Ultrahigh-strength suspension spring steel wire for new energy vehicle and preparation method therefor

Abstract

Disclosed in the present application are an ultrahigh-strength suspension spring steel wire for a new energy vehicle and a preparation method therefor. The chemical composition of the ultrahigh-strength suspension spring steel wire comprises in mass percentage: C: 0.58%-0.66%, Si: 1.6%-2.0%, Mn: 0.4%-0.8%, Cr: 0.8%-1%, V: 0.10%-0.30%, Mo: 0.05%-0.15%, Nb: 0.01%-0.06%, B: 0.001%-0.003%, P≤0.02% and S≤0.02%. In the present invention, synergistic addition of multiple elements V / Mo / Nb / B is used so as to significantly improve the hardenability of the steel wire, and formation of a precipitated phase inhibits the growth of austenite grains. As an induction heating quenching and tempering process is used, the ultrahigh-strength suspension spring steel wire has a tensile strength of 2050-2150 MPa, and a reduction of area of greater than 40%. The suspension spring steel wire of the present application not only can meet the high strength of coarse-gauge suspension spring steel wires for new energy vehicles, but also has the advantages of high precision of steel wire products and high yield rates of coil springs.

Description

A method for preparing ultra-high strength suspension spring steel wire for new energy vehicles.

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411440134.5, filed on October 15, 2024, entitled "An Ultra-High Strength Suspension Spring Steel Wire for New Energy Vehicles and Its Preparation Method", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the fields of automobile manufacturing and metal materials technology, and more specifically, to an ultra-high strength suspension spring steel wire for new energy vehicles and its preparation method. Background Technology

[0004] With the rapid development of modern science and engineering technology, improving vehicle safety and reliability, reducing environmental pollution, and saving energy have become the pursuit of automakers. To this end, automotive components are rapidly advancing towards higher load capacity, lower pollution, lower energy consumption, and lighter weight. On the other hand, my country's production and sales of new energy vehicles have achieved global leadership, and the requirements for weight reduction, emission reduction, and improved safety are constantly increasing. Among these, chassis weight reduction is crucial; reducing chassis weight by 1 kg is equivalent to reducing vehicle body weight by 10 kg, and the improvement in handling performance and driving range of new energy vehicles is more significant.

[0005] Suspension springs are a key component of a car chassis. Compared to traditional vehicles, the suspension springs in new energy vehicles have a larger diameter and are heavier, making weight reduction even more urgent. The most effective way to reduce spring weight is to increase its strength and design stress. For every 100MPa increase in the allowable stress of a spring, its weight can decrease by about 10%, resulting in a significant weight reduction. Currently, 1900MPa-level suspension springs are widely used, 2000MPa-level suspension springs are gradually being promoted, and the research and industrialization of 2100MPa-level suspension springs and materials is imperative.

[0006] Automotive suspension springs endure high-frequency, high-stress reciprocating compression motions during service, requiring spring materials to achieve high strength while also possessing excellent plasticity, toughness, and fatigue resistance. This involves multiple technical fields, including raw materials, deformation processing, surface treatment, and service life. Furthermore, the large diameter of suspension springs used in new energy vehicles makes it difficult to increase strength levels, or even if strength is increased, it results in a large difference in hardness between the spring surface and the core, and issues such as insufficient plasticity and toughness of the steel wire.

[0007] Therefore, this application is hereby submitted. Summary of the Invention

[0008] The purpose of this application is to provide an ultra-high strength suspension spring steel wire for new energy vehicles and its preparation method. The diameter of the suspension spring steel wire can be ≥15mm, the tensile strength can reach 2050MPa-2150MPa, and the reduction of area is greater than 40%.

[0009] In a first aspect, this application provides an ultra-high strength suspension spring steel wire, the chemical composition of which, by mass percentage, includes: C: 0.58%-0.66%, Si: 1.6%-2.0%, Mn: 0.4%-0.8%, Cr: 0.8%-1%, V: 0.10%-0.30%, Mo: 0.05%-0.15%, Nb: 0.01%-0.06%, B: 0.001%-0.003%, P≤0.02%, S≤0.02%.

