800℃ for flattening and punching. Medium frequency induction heating is used, and the heating temperature is 950-1050℃, and then hot bending is carried out.

[0052] (8) Quenching and tempering: adopt the residual heat quenching process, quenching temperature 840 ~ 880 ℃, quenching medium oil, quenching time 3 ~ 8 min, quenching oil temperature 90 ℃, tempering heating temperature 460 ~ 500 ℃, tempering holding time 50 ~ 60 min.

[0053] (9) Finishing, shot blasting, flaw detection, and spraying.

[0054] The present invention uses wire rod as the raw material of the stabilizer bar. Compared with the hollow stabilizer bar, the solid stabilizer bar produced has the characteristics of high material yield, simple processing flow, low manufacturing cost, stable product performance, high product strength and fatigue life;

[0055] By adding a certain amount of C, Mn and Cr, the stabilizer bar obtained by the present invention has excellent mechanical properties and fatigue properties and meets the use requirements of automobile stabilizer bars.

[0056] The present invention adopts a waste heat quenching process, which saves energy and reduces processing costs.

[0057] The chemical composition (Wt%) of the embodiment of the present invention is shown in Table 1; the key process parameters of the embodiment of the present invention are shown in Table 2; the technical performance of the embodiment of the present invention and the comparative example are shown in Table 3.

[0058] Table 1 Comparative table of chemical compositions of the embodiments of the present invention (wt%)

[0059] Element C Si Mn P S Cr standard 0.51-0.58 0.15-0.38 0.70-1.10 ≤0.020 ≤0.015 0.70-1.10 Example 1 0.54 0.20 0.90 0.010 0.007 0.85 Example 2 0.55 0.22 0.91 0.015 0.006 0.87 Example 3 0.53 0.25 0.89 0.008 0.008 0.88 Example 4 0.52 0.28 0.87 0.011 0.006 0.82

[0060] Table 2 Summary of key process parameters of the embodiments of the present invention

[0061]

[0062] Table 3 Summary of performance and fatigue performance tests of the embodiments of the present invention and comparative examples

[0063]

[0064] It can be seen from Table 1-3 that compared with the hollow stabilizer bar, the stabilizer bar is more stable and has better performance by adding C, Cr and Mn alloys.

[0065] The present invention uses wire rod as the raw material for the stabilizer bar. The resulting solid stabilizer bar boasts a high yield, simple processing, low manufacturing cost, stable product performance, and high strength and fatigue life, effectively meeting automotive requirements. The decarburized layer on the wire rod is less than 0.8%D (where D is the wire rod diameter), the stabilizer bar has a hardness of over 41 HRC, and a fatigue life of over 1.2 million cycles.

[0066] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for producing a solid stabilizer bar for an automobile using a wire rod, characterized in that: The wire rod is composed of the following chemical components in weight percentage: C: 0.51% to 0.58%, Si: 0.15% to 0.38%, Mn: 0.7% to 1.1%, P: ≤ 0.020%, S: ≤ 0.015%, Cr: 0.7% to 1.1%, the balance is Fe and unavoidable impurities; The production method of wire rod specifically comprises the following steps: 1) Smelting: Adopt converter smelting + refining outside the furnace, add VD vacuum degassing process, and the vacuum degassing time is greater than 30 minutes; 2) Continuous rolling: The secondary annealing process is adopted, the size of the blank after opening is (100-200) mm × (100-200) mm, and the continuous rolling heating temperature is 1150-1250℃; 3) Heating: The heating temperature is 1000-1070°C, the heating time is 1.5-2h, and the descaling pressure is 18-22MPa; 4) Rolling: The finishing rolling temperature is 850-900℃, the double module temperature is 850-900℃, and the wire rod extrusion temperature is controlled at 850-880℃; 5) Cooling: Air cooling is performed at a cooling rate of 4 to 6°C / s; The process flow of the method for producing solid stabilizer bars for automobiles using wire rods is blanking → end flattening → end punching → hot forming → quenching → tempering → finishing → shot peening → flaw detection → spraying, which specifically includes the following steps: 6) Cutting The wire rod is drawn and ground into straight strips, with a cutting length of 1000-6000mm and a single-side grinding amount of 50-100μm; 7) Thermoforming The end is heated to 750-800℃ for flattening and punching; medium frequency induction heating is used, the heating temperature is 950-1050℃, and then hot bending is performed; 8) Quenching and tempering The residual heat quenching process is adopted, with a quenching temperature of 840-880°C, a quenching time of 3-8 minutes, a quenching medium temperature of 85-100°C, a tempering heating temperature of 460-500°C, and a tempering holding time of 50-60 minutes; 9) Finishing, shot blasting, flaw detection and spraying.

2. The method for producing a solid automobile stabilizer bar using a wire rod according to claim 1, characterized in that: 2) The size after blanking is 160mm×160mm.

3. The method for producing a solid automobile stabilizer bar using a wire rod according to claim 1, wherein: 5) After spinning, the wire rod is air-cooled on an air-cooling roller.

4. The method for producing a solid automobile stabilizer bar using a wire rod according to claim 1, wherein: 6) In the process of drawing and grinding the wire rod into a straight bar, the steps are: Wire rod - drawing - winding - straightening - cutting - polishing - flaw detection - bundling.

5. The method for producing a solid automobile stabilizer bar using a wire rod according to claim 1, wherein: 8), the quenching medium is oil, and the quenching medium temperature is 90°C.

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