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 a cast aluminium alloy suitable particularly for thermally highly stressed cast parts.
• the efficiency of cast parts produced therefrom is improved considerably, their thermal stability being guaranteed up to temperatures of 400° C.
• cast parts for example, can be produced which meet high demands with respect to quality.
• the quality of a diecast part depends not only on the machine adjustment and the selected method but to a great extent also on the chemical composition and the structure of the used cast alloy. It is known that the two latter parameters influence the castability, the feeding behavior, the mechanical characteristics and, which is particularly important in diecasting, the useful life of the casting tools.
• European Patent Document EP 0 687 742 A1 discloses a diecast alloy on an aluminium silicon base, which contain 9.5-11.5% in weight silicon, 0.1-0.5% in weight magnesium, 0.5-0.8% in weight manganese, max. 0.15% in weight iron, max. 0.03% in weight copper, max. 0.10% in weight zinc, max. 0.15% in weight titanium as well as a remainder of aluminium and a permanent finishing with 30 to 300 ppm strontium.
• an aluminium alloy which consists of 5.4-5.8% in weight magnesium, 1.8-2.5% in weight silicon, 0.5-0.9% in weight manganese, max. 0.2% in weight titanium, max. 0.15% in weight iron and aluminium as the remainder with further impurities to an individual max. of 0.02% in weight and totally maximally 0.2% in weight, which are suitable particularly for thixocasting or thixoforging.
• a cast aluminium alloy which is suitable mainly for permanent mold casting and sand casting, and contains at least 0.05-0.5% in weight manganese, 0.2-1.0% in weight magnesium, 4-7% in weight zinc and 0.15-0.45% in weight chromium.
• cast aluminum alloys are conceived mainly for safety-relevant vehicle components, such as control arms, supports, frame parts and wheels, in the case of which a high ductile yield is primarily in the foreground. These alloys are not suitable for thermal stresses of up to 400° C.
• the classical cast aluminium alloys are thermally stable only up to approximately 200° C.
• One object of the present invention is to provide a cast aluminium alloy which is suitable for thermally highly stressed cast parts.
• the high-temperature stability that is the thermal stability, of the mechanical characteristics is to be ensured up to temperatures of 400° C.
• the cast aluminium alloy according to the invention preferable has a good weldability and should be producible by means of a plurality of methods while the castability is good.
• Zr zirconium
• Hf hafnium
• Mo molybdenum
• Tb terbium
• Nb niobium
• Gd gadolinium
• Er erbium
• V vanadium
• % in weight or “% by weight” refers to the weight percentage based on the total weight of the composition.
• the magnesium content in this case is preferably between 2-7% in weight, particularly preferably between 3-6% in weight.
• the silicon content is advantageously between 1.1-4.0% in weight, particularly advantageously between 1.1-3.0% in weight.
• the addition of scandium is essential.
• the scandium causes a grain refining of the cast structure and a recrystallization inhibition as a result of the thermally very stable Al 3 Sc particles.
• Cast parts produced from the alloy according to the invention therefore have the advantage that their mechanical characteristics are stable up to temperatures of 400° C.
• the cast alloy according to the invention is therefore predestined mainly for thermally highly stressed cast parts. It is also advantageous, that, as a result of the high thermal stability, a replacement of aluminium materials by materials of a high density is not required.
• the component weight is guaranteed while the conductivity is increased, which component weight can even be reduced by cast parts which have thinner walls.
• the weldability is also improved by means of the scandium fraction.
• the scandium content is preferably between 0.01-0.45% in weight, particularly preferably between 0.015-0.4% in weight.
• titanium Like scandium, titanium also causes a grain refining and therefore contributes in a corresponding manner to the improvement of the thermal stability. In addition, titanium lowers the electric conductivity.
• the titanium content preferably amounts to between 0.01-0.2% in weight, particularly between 0.05-0.15% in weight.
• zirconium Since zirconium has the same effect as scandium or titanium, it is also advantageous to additionally admix zirconium to the alloy.
• the effect of the scandium of causing an intensive particle hardening by the thermally very stable Al 3 Sc particles, a grain refining of the structure as well as a recrystallization inhibition is further increased by the combined effect of scandium and zirconium.
• Zirconium substitutes Sc atoms and forms particles of the ternary compound Al 3 (Sc 1-x Zr x ) which have less of a tendency to coagulate at higher temperatures than the Al 3 Sc particles.
• the scandium and zirconium constituents again improve the thermal stability of the alloy in comparison to an alloy which contains only scandium. This permits a further optimization in the direction of lower scandium contents for lowering the cost.
• the zirconium content of preferred embodiments is between 0.01-0.3% in weight or 0.05-0.1% in weight.
