Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
  • C22C21/04—Modified aluminium-silicon alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
  • C22F1/043—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with silicon as the next major constituent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60G—VEHICLE SUSPENSION ARRANGEMENTS
  • B60G2206/00—Indexing codes related to the manufacturing of suspensions: constructional features, the materials used, procedures or tools
  • B60G2206/01—Constructional features of suspension elements, e.g. arms, dampers, springs
  • B60G2206/70—Materials used in suspensions
  • B60G2206/71—Light weight materials
  • B60G2206/7102—Aluminium alloys
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60G—VEHICLE SUSPENSION ARRANGEMENTS
  • B60G2206/00—Indexing codes related to the manufacturing of suspensions: constructional features, the materials used, procedures or tools
  • B60G2206/01—Constructional features of suspension elements, e.g. arms, dampers, springs
  • B60G2206/80—Manufacturing procedures
  • B60G2206/81—Shaping
  • B60G2206/8101—Shaping by casting

Definitions

• the present invention relates generally to casting processes and casting alloys. More particularly, the present invention is directed to an aluminum alloy for use with a high pressure casting technique.
• the casting melting temperature of A356 is approximately 1320 degrees Fahrenheit (" 0 F') or 716 degrees Celsius (" 0 C").
• soldering refers to the adherence of aluminum to the cavity of a mold or die, which, after a period of time, renders the mold or die unusable. This leads to repeated and costly replacements of the dies.
• An embodiment of the present invention relates to a rear suspension component for an automobile.
• the rear suspension component includes an ADC12 aluminum alloy.
• the ADC12 aluminum alloy is squeeze cast to generate the rear suspension component.
• the ADC 12 aluminum alloy consists essentially of the following constituents by percentage of weight: 9.6 to 12.0 percent silicon; 0.0 to 1.3 percent iron; 1.5 to 3.5 percent copper; 0.0 to 0.5 percent manganese; 0.0 to 0.3 percent magnesium; 0.0 to 1.0 percent zinc; 0.0 to 0.5 percent nickel; 0.0 to 0.3 percent tin; 0.0 to 0.15 percent one or more other elements; and aluminum as the remainder.
• the cast rear suspension component is T4 tempered.
• FIG. 1 Another embodiment of the present invention pertains to an apparatus for casting a rear suspension component for an automobile.
• the apparatus includes a means for heating an ADC12 aluminum alloy to liquefy the ADC12 aluminum alloy, means for injecting the ADC12 aluminum alloy into a die corresponding to the rear suspension component, means for solidifying the ADC12 aluminum alloy to generate the rear suspension component, and means for tempering the rear suspension component.
• the ADC12 aluminum alloy consists essentially of the following constituents by percentage of weight: 9.6 to 12.0 percent silicon; 0.0 to 1.3 percent iron; 1.5 to 3.5 percent copper; 0.0 to 0.5 percent manganese; 0.0 to 0.3 percent magnesium; 0.0 to 1.0 percent zinc; 0.0 to 0.5 percent nickel; 0.0 to 0.3 percent tin; 0.0 to 0.15 percent one or more other elements; and aluminum as the remainder.
• the apparatus further includes a means for tempering the cast rear suspension component.
• Yet another embodiment of the present invention relates to a method of casting a rear suspension component fox an automobile.
• an ADCl 2 aluminum alloy is heated to liquefy the ADC12 aluminum alloy, the ADC12 aluminum alloy is injected into a die corresponding to the rear suspension component, and the ADC 12 aluminum alloy is solidified to generate the rear suspension component.
• the rear suspension component is tempered.
• the ADC12 aluminum alloy consists essentially of the following constituents by percentage of weight: 9.6 to 12.0 percent silicon; 0.0 to 1.3 percent iron; 1.5 to 3.5 percent copper; 0.0 to 0.5 percent manganese; 0.0 to 0.3 percent magnesium; 0.0 to 1.0 percent zinc; 0.0 to 0.5 percent nickel; 0.0 to 0.3 percent tin; 0.0 to 0.15 percent one or more other elements; and aluminum as the remainder.
• FIG. 1 illustrates a typical microstructure of an ADC12-T4 aluminum alloy.
• FIG.2 illustrates a typical microstructure of an A356 aluminum alloy according to the prior art.
• An embodiment in accordance with the present invention provides a rear suspension component of an automobile that is cast from ADC12 aluminum alloy utilizing a high pressure, slow velocity casting technique such as, for example, squeeze casting, semi-solid metal (SSM) casting, and the like.
