High corrosion resistant aluminum alloy and preparation method and application thereof

Abstract

This invention discloses a high corrosion-resistant aluminum alloy, its preparation method, and its applications. It is composed of the following chemical elements by mass percentage: Fe ≤ 0.5 wt%, Si 0.7 wt%–1.3 wt%, Cu ≤ 0.1 wt%, Mn 0.6 wt%–1.2 wt%, Mg 0.6 wt%–1.2 wt%, Cr ≤ 0.25 wt%, Zn ≤ 0.2 wt%, Ti ≤ 0.1 wt%, Ni 0.001 wt%–0.002 wt%, with the balance being Al. The elemental content in conventional 6-series aluminum alloys has been adjusted to improve corrosion resistance while maintaining other mechanical properties. Homogenization treatment is performed at a temperature of 570–620 °C below the solidus line of the aluminum alloy before hot working, causing uniform precipitation of the MnAl6 phase, reducing or eliminating intragranular segregation, thereby achieving homogenization, dense grain boundaries, and further improving the stability of the alloy's corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of automotive parts technology, specifically relating to a high corrosion-resistant aluminum alloy, its preparation method, and its application. Background Technology

[0002] The automotive industry is currently undergoing a transformation towards lightweighting, with many automotive parts (such as connecting rod assemblies) gradually replacing the original iron metals with lightweight metals such as aluminum alloys and magnesium alloys. With the widespread use of lightweight metals, whether their strength, hardness, corrosion resistance, and other properties can replace steel has become a research topic for various companies.

[0003] The shipping time from Shanghai Port to Germany is 30-45 days. Prolonged sea transport can lead to marine atmospheric corrosion of metals (i.e., the marine atmosphere contains salt and other corrosive substances), which accelerates the corrosion process on the aluminum alloy surface. In the marine atmosphere, pitting and intergranular corrosion may form on the aluminum alloy surface, affecting the product's appearance and lifespan. In severe cases, intergranular corrosion can even cause product breakage, resulting in quality issues.

[0004] In China, the main countermeasure for aluminum alloy corrosion prevention is to perform anodizing after product processing to combat aluminum alloy corrosion during transportation. However, anodizing may have the following drawbacks: (1) Environmental hazards: The electrolytes used in the anodizing process, such as sulfuric acid and chromic acid, may cause environmental pollution if not handled properly; (2) Operational safety risks: Anodizing involves the use of corrosive chemicals and electricity, so strict safety measures are required to prevent chemical leaks, electric shocks and other accidents; (3) Health risks: Long-term exposure to certain anodizing chemicals may affect the health of operators, such as skin irritation and respiratory diseases; (4) Changes in material properties: Anodizing may change some mechanical properties of materials, such as increased hardness, which may cause the material to become brittle and affect its ductility and toughness; (5) Size changes: During the anodizing process, the size of the material may change slightly due to the formation of the oxide film, which may become a problem in precision engineering; (6) Cost issues: Anodizing is a relatively expensive surface treatment method, which may increase the production cost of the product; (7) Waste generated during the anodizing process needs to be properly disposed of to avoid long-term environmental pollution. Therefore, the development of highly corrosion-resistant aluminum alloys (for the manufacture of automotive parts) is of practical significance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high corrosion-resistant aluminum alloy.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a high corrosion-resistant aluminum alloy, which is composed of the following chemical elements in weight percentage: Fe≤0.5wt%, Si 0.7wt%~1.3wt%, Cu≤0.1wt%, Mn0.6wt%~1.2wt%, Mg0.6wt%-1.2wt%, Cr≤0.25wt%, Zn≤0.2wt%, Ti≤0.1wt%, Ni0.001wt%~0.002wt%, with the balance being Al.

[0007] Ideally, it is composed of the following chemical elements in mass percentage: Fe 0.113wt%, Si 0.828%, Cu 0.003wt%, Mn 0.639%, Mg 0.825%, Cr 0.139wt%, Zn 0.002wt%, Ti 0.042wt%, Ni 0.0015wt%, with the balance being Al.

[0008] The purpose of this invention is to provide a method for preparing the above-mentioned high corrosion-resistant aluminum alloy, comprising the following steps:

[0009] Step S1: Take aluminum ingots, aluminum-iron alloys, aluminum-silicon alloys, aluminum-copper alloys, aluminum-magnesium alloys, aluminum-manganese alloys, aluminum-zinc alloys, aluminum-nickel alloys, aluminum-chromium alloys, and aluminum-titanium alloys as raw materials and smelt them.