• 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. In this case, the sum of the selected elements amounts to maximally 0.5% in weight, preferably, however, 0.01-0.3% in weight.
• the alloy it is particularly advantageous for the alloy to contain at least 0.001% in weight, preferably at least 0.008% in weight vanadium. Vanadium acts as a grain refiner, similarly to titanium. Furthermore, it improves the weldability and reduces the scratching tendency of the molten material.
• the alloy contains at least 0.001% in weight gadolinium.
• Chromium 0.001-0.3% in weight, particularly 0.0015-0.2% in weight
• copper 0.001-1.0% in weight, particularly 0.5-1.0% in weight
• zinc 0.001-0.1% in weight, particularly 0.001-0.05% in weight.
• iron and/or manganese it is known that by adding iron and/or manganese, the adhesive effect is reduced.
• a manganese content of maximally 0.01% in weight and an iron content of from 0.05-0.6% in weight is used.
• the technical iron content is typically at least 0.12% in weight.
• the addition of iron and/or manganese is not absolutely necessary for permanent mold casting and sand casting.
• the diecasting method in order to reduce the adhesive effect of the diecast part in the mold.
• the manganese content for the diecasting is preferably between 0.4-0.8% in weight.
• the sum of the manganese and iron content should amount to at least 0.8% in weight.
• sample rods for determining the mechanical characteristics were cast by means of the permanent Diez rod mold.
• the first alloy also contains zirconium.
• the second alloy has a higher scandium content than the first alloy but contains no zirconium.
• the third alloy is a variant with a higher magnesium and silicon content.
• a fourth alloy which also contains copper, was produced by means of diecasting.
• This alloy was obtained by melting in a 200 kg electrically heated crucible furnace. The casting temperature was 700° C. The casting took place on a 400 t (tension holding force) diecasting machine. A plate of the measurements 220 ⁇ 60 ⁇ 3 mm was used as the sample shape. Sample rods for tension tests were taken from the plates. The sample rods were machined only on the narrow sides.
• the mechanical characteristics of the different alloys according to the invention cast by means of a permanent Diez rod mold were measured as cast, after a 3-hour heat treatment at 300° C. and subsequently at different thermal stresses (200E/500 h, 250° C./500 h, 350° C./500 h and 400° C./500 h), for determining the thermal stability.
• the mechanical characteristics of alloy 4 (diecast alloy) were measured only as cast and after a 1-hour 300° C. heat treatment.
• the reference alloy was subjected to a conventional annealing.
• the reference alloy was solution treated at 540° C. for 12 hours; was then quenched with water and was then artificially aged at 165° C. for 6 hours.
• the measuring results are summarized in Table 2, Rp0.2 being the yield strength in MPa, Rm being the tensile strength in MPa, and A5 being the breaking tension in %.
• the tests show that the alloy according to the invention already has good mechanical characteristics as cast.
• a heat treatment here, 300° C. for 3 hours or 300° C. for 1 hour
• the mechanical characteristics are further increased, which is a result of particle hardening by segregation from the oversaturated solid solution during “artificial aging”; thus the formation of secondary precipitations Al 3 (Sc 1-x Zr x ).
• the thermal stability of alloys 1-3 up to temperatures of 400° C. is easily recognizable.
• Particularly the values for the yield strength and the tensile strength are quite high up to temperatures of 400° C.
• the alloy according to the invention has a very good weldability. It has an excellent casting behavior and can be produced by means of conventional casting methods (diecasting, sand casting, permanent mold casting, thixocasting, rheocasting or derivatives of these methods).
• the alloy according to the invention is preferably used for thermally highly stressed cast parts.
• thermally highly stressed cast parts are, for example, cylinder heads, crankcases, components for air conditioners; structural airplane parts, particularly for supersonic aircraft, engine segments, pylons, which are highly stressed connection components between the engine and the wings, 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)
• Mold Materials And Core Materials (AREA)
• Supercharger (AREA)
• Continuous Casting (AREA)
• Cylinder Crankcases Of Internal Combustion Engines (AREA)
• Valve-Gear Or Valve Arrangements (AREA)

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• 2003
  • 2003-11-11 DE DE10352932A patent/DE10352932B4/de not_active Expired - Fee Related
• 2004
  • 2004-11-03 DE DE502004010622T patent/DE502004010622D1/de active Active
  • 2004-11-03 ES ES04802664T patent/ES2339356T3/es active Active
  • 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
  • 2004-11-03 AT AT04802664T patent/ATE454480T1/de active
  • 2004-11-03 EP EP04802664A patent/EP1682688B1/de not_active Not-in-force

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