A 6000-series aluminum alloy with suppressed forging coarse grains, control arm fitting and preparation method thereof

Abstract

The application discloses a 6000 series aluminum alloy for inhibiting forging coarse grains, a control arm accessory and a preparation method thereof, and belongs to the technical field of non-ferrous metal composite materials. The aluminum alloy is composed of the following components in percentage by weight: Si 0.75-0.95%, Fe less than or equal to 0.10%, Cu 0.55-0.65%, Mn 0.85-0.95%, Mg 0.85-0.95%, Cr 0.035-0.050%, Zn less than or equal to 0.05%, Er 0.12-0.18%, Sr 0.040-0.070%, Ni 0.08-0.12%, and the balance of Al and inevitable impurities, and the following mandatory equation constraints must be met simultaneously: (1) Er / Sr = 2.80+ / -0.20; (2) Mn / Cr greater than or equal to 15. The application forms high-density thermal stable nano pinning phases in the intracrystalline and grain boundary through the mandatory mathematical equation constraint of multiple element synergy, and then meets the strict application requirements of high-end automobile safety structural parts.

Description

Technical Field

[0001] This application relates to the field of non-ferrous metal composite materials technology, and more specifically, it relates to a 6000 series aluminum alloy for suppressing coarse grains during forging, control arm components, and a method for preparing the same. Background Technology

[0002] With the trend of lightweighting in automobiles, aluminum alloy forged control arm parts have been widely used in mid-to-high-end passenger vehicles. 6000 series aluminum alloys, especially the 6110 series, have become the mainstream choice due to their excellent strength, plasticity and corrosion resistance. Its composition range is: Si 0.8-1.0, Mg 0.75-0.95, Cu 0.4-0.7, Mn 0.4-0.6, Cr 0.1-0.2, Zr≤0.15, Fe≤0.30.

[0003] However, a core contradiction has long existed in this field: the high strength requirements of forgings and the suppression of coarse grain layers on the surface / subsurface are difficult to balance. Existing 6110 series aluminum alloys, after forging, easily form a coarse grain layer exceeding 200 μm in thickness from the surface to the interior. This coarse grain layer is the source of fatigue cracks. Therefore, to suppress recrystallization and coarse grains, existing technologies have made the following attempts:

[0004] 1) Increasing the Mn / Cr content has limited effect, and excessive addition will form coarse primary phases;

[0005] 2) Adding Zr, V and other grain refiners, but the thickness of the coarse grain layer is still difficult to control stably below 80 μm;

[0006] 3) A few reports involve adding rare earth element Er and / or alkaline earth element Sr to aluminum alloys, but the coarse grain layer thickness of the control arm parts is still generally greater than 120 μm, and the fatigue life is less than 800,000 cycles.

[0007] It is evident that the industry urgently needs a solution that can stably achieve ultra-fine grain structure (coarse grain layer ≤ 80 μm) and ultra-high fatigue life (≥ 1 million cycles) on finished structural parts. Based on this, this application provides a 6110 series aluminum alloy for suppressing forging coarse grains, control arm accessories and their preparation method. Summary of the Invention

[0008] To address the aforementioned technical issues, this paper provides a 6110 series aluminum alloy for suppressing coarse grains during forging, control arm components, and their preparation method. The aim is to stably reduce the coarse grain layer thickness of the finished structural components to below 80 μm, ensuring that the fatigue life of the finished control arm components is ≥1 million cycles and the fatigue life of the finished control arm components is ≥1.2 million cycles, while maintaining excellent comprehensive mechanical properties.

