Manufacturing method of ultra-high strength wheel rims

Abstract

This application discloses a method for manufacturing an ultra-high strength wheel rim. The method includes: pre-treatment of steel coil raw material to obtain a material to be welded; the surface roughness of the four sides of the material to be welded reaches Ra3.2; pre-forming treatment of the material to be welded to obtain a steel rim to be welded; the misalignment of the steel rim to be welded is ±0.1 times the plate thickness; welding treatment of the steel rim to be welded to obtain a welded steel rim; scraping the weld of the welded steel rim to obtain a steel rim retaining weld reinforcement, the weld reinforcement being 0.1mm to 0.3mm; performing post-weld normalizing heat treatment on both sides of the weld of the steel rim retaining weld reinforcement; flaring and spinning the steel rim after post-weld normalizing heat treatment to obtain a hot-formed steel rim; and performing quenching and tempering heat treatment on the formed steel rim to obtain an ultra-high strength wheel rim. The manufacturing method of ultra-high strength wheel rim can improve the weld structure, reduce welding residual stress, give the weld good toughness, reduce the probability of weld cracking, and obtain an ultra-high strength wheel rim.

Description

Technical Field

[0001] This application belongs to the field of wheel manufacturing technology, and in particular relates to a method for manufacturing an ultra-high strength wheel rim. Background Technology

[0002] Aluminum alloys are currently the primary material for lightweight wheels due to their excellent formability and light weight. However, because aluminum alloys have high production costs, significant environmental pollution, low hardness, poor wear resistance and high-temperature resistance, and limited strength improvement, lightweight wheel materials are gradually transitioning to steel materials, such as ultra-high strength hot-formed steel 1500. Hot-formed steel 1500 has a low yield strength ratio and good formability before heat treatment, and high strength and toughness after heat treatment, making it an ideal material for lightweight wheel manufacturing.

[0003] However, due to the high carbon equivalent of hot-formed steel and its strong tendency to harden, if the welding cooling rate is fast, the weld structure is prone to hardness and brittleness. During the wheel expansion and forming processes after the steel rim is welded, the weld is prone to cracking. Summary of the Invention

[0004] This application provides a method for manufacturing ultra-high strength wheel steel rims, which can improve weld structure, reduce welding residual stress, enable the weld to obtain good toughness, and reduce the probability of weld cracking.

[0005] In a first aspect, this application provides a method for manufacturing an ultra-high strength wheel rim, comprising:

[0006] The steel coil raw material is subjected to pre-welding treatment to obtain the material to be welded; the surface roughness of the four sides of the material to be welded reaches Ra3.2;

[0007] The material to be welded is pre-formed to obtain a steel ring to be welded; the misalignment of the steel ring to be welded is ±0.1 times the plate thickness;

[0008] The steel ring to be welded is then welded to obtain a welded steel ring;

[0009] The weld seam of the welded steel ring is scraped smooth to obtain a steel ring with a weld seam allowance of 0.1mm to 0.3mm.

[0010] Post-weld normalizing heat treatment is performed on both sides of the weld area of ​​the steel ring with retained weld reinforcement.

[0011] The steel ring that has undergone post-weld normalizing heat treatment is flared and spun to obtain a hot-formed steel ring.

[0012] The hot-formed steel rim is subjected to quenching and tempering heat treatment to obtain an ultra-high strength wheel rim.

[0013] According to one embodiment of this application, pre-welding treatment of steel coil raw materials includes:

[0014] The steel coil raw material is leveled and laser-cut to obtain flat strips; wherein the difference between the diagonals of the flat strips is ≤0.5mm;

[0015] The four sides of the flat strip are ground to achieve a surface roughness of Ra3.2, thus obtaining the material to be welded.

[0016] According to one aspect of the embodiments of this application, preforming the material to be welded includes:

[0017] The material to be welded is rolled into a round shape to obtain a steel ring to be welded.

[0018] According to one embodiment of this application, the welding process for the steel ring to be welded includes:

[0019] Resistance welding equipment with a welding power of 1500VA to 2400VA is used to perform resistance welding on the gaps of the steel ring to be welded in order to obtain a welded steel ring; wherein, the power-off and pressure holding time of resistance welding is 0.5 seconds to 1.5 seconds.

[0020] According to one embodiment of this application, post-weld normalizing heat treatment of the weld sides of the steel ring with retained weld reinforcement includes:

[0021] The weld areas on both sides of the steel ring with retained weld reinforcement are heated and held at 800℃~900℃ for 5 seconds~10 seconds.

[0022] After the insulation is completed, the steel ring is air-cooled.

