CN101966575A - Process for casting aluminum alloy wheel and heat treatment process - Google Patents

Abstract

A 8356-type A356 aluminum alloy wheel casting process and heat treatment process, the process includes the following steps: a, using a metal mold low-pressure casting process, the pouring temperature is 690 ° C to 735 ° C, and the mold preheating temperature is 250 ° C to 350 ° C ; b, carry out refinement in the smelting furnace, and adjust the content of iron and silicon in the molten aluminum; carry out metamorphism and refining with nitrogen blowing outside the furnace in the refining ladle, and adjust the contents of magnesium, strontium, and titanium in the molten aluminum; c, in the Cooling pipes are added to the thick and large parts of the wheel for quick cooling, and thermal insulation cotton is filled around the side molds to delay the cooling rate in the middle of the rim to achieve sequential solidification; d. After the wheel casting is cooled, it is put into a heat treatment kiln for solid solution aging treatment. The invention designs suitable pouring temperature and reasonable cooling measures, effectively realizes the feeding of castings, and installs a filter screen at the riser pipe during the pouring process to effectively prevent inclusions, and through the control of key process parameters, guarantees 8356 type A356 aluminum alloy wheel casting product quality.

Description

Aluminum alloy wheel casting process and heat treatment process

technical field

The invention relates to an aluminum alloy wheel manufacturing technology, in particular to a casting process and a heat treatment process suitable for an 8356-type A356 aluminum alloy wheel. the

Background technique

After decades of construction in my country's automobile industry, automobile production has increased significantly. Especially after joining the WTO, China's automobile industry has achieved a great leap forward with the help of the capital and technology of the international automobile industry. In the next 5-10 years, China will It is the largest and fastest growing auto market in the world, which has been generally recognized by the international industry. Energy, environment and safety are the three major issues of great concern to all countries in the world today. The development of the automobile industry and the popularization of automobile applications are closely related to these three issues. When a car is running, it consumes a large amount of petroleum fuel and discharges a large amount of harmful waste, such as carbon dioxide, nitrogen oxide, carbon monoxide, etc., causing serious pollution to the atmosphere. With the increasing requirements of modern automobiles for energy saving and consumption reduction, safety and environmental protection regulations are becoming increasingly stringent, and the requirements for automobile lightweight are more urgent. the

The use of aluminum alloy wheels is the fastest and most effective way to reduce the weight of automobiles. The performance of aluminum alloy wheels directly depends on the manufacturing technology it adopts, and its manufacturing process can be divided into forging and casting. At present, the main casting forming methods for producing wheels at home and abroad include metal mold gravity casting, low pressure casting, pressure casting and squeeze casting. The low-cost low-pressure casting process is mainly used in the domestic manufacturing of aluminum alloy automobile wheels, accounting for about 80% of the total output. the

A356 alloy is a kind of light alloy commonly used in wheel casting production at present, and is extremely sensitive to melting conditions. In the process of processing molten aluminum, the three aspects of purification, modification and refinement must be combined, and purification is the most critical control factor. Only by performing appropriate refinement or modification on the basis of efficient purification of molten aluminum can the Give full play to the potential of refinement and metamorphism, and finally achieve the purpose of effectively controlling the metallurgical quality of aluminum melt and improving the performance of aluminum materials. the

Contents of the invention

The object of the present invention is just to provide a kind of 8356 type A356 aluminum alloy wheel casting process and heat treatment process for the deficiencies existing in the above-mentioned prior art. The process of the present invention adopts scientific purification technology, refinement and modification technology and corresponding heat treatment process to improve the material properties, which can effectively solve the problems of casting oxidation inclusions, pores, shrinkage cavities, porosity, etc., and also improve the mechanical properties to a certain extent . the

The purpose of the present invention can be achieved through the following technical measures:

Aluminum alloy wheel casting process and heat treatment process of the present invention comprise the following steps:

Described technology comprises the steps:

a. The metal mold low-pressure casting process is adopted, the pouring temperature is 690 ° C ~ 750 ° C, and the metal mold preheating temperature is 250 ° C ~ 350 ° C;

b. Refining in the smelting furnace, the refining agent is Al-5Ti-B master alloy, and the content of iron and silicon in the molten aluminum is adjusted, among which: Fe≤0.2%, and the content of Si is between 6.5% and 7.5% Carry out modification in the refining bag and nitrogen blowing refining outside the furnace. The modification agent is Ai-10Sr master alloy, and the content of magnesium, strontium and titanium in the aluminum liquid is adjusted, wherein: the content of Mg is between 0.2% and 0.4%. Ti≤0.2%, the amount of Sr added is 0.02%-0.03%Sr, and the adding temperature is 720°C-745°C; after that, it enters the process of degassing and casting;

c. Add cooling pipes to the thick and large part of the metal mold for rapid cooling, and fill insulation cotton around the side mold to delay the cooling speed in the middle of the rim to achieve sequential solidification;

5℃，固溶时间3-4h；淬火水温60℃，淬火时间2-2.5h，时效温度160

5℃，时效时间3-3.5h。d, d. After the wheel castings are cooled, they enter the heat treatment kiln for solution aging treatment, and the solution temperature is 535

5°C, solid solution time 3-4h; quenching water temperature 60°C, quenching time 2-2.5h, aging temperature 160

5°C, aging time 3-3.5h.

The degassing time of the degassing process described in the present invention is 150-200s, and it is 120-160s in winter. After degassing, analyze the alloy composition in the spectrum analyzer; when the metal mold is preheated, when the preheating temperature reaches 250 ° C When left and right, spray paint with a thickness of 0.2-0.5mm. the

The present invention has the following beneficial effects:

1. The process design of the invention is reasonable, shortens the production cycle of castings, improves productivity, adopts a typical low-pressure casting pouring system, and adds cooling pipes to the thick and large parts of the wheel according to the principle of sequential solidification from top to bottom during the solidification process Rapid cooling is carried out, and thermal insulation cotton is filled on the periphery of the side mold to delay the cooling rate of the middle part of the rim, which reduces casting defects and improves casting quality.

2. The invention uses a reasonable smelting process to improve the purity of molten aluminum, adopts a reasonable heat treatment process to homogenize the structure of the casting, alloys the molten aluminum, refines the structure, and improves the performance of the casting, thereby fully realizing the refinement of the material , Purification, homogenization, eliminating defects such as cracks and looseness, the strength of castings has been improved, and the automobile wheels as security parts will be safer. the

3. The 8356 type A356 aluminum alloy wheel produced by the invention has the characteristics of high performance, is easy to be recognized by users, and has great market potential. the

Description of drawings

Figure 1 The distribution of shrinkage cavities and shrinkage porosity in the 8356-type A356 aluminum alloy wheel (X-ray flaw detection test results). the

Figure 2 Schematic diagram of the location of cooling pipes and insulation cotton. the

Serial numbers in the figure: 1-upper mold, 2-side mold, 3-insulation cotton, 4-casting, 5-lower mold, 6-cooling pipe. the

Fig. 3 adopts the cast blank of 8356 type A356 aluminum alloy wheel produced by the present invention. the

Detailed ways

The present invention will be further described below in conjunction with embodiment (accompanying drawing):

The A356 alloy used in the present invention is a kind of light alloy commonly used in wheel casting production at present, and its specific composition is Si6.5%-7.5%, Mg0.2%-0.4%, Ti≤0.2%, Fe≤ 0.2%, Cu<0.2%, Zn<0.3%, balance Al. Since the aluminum liquid is very easy to absorb hydrogen, once the hydrogen content in the aluminum liquid is too high, a large number of pinholes or pores will be formed in the casting, so the aluminum liquid needs to be refined. That is, it needs to be refined in the smelting furnace. The refiner uses Al-5Ti-B master alloy, and the content of iron and silicon in the molten aluminum is adjusted, among which: Fe≤0.2%, and the content of Si is between 6.5% and 7.5%. Carry out modification in the refining bag and refining with nitrogen blowing outside the furnace. The modification agent is Ai-10Sr master alloy, and the content of magnesium, strontium and titanium in the aluminum liquid is adjusted. The content of Mg is between 0.2% and 0.4%, and Ti≤ 0.2%, added at a temperature of 720°C-745°C; after that, it enters the process of degassing and casting;

The invention adopts a metal mold low-pressure casting process, the pouring temperature is 690°C-750°C, and the mold preheating temperature is 250°C-350°C.