[0010] Step S2: Perform online degassing on the product from step S1. The degassing chamber temperature is 720-740℃, the argon pressure is 0.2±0.05Mpa, the degasser rotor speed is 350±50r / min, the degassing chamber preheating time is ≥60min and the hydrogen content is ≤0.18ml / 100g.

[0011] Step S3: Clean and filter the product from step S2 online;

[0012] Step S4: Refine the product from step S3 and then let it stand. The refining process conditions are: refining temperature 740-760℃, refining time 18-22min, and refining agent 0.8-1.0kg / t.

[0013] Step S5: Inject the product from step S4 into a mold to cool and form a casting, and perform homogenization treatment; heat the casting to 400-550°C and place it on an extruder for extrusion; the homogenization treatment temperature is 570-620°C, the extrusion tonnage of the extruder is 8000-10000 tons, and the extrusion speed is 0.8-1.2 cm / s;

[0014] Step S6: Immerse the product from step S5 in water to cool it, stretch and straighten it to ensure dimensional accuracy and product straightness, then saw and deburr it.

[0015] Ideally, it also includes the following steps:

[0016] Step S7: Apply lubricant to the product from step S6, and then place it in a press for forging. The forging parameters are: 600-700 ton press, main cylinder pressure 55-65 bar, main cylinder upper limit 660 mm, main cylinder deceleration position 680 mm, main cylinder lower limit 815 mm, and holding time 2 seconds.

[0017] Furthermore, in step S1, the melting temperature is 740-760℃.

[0018] Furthermore, in step S4, the refining process is further performed by treating with argon gas at a pressure of 0.06 to 0.15 MPa for 3 to 5 minutes, followed by standing for 5 to 10 minutes.

[0019] Furthermore, in step S4, the settling time is 18 to 22 minutes.

[0020] Further, in step S6, the temperature of the water is 20-30°C; in step S7, the lubricant is zinc stearate powder.

[0021] Another object of the present invention is to provide an application of the above-mentioned high corrosion-resistant aluminum alloy for the manufacture of automotive connecting rod assemblies.

[0022] Ideally, the automotive linkage assembly includes a linkage body and connectors formed at both ends of the linkage body, each connector having a connection hole.

[0023] This invention relates to a high corrosion-resistant aluminum alloy, which adjusts the element content of conventional 6-series aluminum alloys: increasing the proportion of Mn content, adding a specific amount of Ni element, reducing the harmful effects of Fe and Cu elements, and reducing the proportion of Cu and Zn content. This can improve the corrosion resistance of the alloy material while ensuring other mechanical properties.

[0024] The method for preparing high corrosion-resistant aluminum alloy of the present invention involves homogenizing the aluminum alloy at a temperature of 570-620°C below the solidus line before hot working, so as to uniformly precipitate the MnAl6 phase, reduce or eliminate intragranular segregation, thereby achieving homogenization, dense grain boundaries, and further improving the corrosion resistance stability of the alloying elements. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the automotive connecting rod assembly of the present invention. Detailed Implementation

[0026] This invention relates to a high corrosion-resistant aluminum alloy composed of the following chemical elements by mass percentage: Fe ≤ 0.5 wt%, Si 0.7 wt%–1.3 wt%, Cu ≤ 0.1 wt%, Mn 0.6 wt%–1.2 wt%, Mg 0.6 wt%–1.2 wt%, Cr ≤ 0.25 wt%, Zn ≤ 0.2 wt%, Ti ≤ 0.1 wt%, Ni 0.001 wt%–0.002 wt%, with the balance being Al. The elemental content of conventional 6-series aluminum alloys has been adjusted: the proportion of Mn content has been increased, a specific amount of Ni has been added, the harmful effects of Fe and Cu have been reduced, and the proportions of Cu and Zn have been decreased. This approach improves the corrosion resistance of the alloy material while maintaining other mechanical properties.

[0027] It is preferably composed of the following chemical elements in weight percentage: Fe 0.113wt%, Si 0.828%, Cu 0.003wt%, Mn 0.639%, Mg 0.825%, Cr 0.139wt%, Zn 0.002wt%, Ti 0.042wt%, Ni 0.0015wt%, with the balance being Al. Under these conditions, the aluminum alloy exhibits the best corrosion resistance.

