WO2017174185A1

WO2017174185A1 - Aluminum alloy, in particular for a casting method, and method for producing a component from such an aluminum alloy

Info

Publication number: WO2017174185A1
Application number: PCT/EP2017/000411
Authority: WO
Inventors: Thomas Stürzel; Karl Weisskopf; Patrick Izquierdo
Original assignee: Daimler Ag
Priority date: 2016-04-07
Filing date: 2017-04-04
Publication date: 2017-10-12
Also published as: DE102016004216A1; US20190093199A1; CN109072354A; JP2019516013A

Abstract

The invention relates to an aluminum alloy, in particular for a casting method, wherein the aluminum alloy comprises at least aluminum, magnesium, manganese and copper, the aluminum alloy comprising: - 0.001 to 0.50 wt.% of molybdenum, - 0.05 to 0.45 wt.% of magnesium, - 0.05 to 0.60 wt.% of manganese, - up to 1.5 wt.% of iron, - 0.25 to 4.00 wt.% of copper and - 0.001 to 0.25 wt.% of vanadium.

Description

Aluminum alloy, in particular for a casting method, and method for producing a component from such an aluminum alloy

The invention relates to an aluminum alloy, in particular for a casting method, according to the preamble of patent claim 1 and a method for producing a component from such an aluminum alloy.

Such an aluminum alloy, in particular for a casting method, can already be taken as known from DE 10 2011 115 345 A1, for example. In this case, the

Aluminum alloy at least aluminum (AI), magnesium (Mg), manganese (Mn) and copper (Cu) on.

Object of the present invention is to provide an aluminum alloy and a method of the type mentioned, so that particularly advantageous, in particular mechanical properties of the component can be realized.

This object is achieved by an aluminum alloy with the features of claim 1 and by a method with the features of

Patent claim 5 solved. Advantageous embodiments with appropriate

Further developments of the invention are specified in the remaining claims.

In order to further develop an aluminum alloy, in particular for a casting method, of the type specified in the preamble of patent claim 1 such that particularly advantageous, in particular mechanical, properties of a

Aluminum alloy manufactured component can be realized, it is

According to the invention provided that the aluminum alloy between 0.001

Percent by weight (wt.%) And 0.50 wt.% (Wt.%) Of molybdenum. Further, the aluminum alloy has magnesium in a range of 0.05 wt% to 0.45 wt%, manganese in a range of 0.05 wt% to 0.60 wt%, iron up to 1.5 Wt% and copper in a range of from 0.25 wt% to 4.00 wt% inclusive and vanadium in a range of 0.001 wt% to 0.25 wt%. Preferably, the aluminum alloy has at least 0.10 wt% and less than 0.40 wt% manganese.

It has been found that by adjusting the magnesium concentration, in particular to less than 0.30 wt.%, The proportion of brittle TT-Al8FeMg3Si6 phases can be reduced so far that these phases are hardly available and thus detrimental to the ductility of Aluminum alloy or a component produced from the aluminum alloy can act. The reduction of the manganese content to less than 0.40 wt.% Is advantageous in that thereby the

Solidification temperature of the iron / manganese-containing intermetallic phases

AI15 (Fe, Mn) 3Si2 can be lowered so that they can not occur in too coarse blocky morphology.

Furthermore, it has proven to be particularly advantageous if the aluminum alloy has molybdenum (Mo) in a range of from 0.001% by weight to 0.50% by weight inclusive, it being preferred that the aluminum alloy is 0.10% by weight. Molybdenum has. The targeted addition of molybdenum, for example, with a proportion of 0.10 wt.%, In addition, a rounding indentation up to a polygonal morphology and a finer distribution of the aforementioned iron / manganese phases (Fe / Mn phases) be effected, leading to another

Increasing ductility leads. Overall, a sufficient ductility in the form of elongation at break can thereby be realized, which is particularly advantageous when the component produced from the aluminum alloy is used in a drive train of a motor vehicle. The component can, for example, as a crankcase of a

Internal combustion engine be formed, which is preferably designed as a diesel engine. Alternatively, the component may also be part of an internal combustion engine of a gasoline engine. Such a component produced from the aluminum alloy has a sufficient strength, in particular high heat resistance, due to the strength mechanism of the aluminum alloy. In addition, the inventive

Aluminum alloy advantageously used to from the aluminum alloy, a cylinder head, for example, as a reciprocating internal combustion engine

trained internal combustion engine, so that a unit alloy for the crankcase and cylinder head is conceivable. This can reduce costs, logistics, energy consumption and CO ₂ emissions in foundries and in the recycling process. Further, it is possible to heat aging of the aluminum alloy Increasing the strength can be achieved by copper and / or magnesium-containing precipitates in the aluminum matrix.