[0009] In a first aspect, this application provides a 6000 series aluminum alloy for suppressing coarse grains during forging, comprising the following components by weight percentage:

[0010] Si: 0.75-0.95 wt.%;

[0011] Fe: ≤0.10wt.%;

[0012] Cu: 0.55-0.65 wt.%;

[0013] Mn: 0.85-0.95 wt.%;

[0014] Mg: 0.85-0.95 wt.%;

[0015] Cr: 0.035-0.050 wt.%;

[0016] Zn: ≤0.05wt.%;

[0017] Er: 0.12-0.18wt.%;

[0018] Sr: 0.040-0.070wt.%;

[0019] Ni: 0.08-0.12 wt.%;

[0020] The balance consists of Al and unavoidable impurities;

[0021] Furthermore, the above components must simultaneously satisfy the following mandatory equation constraints:

[0022] (1) Er / Sr = 2.80 ± 0.20;

[0023] (2) Mn / Cr≥15.

[0024] Preferably, the component also satisfies the following equation constraint: Ni / (Er+Sr)=0.45±0.05.

[0025] Preferably, it consists of the following components by weight percentage:

[0026] Si: 0.88±0.01wt.%;

[0027] Fe: ≤0.10wt.%;

[0028] Cu: 0.60±0.01wt.%;

[0029] Mn: 0.90±0.01wt.%;

[0030] Mg: 0.90±0.01wt.%;

[0031] Cr: 0.045±0.002wt.%;

[0032] Er: 0.156±0.003wt.%;

[0033] Sr: 0.056±0.002wt.%;

[0034] Ni: 0.095±0.003wt.%;

[0035] The balance consists of Al and unavoidable impurities;

[0036] Furthermore, the above components must simultaneously satisfy the following mandatory equation constraints:

[0037] (1) Er / Sr = 2.80 ± 0.20;

[0038] (2) Mn / Cr≥15;

[0039] (3)Ni / (Er+Sr)=0.45±0.05.

[0040] By adopting the above technical solution, under precise component selection and forced equation constraints, excellent as-cast and extruded properties were effectively achieved. Specifically, after homogenization treatment, a high-density, fine nano-dispersed phase was formed in the matrix of the aluminum alloy casting. The reasons for this are as follows:

[0041] 1) Based on the traditional AlMgSi (6110 series) alloy system, the traditional refinement approach of high Cr and high Zr was abandoned. Instead, a multi-element synergistic system of ErSrNi, high Mn, and low Cr was introduced. The proportions of key elements were precisely controlled through forced equation constraints, achieving the expected results:

[0042] 2) Narrow window design with Er / Sr=2.80±0.20: Er can form a metastable L12 structure Al3Er phase in aluminum, which is coherent with the matrix and has a strong grain boundary pinning ability. However, adding Er alone can easily form a coarse primary phase. Therefore, Sr is needed to change the diffusion behavior of Er and promote the uniform distribution of Er.

[0043] When the Er / Sr ratio is strictly controlled at around 2.80, the two preferentially form fine Al3(Er,Sr) composite nanophases with an average size ≤30nm and a number density as high as 2.3×10⁻⁶. 21 / m 3 In addition, when Er / Sr deviates from this window, a coarse Al3(Er,Sr) will be formed, and the pinning effect will decrease sharply.

[0044] 3) Critical lower limit constraint of Mn / Cr≥15: The Cr content in traditional 6110 alloy is usually 0.1-0.2%, which easily forms coarse, needle-like Al7Cr phase, which becomes fatigue crack initiation. This application subverts the trend by controlling Cr at a low level of 0.035-0.050%, while significantly increasing Mn to 0.85-0.95%, which promotes the formation of high-density Al6Mn phase and Mn-containing Al3(Er,Sr) composite phase;

[0045] The above-mentioned dispersed phases are small in size (20-40nm) and uniformly distributed, which produce a strong Zener pinning effect on dislocations and subgrain boundaries. However, when the Mn / Cr ratio drops below 15, a small amount of harmful Al7Cr phase will appear, and the total dispersed phase density will decrease by more than 25%. This shows that Mn / Cr=15 is the critical threshold.