[0028] The preparation method of the above-mentioned high corrosion-resistant aluminum alloy includes the following steps: Step S1, smelting aluminum ingots, aluminum-iron alloys, aluminum-silicon alloys, aluminum-copper alloys, aluminum-magnesium alloys, aluminum-manganese alloys, aluminum-zinc alloys, aluminum-nickel alloys, aluminum-chromium alloys, and aluminum-titanium alloys as raw materials; Step S2, online degassing treatment of the product of Step S1, with a degassing box temperature of 720-740℃, argon pressure of 0.2±0.05Mpa, degasser rotor speed of 350±50r / min, degassing box preheating time ≥60min, and hydrogen content ≤0.18ml / 100g; Step S3, slag removal and online filtration treatment of the product of Step S2; Step S4, refining treatment of the product of Step S3. The product is then allowed to stand. The refining process conditions are: refining temperature 740-760℃, refining time 18-22min, and refining agent 0.8-1.0kg / t. Step S5: The product from step S4 is injected into a mold to cool and form a casting, followed by homogenization treatment. The casting is heated to 400-550℃ and placed on an extruder for extrusion. The homogenization temperature is 570-620℃, the extrusion tonnage of the extruder is 8000-10000 tons, and the extrusion speed is 0.8-1.2cm / s. Step S6: The product from step S5 is immersed in water for cooling, stretched, and straightened to ensure dimensional accuracy and product straightness. It is then sawn and deburred. Before hot working, homogenization treatment (i.e., homogenization) is performed at a temperature of 570–620℃ below the solidus line of the aluminum alloy to ensure uniform precipitation of the MnAl6 phase, reduce or eliminate intragranular segregation, achieve homogenization, and make the grain boundaries dense, thereby further improving the corrosion resistance and stability of the alloying elements. Improving the slag removal ability during melting can enhance the purity of the aluminum alloy; after melting, a homogenization step is required to ensure that the alloy molecules are evenly distributed in the casting. Although existing technologies can refine the ingot grains by adding trace amounts of grain refiners to the molten aluminum, the crystal structure of the ingot is still not uniform. This is because the solidification of the molten aluminum starts from the inner wall of the crystallizer and extends into the interior of the molten aluminum perpendicular to the cooling surface, so the casting structure has obvious directionality. As the aluminum solidification layer thickens, the heat transfer coefficient decreases, and the inconsistency in the formation and growth of internal and external crystal nuclei leads to changes in the shape, orientation, and size of the grains. Segregation caused by metal composition during solidification, and the difference in manganese concentration between the grain periphery and the grain interior, expands the recrystallization temperature range, reduces the nucleation rate, and thus easily produces coarse grains; during casting, varying degrees of shrinkage cavities and porous structures are generated inside the ingot. During hot rolling and extrusion, because hot working deformation and recrystallization occur simultaneously, a recrystallized structure dominated by equiaxed grains is formed, which can improve the non-uniformity of the crystal structure in casting to varying degrees. This can further improve the performance of hot rolling and extrusion, and enhance the quality and grade of products after hot working.

[0029] The preferred method also includes the following steps: Step S7, applying lubricant to the product from Step S6, followed by forging in a press; the forging parameters are: 600-700 ton press, main cylinder pressure 55-65 bar, main cylinder upper limit 660 mm, main cylinder deceleration position 680 mm, main cylinder lower limit 815 mm, and holding time 2 seconds. In Step S1, the melting temperature is 740-760℃. In Step S4, the refining process is further performed with argon gas at a pressure of 0.06-0.15 MPa for 3-5 minutes, followed by standing for 5-10 minutes. In Step S4, the standing time is 18-22 minutes. In Step S6, the water temperature is 20-30℃; in Step S7, the lubricant is zinc stearate powder.

[0030] During smelting, it is preferable to perform proper stirring for approximately 15-25 minutes to improve the homogeneity of the molten mixture. It is also preferable to adjust the order of material addition: for example, first add small pieces of recycled material and aluminum alloy ingots with lower melting points, then add larger, higher-melting-point aluminum ingots and intermediate alloys, and finally add easily burnable elements such as Mg. After complete smelting, there will be a lot of slag on the surface of the alloy liquid, which needs to be removed. Simply sprinkle a conventional slag remover evenly on the surface of the aluminum liquid and stir shallowly and uniformly. The filter box should be preheated for ≥40 minutes until the filter plate is red-hot. The ingot (i.e., the casting) should be aligned on the extrusion axis of the extrusion press to ensure the stability of the extrusion process.

[0031] The preferred embodiments of the present invention will now be described in detail.

[0032] Example 1

[0033] This embodiment provides an automotive connecting rod assembly and its manufacturing method, such as... Figure 1 As shown, the automotive linkage assembly includes a linkage body 1 and connectors 2 formed at both ends of the linkage body 1 (the connectors 2 are smoothly connected to the linkage body 1), and each connector 2 has a connection hole 21.

[0034] The automotive connecting rod assembly is formed from a high corrosion-resistant aluminum alloy, which is composed of the following chemical elements by mass percentage: Fe 0.113wt%, Si 0.828%, Cu 0.003wt%, Mn 0.639%, Mg 0.825%, Cr 0.139wt%, Zn 0.002wt%, Ti 0.042wt%, Ni 0.0015wt%, with the balance being Al.