• This rear suspension component is further T4 tempered.
• ADC 12 aluminum alloy with a T4 temper is referred to as ADC12-T4.
• the mechanical properties of a product are not only dependent on the casting technique utilized, but are also dependent on the casting alloy that is utilized.
• Aluminum alloys are used in the casting industry because they are adaptable to many of the most commonly used casting methods, can readily be cast in metal molds or dies and have a high resistance to corrosion.
• aluminum alloys also provide good fluidity, i.e., most aluminum alloys flow with ease. This is particularly important because if the metal, when in its molten state, does not flow at a rate that is sufficient to fill the die cavity or mold before the molten metal solidifies, then the metal may have difficulty filling, for example, thin sections of a mold or die.
• aluminum alloys have relatively low melting points. Accordingly, the heat required to melt aluminum alloys is less than the heat required for some metals and thus, the cost of producing aluminum alloy castings is less. Further, there is less heat to transfer from the molten aluminum alloy to the mold. As a result, the cycle time required for casting an aluminum alloy product is reduced. In addition, the lifetime of the mold is increased by utilizing aluminum alloys because the molds are subjected to less stress from heat.
• Rear suspension components for automotive vehicles are required to have high mechanical properties in the areas of strength, wear resistance and hardness. Further, they are also are required to be ductile, i.e., have the ability to undergo permanent deformation prior to failure.
• Rear suspension components produced utilizing GPM and the A356 aluminum alloy are typically heat treated to ensure that the products satisfy the minimum property requirements for the respective product.
• rear suspension components are heat treated according to a T6 temper.
• a typical T6 temper consists of solution treating the casting at 1 ,000 0 F (538°C) plus or minus 10°F (5.6°C) for ten hours, water quenching the casting, and artificially aging the casting at 340 0 F (171°C) plus or minus 10 0 F (5.6°C) for four to five hours.
• a T4 temper includes heating to about 930 0 F (499°C), soaking for about seven hours and then water quenching at temperatures between 110 0 F (43°C) and 160 0 F (71°C).
• FIG. 1 illustrates a typical microstructure of an ADC12-T4 aluminum alloy.
• the microstructure includes areas of primary silicon 10 that typically appear as relatively large dark spots.
• the microstructure includes areas of eutectic silicon 12 that typically appear as relatively smaller dark spots.
• the microstructure further includes areas of aluminum matrix 14 that typically appear as relatively light areas.
• the microstructure may include relatively iron-rich areas 16 that are commonly referred to as "Chinese script.”
• FIG.2 illustrates a typical microstructure of an A356 aluminum alloy according to the prior art.
• the microstructure of A356 aluminum alloy may include the areas of eutectic silicon 12 and areas of the aluminum matrix 14.
• an aluminum alloy is utilized with a high pressure, slow velocity casting technique to produce casting products for rear suspension components.
• Such components include knuckles and upper and lower control arms, among others.
• High pressure, slow velocity casting techniques such as squeeze casting, SSM casting and the like, involve injecting molten metal into a mold via a hydraulically powered piston, at a slow rate into the mold/die cavity, and applying and maintaining a high pressure until after the metal has solidified in the mold/die cavity. When the applied high pressure thrusts the molten metal to the walls of the mold/die cavity, the air gap between the molten metal and the walls of the mold/die cavity is quickly minimized.
• GPM the molten metal is poured into the mold without any external mechanical forces.
• conventional die casting which includes high pressure and high velocity casting, the metal is injected into a die.
• products manufactured by the GPM casting technique tend to be higher in strength and are less porous than products produced by conventional die casting.
• rear suspension components are squeeze cast, SSM cast or otherwise utilized with a high pressure, slow velocity casting technique to cast with the ADCl 2-T4 alloy.
• Rear suspension components cast in this manner exhibit mechanical properties that are higher than the mechanical properties of products manufactured according to GPM casting techniques utilizing the A356 aluminum alloy.
• ADC12-T4 includes the below-listed elements, by percentage of weight, as follows:
• the ADC12-T4 aluminum alloy does not require strontium.
• Strontium is utilized in an aluminum alloy as a modifying agent to, for example, improve the ductility of the aluminum alloy. Strontium is often utilized along with casting processes that involve slower solidification rates, such as GPM and sand casting.
• the ADC12-T4 alloy when utilized with a high pressure, slow velocity casting technique, has a higher solidification rate because of the rapid heat transfer rates that are characteristic of high pressure casting techniques. Thus, because the products derive high ductility from being manufactured according to a high pressure, slow velocity casting technique, strontium is not required with the use of the ADC12-T4 alloy.