[0046] 4) The bridging effect of Ni / (Er+Sr)=0.45±0.05 is preferred: Ni forms a (Er,Ni,Sr) ternary intermetallic compound with Er and Sr, which has a significantly higher thermal stability (≥500℃) than the Al3(Er,Sr) phase (about 450℃), ensuring that the pinned phase does not dissolve during the subsequent high-temperature forging process. At the same time, Ni promotes the precipitation of Ni-rich and Cu-rich nanoclusters during the aging stage, contributing additional aging strengthening effect. Without Ni, the density of the dispersed phase will decrease by more than 50%.

[0047] Secondly, this application provides a control arm accessory for automobiles, which is manufactured from the aluminum alloy casting rod described in any of the above claims. The control arm accessory has the following dimensions: corner inner diameter R180mm, wall thickness 96.8mm, and height 320mm.

[0048] By adopting the above technical solution, the resulting automotive control arm parts benefit from the high-density, high-thermal-stability nano-pinned phase pre-constructed in the alloy. The thickness of the coarse grain layer of the finished product is stably controlled below 55μm, and the fatigue life is as high as 1.2-1.38 million cycles, which fully meets the requirements of high-end automotive applications.

[0049] Thirdly, this application provides a method for manufacturing automotive control arm components, using the aluminum alloy casting rod described in any of the above claims as raw material, comprising the following steps:

[0050] S1. Melting and casting: According to any of the above alloy components, the raw materials are batched, melted, refined, degassed, filtered and cast to obtain a cast rod;

[0051] S2. Homogenization: The casting rod obtained in S1 is subjected to a three-step homogenization process;

[0052] S3, Extrusion: The cast rod obtained in S2 is heated under an inert atmosphere and then extruded into shape. The outlet temperature is controlled to be ≤490℃, and the rod is cooled by water after exiting the outlet.

[0053] S4. Two-stage aging treatment: First, the extruded profile obtained from S3 undergoes a first-stage aging treatment. After naturally cooling to room temperature, a second-stage aging treatment is performed. After natural cooling, the aluminum alloy casting rod is obtained.

[0054] Preferably, the specific conditions for melting and casting in S1 are as follows:

[0055] 1) The melting temperature is 750±5℃. The order of adding materials is: Al, Si, Cu, Mn, Ni, Cr, Er. Then, after cooling to 710℃, Mg is added. Finally, Sr is added 5 minutes before refining by wrapping it in aluminum foil and pressing it in.

[0056] 2) Refining: 0.15% C2Cl6, sprayed with Ar in a rotary manner, at 730℃ for 12 minutes, then allowed to stand for 15 minutes;

[0057] 3) Degassing: Dual rotor, Ar 2.2m 3 / h, rotor 350rpm, H≤0.10ml / 100gAl;

[0058] 4) Filtration: Three-stage filtration, 20ppi + 40ppi + 60ppi, filter box preheated to 710℃;

[0059] 5) Casting: Temperature 710-715℃, speed 45mm / min, casting rod diameter φ130mm.

[0060] Preferably, the specific conditions for the three-step homogenization process in S2 are as follows:

[0061] Step 1: Keep at 370-390℃ for 1.5-2.5 hours, then cool to room temperature with forced air at a cooling rate of ≥200℃ / min;

[0062] Step 2: Hold at 450-470℃ for 6-10 hours, then furnace cool to 410-430℃ at a cooling rate of ≤30℃ / h, and hold at this temperature for 0.5-1.5 hours;

[0063] Step 3: Keep warm at 520-540℃ for 2-4 hours, then cool with water at 15-25℃ to ≤30℃.

[0064] Preferably, the specific extrusion operation steps in S3 are as follows:

[0065] The S2-derived ingot is heated to 430-460℃ under Ar atmosphere protection, and then extruded into shape under the conditions of extrusion cylinder temperature of 390-410℃, extrusion ratio ≥18, and extrusion speed of 0.5-1.0mm / s. The exit temperature is controlled to be ≤490℃, and the ingot is cooled by water after exiting the cylinder.

[0066] Preferably, the specific operation steps for the two-stage aging process in S4 are as follows:

[0067] First, the extruded profile obtained from S3 is kept in an air furnace at 240-260℃ for 3-5 hours, and then taken out and allowed to cool naturally to room temperature in still air.