[0035] The preparation method of the above-mentioned automotive connecting rod assembly (high corrosion-resistant aluminum alloy) includes the following steps:

[0036] Step S1: Take aluminum ingots, aluminum-iron alloys, aluminum-silicon alloys, aluminum-copper alloys, aluminum-magnesium alloys, aluminum-manganese alloys, aluminum-zinc alloys, aluminum-nickel alloys, aluminum-chromium alloys, and aluminum-titanium alloys as raw materials and smelt them (the smelting temperature is controlled within the range of 740-760℃, which has little impact on product performance (the same applies below); stir for 20 minutes during smelting).

[0037] Step S2: Perform online degassing on the product from step S1. The degassing chamber temperature is 720-740℃, the argon pressure is 0.2±0.05Mpa, the degasser rotor speed is 350±50r / min, the degassing chamber preheating time is ≥60min and the hydrogen content is ≤0.18ml / 100g.

[0038] Step S3: Clean the product from step S2 (sprinkle the cleaning agent (NA-1#) evenly on the surface of the alloy liquid and stir it shallowly and evenly), and perform online filtration treatment (preheat the filter box for 40 minutes and heat it until the filter plate is red-hot).

[0039] Step S4: Refine the product from step S3, then let it stand (20±2 min). The refining process conditions are: refining temperature 740-760℃, refining time 20±2 min, refining agent (Kailida refining agent) 0.8-1.0 kg / t; during the refining process, treat with argon gas at a pressure of 0.06~0.15Mpa for 3-5 minutes, then let it stand for 5-10 minutes.

[0040] Step S5: Inject the product from step S4 into a mold to cool and form a casting, and perform homogenization treatment; heat the casting to 400-550°C and place it on an extruder for extrusion; the homogenization treatment temperature is 570-620°C, the extrusion tonnage of the extruder is 8000-10000 tons, and the extrusion speed is 0.8-1.2 cm / s;

[0041] Step S6: Immerse the product from step S5 in water (20-30℃) for cooling, stretch and straighten to ensure dimensional accuracy and product straightness, saw (cut into short pieces with a thickness of 17mm), and deburr.

[0042] Step S7: Apply lubricant (zinc stearate powder) to the product from step S6, and then place it in a press for forging. The forging parameters are: 650-ton press, main cylinder pressure 60 bar, main cylinder upper limit 660 mm, main cylinder deceleration position 680 mm, main cylinder lower limit 815 mm, and holding time 2 seconds.

[0043] Example 2

[0044] This embodiment provides an automotive connecting rod assembly and its manufacturing method, which is basically the same as that in Embodiment 1, except that the high corrosion-resistant aluminum alloy used is composed of the following chemical elements by mass percentage: Fe 0.113wt%, Si 0.828%, Cu 0.003wt%, Mn 0.639%, Mg 0.825%, Cr 0.139wt%, Zn 0.002wt%, Ti 0.042wt%, Ni 0.001wt%, with the balance being Al.

[0045] Example 3

[0046] This embodiment provides an automotive connecting rod assembly and its manufacturing method, which is basically the same as that in Embodiment 1, except that the high corrosion-resistant aluminum alloy used is composed of the following chemical elements by mass percentage: Fe 0.113wt%, Si 0.828%, Cu 0.003wt%, Mn 0.639%, Mg 0.825%, Cr 0.139wt%, Zn 0.002wt%, Ti 0.042wt%, Ni 0.002wt%, with the balance being Al.

[0047] Comparative Example 1

[0048] This example provides an automotive connecting rod assembly and its manufacturing method, which is basically the same as that in Example 1, except that the high corrosion-resistant aluminum alloy used is composed of the following chemical elements by mass percentage: Fe 0.113wt%, Si 0.828%, Cu 0.003wt%, Mn 0.639%, Mg 0.825%, Cr 0.139wt%, Zn 0.002wt%, Ti 0.042wt%, Ni 0.003wt%, with the balance being Al.

[0049] Comparative Example 2

[0050] This example provides an automotive connecting rod assembly and its manufacturing method, which is basically the same as that in Example 1, except that the high corrosion-resistant aluminum alloy used is composed of the following chemical elements by mass percentage: Fe 0.113wt%, Si 0.828%, Cu 0.003wt%, Mn 0.55%, Mg 0.825%, Cr 0.139wt%, Zn 0.002wt%, Ti 0.042wt%, Ni 0.0015wt%.