[0010] In some optional embodiments, the chemical composition of the above-mentioned ultra-high strength suspension spring steel wire, by mass percentage, includes: C 0.58%-0.66%, Si 1.6%-2.0%, Mn 0.6%-0.8%, Cr 0.8%-1%, V 0.12%-0.20%, Mo 0.1%-0.13%, Nb 0.02%-0.04%, B 0.001%-0.002%, P≤0.01%, S≤0.01%.

[0011] In some optional embodiments, the V+Nb content in the above spring steel wire is >0.15% by mass percentage.

[0012] In some optional embodiments, the V+Mo+B content in the above spring steel wire is >0.2% by mass percentage.

[0013] Secondly, this application provides a method for preparing the above-mentioned ultra-high strength suspension spring steel wire, which includes: melting, refining and hot rolling the spring steel wire raw material in sequence to obtain wire rod; and then cleaning, drawing, heating and quenching, tempering, flaw detection, demagnetization, oiling and packaging to obtain the spring steel wire product.

[0014] In some alternative embodiments, the main microstructure of the wire rod is sorbite, wherein the content of granular carbides and ferrite is less than 10%.

[0015] In some alternative embodiments, the wire rod is obtained by hot rolling after obtaining steel billets through converter and LF+RH ladle refining or EAF electric furnace + VOD refining; the wire rod is cleaned by shot blasting, wherein the steel shot used is high carbon steel wire with a diameter of 1mm-2mm cut into small pieces of 1mm-2mm.

[0016] In some alternative embodiments, heat quenching is performed by heating the temperature to 920°C-980°C.

[0017] In some optional embodiments, the heating method in the heat quenching is a three-stage induction heating of medium frequency + high frequency + medium frequency; the medium frequency heating frequency of the three-stage induction heating of medium frequency + high frequency + medium frequency is 10kHz-15kHz, the high frequency heating frequency is 40kHz-60kHz, and the line speed is 10m / min-30m / min.

[0018] In some optional embodiments, the wiring speed of the three-stage induction heating system (medium frequency + high frequency + medium frequency) is 10m / min-19m / min.

[0019] In some optional embodiments, the first stage of the three-stage induction heating (medium frequency + high frequency + medium frequency) heats the medium frequency to 780℃-800℃ and holds for 5.2s-6.3s, the second stage heats the high frequency to 880℃-910℃ and holds for 3.0s-3.5s, and the third stage heats the medium frequency to the final quenching temperature and holds for 6.1s-7.0s before quenching.

[0020] In some optional embodiments, the quenching method in the heating quenching is annular spray quenching, the quenching medium is water, and the temperature is 25℃-28℃.

[0021] In some optional embodiments, tempering includes: first, tempering the quenched steel wire at a tempering temperature of 510℃-550℃ and a holding time of 10s-15s; then, using annular jet cooling with water as the cooling medium at a temperature of 25℃-28℃.

[0022] Thirdly, this application also provides the application of the above-mentioned ultra-high strength suspension spring steel wire or the ultra-high strength suspension spring steel wire obtained by the above-mentioned preparation method in the field of new energy vehicles. Specifically, the ultra-high strength suspension spring steel wire can be used in the preparation of chassis parts for new energy vehicles.

[0023] Fourthly, this application also provides an automotive suspension system comprising the aforementioned ultra-high strength suspension spring steel wire.

[0024] Fifthly, this application also provides a new energy vehicle, which includes the aforementioned vehicle suspension system.

[0025] This application has the following beneficial effects:

[0026] By optimizing the composition and preparation method of suspension spring steel wire, this application obtains a new type of ultra-high strength suspension spring steel wire for new energy vehicles, with a tensile strength of 2050MPa-2150MPa and a section reduction rate of more than 40%. The suspension spring steel wire of this application not only meets the high strength requirements of coarse-gauge suspension spring steel wire for new energy vehicles, but also has the advantages of high precision of steel wire products and high yield of coiled springs. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] The left side of Figure 1 shows the wire structure obtained in Example 1, and the right side shows the wire structure obtained in Comparative Example 1 (using a two-stage heating method with the same composition).