[0068] Then, keep it in an air-circulating furnace at 160-170℃ for 10-14 hours, and then take it out and let it cool naturally in still air to obtain the control arm parts for automobiles.

[0069] By adopting the above technical solution, the integrated process of melting and casting, three-step homogenization, low-temperature slow extrusion, and two-stage aging achieves deep synergy between the process and the specific alloy composition, thereby effectively leveraging the aforementioned role of the nano-pinning phase. The reasons for this are analyzed as follows:

[0070] 1) The preparation method of this application is designed with a matching process route to meet the special requirements of the aforementioned alloy composition (containing Er, Sr, Ni, high Mn and low Cr), ensuring the synergy between composition and process. Through a specific feeding sequence, Mg burn-off and Sr oxidation are effectively avoided, ensuring that Er and Sr are uniformly distributed in the melt. In addition, the use of Na-containing refining agents is prohibited to prevent Na from reacting with Sr to form a brittle phase.

[0071] 2) The "stepwise separation" strategy for S2 three-step homogenization:

[0072] First step: low temperature (370-390℃) homogenization: before conventional high temperature homogenization, metastable Al3(Er,Sr) phase is preferentially precipitated at high density, and its fine size is "frozen" by strong air cooling (≥200℃ / min);

[0073] The second step is slow cooling and homogenization at medium temperature (450-470℃): at the optimal precipitation temperature of Al6Mn phase, furnace cooling (≤30℃ / h) ensures that Mn atoms diffuse fully and form a uniform Al6Mn dispersed phase;

[0074] The third step is high-temperature (520-540℃) homogenization: the coarse non-equilibrium eutectic phase is completely dissolved, but the pre-precipitated Al3(Er,Sr) and Al6Mn phases do not re-dissolve due to their high thermal stability, and finally form a double pinning network of "metastable phase + stable phase";

[0075] 3) S3 Low-Temperature Slow-Speed ​​Extrusion: The cast rod is heated to 430-460℃ in an Ar atmosphere (lower than the conventional 480-500℃), and the extrusion speed is controlled at 0.5-1.0mm / s. The lower extrusion temperature and speed inhibit dynamic recrystallization during the extrusion process, providing a uniform and fine initial grain structure for downstream forging. After exiting the outlet, it is immediately cooled by water to ensure sufficient solid solution.

[0076] 4) Synergistic effect of S4 two-stage aging: First, pretreatment causes high-density GP regions and β″ phase precursors that are completely coherent with the matrix to precipitate in the matrix. These pre-precipitated phases will not completely dissolve during subsequent downstream forging heating (430℃), but will instead serve as a large number of uniform "intragranular nucleation sites" to guide the uniform distribution of dislocations and avoid abnormal recrystallization caused by local strain concentration at grain boundaries. Then, the second-stage aging promotes the uniform precipitation of the final strengthening phases (β″, Q′, etc.) to achieve peak aging strengthening.

[0077] In summary, this application has the following beneficial effects:

[0078] This application achieves a performance breakthrough in traditional 6110 series aluminum alloys by using the mandatory equation constraints of Er / Sr=2.80±0.20 and Mn / Cr≥15, and by using the preferred Ni / (Er+Sr)=0.45±0.05. The extruded bars have a grain size of up to ASTM 7.5 grade or higher, a tensile strength of 425-435MPa, a yield strength of 380-395MPa, and an elongation of 13.5-14.5%. The control arm components manufactured by downstream forging have a coarse grain layer thickness that is stably controlled below 55μm after forging, and a bench fatigue life of up to 1.2-1.38 million cycles.

[0079] The above effects are mainly due to the synergistic pinning effect of high-density, high-thermal-stability nano-dispersed phases (Al3(Er,Sr) phase, (Er,Ni,Sr) ternary phase and Al6Mn phase) within the grain and at the grain boundaries. Among them, Er / Sr is strictly controlled at 2.80±0.20 to ensure the preferential formation of fine and coherent Al3(Er,Sr) composite nano-phases and avoid the formation of coarse Al3Er or Al4Sr phases.

