RU2576707C2 - Aluminium-based cast alloy - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: aluminium-based cast alloy containing silicon, magnesium, manganese, iron, additionally contains in wt %: silicon 10.0-13.0, magnesium max. 0.15, iron max. 0.5, manganese max. 0.5, modification elements to grind eutectic from row Sb, Sr, Na, K, Ca in total max. 0.05, modification elements to grind α-solid solution from row Ti, B, Zr, Sc in total max. 0.12, aluminium - rest, at iron to manganese ratio 1:1.

EFFECT: increased offset yield stress, ultimate strength and hardness.

1 tbl, 1 ex

Description

The invention relates to the metallurgy of aluminum alloys and can be used for the manufacture of wheels of automobile wheels obtained by injection molding under low pressure.

Known alloy based on aluminum, containing, wt.%: Silicon 10-12; magnesium 0.25-0.35; beryllium 0.05-0.2; titanium 0.1-0.3; boron 0.05-0.15; manganese 0.05-0.2; strontium 0.02-0.06; impurities (no more) iron 0.4; copper 0.3; aluminum - the rest (application for invention No. 95114156).

The disadvantage of this alloy in the manufacture of automobile wheel disks is the presence of beryllium, which increases the cost of the alloy and has a harmful effect on human health. In addition, the presence of copper leads to a decrease in the corrosion resistance of the finished wheels.

The closest alloy to the proposed one is a casting alloy for the manufacture of automobile wheels, containing, wt.%: Si 5-12, Mg 0.1-1, Fe 0.16, Mn 1.5 or less, Cu 1.0 or less, modifier elements for grinding structures from the Ti series 0.3-0.2, Sr 0.005-0.1, the rest is aluminum (CN 102206778 A, C22C 21/04, 05/10/2011, abstract).

The disadvantage of this alloy in the manufacture of automobile wheel disks is a small number of elements that can be used as modifiers, and the ratio of iron and manganese has been established, which provides a change in the morphology of the iron-containing β-phase from needle to skeleton shape.

The objective of the invention is to create an alloy based on aluminum, used in the manufacture of rims of automobile wheels with high mechanical properties and prepared on the basis of primary aluminum with a high iron content.

The problem is solved in that the aluminum-based casting alloy contains silicon, magnesium, manganese, iron, modifier elements for grinding eutectics from the Sb, Sr, Na, K, Ca series and modifier elements for grinding α-solid solution from the Ti series , B, Zr, Sc in the following ratio of components, wt.%:

silicon 10.0-13.0

magnesium no more than 0.15

iron no more than 0.5

manganese not more than 0.5: 0.5

modifier elements for grinding eutectics from the series Sb, Sr, Na, K, Ca in the amount of not more than 0.05

modifier elements for grinding α-solid solution from the series Ti, B, Zr, Sc in the amount of not more than 0.12

aluminum - the rest, with a ratio of iron to manganese 1: 1.

The silicon content in the amount of 10.0-13.0% provides the alloy with good casting properties due to the presence of Al-Si eutectic. A decrease or increase in the silicon content changes the nature of the crystallization of the alloy, which affects the casting properties and does not allow to obtain high-quality, complex in configuration, high-precision castings of wheel disks by low-pressure casting.

The introduction of magnesium in an amount of up to 0.15 wt.% Provides the alloy with high strength properties and improves the processing by cutting of finished products. An increase in magnesium content of more than 0.15 wt.% Leads to greater distortion of the crystal lattice of aluminum and, as a result, to a decrease in the ductility of finished products.

The ratio of iron: manganese 1: 1 provides a change in the morphology of the iron-containing β-phase from needle to skeleton-like form, which leads to an increase in the mechanical properties of wheel disks when casting under low pressure. An increase or decrease in the amount of manganese in this ratio does not lead to the formation of a skeletal phase in the entire volume of the casting during its crystallization.

Modifier elements from the series Sb, Sr, Na, K, Ca are introduced into the composition of the alloy to modify silicon in the eutectic. An increase in their content of more than 0.05 wt.% Leads to the formation of phases that embrittle the alloy.

Modifier elements from a number of Ti, B, Zr, Sc are introduced for grinding grain of an aluminum-based solid solution. An increase in their content of more than 0.12 wt.% Leads to an increase in the cost of the alloy, but does not contribute to further grinding of the grain of the castings.

EXAMPLE

Three experimental alloys were prepared, the compositions of which are indicated in Table 1. Alloys were prepared in the IAT-2.5 induction furnace in the factory conditions of KiK LLC (Krasnoyarsk) based on primary aluminum of grade A7. The chemical composition of the alloy was determined on a SPECTROmax emission spectrometer (during melting, the composition was adjusted to specified values). From experimental alloys, automobile wheel disks were obtained by low-pressure casting on a GIMMA machine.

The mechanical properties during tensile testing of specimens machined from wheel castings were determined according to GOST 1497-84, Brinell hardness - according to GOST 9012-59.

It can be seen from the table that alloys 1 and 4 do not provide the discs with high mechanical properties.

Composition 2, 3 provides the best combination of conditional yield strength, temporary tensile strength, elongation and hardness of castings of wheel disks that meet the requirements of GOST R 50511-93. In this case, when the iron to manganese content is 1: 1, inclusions of the glandular β-phase pass from needle-shaped to a compact skeletal form, which reduces the harmful effect of iron on the mechanical properties of the alloy. In addition, the use of primary aluminum of low grade (A7, A7E, GOST 11069-2001) as part of the charge reduces the cost of finished wheels of automobile wheels. The presence of modifier elements from the series Sb, Sr, Na, K, Ca allows the grinding of silicon, which is part of the eutectic, thereby increasing the relative elongation of the alloy. The presence of modifier elements from the Ti, B, Zr, Sc series allows grinding the grain of the α-solid solution, which increases the conditional yield strength, tensile strength, and Brinell hardness.

Claims (1)

Aluminum-based casting alloy for the manufacture of automobile wheel disks containing silicon, magnesium, manganese and iron, characterized in that it further comprises modifier elements for grinding eutectics from the series Sb, Sr, Na, K, Ca and grinding modifier elements α-solid solution from the series Ti, B, Zr, Sc, in the following ratio of components, wt.%:
silicon 10.0-13.0 magnesium no more than 0,15 iron no more than 0.5 manganese no more than 0.5 modifier elements for grinding eutectic from the series Sb, Sr, Na, K, Ca in total no more than 0,05 modifier elements for grinding α-solid solution from the series Ti, B, Zr, Sc in total no more than 0.12 aluminum rest
with a ratio of iron to manganese 1: 1.