[0023] According to one embodiment of this application, the flaring and spinning process of a steel ring that has undergone post-weld normalizing heat treatment includes:

[0024] The steel rim that has undergone post-weld normalizing heat treatment is flared using a rim-expanding device to obtain a steel rim with the outer contour of a wheel.

[0025] A hot-formed steel rim is obtained by spinning a steel rim with a wheel outline using a spinning equipment.

[0026] According to one embodiment of this application, the tempering heat treatment of the formed steel ring includes:

[0027] Under the clamping of the mold, the hot-formed steel ring is heated to 850℃~950℃ and held for 3 minutes~8 minutes;

[0028] The hot-formed steel rim, after being heated and kept warm, is quenched and then tempered at 200℃ to 400℃ for 20 to 40 minutes to obtain an ultra-high strength wheel rim with a tensile strength of 1GPa to 1.5GPa.

[0029] According to one embodiment of this application, the method for manufacturing ultra-high strength wheel rims further includes:

[0030] Wheel load fatigue tests were conducted on ultra-high strength wheel rims to obtain ultra-high strength wheel rims with qualified comprehensive mechanical properties.

[0031] According to one embodiment of this application, the method for manufacturing ultra-high strength wheel rims further includes:

[0032] The ultra-high strength wheel rim is descaled to remove iron oxides from it, resulting in a descaled ultra-high strength wheel rim.

[0033] According to one embodiment of this application, the method for manufacturing ultra-high strength wheel rims further includes:

[0034] The ultra-high strength wheel rims with scales removed are coated to form a protective coating on their outer surface.

[0035] The method for manufacturing ultra-high strength wheel rims according to embodiments of this application involves pre-welding treatment of the steel coil raw material to reduce the impact of the edge quality of the material to be welded on the welding quality, and pre-forming treatment of the material to be welded to reduce the misalignment of the hot-formed steel at the welding site and the circumferential stress difference of the rim. Furthermore, by retaining a certain weld reinforcement height during the scraping process of the weld seam of the welded rim, the cooling rate of the weld seam is reduced and the cooling time is extended. This, together with the post-weld normalizing heat treatment of the weld seam areas on both sides of the rim with retained weld reinforcement height, achieves the effect of refining the weld seam grain, improving the weld seam structure, reducing residual stress and cracking probability. Finally, the hot-formed steel rim is subjected to quenching and tempering heat treatment to manufacture ultra-high strength wheel rims. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic flowchart of a method for manufacturing an ultra-high strength wheel rim according to an embodiment of this application.

[0038] Figure 2This is a schematic diagram of the longitudinal cracks generated at both ends of the weld along the length direction during the flaring process of the steel ring provided in this application.

[0039] Figure 3 This is a schematic diagram of the cross-section of an ultra-high strength wheel rim passing through the center.

[0040] Figure 4 yes Figure 3 The enlarged view of local structure A in the figure is a schematic diagram of the weld's limit R-angle bending segment in the spinning forming process provided in this application.

[0041] Figure 5 This is a schematic diagram of the transverse cracks that occur in the weld limit R-angle bending section of the steel ring provided in this application during the spinning process.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Steel rim base material, i.e. the unwelded part of the steel rim to be welded; 2. Weld between steel rim base materials; 3. Longitudinal crack; 4. Transverse crack; 5. Weld radius (R-angle); 6. Weld limit radius (R-angle); 7. Ultra-high strength wheel rim; W, weld width direction; L, weld length direction. Detailed Implementation

[0044] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0045] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0046] As mentioned in the background section, hot-formed steel 1500 is prone to weld cracking during the expansion and forming process.

[0047] To address the problems of the prior art, this application provides a method for manufacturing ultra-high strength wheel rims. The method for manufacturing ultra-high strength wheel rims provided in this application will be described below. Figure 1 A schematic flowchart of a method for manufacturing an ultra-high strength wheel rim according to an embodiment of this application is shown.

[0048] like Figure 1 As shown, the manufacturing method of ultra-high strength wheel rims includes:

[0049] S1. The steel coil raw material is subjected to pre-welding treatment to obtain the material to be welded; the surface roughness of the four sides of the material to be welded reaches Ra3.2;

[0050] S2. The steel coil raw material is pre-formed to obtain a steel ring to be welded; the misalignment of the steel ring to be welded is ±0.1 times the plate thickness;

[0051] S3. Weld the steel ring to be welded to obtain a welded steel ring;

[0052] S4. The weld seam of the welded steel ring is scraped smooth to obtain a steel ring with a weld seam allowance of 0.1mm to 0.3mm.

[0053] S5. Perform post-weld normalizing heat treatment on both sides of the weld area of ​​the steel ring with retained weld reinforcement.