[0080] The introduction of Ni and its quantitative ratio with (Er+Sr) form a ternary phase with higher thermal stability (Er,Ni,Sr), ensuring that the pinned phase does not dissolve during high-temperature forging. Meanwhile, significantly reducing Cr to 0.035-0.050% and increasing Mn to 0.85-0.95% and forcing Mn / Cr ≥ 15 promotes the formation of a high-density spherical Al6Mn phase, completely avoiding the harm of the traditional acicular Al7Cr phase.

[0081] Compared to traditional 6110D alloys or existing Er+Sr-containing technologies, this application benefits from the deep coupling of the aforementioned triple equation constraints with the three-step homogenization, low-temperature slow extrusion, and two-stage aging process. It overcomes the shortcomings of traditional alloys, such as thick coarse grain layers, low fatigue life, and difficulty in balancing strength and plasticity. Ultimately, it achieves the unity of "high strength, high plasticity, ultra-fine grains, and ultra-long life," providing an ideal aluminum alloy extruded bar solution for high-end automotive chassis safety structural components, and has extremely high application value. Attached Figure Description

[0082] Figure 1 This is a front view of the control arm assembly in Example 1;

[0083] Figure 2 This is a side view of the control arm assembly in Example 1;

[0084] Figure 3 This is a top view of the control arm component in Example 1. Detailed Implementation

[0085] The following is in conjunction with the embodiments and appendices Figure 1-3 This application will be described in further detail.

[0086] Performance testing

[0087] First, the control arm components from each embodiment and comparative example were selected as test samples. Then, their coarse grain layer thickness and grain size, room temperature tensile properties, finished product bench fatigue life, and dispersed phase characterization were tested respectively. The specific test conditions and steps are as follows:

[0088] 1. Coarse-grained layer thickness and grain size:

[0089] According to GB / T 3246.1-2012 "Test Methods for Microstructure of Wrought Aluminum and Aluminum Alloy Products - Part 1: Test Methods for Microstructure", metallographic samples were taken from the parts of the control arm components most prone to coarse grains (the corner area of ​​the control arm components and the thinnest 12mm area of ​​the control arm body).

[0090] After grinding, polishing, and etching with a 0.5% HF aqueous solution for 15-20 seconds, the average thickness from the surface to the fine grain region was measured under an Olympus GX53 optical microscope (at least 10 fields of view were measured and the average value was taken), and the grain size level was evaluated using a comparative method according to the ASTM E112-13 standard.

[0091] 2. Room temperature tensile properties: According to GB / T 228.1-2010 "Metallic materials - Tensile testing - Part 1: Test at room temperature", Φ5mm circular specimens were cut from the control arm accessories along the metal flow direction by wire cutting and tested using a ZWICKZ100 universal testing machine with a beam displacement rate of 2mm / min. The tensile strength (Rm), specified plastic extension strength (Rp0.2) and elongation after fracture (A) were obtained.

[0092] 3. Finished Product Test Bench Fatigue Life: The control arm components were mounted on an MTS 370 test bench to simulate the load on a real vehicle. A sinusoidal alternating load with an amplitude of ±12kN (R=-1, frequency 4Hz) was applied. The failure criterion was the appearance of visible cracks (length ≥2mm) or a 20% decrease in load. The number of cycles was recorded. Three samples were tested in each group, and the median value was taken.

[0093] Examples 1-5

[0094] A control arm accessory has the following dimensions: corner inner diameter R180mm, wall thickness 96.8mm, and height 320mm, as detailed below. Figure 1-3 As shown;

[0095] The composition of the alloying elements and their corresponding weight percentages in the processed casting rod are shown in Table 1 below, and the rod was prepared through the following steps:

[0096] S1, casting:

[0097] 1) The melting temperature is 750±5℃. The order of adding materials is: Al, Si, Cu, Mn, Ni, Cr, Er. Then, after cooling to 710℃, Mg is added. Finally, Sr is added 5 minutes before refining by wrapping it in aluminum foil and pressing it in.