By using the aluminum alloy according to the invention for producing a component, it is possible that the component in the heat treatment state T5mod a 0.2% proof stress R _p0 , 2 of more than 180 megapascals, a tensile strength R _m of more than 220 megapascals and an elongation at break A ₅ of more than 1 percent at

Room temperature and in the heat treatment state T6red has a 0.2% proof stress Rpo, 2 of more than 200 megapascals, a tensile strength R _m of more than 230 megapascals and an elongation at break A ₅ of more than 1.5 percent at room temperature. At a test temperature of 150 degrees Celsius could

Heat treatment state T5mod the following values can be achieved: R _p o, 2> 1 0

Megapascal, R _m > 210 megapascals and As> 1, 5 percent.

At a test temperature of 150 degrees Celsius, the following values could be achieved in the heat treatment _{state T6red} : R _p0 , 2> 200 megapascals, R _m > 220 megapascals and A ₅ > 3 percent.

The invention is based in particular on the following findings: Due to the low magnesium content or magnesium content, in alloys with a high Fe content (Fe-iron), brittle intermetallic phases are suppressed, which leads to an increase in ductility. Copper leads to a strong increase in strength due to thermal aging as well as to an increased heat resistance of the aluminum alloy.

The aluminum alloy according to the invention has proven to be particularly advantageous for the production of thick-walled components which have a wall thickness in a range of from 4 millimeters to 30 millimeters inclusive. Furthermore, it is preferably provided that the casting method in which the component is produced from the aluminum alloy is a die-casting method or laminar die-casting or a sand / mold method. The

Aluminum alloy according to the invention is in particular a heat-resistant

Aluminum alloy, in particular a heat-resistant cast aluminum alloy, which is particularly advantageous for the production of components for drive trains.

The invention also includes a method for producing a component from an aluminum alloy according to the invention. Advantageous and advantageous embodiments The aluminum alloy according to the invention are advantageous and advantageous

To consider embodiments of the method according to the invention and vice versa.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing; these show in:

Fig. 1 is a schematic representation of a backscattered electron image (BSE image) of the alloy 233 with Kuper (Cu) and molybdenum (Mo) in

Heat treatment state T5mod, for example, as a

Crankcase formed component of said alloy is made by die casting;

Fig. 2 is a schematic representation of a BSE image of the alloy 226D

(AISi10Cu3) in the heat treatment state T5mod, for example, where a crankcase is made of the alloy;

Fig. 3 is a BSE image of the alloy 233 with Cu and Mo im

Heat treatment condition T6red;

Fig. 4 is a BSE image of the alloy 226D in the heat treatment state T6red;

Fig. 5 is a diagram illustrating mechanical characteristics of the component formed of the respective alloy at room temperature; and

6 shows a diagram for illustrating mechanical characteristics of the component produced from the respective alloy at 150 degrees Celsius.

In the figures, identical or functionally identical elements are provided with the same reference numerals.

Figures 1 to 4 show respective backscattered electron images (BSE images) of alloys from which respective components are made. The respective alloy is, for example, an aluminum alloy, in particular an aluminum casting alloy and preferably a heat-resistant aluminum casting alloy. The respective component produced from the respective alloy is, for example, a component which is used in a drive train of a motor vehicle, the component being, for example, a crankcase, in particular a die-cast crankcase. This means that the component is produced from the respective alloy by casting, in particular by die casting. In particular, the component may be a thick-walled component which has a wall thickness in a range of 4 mm to 30 mm inclusive. By the aluminum alloy described in more detail below, particularly advantageous properties, in particular mechanical properties, of the component can be realized. Preferably, the respective aluminum alloy has the following composition:

8.0% by weight to 11.0% by weight of silicon,

0.25% by weight to 4.00% by weight copper,

0.10% by weight to 0.50% by weight of magnesium,

0.05% by weight to 0.60% by weight of manganese,

less than or equal to 0.3% by weight of titanium,

less than or equal to 0.3% by weight zirconium,

less than 400 parts per million (ppm) strontium,

at most 1.5% by weight of iron,

at most 1.5% by weight of zinc,

0.001% by weight to 0.25% by weight of vanadium,

in addition further additions of 0.01% by weight to 0.50% by weight of molybdenum,

not more than 0.25% by weight of chromium,

not more than 0.20% by weight of nickel,

at most 0.15% by weight of cobalt,

and aluminum as the remainder, it being possible for impurities or further elements to be provided which have a proportion of less than

0.05% by weight.

In particular, it is preferably provided that the aluminum alloy comprises magnesium with at least 0.10% by weight and less than 0.30% by weight. Alternatively or additionally, it is preferably provided that the aluminum alloy has manganese with at least 0.10 wt.% And less than 0.40 wt.%. By lowering the manganese concentration, the far-primary formation of iron-manganese-containing intermetallic Ali ₅ (Fe, Mn) ₃ Si ₂ phases precedes the aluminum mixed crystals

counteracted and thus prevents a coarse blocky morphology. For the setting of iron (Fe), however, in addition molybdenum (Mo) is added, which leads to a polygonal morphology and finer distribution of Fe intermetallic phases. As a result, the formation of needle-like or plate-shaped ß-A FeSi phases is suppressed, which would occur at a high Fe and low Mn content (Mn - manganese). The magnesium content is lowered so far that there is no possible formation of the TT-A FeMgaSie phase. This phase does not dissolve at a solution annealing temperature of 465 degrees Celsius and would due to the increased Fe content additionally alloyed magnesium (Mg) only and lead to skeletal Fe-containing intermetallic phases, which are detrimental to the ductility in the form of waste Elongation at break and not more for one

strength-increasing elimination formation are available.

The copper content (Cu content) is used for the targeted adjustment of the required strength due to the formation of strength-increasing precipitates during thermal aging. However, it must be ensured that an excessively high copper content during T5 heat treatment leads to embrittlement. In a T6 heat treatment, the full

Strength potential of the copper of the alloy are exhausted.

The addition of titanium (Ti) causes grain refining of the aluminum dendrites. A combination with zirconium (Zr) in adjusted concentration can lead to Al ₃ (Ti, Zr) precipitations, which can increase the strength. Care must be taken to ensure that both titanium and zirconium are not alloyed in excessively high concentrations, since otherwise unwanted formation of Al-Ti-Zr intermetallic phases, which reduce ductility, occurs. The addition of strontium (Sr) results in a refining of the Al / Si eutectic from coarse-plate to a refined, coral-like morphology, which increases ductility. This fine Si morphology can be easily and quickly formed by a T6 solution annealing and thus the ductility can be increased again.

In the following, a production of a component made of such an aluminum alloy will be described. During production, the aforementioned aluminum alloy is melted from master alloys, pure elements, or prepared by alloying suitable secondary alloys such as 233 or 226 at a sufficiently high temperature. Furthermore, the alloy is poured off at at least 650 degrees Celsius to 720 degrees Celsius in a tempered and forced or vacuum-vented tempered permanent mold. If the casting temperature is too low, there is a risk of inadequate mold filling and cold runs as well as undesirable formation of intermetallic phases. Excessive casting temperatures increase the risk of porosity, shrinkage and shrinkage Hot cracking. After removal of the component produced by casting, the component is - to the realization of the heat treatment state T6red - in air or -

Realization of the heat treatment state T5mod - cooled by water.