[0054] S6. After the steel ring has undergone post-weld normalizing heat treatment, it is flared and spun to obtain a hot-formed steel ring.

[0055] S7. The hot-formed steel rim is subjected to quenching and tempering heat treatment to obtain an ultra-high strength wheel rim.

[0056] The method for manufacturing ultra-high strength wheel rims according to embodiments of this application reduces the impact of edge quality of the material to be welded on the welding quality by pre-treatment of the steel coil raw material; reduces the misalignment of the hot-formed steel at the welding site and the circumferential stress difference of the steel rim by pre-forming the material to be welded; further, retains a certain weld reinforcement height when scraping the weld of the welded rim to reduce the cooling rate of the weld and extend the cooling time; together with the post-weld normalizing heat treatment of the weld areas on both sides of the steel rim with retained weld reinforcement height, the method achieves the effect of refining the weld grain, improving the weld structure, reducing residual stress and cracking probability; finally, the hot-formed steel rim is subjected to quenching and tempering heat treatment to obtain ultra-high strength wheel rims.

[0057] In the embodiments of this application, steel with a tensile strength of 600MPa to 750MPa is used as the base material to manufacture ultra-high strength wheel rims. The steel is hot-formed steel that has undergone hot rolling and cold rolling treatment, and the thickness of the base material is 3mm to 5mm.

[0058] In the process of improving existing aluminum alloy wheels, the applicant of this application discovered that hot-formed steel 1500 is more sensitive to defects during welding than aluminum alloy wheels, especially the edge quality of the flat material to be welded, such as burrs and straightness. Therefore, before the welding process of hot-formed steel 1500, the material to be welded is pre-treated, such as grinding the burrs on the four sides of the flat steel coil raw material to ensure that the surface roughness of the four sides reaches the Ra3.2 level.

[0059] In some embodiments of this application, pre-welding treatment of steel coil raw materials includes:

[0060] S101. The steel coil raw material is leveled and laser-cut to obtain flat strips; wherein the difference between the diagonals of the flat strips is ≤0.5mm;

[0061] S102. Grind the four sides of the flat strip to achieve a surface roughness of Ra3.2, thus obtaining the material to be welded.

[0062] In the embodiments of this application, the difference between the diagonals of the flat strip refers to the difference between the two diagonals of a rectangular flat strip, and the difference is ≤0.5mm. Using laser cutting can prevent edge cracking of the flat strip and reduce the impact of poor edge quality of the steel coil raw material on welding quality.

[0063] The main purpose of imposing high requirements on the edge quality of the four sides of the flat strip after cutting is to: prevent the edge quality of the two short sides to be welded on the steel ring after preforming from affecting the internal quality of the resistance weld, and prevent welding defects such as slag inclusions, residual oxides in the burnt hole that cannot be cleaned, and incomplete welding; and to reduce the impact of the edge quality of the two long sides that are not welded on the cracking rate during wheel processing and forming, and prevent crack propagation caused by burrs and microcracks on the edge of the flat strip during the flaring and spinning drawing processes.

[0064] In some embodiments of this application, the grinding process of the flat strip material further includes:

[0065] The four sides of the flat strip are transitioned with a radius of R≤1mm.

[0066] In some embodiments of this application, preforming the material to be welded includes:

[0067] The material to be welded is rolled into a round shape to obtain a steel ring to be welded; the misalignment of the steel ring to be welded is ±0.1 times the plate thickness.

[0068] In the embodiments of this application, the applicant discovered that: due to the higher strength of hot-formed steel 1500, it is more difficult to process and has a larger rebound angle. In order to reduce the misalignment of hot-formed steel 1500 at the welding site and the circumferential stress difference of the steel ring to be welded, compared with the pre-welding process of aluminum alloy wheels, it is necessary to add one or more pre-forming reciprocating roll bending before welding, so that the material to be welded is rolled into a cylindrical steel ring with a gap to be welded, thereby reducing the misalignment of hot-formed steel 1500 at the welding site. The steel ring to be welded has a gap to be welded, wherein the misalignment of the material to be welded at both ends of the gap to be welded is more suitable to be controlled within ±0.1 times the plate thickness. Here, the misalignment refers to the height difference of the base material on both sides of the gap of the steel ring to be welded, and the misalignment of ±0.1 times the plate thickness means that the height difference of the base material on both sides is less than 0.1 times the plate thickness; the circumferential stress difference of the steel ring refers to the stress imbalance during one rolling due to the strength fluctuation of the base material, which will cause spiral deformation and roundness tolerance. For example, the material to be welded is subjected to a rolling process, also known as rolling, which can be rolled 1, 2, 3, 4, or 5 times.