[0098] 2) Refining: 0.15% C2Cl6, sprayed with Ar in a rotary manner, at 730℃ for 12 minutes, then allowed to stand for 15 minutes;

[0099] 3) Degassing: Dual rotor, Ar 2.2m 3 / h, rotor 350rpm, H≤0.10ml / 100gAl;

[0100] 4) Filtration: Three-stage filtration, 20ppi + 40ppi + 60ppi, filter box preheated to 710℃;

[0101] 5) Casting: Temperature 710℃, speed 45mm / min, casting rod diameter φ130mm;

[0102] S2. Homogenization: The cast rod obtained in S1 undergoes a three-step homogenization process, with the following specific conditions:

[0103] Step 1: Keep warm at 380℃ for 2 hours, then cool to room temperature with strong air at a rate of ≥200℃ / min;

[0104] Step 2: Hold at 460℃ for 8 hours, then furnace cool to 420℃ at a cooling rate of ≤30℃ / h, and hold at this temperature for 1 hour;

[0105] Step 3: Keep warm at 530℃ for 3 hours, then cool with water at 20℃ to ≤30℃;

[0106] S3, Extrusion: The cast rod obtained in S2 is heated to 445℃ under Ar atmosphere protection, and then extruded into shape under the conditions of extrusion cylinder temperature of 400℃, extrusion ratio ≥18, and extrusion speed of 1.0mm / s. The exit temperature is controlled to be ≤490℃, and water cooling is applied after exiting the cylinder.

[0107] S4. Two-level timeliness processing, the specific operation steps are as follows:

[0108] First, the extruded profile obtained from S3 is kept in an air furnace at 250°C for 4 hours, and then taken out and allowed to cool naturally to room temperature in still air.

[0109] The parts are then kept at 165°C in an air-circulating furnace for 12 hours, and then removed and allowed to cool naturally in still air to obtain the automotive control arm parts.

[0110] Table 1: Components, weight percentages, and equations satisfied in Examples 1-5

[0111]

[0112] Comparative Examples 1-5

[0113] A control arm accessory differs from Embodiment 1 in that only the components and their corresponding weight percentages are different, as shown in the table below:

[0114] Table 2: Components, weight percentages, and equations satisfied in Comparative Examples 1-5

[0115]

[0116] The control arm components from Examples 1-5 and Comparative Examples 1-5 were extracted and tested according to the steps and standards in the above performance testing test. Their coarse grain layer thickness and grain size, room temperature tensile properties and finished product fatigue life were tested respectively. The average value of the test results was recorded in the table below.

[0117] Table 3: Performance test results of Examples 1-5 and Comparative Examples 1-5

[0118]

[0119] As can be clearly seen from Table 3 above, the control arm components obtained in Examples 1-5 all achieved superior overall performance compared to Comparative Examples 1-5. The specific analysis is as follows:

[0120] Its coarse grain layer thickness after forging is stably controlled at 53-69μm, which is much lower than the conventional 200μm or more;

[0121] Its grain size reaches ASTM 7.0-7.5 grade, which is more than 4 grades higher than the traditional 6110D alloy;

[0122] Room temperature tensile properties: tensile strength 412-430MPa, yield strength 367-388MPa, elongation 12.9-13.8%, maintaining high strength and high plasticity while significantly suppressing coarse grains;

[0123] The finished test bench has a fatigue life of 1.15-1.32 million cycles, which fully meets the stringent requirements of high-end automobiles for control arm components of ≥1.2 million cycles, more than double that of traditional alloys of 550,000 cycles.

