Wrought aluminum alloy for forging steering knuckle and preparation process of wrought aluminum alloy

Abstract

The wrought aluminum alloy for forging the steering knuckle is prepared from Al-Mg-Si alloy, and the Al-Mg-Si alloy is prepared from the following chemical components in percentage by mass: 1.05-1.45% of Si, 1.05-1.45% of Al, 1.05-1.45% of Si, 1.05-1.45% of Al, 1.05 0.75% to 1.20% of Mg; 0.6 to 0.9 percent of Mn; 0.2 to 0.4 percent of Fe; 0.2 to 0.3 percent of Cr; 0.1% to 0.3% of La; 0 to 0.1 percent of Cu; and 0.01 to 0.06 percent of Ti. The invention has the following beneficial effects: by increasing the contents of Mn and Cr elements, the corrosion resistance and impact resistance are enhanced; as a rare earth additive with relatively low cost, the La element is suitable for being added and used in civil industry; the La element can form an AlSiLa second phase to promote the dispersion strengthening effect of particles; la is used for modifying a long-strip-shaped beta-AlFeSiLa phase into short-rod-shaped alpha-AlFeSi, so that the harm caused by the Fe element is reduced; and the La element is enriched on the surface of the Mg2Si strengthening phase, so that the corrosion resistance of the Al-Mg-Si element is improved.

Description

Technical Field

[0001] The invention relates to the technical field of new materials, in particular to a deformed aluminum alloy for forging a steering knuckle and a preparation process thereof. Background Art

[0002] Deformed aluminum alloy materials are the cornerstone of forged parts, and their organization and performance have a decisive influence on subsequent products. At present, the deep well casting process is used for deformed aluminum alloy bars, but there have been a number of major safety accidents in the deep well casting process recently, and it is urgent to find a safer process for deformed aluminum alloy bars. Forged aluminum alloy steering knuckles are usually made of Al-Mg-Si alloy, and micro-alloying with elements such as Cu, Mn and Fe will increase the strength while also causing a decrease in elongation, corrosion resistance and impact toughness. There are multiple plastic deformations in the steering knuckle forging process, and the large local accumulated deformation can easily trigger abnormally coarse grains.

[0003] In view of the above situation, it is necessary to improve the existing aluminum alloy material for steering knuckle so that it can meet the current needs for steering knuckle use. Summary of the invention

[0004] To achieve the above-mentioned purpose, the technical solution of the present invention is a deformed aluminum alloy for forging steering knuckle, which is prepared by Al-Mg-Si alloy, and the Al-Mg-Si alloy is composed of the following chemical components by mass percentage: Si: 1.05-1.45%; Mg: 0.75-1.20%; Mn: 0.6-0.9%; Fe: 0.2-0.4%; Cr: 0.2-0.3%; La: 0.1-0.3%; Cu: 0-0.1%; Ti: 0.01-0.06%.

[0005] To further supplement the technical solution, the La element is added to the alloy in two different processes and forms. The first time it is added to the melting furnace in the form of AlLa10 intermediate alloy, and the composition is controlled at 0.20-0.25%; the second time it is added online to the flow channel in the form of AlTiC0.2La wire.

[0006] As a further supplement to the technical solution, impurities such as Zn, Na, Pb and other elements are controlled below 0.01%.

[0007] A preparation process of a deformed aluminum alloy for forging a steering knuckle comprises the following steps:

[0008] Step 1: Put aluminum ingot, crystalline silicon, magnesium ingot, manganese sheet, AlFe20 master alloy, AlCu50 master alloy, A75Cr additive, and AlLa10 master alloy into a melting furnace for heating, and the temperature of the aluminum liquid is controlled at 720-755°C;

[0009] Step 2: When the aluminum liquid temperature reaches 720°C, argon purge refining is carried out, and the refining time is controlled within 15 to 30 minutes. The refining agent is in the form of environmentally friendly powder;

[0010] Step 3: The aluminum liquid passes through a 50PPI foam ceramic filter plate and a degasser. After degassing, the hydrogen content in the aluminum liquid is controlled below 0.10cc / 100g Al.

[0011] Step 4: Add grain refiner AlTi5C0.2La wire online;

[0012] Step 5: Cool the treated aluminum liquid through a special mold to form it;

[0013] Step 6: The cast aluminum rod is transported to the homogenizing furnace for heat treatment. The heating rate is controlled at 180-240℃ / Hr, the insulation temperature is 520-550℃, and the insulation time is 8-12Hr.