[0069] In some embodiments of this application, the welding process for the steel ring to be welded includes:

[0070] Resistance welding equipment with a welding power of 1500VA to 2400VA is used to perform resistance welding on the gap of the steel ring to be welded in order to obtain a welded steel ring; wherein, the power-off and pressure holding time of the resistance welding parameters is 0.5 seconds to 1.5 seconds.

[0071] In improving the existing technical solution, the applicant of this application discovered that the highest temperature of the molten metal during welding causes a change in the microstructure of the steel, transforming it from bainitic to martensitic, resulting in an excessively large hardness difference in the weld cross-section, which fails to meet requirements. Therefore, in the embodiments of this application, to reduce the residence time of the molten metal at its highest temperature and decrease the heat-affected zone width, this application employs resistance welding to weld the gap of the steel ring to be welded, and selects relatively hard welding parameters, wherein the welding power is 1500VA~2400VA. The requirement for the power of the resistance welding machine is mainly to achieve a hard process specification of using high current and short welding time during welding, reducing the residence time of the molten metal in the weld, and reducing the formation of hardened microstructure.

[0072] The applicant discovered that high-strength materials experience significant residual stress due to post-weld thermal shrinkage and phase transformation in the weld microstructure. Therefore, it is necessary to actively apply pressure to the weld joint to reduce the residual tensile stress caused by thermal shrinkage and phase transformation, preventing the superposition of residual tensile stress with tensile stress during subsequent cold working, which could lead to crack formation. In the embodiments of this application, to reduce the welding stress difference of the weld joint, the power-off holding time of the resistance welding parameters is set to 0.5 to 1.5 seconds. That is, after the welding power is cut off, the hydraulic upsetting force applied to the welding position remains unchanged and is maintained for 0.5 to 1.5 seconds. The weld joint is a structure including the weld microstructure and the substrate region connected to the weld microstructure. The hardened welding parameters, also known as the resistance welding hard specification, refer to the resistance welding process specification with high current and short welding time. The welding stress difference refers to the difference between the stresses in the weld region caused by the different expansion rates of bainite and martensite formed between the ferrite and pearlite of the substrate and the weld microstructure during the welding process.

[0073] In the embodiments of this application, weld reinforcement refers to the height of the base metal surface from the top of the weld. Reducing the amount of weld reinforcement scraped off, i.e., retaining a certain amount of weld reinforcement, helps to prolong the cooling time, thereby reducing the cooling rate of the weld and improving the weld microstructure. However, excessive weld reinforcement can exacerbate stress concentration at the weld edge, causing weld cracking. Therefore, controlling the weld reinforcement to 0.1mm to 0.3mm is more suitable. The weld reinforcement is not scraped off in subsequent steps; after post-weld normalizing heat treatment, flaring, and spinning, the weld reinforcement tends to be consistent with the steel surface.

[0074] In some embodiments of this application, post-weld normalizing heat treatment of the weld sides of the steel ring with retained weld reinforcement includes:

[0075] S501. The weld areas on both sides of the steel ring with retained weld reinforcement shall be heated and kept at 800℃~900℃ for 5 seconds~10 seconds.

[0076] S502. After the insulation is completed, the steel ring is air-cooled.

[0077] In some embodiments of this application, a medium-frequency induction normalizing device is used to perform post-weld normalizing heat treatment on both sides of the weld of the steel ring with retained weld reinforcement at 800°C to 900°C.

[0078] In the embodiments of this application, the weld areas on both sides of the steel ring with retained weld reinforcement are subjected to post-weld normalizing heat treatment at 800℃~900℃ to refine the grain size of the weld structure, improve the weld microstructure, reduce residual stress in the weld, and simultaneously reduce the hardness difference between different areas of the weld and the substrate. Figure 2As shown, the two ends of the weld along its length cool quickly and have high hardness. Post-weld normalizing heat treatment of the weld sides of the steel ring retaining weld reinforcement can reduce the hardness difference between the two ends of the weld along its length L and the substrate, preventing longitudinal cracking at both ends of the weld along its length during the flaring process, thus preventing the formation of longitudinal cracks 3. Simultaneously, as... Figure 3 , Figure 4 , Figure 5 As shown, the limiting R-angle 6, i.e., the bending radius R value of the hot-formed steel ring after spinning, is close to the upper limit of the bending performance allowed by the steel coil raw material, which easily leads to circumferential cracks in the steel ring and transverse cracks 4 in the weld. Post-weld normalizing heat treatment at 800℃~900℃ is performed on both sides of the weld of the steel ring with retained weld reinforcement. This reduces the hardness difference between different parts of the weld 2 (head, middle, and tail) caused by different cooling rates along the weld length L, and prevents the generation of transverse cracks 4 along the weld width W in the bending section of the weld with the limiting R-angle 6 during the spinning process. After the post-weld normalizing heat treatment and holding period, the steel ring is air-cooled to room temperature (20℃~30℃).