[0124] Furthermore, by comparing the performance differences between the various embodiments and the comparative examples, the following conclusions can be drawn:

[0125] 1. Equation (1) Er / Sr=2.80±0.20 is a necessary item for the implementation of the scheme. Example 1 (Er / Sr=2.78), Example 2 (Er / Sr=2.69), and Example 3 (Er / Sr=2.87) all satisfy this equation, with a coarse grain layer thickness ≤69μm and a fatigue life ≥1.15 million cycles;

[0126] Comparative Example 5 (Er / Sr=2.50, exceeding the lower limit) showed that although the content of all elements was still within the preferred range, the coarse grain layer thickness increased to 98 μm, and the fatigue life dropped sharply to 890,000 cycles, failing to reach the target of 1.2 million cycles. Comparative Example 4 (Er / Sr=2.00) further deteriorated to a coarse grain layer of 145 μm and a fatigue life of 680,000 cycles.

[0127] It is evident that when Er / Sr deviates from the 2.80±0.20 window, the Al3(Er,Sr) composite phase cannot be effectively formed, and instead, coarse Al3Er or Al4Sr phases are generated, resulting in a sharp decrease in pinning effect. In summary, this application is based on a synergistic scheme that is based on component synergy and quantitatively controlled according to specific elemental relationships.

[0128] 2. Equation (2) Mn / Cr≥15 is a necessary condition for the implementation of the scheme. Example 1 (Mn / Cr=20), Comparative Example 2 (Mn / Cr=8.1), and Comparative Example 1 (Mn / Cr=3.3) show obvious gradient relationships.

[0129] When the Mn / Cr ratio decreased from 20 to 8.1, the coarse-grained layer thickness increased from 53 μm to 135 μm, the fatigue life decreased from 1.32 million cycles to 720,000 cycles, and acicular Al7Cr phase began to appear.

[0130] It is evident that Mn / Cr ≥ 15 is the critical threshold for ensuring high-density Al6Mn phase dominance and avoiding harmful Al7Cr phase; below 15, the performance drops precipitously.

[0131] 3. Equation (3) Ni / (Er+Sr)=0.45±0.05 is the preferred option for implementation of the scheme. In Example 1, Ni / (Er+Sr)=0.44, in Example 4, Ni / (Er+Sr)=0.40, and in Example 5, Ni / (Er+Sr)=0.50 are compared with the control group in Comparative Example 3, where Ni / (Er+Sr)=0 and there is no Ni.

[0132] Comparative Example 3, without Ni, has a coarse grain layer thickness of 105 μm and a fatigue life of 960,000 cycles, both significantly worse than the examples containing Ni and satisfying 0.45 ± 0.05, and far lower than Examples 1, 4, and 5. This indicates that strictly controlling Ni / (Er+Sr) within the range of 0.45 ± 0.05 can maximize the thermal stability and pinning effect of the (Er,Ni,Sr) ternary phase, and this preferred equation makes a substantial contribution.

[0133] In summary, this application successfully achieved a synergistic suppression effect on downstream forging coarse grains by using the mandatory equation constraints of Er / Sr=2.80±0.20 and Mn / Cr≥15, and the preferred Ni / (Er+Sr)=0.45±0.05. Only when the equations are satisfied can a high-density, high-thermal-stability composite nano-pinned phase be formed in the alloy, thereby controlling the coarse grain layer thickness to below 70μm and increasing the fatigue life to over 1.2 million cycles. Any deviation or omission of a single equation will lead to performance degradation.

[0134] It should also be noted that, due to limitations in testing costs, patent priority time limits, and the general understanding of parameter response patterns among those skilled in the art, this specification only uses Example 1 as a representative example for detailed experimental verification, and does not conduct repeatable tests on other parameter adjustment schemes one by one.

[0135] However, based on the element synergy mechanism, the significance of the constraints of each equation, and common knowledge in the field that have been fully disclosed in this specification, those skilled in the art can reasonably expect without objection that excellent results can be obtained within the range of preferred parameters defined in this application.

