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
  • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
  • C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
• • 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
  • C22F1/047—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 magnesium as the next major constituent

Definitions

• the present invention relates to an aluminum casting alloy, which is particularly suitable for thermally highly stressed castings.
• the performance of castings produced therefrom is considerably improved, the thermal stability of which is ensured up to temperatures of 400 ° C.
• castings are used to produce castings with high quality standards.
• quality of a die-cast part depends not only on the machine setting and the chosen method, but also to a great extent on the chemical composition and microstructure of the casting alloy used. These two latter parameters are known to affect the castability, the feeding behavior, the mechanical properties and, most importantly in die casting, the life of the casting tools.
• compositions for aluminum casting alloys are known in the art.
• EP 0 687 742 A1 discloses, for example, an aluminum-silicon based pressure casting alloy containing 9.5-11.5 wt% silicon, 0.1-0.5 wt% magnesium, 0.5-0.8 wt% manganese , Max. 0.15% by weight of iron, max. 0.03 wt% copper, Max. 0.10 zinc, max. 0.15% by weight of titanium and the remainder of aluminum and permanent finishing contains 30 to 300 ppm of strontium.
• An aluminum alloy which consists of 5.4-5.8% by weight of magnesium, 1.8-2.5% by weight of silicon, 0.5-0.9% by weight of manganese, max. 0.2% by weight of titanium, max. 0.15 wt.% Iron, and aluminum as a remainder with further impurities individually max. 0.02% by weight, in total max. 0.2 wt .-%, which is particularly suitable for thixocasting or Thixoschmieden.
• an aluminum casting alloy is known, which is particularly suitable for chill casting and sand casting, and at least 0.05 - 0.5 wt.% Manganese, 0.2 -1.0 wt.% Magnesium, 4-7 wt. % Zinc and 0.15-0.45 wt% chromium.
• these aluminum casting alloys are mainly designed for safety-relevant vehicle components, such as, for example, handlebars, carriers, frame parts and wheels, in which primarily a high elongation at break is in the foreground.
• safety-relevant vehicle components such as, for example, handlebars, carriers, frame parts and wheels, in which primarily a high elongation at break is in the foreground.
• thermal loads up to 400 ° C, these alloys are not suitable.
• the classic cast aluminum materials are only thermally stable up to approx. 200 ° C.
• Aluminum alloys with scandium are known for increasing strength.
• the high strength results from a heat aging after solution treatment and quenching with water.
• the disadvantage is that the solution annealing usually leads to a delay, which must be corrected by additional measures or work steps (resizing and straightening).
• Out JP-A-09279280 is an aluminum wrought alloy known and made EP 1138794 A1 and WO 96/15281 Further aluminum casting alloys are known.
• the present invention has for its object to develop an aluminum casting alloy, which is suitable for thermally highly stressed castings.
• the heat resistance i.
• the thermal stability of the mechanical properties should be ensured up to temperatures of 400 ° C.
• the aluminum casting alloy according to the invention should have a good weldability and can be produced with a variety of methods with good castability.
• a silicon content of 1.1-4.0% by weight is advantageous. Particularly advantageous is a silicon content of 1.1 to 3.0 wt .-%.
• the scandium In addition to intensive particle hardening by the thermally very stable Al 3 Sc particles, the scandium causes grain refining of the cast structure and recrystallization inhibition. Castings made from the alloy of the invention thus have the advantage that their mechanical properties are stable up to temperatures of 400 ° C.
• the casting alloy according to the invention is thus predestined, above all, for castings which are subjected to high thermal loads. Furthermore, it is advantageous that due to the high heat resistance replacement of aluminum materials by materials with high density is not required. By using the alloy according to the invention, the component weight is guaranteed with increased conductivity and can even be reduced by thinner-walled castings.
• the scandium content also improves weldability.
• the scandium content is between 0.01-0.45 wt .-%. Particularly preferred is a scandium content of 0.015-0.4 wt .-%.
• titanium Like scandium, titanium also causes grain refining, thus contributing in a corresponding way to improving the heat resistance. In addition, titanium lowers the electrical conductivity.
• the titanium content is preferably 0.01-0.2% by weight, in particular 0.05-0.15% by weight.
• zirconium Since zirconium has the same effect as scandium or titanium, it is also advantageous to additionally add zirconium to the alloy.
• Zirconium substitutes Sc atoms and forms particles of the ternary compound Al 3 (Sc 1-x , Zr x ) which are less prone to coagulation at higher temperatures than the Al 3 Sc particles.
• the constituents scandium and zirconium again improve the heat resistance of the alloy compared to an alloy containing only scandium. This allows further optimization in the direction of lower scandium contents to reduce costs.
• the zirconium content of preferred embodiments is between 0.01-0.3% by weight and 0.05-0.1% by weight.
• the aluminum casting alloy according to the invention already exhibits the heat-resistance-increasing effect in the cast state.
• a subsequent heat treatment in a temperature range of typically 250 - 400 ° C, the mechanical properties are finally achieved with the appropriate heat resistance.
• the time duration is known to depend on the component size or thickness, the heat resistance can be varied accordingly.