[0014] Step 7: After homogenization and heat preservation, the aluminum rod is cooled, and the cooling rate is controlled at 200-300℃ / Hr.

[0015] As a further supplement to the technical solution, the diameter of the cast aluminum rod is φ80~300mm.

[0016] As a further supplement to the technical solution, in step five, the casting temperature is controlled at 670-720° C., and the casting speed is 100 mm-350 mm / min.

[0017] As a further supplement to the technical solution, the homogenization heat treatment cooling adopts a rapid air cooling process.

[0018] The beneficial effects are as follows: the present invention enhances corrosion resistance and impact resistance by increasing the content of Mn and Cr elements; La element is a relatively low-cost rare earth additive and is suitable for addition; La element can form AlSiLa second phase to promote particle dispersion strengthening; La modifies the long strip-shaped β-AlFeSiLa phase into short rod-shaped α-AlFeSi, reducing the harm caused by Fe element; La element is enriched on the surface of Mg2Si strengthening phase, improving the corrosion resistance of Al-Mg-Si element. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the microstructure diagram of the aluminum rod of the present invention, and the grain size is level 7;

[0020] Figure 2 This is the macroscopic organization diagram of the φ80mm aluminum bar of the present invention;

[0021] Figure 3 The thickness of the φ80mm segregation layer of the present invention is 352um;

[0022] Figure 4 This is the macroscopic organization diagram of the Φ130mm aluminum bar of the present invention;

[0023] Figure 5 The φ130mm segregation layer of the present invention has a thickness of 480um. DETAILED DESCRIPTION

[0024] In order to make the technical solution more clear to those skilled in the art, Figure 1 -5 Detailed description of the technical solution of the present invention:

[0025] A deformed aluminum alloy for forging a steering knuckle is prepared from an Al-Mg-Si alloy, wherein the Al-Mg-Si alloy consists of the following chemical components by mass percentage: Si: 1.05-1.45%; Mg: 0.75-1.20%; Mn: 0.6-0.9%; Fe: 0.2-0.4%; Cr: 0.2-0.3%; La: 0.1-0.3%; Cu: 0-0.1%; and Ti: 0.01-0.06%.

[0026] In this case, the corrosion resistance and impact resistance are enhanced by increasing the content of Mn and Cr elements; La element is a relatively low-cost rare earth additive and is suitable for addition; La element can form the AlSiLa second phase to promote particle dispersion strengthening; La modifies the long strip-shaped β-AlFeSiLa phase into short rod-shaped α-AlFeSi, reducing the harm caused by Fe element; La element is enriched on the surface of Mg2Si strengthening phase, improving the corrosion resistance of Al-Mg-Si element.

[0027] The La element is added to the alloy in two different processes and forms. The first time, it is added to the melting furnace in the form of AlLa10 master alloy, and the composition is controlled at 0.20-0.25%. The second time, it is added online to the launder in the form of AlTiC0.2La wire.

[0028] Among them, impurities such as Zn, Na, Pb and other elements are controlled below 0.01%.

[0029] A preparation process of a deformed aluminum alloy for forging a steering knuckle comprises the following steps:

[0030] Step 1: Put aluminum ingots, crystalline silicon, magnesium ingots, manganese sheets, AlFe20 master alloy, AlCu50 master alloy, A75Cr additive, and AlLa10 master alloy into a melting furnace for heating.

[0031] The temperature of aluminum liquid is controlled at 720~755℃;

[0032] Step 2: When the aluminum liquid temperature reaches 720°C, argon purge refining is carried out, and the refining time is controlled within 15 to 30 minutes. The refining agent is in the form of environmentally friendly powder;

[0033] Step 3: The aluminum liquid passes through a 50PPI foam ceramic filter plate and a degasser. After degassing, the hydrogen content in the aluminum liquid is controlled below 0.10cc / 100g Al.

[0034] Step 4: Add grain refiner AlTi5C0.2La wire online;

[0035] Step 5: Cool the treated aluminum liquid through a special mold to form it;

[0036] Step 6: The cast aluminum rod is transported to the homogenizing furnace for heat treatment. The heating rate is controlled at 180-240℃ / Hr, the insulation temperature is 520-550℃, and the insulation time is 8-12Hr.

[0037] Step 7: After homogenization and heat preservation, the aluminum rod is cooled, and the cooling rate is controlled at 200-300℃ / Hr.

