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 cast parts subject to high thermal stress.
• the performance of cast parts produced therefrom is considerably improved, with their thermal stability being guaranteed up to temperatures of 400.degree.
• die castings are used to produce castings with high quality standards.
• the quality of a die-cast part does not only depend on the
• Machine settings and the selected process but also to a large extent on the chemical composition and structure of the cast alloy used. These last two parameters are known to influence the castability, the feeding behavior, the mechanical properties and, particularly important in die casting, the service life of the casting tools.
• EP 0 687 742 A1 discloses a die-casting alloy based on aluminum-silicon which contains 9.5-11.5% by weight silicon, 0.1-0.5% by weight magnesium, 0.5-0, 8% by weight manganese, max. 0.15% by weight iron, max. 0.03% by weight copper, Max. 0.10 zinc, max. 0.15 wt .-% titanium and the rest of aluminum and permanent refinement contains 30 to 300 ppm strontium.
• An aluminum alloy is known from EP 0 792 380 A1, 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.
• an aluminum casting alloy is known from EP 1 229 141 A1, which is particularly suitable for permanent mold casting and sand casting, and at least 0.05-0.5% by weight of manganese, 0.2-1.0%. -% Magnesium, 4 - 7 wt .-% zinc and 0.15 - 0.45 wt .-% chromium.
• the disadvantage is that there is usually a delay in solution annealing, which must be corrected by additional measures or work steps (remeasuring and straightening).
• the present invention has for its object to develop an aluminum casting alloy that is suitable for thermally highly stressed cast parts.
• the heat resistance ie the thermal stability of the mechanical properties, should be guaranteed up to temperatures of 400 ° C.
• the cast aluminum alloy according to the invention is said to have good weldability and to be able to be produced using a large number of processes with good castability.
• the task is solved by a cast aluminum alloy, which at least consists of
• Ti titanium
• element or a group of elements selected from the
• Zr zircon
• Hf hafnium
• Mo molybdenum
• Tb terbium
• Be beryllium
• the magnesium content is preferably between 2-7% by weight and particularly preferably between 3-6% by weight.
• a silicon content of 1.1-4.0% by weight is advantageous.
• a silicon content of 1.1-3.0% by weight is particularly advantageous.
• the addition of scandium is essential.
• the scandium In addition to intensive particle hardening due to the thermally very stable Al 3 Sc particles, the scandium also causes grain refinement of the cast structure and recrystallization inhibition. Castings made from the alloy according to the invention therefore have the advantage that their mechanical properties are stable up to temperatures of 400 ° C.
• the cast alloy according to the invention is therefore predestined especially for cast parts subject to high thermal stress.
• the high heat resistance means that it is not necessary to replace aluminum materials with high-density materials.
• the component weight is guaranteed with increased conductivity or can even be reduced by thin-walled castings.
• Another advantage is that the scandium content also improves weldability.
• the scandium content is preferably between 0.01-0.45% by weight.
• a scandium content of 0.015-0.4% by weight is particularly preferred.
• titanium Like scandium, titanium also causes grain refinement and thus contributes accordingly to improving the heat resistance. In addition, titanium lowers electrical conductivity.
• the titanium content is preferably 0.01-0.2% by weight, in particular 0.05-0.15% by weight.
• zircon Since zircon has the same effect as scandium or titanium, it is also advantageous to add zircon to the alloy.
• the combined effect of scandium and zircon increases the effect of the scandium, an intensive particle hardening by the thermally very stable AI 3 Sc particles, a grain refinement of the structure as well as a recrystallization inhibition.
• Zircon substitutes for 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 Alasc particles.
• the scandium and zircon components thus further improve the heat resistance of the alloy compared to an alloy that contains only scandium. This enables further optimization towards lower scandium contents in order 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 has the effect of increasing the heat resistance even in the as-cast state.
• the heat resistance can be varied accordingly by a suitable choice of temperature and time period, the time period being known to depend on the component size or thickness.