[0029] The left side of Figure 2 shows the original austenite grains of the steel wire obtained in Example 1, and the right side shows a comparison of the original austenite grains of Comparative Example 6 (existing 55CrSi suspension spring steel wire product). Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0031] This application provides a 2100MPa grade ultra-high strength spring steel wire, the chemical composition of which, by mass percentage, includes: C 0.58%-0.66%, Si 1.6%-2.0%, Mn 0.4%-0.8%, Cr 0.8%-1%, V 0.10%-0.30%, Mo 0.05%-0.15%, Nb 0.01%-0.06%, B 0.001%-0.003%, P≤0.02%, S≤0.02%, with the remainder being Fe and unavoidable impurities.

[0032] To further improve the overall performance of the aforementioned 2100MPa grade ultra-high strength spring steel wire, the chemical composition of the aforementioned 2100MPa grade ultra-high strength spring steel wire, by mass percentage, includes: C 0.59%-0.64%, Si 1.6%-2.0%, Mn 0.6%-0.8%, Cr 0.8%-1%, V 0.12%-0.20%, Mo 0.1%-0.13%, Nb 0.02%-0.04%, B 0.001%-0.002%, P≤0.01%, S≤0.01%, with the remainder being Fe and unavoidable impurities.

[0033] This application optimizes the main components of existing spring steel wire, primarily in the following aspects:

[0034] (1) The carbon content has been increased. Carbon is the main strengthening element in spring steel and significantly affects the strength and toughness of spring steel wire. However, excessive carbon content will lead to high hardness of the quenched structure and increased brittleness of the material. Therefore, the carbon content range of this application is 0.58% to 0.66%.

[0035] (2) The silicon content has been increased. Increased silicon content significantly improves the hardness and strength of steel. Silicon is also an effective deoxidizer, reducing non-metallic inclusions in steel and thus improving its quality. However, excessively high silicon content reduces the material's plasticity and toughness. Therefore, the silicon content range in this application is 1.6% to 2.0%.

[0036] (3) Molybdenum and boron were added in combination. By increasing the silicon content and adding molybdenum and boron, the hardenability of the steel wire can be further improved, and the hardness difference between the core and the edge of the steel wire can be reduced. At the same time, since molybdenum and boron will segregate at the original austenite grain boundaries during the cooling process of austenite, they can improve the strength of the grain boundaries. Therefore, the addition of molybdenum and boron can also improve the strength of the original austenite grain boundaries of the steel wire, and improve the resistance of ultra-high strength spring steel wire to intergranular fracture and hydrogen embrittlement. However, excessive content will lead to coarse carbides and increase the alloy cost of the steel. Therefore, the total content of silicon, molybdenum and boron in this application is >0.2%.

[0037] (4) The addition of niobium and vanadium ensures good plasticity and toughness while maintaining the high strength of the spring steel wire. Specifically, the addition of niobium and vanadium refines the original austenite grains and promotes the formation of dislocation-type martensite, thereby improving the plasticity and toughness of the steel wire. However, excessively high content will increase the alloy cost of the steel. Therefore, the total content of niobium and vanadium in this application is >0.15%.

[0038] This application also provides a method for preparing the above-mentioned 2100MPa grade ultra-high strength spring steel wire, including the following steps:

[0039] S1. Prepare the feedstock according to the chemical composition of the 2100MPa grade ultra-high strength spring steel wire mentioned above.

[0040] S2. Steel billets are obtained by converter and LF+RH ladle refining or EAF electric furnace + VOD refining, and then hot rolling is used to obtain wire rods.

[0041] S3. Cool the wire rod.

[0042] The wire rod obtained in this application has a sorbitic microstructure, with granular carbides and ferrite content of less than 10%. If the content of granular carbides and ferrite is greater than 10%, the granular pearlite and ferrite will lead to uneven microstructure of the steel wire after quenching, reducing the plasticity and toughness of the material.

[0043] S4. Use a shot blasting machine for cleaning and rust removal.

[0044] In this application, the steel shot used for shot blasting is high carbon steel wire with a diameter of 1mm-2mm cut into small pieces of 1mm-2mm.

[0045] S5. Drawing, followed by online induction heating quenching and tempering technology to heat treat the steel wire. Specifically, it is heated to 920℃-980℃ through a three-stage induction heating process of medium frequency + high frequency + medium frequency, and then quenched. Among these methods, medium frequency heating ensures uniform heating of the steel wire, while high frequency heating results in a faster temperature rise. Under these conditions, steel wire with uniform structure and hardness can be obtained.

