CAST PART

Abstract

The invention relates to a cast part.

Description

The invention relates to a cast part, particularly as a chassis application.

For chassis applications, sub-eutectic Al alloys having a Si content between 7 and 12 wt.-% are usually used. In gravity ingot mold casting, the alloy AlSi11Mg is frequently used; in low-pressure ingot mold casting, the alloy AlSi7Mg is frequently used. Low-Si AlSiMg alloys, which are characterized by clearly improved mechanical properties as compared with the common cast AlSi alloys mentioned above, are known from WO 2007/025528 A2 and WO/2009/059593.

Proceeding from this state of the art, the invention is based on the task of further improving a cast part made from a low-Si Al alloy with regard to its mechanical properties.

This is achieved, according to the invention, by means of a cast part made from an Al casting alloy that contains at least five of the alloy components listed below

• Si: 2.5 to 3.3, preferably 2.7 to 3.1 wt.-%,
• Mg: 0.2 to 0.7, preferably 0.3 to 0.6 wt.-%,
• Fe: <0.18, preferably 0.05 to 0.16 wt.-%,
• Mn: <0.5, preferably 0.05 to 0.4 wt.-%,
• Ti: <0.1, preferably 0.01 to 0.08 wt.-%,
• Sr: <0.03, preferably 0.01 to 0.03 wt.-%,
• Cr: 0.3 to 1.3, preferably 0.4 to 1.0,
  • particularly preferably 0.5 to 0.8 wt.-%,
• Others: <0.1 wt.-%,
  and is supplemented to 100 wt.-% with Al, in each instance,

wherein the cast part is artificially aged between 150 to 240° C. for 15 to 120 minutes, preferably for 15 to 60 minutes, particularly preferably for 20 to 55 minutes, very particularly preferably for 30 to 55 minutes, and absolutely particularly preferably between 30 and 45 minutes.

It can be advantageous if the cast part is artificially aged between 170 to 230° C. for 15 to 120 minutes, preferably for 15 to 60 minutes, particularly preferably for 20 to 55 minutes, very particularly preferably for 30 to 55 minutes, and absolutely particularly preferably between 30 and 45 minutes.

It can be practical if the cast part is artificially aged between 200 to 220° C. for 15 to 120 minutes, preferably for 15 to 60 minutes, particularly preferably for 20 to 55 minutes, very particularly preferably for 30 to 55 minutes, and absolutely particularly preferably between 30 and 45 minutes.

A further advantage can consist in that the cast part is solution-annealed before artificial aging, between 490 and 550° C. for 1 to 10 hours, preferably for 5 to 9 hours, particularly preferably for 6 to 8 hours.

It can be advantageous if the cast part is solution-annealed before artificial aging, between 530 and 550° C. for 1 to 10 hours, preferably for 5 to 9 hours, particularly preferably for 6 to 8 hours.

The aforementioned heat treatments lead to a further significant improvement in the mechanical properties of the cast component or of the cast part.

For chassis applications, particularly for wheel-guiding components, increased mechanical characteristic values are obtained in this way, in total.

The alloys according to the invention can contain production-related contaminants, for example Pb, Ni, Zn, etc., as they are generally known to a person skilled in the art. Such contaminants are included among what are called the other alloy components.

The cast parts according to the invention particularly demonstrate improved strength as compared with conventional cast parts or cast parts that are not heat-treated at all, but also demonstrate an improved strength/elongation ratio.

Fundamentally, a permanent mold method is suitable as a production method for heat-treated cast parts for or of chassis parts of motor vehicles, in particular, according to the invention. Because of the very good mechanical properties of work pieces, components, or parts that are subject to great stress, gravity ingot mold casting and low-pressure ingot mold casting are particularly suitable as production methods.

In the case of pressure-supported casting methods, in particular, for example the low-pressure counter-pressure casting method (CPC method), semi-solid casting method, as well as other pressure-supported casting methods such as squeeze-casting, casting-forging (Cobapress), or mold system-automated low-pressure sand-casting, better mechanical technological properties result from the good casting structure. In this connection, the counter-pressure ingot mold casting method (CPC method) is particularly preferred.

Aside from the advantages already mentioned, which cast parts heat-treated according to the invention demonstrate, in addition the corrosion resistance of the cast parts is significantly increased because of the absence of the alloy components Cu and Zn. Such cast parts are also relatively inexpensive, because no alloy additives that make them more expensive, such as rare earth metals, for example, are used; the usual melt treatment can be applied, and no particular effort for separating the circulation is required.

EXAMPLE

For a determination of the mechanical properties of a heat-treated cast part, pivot bearings made of the alloy AlSi3Mg0.5Cr0.7 are cast using the low-pressure counter-pressure ingot mold casting method, and tensile rods are produced from these, according to DIN 50125:2009-07. Subsequently, solution annealing takes place at 545° C. for 0.5 to 6 hours, as does artificial aging at 200-220° C., also for 0.5 to 6 hours. The mechanical properties of tensile strength R_m, yield strength R_p0.2, and elongation to rupture A5 are determined. DIN EN ISO 6842-1: 2009-12 is used for this. The values determined are shown graphically in FIG. 1.

It is shown that in the case of artificial aging between 200 and 220° C. for less than 60 minutes, particularly for 30 to 59 minutes, a significant increase in the elongation to rupture can be found, which is also accompanied by an increase in the tensile strength. In this connection, the yield strength demonstrates a level that remains approximately the same.

Claims

1. Cast part made from an Al casting alloy, containing at least five of the alloy components listed below: and is supplemented to 100 wt.-% with Al, in each instance, wherein the cast part is artificially aged between 150 to 240° C. for 15 to 120 minutes, preferably for 15 to 60 minutes, particularly preferably for 20 to 55 minutes, and very particularly preferably for 30 to 55 minutes.

Si: 2.5 to 3.3, preferably 2.7 to 3.1 wt.-%,

Mg: 0.2 to 0.7, preferably 0.3 to 0.6 wt.-%,

Fe: <0.18, preferably 0.05 to 0.16 wt.-%,

Mn: <0.5, preferably 0.05 to 0.4 wt.-%,

Ti: <0.1, preferably 0.01 to 0.08 wt.-%,

Sr: <0.03, preferably 0.01 to 0.03 wt.-%,

Cr: 0.3 to 1.3, preferably 0.4 to 1.0, particularly preferably 0.5 to 0.8 wt.-%,

Others: <0.1 wt.-%,

2. Cast part, particularly according to claim 1, wherein the cast part is artificially aged between 170 to 230° C. for 15 to 120 minutes, preferably for 15 to 60 minutes, particularly preferably for 20 to 55 minutes, and very particularly preferably for 30 to 55 minutes.

3. Cast part, particularly according to claim 1, wherein the cast part is artificially aged between 200 to 220° C. for 15 to 120 minutes, preferably for 15 to 60 minutes, particularly preferably for 20 to 55 minutes, and very particularly preferably for 30 to 55 minutes.

4. Cast part, particularly according to claim 1, wherein the cast part is solution-annealed between 490 and 550° C. for 1 to 10 hours, preferably for 5 to 9 hours, particularly preferably for 6 to 8 hours.

5. Cast part, particularly according to claim 1, wherein the cast part is solution-annealed between 530 and 550° C. for 1 to 10 hours, preferably for 5 to 9 hours, particularly preferably for 6 to 8 hours.

6. Use of a cast part according to claim 1 as a component or part for or of chassis parts of motor vehicles.