• the aluminum content is increased in ADC12-T4 alloy products.
• the cost of the aluminum is cheaper than the cost of strontium. Accordingly, the cost of ADC12-T4 alloy products is cheaper than products made with added strontium. However, beneficial properties are still retained.
• the ADC12-T4 alloy has a silicon content of 9.6 to 12.0 percent of its weight and is higher than the silicon content of the A356 aluminum alloy, which is 6.5 to 7.5 percent of its weight.
• A356 includes the following components:
• the higher silicon content of the ADC12-T4 alloy leads to the ADC12-T4 alloy having a metal casting temperature of 125O°F (677°C), which is lower than the metal casting temperature of approximately 1320°F (715°C) for the A356 aluminum alloy. Accordingly, less energy is required to melt the ADC12-T4 alloy than is required to melt the A356 aluminum alloy- Thus, the cost associated with manufacturing ADC12-T4 products is less than the cost associated with manufacturing the A356 product.
• the lower metal casting temperature of the ADCl 2-T4 alloy leads to approximately 35% less dross formation than that produced by the A356 aluminum alloy.
• Dross refers to the metal oxide that is formed when the molten metal reacts with air. Dross formation typically occurs before the molten metal is transferred to the mold/die cavity. If the dross enters the mold/die cavity and becomes a part of the casting, it can lead to a defective casting because the casting will not consist purely of the intended alloy.
• the lower metal casting temperature of the ADC12-T4 alloy leads to less occurrences of soldering, approximately 15% less, than that produced by the A356 aluminum alloy. Accordingly, utilizing the ADC12-T4 alloy over the A356 alloy reduces soldering and prolongs the life of the mold/die cavity.
• the ADC12-T4 alloy has a higher tensile strength than the A356 aluminum alloys.
• the tensile strength corresponds to the maximum load bearing ability of the metal before the metal breaks down.
• the ADC12-T4 alloy has a higher resistance to applied forces.
• the higher strength of the ADC12-T4 alloy is attributed, at least in part, to the refined microstructure, i.e., the smaller grain size of the casting that is developed from use of a high pressure, slow velocity casting technique. Accordingly, the ADC12-T4 alloy is stronger than the A356 aluminum alloy and therefore, is more suitable for products requiring high strength, for example, components of rear suspension systems, such as knuckles and upper and lower control arras.
• the ADC12-T4 alloy outperformed the A356 alloy in wear resistance.
• the higher wear resistance i.e., lower volume loss of material, is attributed, at least in part, to the refined microstructure, i.e., the smaller grain size of the casting that is developed from use of high pressure, slow velocity casting technique.
• Products for example, knuckles and upper and lower control arms have been anodized to increase the wear resistance of those products.
• ADC12-T4 alloy in conjunction with a high pressure casting technique, the amount of anodizing is reduced or eliminated, leading to yet more efficiency.
• ADC12-T4 has a maximum iron content of 1. 3 percent of its weight that is higher than the iron content of the A356 alloy.
• the iron content of an ADCl 2-T4 casting is greater than the maximum iron content of the A356 alloy, the ADC12-T4 product is easier to machine than an A356 product.
• the high iron content of the ADC12-T4 alloy product also facilitates chip formation, i.e., the generation of shavings, as the product is machined. Accordingly, less force or pressure has to be applied to the machine tool when feeding/thrusting the machine/cutting tool onto the ADC12-T4 alloy product to make the initial cut into the ADC12-T4 product, and also when cutting the ADC12-T4 alloy product, than when performing the same actions on an A356 alloy product. Accordingly, the machine/cutting tool is subjected to less stress and the lifetime of the machine/cutting tool is prolonged with the ADC12-T4 alloy. Moreover, the higher iron content of the ADC12-T4 also leads to less soldering, thereby lengthening the life of the dies.
• ADC12-T4 alloy stock/ingots is less expensive than the cost of the A356 stock or ingot. Accordingly, when the ADC12-T4 alloy is utilized in conjunction with a high pressure casting technique to manufacture products, for example, rear suspension components, the products have high mechanical properties and are less expensive to produce.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Vehicle Body Suspensions (AREA)

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• 2007
  • 2007-03-26 EP EP07754006A patent/EP2010685A4/de not_active Withdrawn
  • 2007-03-26 US US11/727,234 patent/US20070246132A1/en not_active Abandoned
  • 2007-03-26 WO PCT/US2007/007429 patent/WO2007126744A2/en active Application Filing

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