The special feature in the structure of the component produced from the aluminum alloy can be seen from FIGS. 1 to 4. FIG. 1 shows a backscattered electron image of said secondary alloy 233 with copper and molybdenum. Roundish to polygonal molybdenum-containing AlFeMnSi intermetallic phases are recognizable. These are

comparatively regularly distributed between the Al dendrites in the Al / Si eutectic, since these solidify with this at the same time. Their small size and rounded morphology increase the ductility of the secondary alloy. Sporadically, the ττ phase AI ₈ FeMg ₃ Si _{6 is} found, which can not be resolved by solution heat treatment at 465 degrees Celsius (see FIG. 3). By lowering the Mg content, the formation of this brittle phase can be suppressed and thus the ductility further increased. Possible phases of solidification O-AbCu and Q-Al ₅ Cu2Mg ₈ Si6 are to be dissolved by solution heat treatment at 450 degrees Celsius for three hours

(See Fig. 3), so that the alloying elements Mg and Cu, which had set in these phases, are available in the Al mixed crystal for precipitation formation.

FIG. 2 shows a backscatter electron image of said secondary alloy 226D

(AISi10Cu3). Due to the high Fe and Mn content are coarse, blocky

intermetallic Alis (Fe, Mn, Cr, Cu) ₃ Si2 phases present, which have formed due to their size primarily in the casting chamber of the die casting machine. These

Accumulation of brittle phases prevents ductility. In addition, smaller, polygonal Fe- containing intermetallic phases are present, which only in the actual

Die casting mold have emerged. In addition to these Fe-containing intermetallic phases and β-A FeSi phases are present due to the high Fe content, which in

Two-dimensional grinding appear as needles and are present in reality as three-dimensional plates and thus exist as large-scale, sharp-edged Gefügetrennungen between the ductile Al dendrites. These phases significantly reduce ductility.

Due to the relatively high content of Ni contamination in this

Secondary alloy also form Al7Cu2 (Fe, Ni) phases, which can not be resolved by a solution annealing at 465 degrees Celsius and thus continue to exist as brittle phases and also set Cu (see Fig. 4).

During the solidification of the alloy formed Al ₂ Cu, which is not pronounced in eutectic form Al-Al ₂ Cu-AlsCu2Mg ₈ Si6-Si, can be prepared by a solution annealing at 465 Celsius degrees are completely dissolved (see Fig. 4), so by a

Water quenching then the Al mixed crystal is present supersaturated on Cu. However, the eutectic pockets Al-AbCu-A C ^ MgeSie-Si can not be completely dissolved at 465 degrees Celsius and three hours. Figs. 5 and 6 are diagrams for illustrating mechanical properties of components made of the aforementioned aluminum alloy. In this case, beams 10 illustrate the 0.2% yield strength R _p0 , 2, with bars 12 illustrating the yield strength R _m . Furthermore, triangles 14 illustrate the elongation at break A5.

Claims

claims

1. Aluminum alloy, in particular for a casting process, wherein the

Aluminum alloy comprises at least aluminum, magnesium, manganese and copper,

characterized in that

the aluminum alloy has:

0.001% by weight to 0.50% by weight of molybdenum,

From 0.05% to 0.45% by weight of magnesium,

From 0.05% by weight to 0.60% by weight of manganese,

- up to 1, 5 wt.% Iron,

- 0.25 wt.% To 4.00 wt.% Copper and

0.001% by weight to 0.25% by weight of vanadium.

2. Aluminum alloy according to claim 1,

characterized in that

the aluminum alloy is at least 0.10% by weight and less than

0.40 wt.% Manganese.

3. Aluminum alloy according to one of the preceding claims,

characterized in that

the aluminum alloy has 8.0 wt.% To 11, 0 wt.% Silicon.

4. Aluminum alloy according to one of the preceding claims,

characterized in that

the aluminum alloy has: at most 0.3% by weight of titanium,

at most 0.3% by weight of zirconium,

at most 400 parts per million strontium,

- not more than 1, 5% by weight of zinc,

not more than 0.25% by weight of chromium,

not more than 0.20% by weight of nickel,

at most 0.15% by weight of cobalt.

5. A method for producing an aluminum alloy component according to one of the preceding claims by casting, pressureless or pressurized with an effective pressure between 0 bar and 1000 bar.

6. The method according to claim 5,

characterized in that

the aluminum alloy is poured into a mold at a temperature of 650 degrees Celsius to 730 degrees Celsius.

7. The method according to claim 6,

characterized in that

The aluminum alloy at a temperature of 580 degrees Celsius to 650 degrees Celsius thixoptrop, pressureless or pressurized at an effective pressure between 0 bar and 1000 bar, potted.