• a solution annealing with subsequent thermal aging is not required, which is advantageous in that thus the problem of distortion, which usually involves a resizing and straightening and is known to occur in the classic, solution-treated and warm-aged aluminum casting alloys, does not matter.
• hafnium, molybdenum, terbium, niobium, gadolinium, erbium and / or vanadium may be added to the alloy.
• the alloy contains one or more elements selected from the group consisting of zirconium, hafnium, molybdenum, terbium, niobium, gadolinium, erbium and vanadium. The sum of the selected elements is at most 0.5% by weight, but preferably 0.01-0.3% by weight.
• the alloy contains at least 0.001 wt .-%, preferably at least 0.008 wt .-% vanadium.
• Vanadium acts as a grain refiner similar to titanium. In addition, it improves weldability and reduces the tendency of the melt to be scratched.
• the alloy contains at least 0.001% by weight of gadolinium.
• chrome 0.001-0.3% by weight, in particular 0.0015-0.2% by weight
• Copper 0.001-1.0 wt .-%, in particular 0.5-1.0% by weight
• Zinc 0.001-0.05% by weight.
• the addition of iron and / or manganese is known to reduce the adhesive effect. Preference is given to using a manganese content of not more than 0.01% by weight and an iron content of from 0.05 to 0.6% by weight, in particular from 0.05 to 0.2% by weight.
• the technical grade iron is typically at least 0.12 wt%. However, the addition of iron and / or manganese during die casting and sand casting is not absolutely necessary.
• the die casting process is different.
• an addition of iron and / or manganese is required to reduce the adhesive effect of the die casting in the mold.
• the manganese content is preferably between 0.4 and 0.8% by weight.
• the sum of manganese and iron should be at least 0.8 wt .-%.
• the diecasting alloy contains either only iron or only manganese.
• the first alloy also contains zirconium.
• the second alloy has a higher scandium content than the first alloy but does not contain zircon.
• the third alloy is a variant with higher magnesium and silicon content.
• a fourth alloy was made by die casting, which also contains copper. This alloy was melted in a 200 kg electric heated crucible furnace. The casting temperature was 700 ° C. It was cast on a 400 t (tensile holding force) die casting machine. The sample used was a plate with the dimensions 220 ⁇ 60 ⁇ 3 mm. From the plates samples for tensile tests were taken. The test bars were only worked on the narrow sides.
• the mechanical properties of the various die cast alloys of the present invention were cast as cast, after 3 hours of heat treatment at 300 ° C and under various thermal loads (200 ° C / 500h, 250 ° C / 500h, 350 ° C / 500h and 400 ° C / 500h) to determine thermal stability.
• the mechanical properties of Alloy 4 Die Casting Alloy
• Alloy 4 Die Casting Alloy
• the Reference alloy was subjected to conventional high-temperature annealing.
• the reference alloy was solution annealed at 540 ° C for 12h, then quenched with water and then warm-aged at 165 ° C for 6h.
• the measurement results are summarized in Table 2, where Rp0.2 is the yield strength in MPa, Rm the tensile strength in MPa and A5 the elongation at break in%.
• the alloy according to the invention has good mechanical properties already in the cast state.
• a heat treatment here 300 ° C for 3h or 300 ° C for 1h
• the mechanical properties are further increased, which is due to particle hardening by segregation from the supersaturated mixed crystal in "hot Ausausung", ie formation of secondary precipitates Al 3 (Sc 1-x , Zr x ) is due.
• the thermal stability of alloys 1-3 can be seen well up to temperatures of 400 ° C.
• the values for the yield strength and the tensile strength are quite high up to temperatures of 400 ° C. If one compares the measured values of the reference alloy at 250 ° C. with the corresponding values of the alloy according to the invention, it is clearly evident that the very good mechanical properties are retained in the alloy according to the invention.
• the reference alloy at 250 ° C already shows a significant reduction in the yield strength and the tensile strength.
• the alloy of the invention has a very good weldability. It has an excellent G discernvertialten and can be produced with the usual casting methods (die casting, sand casting, chill casting, thixocasting, rheocasting or derivatives of these methods).
• the alloy according to the invention is preferably used for thermally highly stressed castings.
• These are, for example, cylinder heads, crankcases, components for air conditioning systems, aircraft structural components, in particular for Supersonic aircraft, engine segments, pylons, which are highly loaded connection components between the engine and wing, and the like.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Crystallography & Structural Chemistry (AREA)
• Thermal Sciences (AREA)
• Physics & Mathematics (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Valve-Gear Or Valve Arrangements (AREA)
• Cylinder Crankcases Of Internal Combustion Engines (AREA)
• Mold Materials And Core Materials (AREA)
• Continuous Casting (AREA)
• Supercharger (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 2003
  • 2003-11-11 DE DE10352932A patent/DE10352932B4/de not_active Expired - Fee Related
• 2004
  • 2004-11-03 AT AT04802664T patent/ATE454480T1/de active
  • 2004-11-03 DE DE502004010622T patent/DE502004010622D1/de active Active
  • 2004-11-03 ES ES04802664T patent/ES2339356T3/es active Active
  • 2004-11-03 EP EP04802664A patent/EP1682688B1/de not_active Not-in-force
  • 2004-11-03 WO PCT/DE2004/002425 patent/WO2005047554A1/de active Application Filing
  • 2004-11-03 US US10/579,075 patent/US20070240796A1/en not_active Abandoned

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