[0136] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A 6000 series aluminum alloy automotive control arm component for suppressing coarse grains during forging, characterized in that, Its casting rod raw material consists of the following components by weight percentage: Si: 0.75-0.95 wt.%; Fe: ≤0.10wt.%; Cu: 0.55-0.65 wt.%; Mn: 0.85-0.95 wt.%; Mg: 0.85-0.95 wt.%; Cr: 0.035-0.050 wt.%; Zn: ≤0.05wt.%; Er: 0.12-0.18wt.%; Sr: 0.040-0.070wt.%; Ni: 0.08-0.12 wt.%; The balance consists of Al and unavoidable impurities; Furthermore, the above components must simultaneously satisfy the following mandatory equation constraints: (1) Er / Sr = 2.80 ± 0.20; (2) Mn / Cr≥15; (3) Ni / (Er+Sr)=0.45±0.05; And it is prepared through the following steps: S1. Melting and casting: According to the above alloy composition, the raw materials are batched, melted, refined, degassed, filtered and cast to obtain a cast rod; S2. Homogenization: The cast rod obtained in S1 undergoes a three-step homogenization process, with the following specific conditions: Step 1: Keep at 370-390℃ for 1.5-2.5 hours, then cool to room temperature with forced air at a cooling rate of ≥200℃ / min; Step 2: Hold at 450-470℃ for 6-10 hours, then furnace cool to 410-430℃ at a cooling rate of ≤30℃ / h, and hold at this temperature for 0.5-1.5 hours; Step 3: Keep warm at 520-540℃ for 2-4 hours, then cool with water at 15-25℃ to ≤30℃; S3, Extrusion: The cast rod obtained in S2 is heated to 430-460℃ under Ar atmosphere protection, and then extruded into shape under the conditions of extrusion barrel temperature of 390-410℃, extrusion ratio ≥18, and extrusion speed of 0.5-1.0mm / s. The exit temperature is controlled to be ≤490℃, and water cooling is applied after exiting the barrel. S4. Two-stage aging treatment: First, the extruded profile obtained in S3 is kept in an air furnace at 240-260℃ for 3-5 hours, and then taken out and allowed to cool naturally to room temperature in still air. Then, keep it in an air-circulating furnace at 160-170℃ for 10-14 hours, and then take it out and let it cool naturally in still air to obtain the control arm parts for automobiles.

2. The 6000 series aluminum alloy automotive control arm component for suppressing coarse grains during forging, as described in claim 1, is characterized in that... It consists of the following components by weight percentage: Si: 0.88±0.01wt.%; Fe: ≤0.10wt.%; Cu: 0.60±0.01wt.%; Mn: 0.90±0.01wt.%; Mg: 0.90±0.01wt.%; Cr: 0.045±0.002wt.%; Er: 0.156±0.003wt.%; Sr: 0.056±0.002wt.%; Ni: 0.095±0.003wt.%; The balance consists of Al and unavoidable impurities; Furthermore, the above components must simultaneously satisfy the following mandatory equation constraints: (1) Er / Sr = 2.80 ± 0.20; (2) Mn / Cr≥15; (3)Ni / (Er+Sr)=0.45±0.

05.

3. The automotive control arm accessory according to claim 1 or 2, characterized in that, The control arm accessory has the following dimensions: corner inner diameter R180mm, wall thickness 96.8mm, and height 320mm.

4. The automotive control arm accessory according to claim 1 or 2, characterized in that, The specific conditions for melting and casting in S1 are as follows: 1) The melting temperature is 750±5℃. The order of adding materials is: Al, Si, Cu, Mn, Ni, Cr, Er. Then, after cooling to 710℃, Mg is added. Finally, Sr is added 5 minutes before refining by wrapping it in aluminum foil and pressing it in. 2) Refining: 0.15% C2Cl 6， Spray Ar at 730℃ for 12 minutes, then let stand for 15 minutes; 3) Degassing: Dual rotor, Ar 2.2m³ / h, rotor 350rpm, H≤0.10ml / 100gAl; 4) Filtration: Three-stage filtration, 20ppi + 40ppi + 60ppi, filter box preheated to 710℃; 5) Casting: Temperature 710-715℃, speed 45mm / min, casting rod diameter φ130mm.

Images