[0079] In the embodiments of this application, a medium-frequency induction normalizing device is used to heat the weld seam of the welded steel ring to 800°C–900°C within a 20mm–30mm area on both sides, hold the temperature for 5–10 seconds, and then air-cool it for post-weld normalizing heat treatment. Conventional post-weld normalizing heat treatment does not require a holding time. This application employs a step of holding the temperature for 5–10 seconds after normalizing heat treatment, which increases the product qualification rate from approximately 90% to 95%–99.9% compared to products without this step.

[0080] In some embodiments of this application, the flaring and spinning process of the steel ring after post-weld normalizing heat treatment includes:

[0081] S601. After the steel ring has undergone post-weld normalizing heat treatment, an expansion device is used to expand the opening to obtain a steel ring with the outer contour of a wheel.

[0082] S602. A steel rim with a wheel outline is spun using a spinning equipment to obtain a hot-formed steel rim.

[0083] In the embodiments of this application, the steel ring that has undergone post-weld normalizing heat treatment is flared to give it a wheel outline, so that it can be sealed and connected to the tire through the wheel outline; the flared steel ring is then spun to give it a set structure, shape or pattern.

[0084] In some embodiments of this application, the quenching and tempering heat treatment of the hot-formed steel ring includes:

[0085] S701. Under the clamping of the mold, heat the hot-formed steel ring to 850℃~950℃ and hold it for 3 minutes~8 minutes;

[0086] S702. The hot-formed steel ring that has been heated and kept warm is subjected to quenching treatment. After quenching, it is tempered at 200℃~400℃ for 20 minutes~40 minutes to obtain an ultra-high strength wheel steel ring with a tensile strength of 1GPa to 1.5GPa.

[0087] In the embodiments of this application, the hot-formed steel ring undergoes quenching and tempering heat treatment, transforming the tensile strength of the hot-formed steel ring (i.e., steel coil raw material) from 600MPa to 750MPa to a higher tensile strength of 1GPa to 1.6GPa, thereby producing an ultra-high strength wheel steel ring. Exemplarily, the tensile strength of the ultra-high strength wheel steel ring can reach 1.0GPa, 1.1GPa, 1.2GPa, 1.3GPa, 1.4GPa, 1.5GPa, 1.55GPa, and 1.6GPa.

[0088] In embodiments of this application, the method for manufacturing ultra-high strength wheel rims further includes:

[0089] S8. Conduct wheel load fatigue tests on ultra-high strength wheel rims to obtain ultra-high strength wheel rims with qualified comprehensive mechanical properties. The wheel load fatigue tests are conducted in accordance with GB / T 5909 Requirements and Test Methods for Bending and Radial Fatigue Performance of Commercial Vehicle Wheels and GB / T 5334 Requirements and Test Methods for Bending and Radial Fatigue Performance of Passenger Vehicle Wheels.

[0090] In embodiments of this application, the method for manufacturing ultra-high strength wheel rims further includes:

[0091] S9. Descaling is performed on the ultra-high strength wheel rim to remove iron oxides from it, resulting in an ultra-high strength wheel rim with scales removed. The scales refer to the patchy iron oxides formed on the ultra-high strength wheel rim.

[0092] For example, methods for removing iron oxides from ultra-high strength wheel rims may include SED high-pressure abrasive water jet descaling, acid pickling descaling, and shot blasting descaling.

[0093] In embodiments of this application, the method for manufacturing ultra-high strength wheel rims further includes:

[0094] S10. The ultra-high strength wheel rim, after the scales have been removed, is coated to form a protective coating on its outer surface. This protective coating refers to a coating that provides corrosion protection, rust prevention, or both. For example, the protective coating may be an anti-corrosion film, an anti-rust paint film, or a composite layer of a film and a paint film with both anti-corrosion and rust prevention functions on the rim surface. The paint film or film may be formed using materials available through existing commercial channels.

[0095] The technical solution of this application will be further illustrated below through specific embodiments and comparative examples.

[0096] Example 1

[0097] A method for manufacturing an ultra-high strength wheel rim, comprising:

[0098] S1. Pre-welding treatment of steel coil raw materials, including:

[0099] S101. The steel coil raw material is leveled and laser-cut to obtain flat strips; wherein, the difference between the diagonals of the flat strips is 0.3mm; the steel coil raw material is steel with a tensile strength of 700MPa and a thickness of 3mm;

[0100] S102. Grind the four sides of the flat strip to make the four sides of the flat strip transition with a radius of R=0.5mm, and the surface roughness of the four sides reaches Ra3.2, to obtain the material to be welded; the surface roughness of the four sides of the material to be welded reaches Ra3.2.