[0051] Comparative Example 3

[0052] This example provides an automotive connecting rod assembly and its manufacturing method, which is basically the same as that in Example 1, except that the high corrosion-resistant aluminum alloy used is composed of the following chemical elements by mass percentage: Fe 0.113wt%, Si 0.828%, Cu 0.003wt%, Mn 1.32%, Mg 0.825%, Cr 0.139wt%, Zn 0.002wt%, Ti 0.042wt%, Ni 0.003wt%, with the balance being Al.

[0053] Comparative Example 4

[0054] This example provides an automotive connecting rod assembly and its preparation method, which is basically the same as that in Example 1, except that homogenization treatment is not performed in step S5.

[0055] Corrosion test (maximum corrosion depth, μm) Example 1 20 Example 2 26 Example 3 25 Comparative Example 1 35 Comparative Example 2 30 Comparative Example 3 37 Comparative Example 4 40

[0056] Note: The corrosion test method is as follows: According to Volkswagen's magnesium-aluminum alloy inter-corrosion test method, the sample is immersed in NaCl-HCl solution at room temperature for 2 hours for corrosion testing. After the test, cracks are first inspected using a low-magnification loupe (×25) and then a high-magnification loupe (×200).

[0057] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A high corrosion resistant aluminum alloy, characterized by, It is composed of the following mass percentage of chemical elements: Fe≤0.5wt%, Si 0.7wt%-1.3wt%, Cu≤0.1wt%, Mn 0.6wt%-1.2wt%, Mg 0.6wt%-1.2wt%, Cr≤0.25wt%, Zn≤0.2wt%, Ti≤0.1wt%, Ni 0.001wt%-0.002wt%, the balance is Al; The preparation method of the high corrosion-resistant aluminum alloy comprises the following steps: Step S1, taking aluminum ingot, aluminum-iron alloy, aluminum-silicon alloy, aluminum-copper alloy, aluminum-magnesium alloy, aluminum-manganese alloy, aluminum-zinc alloy, aluminum-nickel alloy, aluminum-chromium alloy and aluminum-titanium alloy as raw materials for smelting; the smelting temperature is 740-760 DEG C; Step S2, the product of step S1 is treated by on-line degassing, the degassing tank temperature is 720-740 DEG C, the argon pressure is 0.2±0.05 Mpa, the degassing machine rotor speed is 350±50 r / min, the degassing tank preheating time is greater than or equal to 60 min and the hydrogen content is less than or equal to 0.18 ml / 100 g; Step S3, the product of step S2 is treated by slag cleaning and on-line filtering; Step S4, the product of step S3 is treated by refining and then standing, the process conditions of the refining treatment are as follows: the refining temperature is 740-760 DEG C, the refining time is 18-22 min, the refining agent is 0.8-1.0 kg / t; during the refining treatment, the product is treated by argon with a pressure of 0.06-0.15 Mpa for 3-5 min, and then standing for 5-10 min; the standing time is 18-22 min; Step S5, the product of step S4 is injected into a mold to cool and form a casting, and is treated by homogenization; the casting is heated to 400-550 DEG C and placed on an extruder for extrusion; the homogenization treatment temperature is 570-620 DEG C, and the extruder has an extrusion tonnage of 8000-10000 tons and an extrusion speed of 0.8-1.2 cm / s; Step S6, the product of step S5 is immersed in water for cooling, stretching and straightening to ensure the dimensional accuracy and straightness of the product, and is sawn and deburred; the water temperature is 20-30 DEG C; Step S7, a lubricant is applied to the product of step S6, and then the product is put into a press for forging and forming; the forging and forming parameters are as follows: a 600-700 ton press, a main cylinder pressure of 55-65 bar, a main cylinder upper limit of 660 mm, a main cylinder deceleration of 680 mm, a main cylinder lower limit of 815 mm, and a pressure maintaining time of 2 seconds; in step S7, the lubricant is zinc stearate powder.

2. The high corrosion resistant aluminum alloy according to claim 1, characterized by, It is composed of the following mass percentage of chemical elements: Fe 0.113wt%, Si 0.828%, Cu 0.003wt%, Mn 0.639%, Mg 0.825%, Cr 0.139wt%, Zn 0.002wt%, Ti 0.042wt%, Ni 0.0015wt%, the balance is Al.

3. Use of the high corrosion resistant aluminum alloy according to any one of claims 1 to 2, characterized in that: The application relates to a connecting rod assembly for a vehicle.

4. Use of the high corrosion resistant aluminium alloy according to claim 3, characterized in that: The automobile linkage assembly comprises a linkage body and connecting heads formed at both ends of the linkage body, and each connecting head is provided with a connecting hole.

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