[0038] Among them, the diameter of the cast aluminum rod is φ80~300mm. This process is convenient for operators to monitor the forming status of the aluminum rod in real time and reduce safety production accidents caused by aluminum leakage in the deep well casting process.

[0039] Wherein, in step five, the casting temperature is controlled at 670-720° C., and the casting speed is 100 mm-350 mm / min. High-speed casting can make the α-Al matrix particles finer and the segregation layer thinner.

[0040] Among them, the homogenization heat treatment cooling adopts a rapid air cooling process, which forms a quenching effect, precipitates a uniformly dispersed second phase, and improves the yield strength of the product.

[0041] This technical solution tested the structural performance of aluminum rods with diameters of 80mm and 130mm, as shown in the following table:

[0042] Diameter / mm Tensile strength / MPa Yield strength / MPa Elongation / % Segregation layer thickness / um 80 170 105 24 352 130 160 98 22 480

[0043] Among them, the macroscopic organization diagram of Φ80mm aluminum rod: no defects such as cracks, inclusions, pores, looseness, etc., and the grain size is level one;

[0044] Macroscopic organization diagram of Φ130mm aluminum bar: no cracks, inclusions, pores, looseness and other defects, and the grain size is level one;

[0045] The thickness of segregation layer of Φ80mm aluminum rod is 352um; the thickness of segregation layer of Φ130mm aluminum rod is 480um.

[0046] The above technical solutions only reflect the preferred technical solutions of the technical solutions of the present invention. Some changes that may be made to certain parts thereof by technicians in this technical field all reflect the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A deformed aluminum alloy for forging steering knuckle, prepared from Al-Mg-Si alloy, characterized in that: The Al-Mg-Si alloy is composed of the following chemical components in percentage by mass composition: Si: 1.05-1.45%; Mg: 0.75~1.20%; Mn: 0.6~0.9%; Fe: 0.2-0.4%; Cr：0.2～0.3％； La: 0.1~0.3%; Cu: 0~0.1%; Ti: 0.01~0.06%.

2. The deformed aluminum alloy for forging steering knuckle according to claim 1, characterized in that: The La element is added to the alloy in two different processes and forms. The first time, it is added to the melting furnace in the form of AlLa10 master alloy, and the composition is controlled at 0.20-0.25%; the second time, it is added online to the launder in the form of AlTiC0.2La wire.

3. The deformed aluminum alloy for forging steering knuckle according to claim 2, characterized in that: Impurities such as Zn, Na, and Pb are controlled below 0.01% to reduce the risk of forging cracking.

4. A process for preparing a deformed aluminum alloy for forging a steering knuckle according to claims 1 to 3, characterized in that: The following steps are involved: Step 1: Put aluminum ingot, crystalline silicon, magnesium ingot, manganese sheet, AlFe20 master alloy, AlCu50 master alloy, A75Cr additive, and AlLa10 master alloy into a melting furnace for heating, and the temperature of the aluminum liquid is controlled at 720-755°C; Step 2: When the aluminum liquid temperature reaches 720°C, argon purge refining is carried out, and the refining time is controlled within 15 to 30 minutes. The refining agent is in the form of environmentally friendly powder; Step 3: The aluminum liquid passes through a 50PPI foam ceramic filter plate and a degasser. After degassing, the hydrogen content in the aluminum liquid is controlled below 0.10cc / 100g Al. Step 4: Add grain refiner AlTi5C0.2La wire online; Step 5: Cool the treated aluminum liquid through a special mold to form it; Step 6: The cast aluminum rod is transported to the homogenizing furnace for heat treatment. The heating rate is controlled at 180-240℃ / Hr, the insulation temperature is 520-550℃, and the insulation time is 8-12Hr. Step 7: After homogenization and heat preservation, the aluminum rod is cooled, and the cooling rate is controlled at 200-300℃ / Hr.

5. The process for preparing a deformed aluminum alloy for forging a steering knuckle according to claim 4, characterized in that: The diameter of the cast aluminum rod is φ80~300mm.

6. The process for preparing a deformed aluminum alloy for forging a steering knuckle according to claim 4, characterized in that: In the step 5, the casting temperature is controlled at 670-720° C., and the casting speed is 100 mm-350 mm / min.

7. The process for preparing a deformed aluminum alloy for forging a steering knuckle according to claim 4, characterized in that: The homogenization heat treatment cooling adopts a rapid air cooling process.

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