[0101] S2. Pre-forming treatment of the material to be welded, including:

[0102] The material to be welded is repeatedly rolled twice to make the misalignment of the steel ring to be welded 0.1 times the plate thickness, thus obtaining the steel ring to be welded;

[0103] S3. Welding process for the steel ring to be welded, including:

[0104] Resistance welding equipment with a welding power of 1550VA to 1600VA is used to perform resistance welding on the gap of the steel ring to be welded in order to obtain a welded steel ring; wherein, the power-off holding time of resistance welding is 0.8 seconds to 1.0 seconds to obtain a welded steel ring.

[0105] S4. The weld seam of the welded steel ring is scraped smooth to obtain a steel ring with a weld seam allowance of 0.15mm.

[0106] S5. Perform post-weld normalizing heat treatment on a 20mm area on both sides of the weld of the steel ring with retained weld reinforcement, including:

[0107] S501. Use a medium-frequency induction normalizing device to heat and hold the 20mm area on both sides of the weld of the steel ring with retained weld height at 820℃~850℃ for 6 seconds.

[0108] S502. After the insulation is completed, the steel ring is air-cooled to 30°C.

[0109] S6. After the heat treatment is completed, the steel ring is flared and spun, including:

[0110] S601. After the heat treatment is completed, the steel ring is widened using a ring widening device to obtain a steel ring with the outer contour of a wheel.

[0111] S602. Use spinning equipment to spin the steel rim with the wheel outline three times to obtain the hot-formed steel rim. Perform a preliminary inspection on the hot-formed steel rim to check whether the steel rim with the wheel outline has cracks. The hot-formed steel rim without cracks is judged to be qualified.

[0112] S7. Perform quenching and tempering heat treatment on the hot-formed steel ring, including:

[0113] S701. Under the clamping of the mold, the hot-formed steel ring is heated to 860℃ and held for 3.5 minutes;

[0114] S702. The hot-formed steel ring that has been heated and kept warm is quenched. After the hot-formed steel ring is quenched, it is tempered at 200℃~240℃ for 30 minutes to obtain an ultra-high strength wheel steel ring with a tensile strength of 1.2GPa. The product qualification rate of the ultra-high strength wheel steel ring is 99.1%.

[0115] S8. Conduct wheel load fatigue tests on ultra-high strength wheel rims to obtain ultra-high strength wheel rims with qualified comprehensive mechanical properties.

[0116] S9. Shot blasting is performed on the ultra-high strength wheel rim to remove iron oxides from it, resulting in an ultra-high strength wheel rim with scales removed.

[0117] S10. Apply a coating to the ultra-high strength wheel rim after removing the scales to form an anti-corrosion and anti-rust coating on the outer surface of the ultra-high strength wheel rim.

[0118] Example 2

[0119] The difference between Example 2 and Example 1 is that in step S5, after resistance welding, post-weld normalizing heat treatment is performed, but no heat preservation is performed. After cooling, the opening is directly flared and spun. The product qualification rate of ultra-high strength wheel steel rim is 95%, and the tensile strength of ultra-high strength wheel steel rim is 1.3 GPa.

[0120] Example 3

[0121] The difference between Example 3 and Example 1 is that the heat preservation time in step S5 is 10 seconds. The product qualification rate of the ultra-high strength wheel steel rim is 99.2%, and the tensile strength of the ultra-high strength wheel steel rim is 1.2 GPa.

[0122] Example 4

[0123] The difference between Example 4 and Example 1 is that in step S3, a welding machine with a welding power of 1800VA is used to perform resistance welding on the steel rim to be welded. The product qualification rate of the ultra-high strength wheel steel rim is 99.6%, and the tensile strength of the ultra-high strength wheel steel rim is 1.0 GPa.

[0124] Comparative Example 1

[0125] The difference between Comparative Example 1 and Example 1 is that in step S1, the difference between the diagonals of the flat strip is 0.75mm, and the product qualification rate of the ultra-high strength wheel steel rim is 71%.

[0126] Comparative Example 2

[0127] The difference between Comparative Example 2 and Example 1 is that in step S1, the four sides of the flat strip are transitioned with a radius of R=1.2mm, and the product qualification rate of the ultra-high strength wheel steel rim is 65%.

[0128] Comparative Example 3

[0129] The difference between Comparative Example 3 and Example 1 is that in step S3, a welding machine with a welding power of 1400VA is used to perform resistance welding on the gap of the steel ring to be welded, and the product qualification rate of the ultra-high strength wheel steel ring is 30%.