[0046] The intermediate frequency heating frequency is 10kHz-15kHz, the high frequency heating frequency is 40kHz-60kHz, and the trace speed is 10m / min-30m / min. More preferably, the trace speed is 10m / min-19m / min. This range of trace speeds ensures sufficient dissolution of carbides, reduces the content of retained austenite, and achieves higher toughness.

[0047] The first stage involves medium-frequency heating to 780℃-800℃, held for 5.2s-6.3s, followed by high-frequency heating to 880℃-910℃, held for 3.0s-3.5s, and then medium-frequency heating to the final quenching temperature, held for 6.1s-7.0s before quenching. The quenching method is annular spray quenching, the quenching medium is water, and the temperature is 25℃-28℃.

[0048] S6. After quenching, tempering and cooling are performed.

[0049] The tempering temperature is 510℃-550℃, and the holding time is 10s-15s. Then, annular jet cooling is used, with water as the cooling medium and a temperature of 25℃-28℃.

[0050] S7. After tempering, the steel wire undergoes flaw detection, demagnetization, oiling, and packaging.

[0051] This application employs a synergistic addition of V / Mo / Nb / B elements to significantly improve the hardenability of the steel wire, while simultaneously forming precipitates that inhibit austenite grain growth. After induction heating quenching and tempering, the ultra-high strength suspension spring steel wire can achieve a diameter greater than or equal to 15mm, a tensile strength of 2050MPa-2150MPa, and a reduction of area greater than 40%. This process achieves coarse-gauge spring steel wire while ensuring high strength, good plasticity, and toughness.

[0052] Because the suspension springs for new energy vehicles require higher strength, and the spring steel wire provided in this application possesses high strength as well as good plasticity and toughness, it can be applied in the field of new energy vehicles. Specifically, this ultra-high strength suspension spring steel wire can be used in the manufacture of automotive suspension systems for new energy vehicles. Based on this, this application can also provide an automotive suspension system that includes the aforementioned ultra-high strength suspension spring steel wire.

[0053] Based on the above-mentioned vehicle suspension system, this application can also provide a new energy vehicle that includes the above-mentioned vehicle suspension system.

[0054] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0055] Example 1

[0056] The chemical composition of the spring steel wire prepared in this embodiment, by weight percentage, is as follows:

[0057] The specific steps of its preparation method are as follows:

[0058] A: The spring steel wire is batched according to the above chemical composition, then refined in a converter and LF+RH ladle to obtain steel billets, and then rolled to obtain wire rods.

[0059] B: After cooling, the wire rods have a structure mainly composed of sorbite.

[0060] C: Rust removal is performed using a shot blasting machine. The steel shot used is high carbon steel wire with a diameter of 1.2mm cut into small pieces of 1mm.

[0061] D: The diameter after drawing is 16mm, and then it is heated to 940℃ through a three-stage induction heating process of medium frequency + high frequency + medium frequency. The medium frequency heating frequency is 12kHz, the high frequency heating frequency is 50kHz, and the trace speed is 15m / min.

[0062] The first stage involves medium-frequency heating to 790℃ and holding for 6 seconds. The second stage involves high-frequency heating to 900℃ and holding for 3.2 seconds. The third stage involves medium-frequency heating to the final quenching temperature and holding for 6.7 seconds before quenching. The quenching method is annular spray quenching, the quenching medium is water, and the temperature is 26℃.

[0063] E: The tempering temperature of the quenched steel wire is 520℃, and the holding time is 12s. Then, annular jet cooling is used, with water as the cooling medium and a temperature of 25℃.

[0064] F: After tempering, the steel wire undergoes flaw detection, demagnetization, oiling, and packaging.

[0065] The tensile properties of the steel wire were tested according to standard GB / T228.1-2010, with an extensometer gauge length of 25 mm. The tensile strength of the steel wire was measured to be 2090 MPa, the reduction of area was 44%, and the elongation was 9.0%.

[0066] Example 2

[0067] The chemical composition of the spring steel wire prepared in this embodiment, by weight percentage, is as follows:

[0068] The specific steps of its preparation method are as follows:

[0069] A: The spring steel wire is batched according to the above chemical composition, then refined in a converter and LF+RH ladle to obtain steel billets, and then rolled to obtain wire rods.