The degassing time of the degassing process described in the present invention is 150-200s in summer, and 120-160s in winter. After degassing, the alloy composition is analyzed in the spectrum analyzer; when the metal mold is preheated, when the preheating temperature reaches When the temperature is about 250℃, spray paint with a thickness of 0.2-0.5mm. the

According to the principle of sequential solidification from top to bottom, the present invention adds cooling pipes to the thick part of the wheel of the metal mold for rapid cooling, and fills the periphery of the side mold with thermal insulation cotton to delay the cooling speed of the middle part of the rim (as shown in Figure 2). the

The solution aging treatment process parameter that the present invention adopts is solution temperature 535 5°C, solid solution time 3-4h; quenching water temperature 60°C, quenching time 2-2.5h, aging temperature 160 5°C, aging time 3-3.5h.

The invention simulates the solidification process of the casting and field tests prove that after the pouring of the casting is completed, the sprue feeds the casting, and the probability of defects at the joint between the rim and the spoke is much higher than that at other parts. Therefore, installing a filter screen at the riser during the pouring process can effectively prevent inclusions and reduce casting defects. Adding cooling pipes to the thick and large parts of the castings and filling insulation cotton around the side molds can further improve the quality of the castings. the

Working process and result of the present invention:

Since the present invention adopts refining and alloying outside the furnace during the smelting process, a filter screen is placed at the riser pipe during the pouring process to ensure the purity of the molten metal; the cooling pipe and the filled insulation cotton installed by computer simulation technology are effective The ground acts as a sequential solidification, producing high performance castings with fewer casting defects (see Figure 3).

Comparative example (see Figure 1)

No cooling pipe and insulation cotton were installed, and the pouring process was observed, and it was found that there were shrinkage cavities at the joint between the rim and the spokes of the wheel castings and the rear edge of the rim. After machining, it was found that the subsurface of the casting had defects, and the impact performance met the design requirements, but the fatigue bending performance did not meet the design requirements.

Claims (3)

1. type A356 aluminum-alloy wheel casting technique and Technology for Heating Processing, it is characterized in that: described technology comprises the steps:

A, employing metal pattern low-pressure casting process, pouring temperature is 690 ℃～735 ℃, the metal die preheat temperature is 250 ℃～350 ℃;

B, carry out refinement in smelting furnace, fining agent adopts the Al-5Ti-B intermediate alloy, and adjusts the content of iron, silicon in the aluminium liquid, wherein: Fe≤0.2%, the content of Si is between 6.5%-7.5%; Go bad in the refining bag and the outer nitrogen blowing refining of stove, alterant adopts the Ai-10Sr intermediate alloy, and the content of magnesium, strontium, titanium in the adjustment aluminium liquid, wherein: the content of Mg is between 0.2%-0.4%, Ti≤0.2%, Sr addition are 0.02%-0.03%Sr, add 720 ℃-745 ℃ of temperature; Enter degasification, cast molding operation afterwards;

C, add cooling tube in the thick large part of wheel of metal pattern and carry out coldly soon, fill the cooling velocity that heat-preservation cotton delays the wheel rim middle part in that side form is peripheral, to realize consecutive solidification;

Go into heat treatment kiln after d, the cooling of wheel foundry goods, carry out solid solution aging and handle solid solubility temperature 535

5 ℃, solution time 3-4h; 60 ℃ of quenching water temperatures, cool time 2-2.5h, aging temp 160

5 ℃, aging time 3-3.5h.

2. technology according to claim 1 is characterized in that: be 150-200s summer degasification time of described degasification operation, and be 120-160s winter, analyzes alloying component after the degasification in spectroanalysis instrument.

3. technology according to claim 1 is characterized in that: when metal die was carried out preheating, when preheat temperature reached 250 ℃ of left and right sides, sprayed coating, thickness were 0.2-0.5mm.

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