[0130] Comparative Example 4

[0131] The difference between Comparative Example 4 and Example 1 is that in step S3, a welding machine with a welding power of 2500VA was used to perform resistance welding on the gap of the steel ring to be welded, and the product qualification rate of the ultra-high strength wheel steel ring was 0%.

[0132] Comparative Example 5

[0133] The difference between Comparative Example 5 and Example 1 is that in step S3, no power-off pressure holding was implemented during resistance welding, and no post-weld normalizing heat treatment was performed after resistance welding, resulting in a product qualification rate of 60% for ultra-high strength wheel steel rims.

[0134] Comparative Example 6

[0135] The difference between Comparative Example 6 and Example 1 is that in step S5, no post-weld normalizing heat treatment is performed after resistance welding, and the wheel is directly flared and spun, resulting in a product qualification rate of 80% for ultra-high strength wheel steel rims.

[0136] A comparison of the product yield rates of ultra-high strength wheel rims manufactured using the respective process steps and parameters of Examples 1-4 and Comparative Examples 1-6 shows that:

[0137] Compared to Comparative Example 1, where the difference in the diagonals of the flat strip in step S1 was 0.75 mm, the product qualification rate of the ultra-high strength wheel rim produced in Comparative Example 1 was 71%. Compared to Comparative Example 2, where the four sides of the flat strip were transitioned with rounded corners of R=1.2 mm in step S1, the product qualification rate of the ultra-high strength wheel rim produced in Example 1 was 65%. In the manufacturing method of Example 1, the difference in the diagonals of the flat strip was 0.3 mm, and a rounded corner of R=0.5 mm was used for transition. The product qualification rate of the ultra-high strength wheel rim produced in Example 1 was 99.1%. The finished product qualification rates of Comparative Examples 1 and 2 were both low, indicating that the difference in the diagonals of the flat strip and the rounded corners of the sides have a significant impact on the finished product rate of the wheel rim within the range defined in this application.

[0138] Compared to Comparative Example 3, which used a welding machine with a welding power of 1400VA in step S3 to perform resistance welding on the gaps of the steel rim to be welded, resulting in an ultra-high strength wheel rim with a product qualification rate of 30%; and Comparative Example 4, which used a welding machine with a welding power of 2500VA in step S3 to perform resistance welding on the gaps of the steel rim to be welded, resulting in an ultra-high strength wheel rim with a product qualification rate of 0%; Example 1 used welding equipment with a welding power of 1550VA to 1600VA to perform resistance welding on the gaps of the steel rim to be welded, and the ultra-high strength wheel rim obtained in Example 1 had a product qualification rate of 99.1%. It can be concluded that setting the welding power between 1500VA and 2500VA is more suitable and can achieve a relatively high product qualification rate.

[0139] Compared to Comparative Example 5, which did not perform power-off pressure holding during resistance welding in step S3 and did not undergo post-weld normalizing heat treatment, the product qualification rate of the ultra-high strength wheel steel rims obtained in Comparative Example 5 was 60%. Compared to Comparative Example 6, which performed power-off pressure holding during resistance welding after resistance welding in step S3 but did not undergo post-weld normalizing heat treatment in step S5, the product qualification rate of the ultra-high strength wheel steel rims obtained in Comparative Example 6 was 80%. In Example 2, post-weld normalizing heat treatment was performed after resistance welding, and the qualification rate was increased to 95%. Through the comparison of Comparative Examples 6, 5, and 1, it is demonstrated that power-off pressure holding after resistance welding and post-weld normalizing heat treatment can effectively improve the product qualification rate of ultra-high strength wheel steel rims to varying degrees.

[0140] Furthermore, compared to the manufacturing method of ultra-high strength wheel rims in Example 1, Example 2 performs normalizing heat treatment after resistance welding in step S5, but does not perform heat preservation. The product qualification rate of the manufactured ultra-high strength wheel rims is 95%. The comparison results between Example 1 and Example 2 show that not performing heat preservation treatment after normalizing heat treatment after welding leads to a decrease in the product qualification rate of ultra-high strength wheel rims, indicating that heat preservation treatment of steel rims after normalizing heat treatment can effectively improve the product qualification rate of ultra-high strength wheel rims. In Example 3, the steel rims after normalizing heat treatment are heat preserved for 10 seconds in step S5, i.e., a longer heat preservation time. The product qualification rate of its ultra-high strength wheel rims is 99.2%, indicating that increasing the heat preservation time of steel rims after normalizing heat treatment can further improve the product qualification rate of ultra-high strength wheel rims. In Example 4, resistance welding is performed on the weld seam of the steel rim to be welded using a welding machine with a welding power of 1800VA in step S3. The product qualification rate of its ultra-high strength wheel rims is 99.6%. Compared to Comparative Example 6, which generally does not require a holding time after resistance welding normalizing heat treatment, Example 1 uses a 6-second holding process for the steel rim after welding normalizing heat treatment in step S5, which increases the product qualification rate of the ultra-high strength wheel steel rim from 90% to 99.9% compared to the one without the holding process.