[0070] B: After cooling, the wire rods have a structure mainly composed of sorbite.

[0071] C: Rust removal is performed using a shot blasting machine. The steel shot used is high carbon steel wire with a diameter of 1.2mm cut into small pieces of 1mm.

[0072] D: The diameter after drawing is 16mm, and then it is heated to 950℃ through a three-stage induction heating process of medium frequency + high frequency + medium frequency. The medium frequency heating frequency is 12kHz, the high frequency heating frequency is 50kHz, and the trace speed is 14m / min.

[0073] The first stage involves medium-frequency heating to 770℃ and holding for 6 seconds. The second stage involves high-frequency heating to 920℃ and holding for 3.2 seconds. The third stage involves medium-frequency heating to the final quenching temperature and holding for 6.7 seconds before quenching. The quenching method is annular spray quenching, the quenching medium is water, and the temperature is 25℃.

[0074] E: Then, ring-shaped jet cooling is used, with water as the cooling medium and a temperature of 25°C.

[0075] F: After tempering, the steel wire undergoes flaw detection, demagnetization, oiling, and packaging.

[0076] The tensile properties of the steel wire were tested according to standard GB / T228.1-2010, with an extensometer gauge length of 25 mm. The tensile strength of the steel wire was measured to be 2110 MPa, the reduction of area was 46%, and the elongation was 9.8%.

[0077] Example 3

[0078] The chemical composition of the spring steel wire prepared in this embodiment, by weight percentage, is as follows:

[0079] The specific steps of its preparation method are as follows:

[0080] A: The spring steel wire is prepared according to the above chemical composition, then refined in an EAF electric furnace + VOD to obtain steel billets, and then rolled to obtain wire rods.

[0081] B: After cooling, the wire rods have a structure mainly composed of sorbite.

[0082] C: Rust removal is performed using a shot blasting machine. The steel shot used is high carbon steel wire with a diameter of 1.2mm cut into small pieces of 1mm.

[0083] D: The diameter after drawing is 16mm, and then it is heated to 950℃ by a three-stage induction heating method of medium frequency + high frequency + medium frequency. The medium frequency heating frequency is 12kHz, the high frequency heating frequency is 50kHz, and the trace speed is 15m / min.

[0084] The first stage involves medium-frequency heating to 780℃ and holding for 6 seconds. The second stage involves high-frequency heating to 900℃ and holding for 3.2 seconds. The third stage involves medium-frequency heating to the final quenching temperature and holding for 6.7 seconds before quenching. The quenching method is annular spray quenching, the quenching medium is water, and the temperature is 26℃.

[0085] E: The tempering temperature of the quenched steel wire is 510℃, and the holding time is 12s. Then, annular jet cooling is used, with water as the cooling medium and a temperature of 25℃.

[0086] F: After tempering, the steel wire undergoes flaw detection, demagnetization, oiling, and packaging.

[0087] The tensile properties of the steel wire were tested according to standard GB / T228.1-2010, with an extensometer gauge length of 25 mm. The experimentally measured tensile strength of the steel wire was 2090 MPa, the reduction of area was 45%, and the elongation was 9.4%.

[0088] Example 4

[0089] The chemical composition of the spring steel wire prepared in this embodiment, by weight percentage, is as follows:

[0090] The specific steps of its preparation method are as follows:

[0091] A: The spring steel wire is prepared according to the above chemical composition, then refined in an EAF electric furnace + VOD to obtain steel billets, and then rolled to obtain wire rods.

[0092] B: After cooling, the wire rods have a structure mainly composed of sorbite.

[0093] C: Rust removal is performed using a shot blasting machine. The steel shot used is high carbon steel wire with a diameter of 1.2mm cut into small pieces of 1mm.

[0094] D: The diameter after drawing is 18mm, and then it is heated to 940℃ by a three-stage induction heating method of medium frequency + high frequency + medium frequency. The medium frequency heating frequency is 10kHz, the high frequency heating frequency is 46kHz, and the trace speed is 15m / min.