• Solution annealing with subsequent hot aging is not necessary, which is advantageous insofar as the problem of warpage, which usually entails re-measuring and straightening and is known to occur with the classic, solution-annealed and heat-aged cast aluminum alloys, does not matter.
• hafnium, molybdenum, terbium, niobium, gadolinium, erbium and / or vanadium can 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% by weight, preferably at least 0.008% by weight, of vanadium. Vanadium acts as a grain refiner similar to titanium. It also improves weldability and reduces the tendency of the melt to scratch.
• the alloy contains at least 0.001% by weight of gadolinium.
• Chromium 0.001-0.3% by weight, in particular 0.0015-0.2% by weight of copper: 0.001-1.0% by weight, in particular 0.5-1.0% by weight of zinc: 0.001-0.1% by weight, in particular 0.001-0.05% by weight.
• iron and / or manganese reduces the adhesive effect.
• the technical iron content is typically at least 0.12% by weight.
• the addition of iron and / or manganese is not absolutely necessary when casting molds and sand.
• Manganese content preferably between 0.4-0.8% by weight.
• the sum of manganese and iron content should be at least 0.8% by weight.
• the die-casting alloy contains either only iron or only manganese.
• Sample rods for determining the mechanical properties were cast from three different alloys using the die rod mold.
• the first alloy also contains zircon.
• the second alloy has a higher scandium content than the first alloy, but does not contain zircon.
• the third alloy is a variant with a higher magnesium and silicon content.
• a fourth alloy was produced using die casting, which also contains copper. This alloy was melted in a 200 kg, electrically heated crucible furnace. The casting temperature was 700 ° C. It was cast on a 4001 (tensile holding force) die casting machine. A plate with the dimensions 220 x 60 x 3 mm was used as the sample form. Test bars for tensile tests were taken from the plates. The test bars were only processed on the narrow sides.
• the mechanical properties of the various alloys according to the invention cast by means of die die mold were obtained in the as-cast state, after 3 hours of heat treatment at 300 ° C. and then under various thermal loads (200 ° C./500 h, 250 ° C./500 h, 350 ° C./500 h and 400 ⁇ C / 500h), to determine the thermal stability.
• the mechanical properties of alloy 4 (die casting alloy) were measured only in the as-cast state and after 1 hour, 300 ° C. heat treatment.
• the Reference alloy was subjected to conventional high temperature annealing.
• the reference alloy was solution annealed at 540 ° C for 12 hours, then quenched with water and then aged at 165 ° C for 6 hours.
• the measurement results are summarized in Table 2, where Rp0.2 is the yield strength in MPa, Rm is the tensile strength in MPa and A5 is the elongation at break in%.
• the tests show that the alloy according to the invention has good mechanical properties even in the as-cast state.
• the mechanical properties are further increased by a heat treatment (here 300 ° C. for 3 hours or 300 ° C. for 1 hour), which is due to particle hardening by segregation from the supersaturated mixed crystal during “warm aging”, ie formation of secondary precipitates AI 3 (Sc ⁇ - x , Zr x ) and the thermal stability of alloys 1 - 3 up to temperatures of 400 ° C is clearly visible.
• the yield strength and tensile strength values are quite high up to temperatures of 400 ° C. If the measured values of the reference alloy at 250 ° C. are compared with the corresponding values of the alloy according to the invention, one can clearly see that the very good mechanical properties of the alloy according to the invention are retained. In contrast, the reference alloy already shows a significant reduction in the yield strength and tensile strength at 250 ° C.
• the alloy according to the invention has very good weldability. It has excellent casting behavior and can be produced using the usual casting processes (die casting, sand casting, mold casting, thixocasting, rheocasting or derivatives of these processes).
• the alloy according to the invention is preferably used for cast parts subject to high thermal loads.
• 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 stressed connecting components between engine and wing, and the like.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Metallurgy (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (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)
• Cylinder Crankcases Of Internal Combustion Engines (AREA)
• Valve-Gear Or Valve Arrangements (AREA)
• Continuous Casting (AREA)
• Mold Materials And Core Materials (AREA)
• Supercharger (AREA)

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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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