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
  • C22C21/10—Alloys based on aluminium with zinc as the next major constituent

Definitions

• the invention relates to a cast alloy based on aluminum and their use.
• AISi cast alloys also have the disadvantage that with this type of alloy, due to the eutectic silicon, which is especially for safety-relevant Components in vehicle construction often require high ductility cannot be reached.
• the alloys of the AlSi group must therefore to improve the castability and the mechanical properties Sodium or strontium can be refined.
• These finishing elements work but are disadvantageous in that, on the one hand, they burn quickly (especially Sodium) and on the other hand the tendency of the melt to absorb hydrogen increase strongly (especially strontium). In practice, this leads to increased Gas porosity and thus to reduce ductility and fatigue strength.
• the invention has for its object to an aluminum casting alloy create the required properties after casting without one Heat treatment already by aging at room temperature at least 14 days or only with limited heat treatment T5, i.e. achieved without solution annealing.
• the casting alloy should above all suitable for die casting and sand casting.
• the alloy should also be used in particular for safety-relevant components in vehicle construction, ie the castings made from the alloy must have high strength combined with high ductility.
• the mechanical properties sought in the casting are defined as follows: yield strength Rp0.2> 170 MPa tensile strenght Rm> 230 MPa elongation A5> 6%
• the corrosion tendency of the cast alloy should depend on the applications be kept as deep as possible and the alloy must also have a corresponding have good fatigue strength.
• the castability of the alloy should be comparable be with the currently used AISi casting alloys, and the Alloy must not show any tendency to crack hot.
• a cast alloy based on aluminum is used to achieve the object according to the invention silicon Max. 0.25 Wt .-% iron Max. 0.2 Wt .-% copper Max. 0.3 Wt .-% manganese 0.05 to 0.5 Wt .-% magnesium 0.2 to 1.0 Wt .-% zinc 4 to 7 Wt .-% titanium Max. 0.2 Wt .-% chrome 0.15 to 0.45 Wt .-% boron Max. 0.0065 Wt .-% nickel Max. 0.25 Wt .-% tin Max. 0.25 Wt .-% silver Max. 0.25 Wt .-% cerium Max. 0.25 Wt .-% zirconium Max. 0.25 Wt .-% scandium Max. 0.25 Wt .-% as well as aluminum as the rest with other elements and manufacturing-related impurities individually max. 0.05% by weight, max. 0.15% by weight.
• the following content ranges are preferred for the individual alloy elements: silicon Max. 0.15% by weight, in particular max. 0.10% by weight iron Max. 0.15% by weight, in particular max. 0.10% by weight copper Max. 0.1% by weight, in particular max. 0.07% by weight manganese 0.1 to 0.3% by weight, in particular 0.15 to 0.25% by weight magnesium 0.4 to 0.8% by weight zinc 4.5 to 6% by weight, in particular 4.7 to 5.8% by weight titanium 0.03 to 0.15% by weight, in particular 0.05 to 0.10% by weight chrome 0.20 to 0.30% by weight boron 0.0005 to 0.005% by weight
• the alloy can contain 0.10 to 0.25% by weight Nickel, in particular 0.10 to 0.15 wt .-% nickel.
• the cast alloy according to the invention has, because of the cold hardening Main alloy element zinc. This type of alloy has next to none Eutectic on the grain boundaries and therefore leads to good ductility but known to be problematic in terms of casting technology because of the pronounced Tendency to heat crack, see e.g. John E. Hatsch, Properties and Physical Metallurgy page 347.
• a tendency to stress corrosion cracking with a high zinc content and to counteract intergranular corrosion is preferred ensured that the zinc content remains below 6% by weight.
• Chromium also improves the mechanical properties, especially in Direction of higher ductility, since it is the morphology of the Fe / Mn-containing phases changed from a more angular to a round shape.
• a certain amount of titanium combined with boron is required for grain refinement. Good grain refinement significantly improves the casting properties at.
• a preferred area of application of the cast alloy according to the invention is the production of safety-related components in vehicle construction, in particular Handlebars, brackets, frame parts and wheels. Also for roasting and cooking dishes, especially for frying pans, the alloy according to the invention is excellent suitable.
• Alloys with a composition according to Table 1 based on aluminum with other manufacturing-related impurities individually max. 0.05% by weight, max. 0.15% by weight was cast in a die rod test die according to Diez to give round bars 16 mm in diameter.
• Alloys Nos. 1 and 2 are compositions according to the invention, and Alloys 3 to 9 are comparative examples.
• the mechanical properties of the yield strength (Rp0.2), tensile strength (Rm) and elongation at break (A5) in the as-cast state were determined on test bars.
• the hot crack number as a measure of the hot crack tendency was determined on the basis of a visual assessment of a cast part produced specifically for this determination.
• This special cast part has a central area, from which 6 arms of different lengths of the same diameter extend in a star shape, with a spherical end piece being formed at the end of each arm.
• the number of torn arms and the tears that occurred were assessed.
• the evaluation is carried out using an evaluation scheme with levels 0 to 6.
• the hot crack number means: 0 no cracks 1 to 5 Increase in cracks, from cracks that can only be seen with a magnifying glass to several torn arms 6 all arms torn off

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Continuous Casting (AREA)

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Publications (1)

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Cited By (9)

Citations (7)

• 2001
  • 2001-02-05 EP EP01810109A patent/EP1229141A1/fr not_active Withdrawn

Patent Citations (7)

Non-Patent Citations (6)

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