[0095] The first stage involves medium-frequency heating to 780℃ and holding for 6 seconds. The second stage involves high-frequency heating to 910℃ and holding for 3.2 seconds. The third stage involves medium-frequency heating to the final quenching temperature and holding for 6.7 seconds before quenching. The quenching method is annular spray quenching, the quenching medium is water, and the temperature is 25℃.

[0096] E: The tempering temperature of the quenched steel wire is 540℃, and the holding time is 12s. Then, annular jet cooling is used, with water as the cooling medium and a temperature of 25℃.

[0097] F: After tempering, the steel wire undergoes flaw detection, demagnetization, oiling, and packaging.

[0098] The tensile properties of the steel wire were tested according to standard GB / T228.1-2010, with an extensometer gauge length of 25 mm. The experimentally measured tensile strength of the steel wire was 2070 MPa, the reduction of area was 46%, and the elongation was 9.7%.

[0099] Comparative Example 1

[0100] The difference from Example 1 is that, during the quenching heating process, a two-stage heating method of high frequency + medium frequency is used instead of a three-stage heating method of medium frequency + high frequency + medium frequency.

[0101] The experiment was conducted according to standard GB / T228.1-2010, with an extensometer gauge length of 25 mm. The tensile strength of the steel wire was measured to be 1990 MPa, the reduction of area was 36%, and the elongation was 8.3%.

[0102] As shown in Figure 1, the left figure is the spring steel wire obtained in Example 1, and the right figure is the spring steel wire obtained in this comparative example. Compared with the two, the steel wire obtained in Example 1 does not contain carbides in its structure, while a large amount of undissolved carbides can be observed in the steel wire structure of Comparative Example 1.

[0103] Comparative Example 2

[0104] The difference from Example 1 is that the wire speed is different, and a wire speed of 50m / min is used.

[0105] The experiment was conducted according to standard GB / T228.1-2010, with an extensometer gauge length of 25 mm. The tensile strength of the steel wire was measured to be 2095 MPa, the reduction of area was 34%, and the elongation was 8.1%.

[0106] Comparative Example 3

[0107] The difference from Example 1 is that the wire speed is different, and a wire speed of 50m / min is used.

[0108] The experiment was conducted according to standard GB / T228.1-2010, with an extensometer gauge length of 25 mm. The tensile strength of the steel wire was measured to be 2095 MPa, the reduction of area was 34%, and the elongation was 8.1%.

[0109] Comparative Example 4

[0110] The difference from Example 1 is that the quenching temperature is 1000℃.

[0111] The experiment was conducted according to standard GB / T228.1-2010, with an extensometer gauge length of 25 mm. The tensile strength of the steel wire was measured to be 1880 MPa, the reduction of area was 24%, and the elongation was 4.1%.

[0112] Comparative Example 5

[0113] The difference from Example 1 is that the tempering temperature of the steel wire is 600°C.

[0114] The experiment was conducted according to standard GB / T228.1-2010, with an extensometer gauge length of 25 mm. The tensile strength of the steel wire was measured to be 1900 MPa, the reduction of area was 42%, and the elongation was 8.1%.

[0115] Comparative Example 6

[0116] The comparison is made with commercial 55CrSi spring steel wire with a diameter of 12 mm, whose composition by weight percentage is shown in the table below:

[0117] The experiment was conducted according to standard GB / T228.1-2010, with an extensometer gauge length of 25 mm. The tensile strength of the steel wire was measured to be 1920 MPa, the reduction of area was 40%, and the elongation was 9.9%.

[0118] As shown in Figure 2: the left figure is the spring steel wire obtained in Example 1, and the right figure is the spring steel wire obtained in this comparative example. Compared with the comparative example, the original austenite grain size of the steel wire obtained in Example 1 is much smaller.

[0119] Comparative Example 7

[0120] The comparison is made with commercially available 65Si2CrV spring steel wire with a diameter of 11 mm, whose composition by weight percentage is shown in the table below:

[0121] The experiment was conducted according to standard GB / T228.1-2010, with an extensometer gauge length of 25 mm. The tensile strength of the steel wire was measured to be 2080 MPa, the reduction of area was 39%, and the elongation was 7.8%.