[0141] Compared to other ultra-high strength substrates that are difficult to process, form, and weld, the manufacturing method of ultra-high strength wheel rims in this application utilizes a substrate that can be cold-formed in a lower strength range followed by tempering heat treatment to obtain a significantly increased strength. This method is more suitable for most current wheel production lines, allowing for low-cost modifications to existing wheel production lines to achieve wheel weight reduction, quality improvement, and efficiency enhancement. Fine-tuning of the subsequent tempering process allows for obtaining ultra-high strength wheel rim products with any stable strength value within the tensile strength range of 1GPa to 1.6GPa, making it widely applicable and beneficial for wheel design.

[0142] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for manufacturing an ultra-high strength wheel rim, characterized in that, include: The steel coil raw material is subjected to pre-welding treatment to obtain the material to be welded; The surface roughness of the four sides of the material to be welded reaches Ra3.2; The pre-welding treatment of the steel coil raw material includes: leveling and laser cutting the steel coil raw material to obtain flat strips; the difference between the diagonals of the flat strips is ≤0.5mm; grinding the four sides of the flat strips to make the surface roughness of the four sides reach Ra3.2, thus obtaining the material to be welded. The material to be welded is pre-formed to obtain a steel ring to be welded; the misalignment of the steel ring to be welded is ±0.1 times the plate thickness; The steel ring to be welded is subjected to welding treatment to obtain a welded steel ring; the welding treatment of the steel ring to be welded includes: using a resistance welding equipment with a welding power of 1500VA to 2400VA to perform resistance welding treatment on the gap of the steel ring to be welded to obtain a welded steel ring; wherein, the power-off and pressure holding time of the resistance welding is 0.5 seconds to 1.5 seconds; The weld seam of the welded steel ring is scraped smooth to obtain a steel ring with a weld seam allowance of 0.1mm to 0.3mm. The weld sides of the steel ring with retained weld reinforcement are subjected to post-weld normalizing heat treatment; the post-weld normalizing heat treatment of the weld sides of the steel ring with retained weld reinforcement includes: heating and holding the weld sides of the steel ring with retained weld reinforcement at 800℃~900℃ for 5 seconds~10 seconds; and air cooling the steel ring after the heat holding is completed. The steel rim that has undergone post-weld normalizing heat treatment is flared and spun to obtain a hot-formed steel rim; the flaring and spun treatment of the steel rim that has undergone post-weld normalizing heat treatment includes: flaring the steel rim that has undergone post-weld normalizing heat treatment using a flaring device to obtain a steel rim with a wheel outline; and spun the steel rim with a wheel outline using a spun device to obtain a hot-formed steel rim; The hot-formed steel rim is subjected to quenching and tempering heat treatment to obtain an ultra-high strength wheel rim.

2. The manufacturing method according to claim 1, characterized in that, The grinding process of the flat strip includes making the four sides of the flat strip transition with a radius of R≤1mm.

3. The manufacturing method according to claim 1, characterized in that, The preforming process of the material to be welded includes: The material to be welded is subjected to a rolling process to obtain a steel ring to be welded.

4. The manufacturing method according to claim 1, characterized in that, The post-weld normalizing heat treatment of the steel ring with retained weld reinforcement includes: The weld areas on both sides of the steel ring with retained weld height were subjected to post-weld normalizing heat treatment at 800℃~900℃ using a medium-frequency induction normalizing device.

5. The manufacturing method according to claim 1, characterized in that, The heat treatment of the hot-formed steel ring includes: Under the clamping of the mold, the hot-formed steel ring is heated to 850℃~950℃ and held at that temperature for 3 minutes~8 minutes; The hot-formed steel rim, after being heated and kept warm, is quenched and then tempered at 200℃ to 400℃ for 20 to 40 minutes to obtain an ultra-high strength wheel rim with a tensile strength of 1GPa to 1.5GPa.

6. The manufacturing method according to claim 1, characterized in that, Also includes: Wheel load fatigue test was performed on the ultra-high strength wheel rim to obtain an ultra-high strength wheel rim with qualified comprehensive mechanical properties; The ultra-high strength wheel rim is descaled to remove iron oxides from it, resulting in an ultra-high strength wheel rim with scales removed. The ultra-high strength wheel rims with scales removed are coated to form a protective coating on the outer surface of the ultra-high strength wheel rims.

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