[0122] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. Industrial applicability

[0123] The ultra-high strength suspension spring steel wire provided in this application has a tensile strength of 2050-2150 MPa and a reduction of area greater than 40%. It not only meets the high strength requirements of coarse-gauge suspension spring steel wire for new energy vehicles but also boasts advantages such as high wire precision and high yield of coiled springs. Therefore, this ultra-high strength suspension spring steel wire possesses excellent practical performance and broad market application prospects.

Claims

1. An ultra-high strength suspension spring wire, characterized by, Its chemical composition, by mass percentage, includes: C 0.58%-0.66%, Si 1.6%-2.0%, Mn 0.4%-0.8%, Cr 0.8%-1%, V 0.10%-0.30%, Mo 0.05%-0.15%, Nb 0.01%-0.06%, B 0.001%-0.003%, P≤0.02%, and S≤0.02%.

2. The ultra-high strength suspension spring wire of claim 1 wherein, Its chemical composition, by mass percentage, includes: C 0.58%-0.66%, Si 1.6%-2.0%, Mn 0.6%-0.8%, Cr 0.8%-1%, V 0.12%-0.20%, Mo 0.1%-0.13%, Nb 0.02%-0.04%, B 0.001%-0.002%, P≤0.01%, S≤0.01%.

3. The ultra-high strength suspension spring wire of claim 1 or 2, wherein, The V+Nb content in the spring steel wire is >0.15% by mass percentage.

4. The ultra-high strength suspension spring wire of claim 1 or 2, wherein, The content of V+Mo+B in the spring steel wire is >0.2% by mass percentage.

5. The method of producing an ultra-high strength suspension spring wire according to any one of claims 1 to 4, wherein the wire rod is heated to a temperature of 1,100 to 1,200°C and is then cold-drawn to a diameter of 5 to 8 mm. include: The spring steel wire raw material is smelted, refined and hot rolled in sequence to obtain wire rod; then it is cleaned, drawn, heated and quenched, tempered, inspected for flaws, demagnetized, oiled and packaged to obtain the spring steel wire product.

6. The production method according to claim 5, wherein The main microstructure of the wire rod is sorbite, wherein the content of granular carbides and ferrite is less than 10%.

7. The production method according to claim 6, wherein The wire rod is obtained by hot rolling after steel billet is obtained through converter and LF+RH ladle refining or EAF electric furnace + VOD refining. The wire rod is cleaned using a shot blasting machine, where the steel shot used is high carbon steel wire with a diameter of 1mm-2mm cut into small pieces of 1mm-2mm.

8. The preparation method according to claim 5, characterized in that, The heating and quenching process involves heating the material to 920℃-980℃ before quenching.

9. The production method according to claim 8, characterized by, The heating method in the heating and quenching process is a three-stage induction heating system consisting of medium frequency + high frequency + medium frequency. The intermediate frequency heating frequency of the three-stage induction heating system (intermediate frequency + high frequency + intermediate frequency) is 10kHz-15kHz, the high frequency heating frequency is 40kHz-60kHz, and the wiring speed is 10m / min-30m / min.

10. The method of claim 9, wherein, The wiring speed of the three-stage induction heating system (medium frequency + high frequency + medium frequency) is 10m / min-19m / min.

11. The method of claim 10, wherein, The three-stage induction heating system (medium frequency + high frequency + medium frequency) first stage heats the medium frequency to 780℃-800℃ and holds for 5.2s-6.3s, then the second stage heats the high frequency to 880℃-910℃ and holds for 3.0s-3.5s, and finally the third stage heats the medium frequency to the final quenching temperature and holds for 6.1s-7.0s before quenching.

12. The method of claim 5, wherein, The quenching method in the heating and quenching process is annular spray quenching, the quenching medium is water, and the temperature is 25℃-28℃.

13. The preparation method according to claim 5, characterized in that, The tempering process includes: first, tempering the quenched steel wire at a temperature of 510℃-550℃ and holding it for 10s-15s; then, using annular jet cooling with water as the cooling medium at a temperature of 25℃-28℃.

14. Use of the ultra-high strength suspension spring steel wire according to any one of claims 1 to 4 or the ultra-high strength suspension spring steel wire obtained by the manufacturing method according to any one of claims 5 to 13 in the field of new energy vehicles.

15. An automotive suspension system characterized by, The ultra-high strength suspension spring steel wire according to any one of claims 1 to 4.

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