DIE-CAST COMPONENT, BODY COMPONENT HAVING SAID DIE-CAST COMPONENT, MOTOR VEHICLE HAVING SAID BODY COMPONENT, AND METHOD FOR PRODUCING SAID DIE-CAST COMPONENT

Abstract

A method for producing a die-cast component and a die-cast component that is produced therewith. According to the invention, an outstanding punch riveting suitability is achieved if the die-cast component has a temperable aluminum alloy with the following alloying components: from 5.0 to 9.0 wt % silicon (Si), from 0.25 to 0.5 wt % magnesium (Mg), and residual aluminum as well as inevitable production-related impurities, containing at most 0.05 wt % of each and at most 0.15 wt % collectively, wherein the die-cast component has a yield strength (R.sub.p0.2) of greater than 190 MPa and an elongation at break (A.sub.5) of greater than or equal to 7% and the uniform elongation (A.sub.g) and necking elongation (A.sub.z) satisfy the condition A.sub.z≥A.sub.g/2.

Claims

1. A die-cast component made of a temperable aluminum alloy comprising the following alloy components: from 5.0 to 9.0 wt % silicon (Si), from 0.25 to 0.5 wt % magnesium (Mg), and optionally up to 0.8 wt % manganese (Mn), from 0.08 to 0.35 wt % zinc (Zn), from 0.08 to 0.35 wt % chromium (Cr), up to 0.30 wt % zirconium (Zr), up to 0.25 wt % iron (Fe), up to 0.15 wt % titanium (Ti), up to 0.20 wt % copper (Cu), up to 0.025 wt % strontium (Sr), up to 0.2 wt % vanadium (V), up to 0.2 wt % molybdenum (Mo) and residual aluminum as well as inevitable production-related impurities, containing at most 0.05 wt % of each and at most 0.15 wt % collectively, wherein the die-cast component has a yield strength (R.sub.p0.2) of greater than 190 MPa and an elongation at break (A.sub.5) of greater than or equal to 7% and a uniform elongation (A.sub.g) and necking elongation (A.sub.z) satisfy the condition A.sub.z≥A.sub.g/2.

2. The die-cast component according to claim 1, wherein the die-cast component has a uniform elongation (A.sub.g) of at least 6% and a necking elongation (A.sub.z) of at least 4%.

3. The die-cast component according to claim 1, wherein the temperable aluminum alloy has at least one of the group consisting of: from greater than 6.5 to 9.0 wt % silicon (Si), from 0.3 to 0.5 wt % magnesium (Mg), from 0.3 to 0.6 wt % manganese (Mn), from 0.15 to 0.3 wt % zinc (Zn), from 0.10 to 0.20 wt % copper (Cu), from 0.10 to 0.25 wt % iron (Fe), from 0.05 to 0.15 wt % titanium (Ti), and from 0.015 to 0.025 wt % strontium (Sr).

4. The die-cast component according to claim 3, wherein the temperable aluminum alloy has at least one of the group consisting of: from greater than 6.5 to 8 wt % silicon (Si), from 0.15 to 0.25 wt % zinc (Zn), from 0.15 to 0.25 wt % iron (Fe).

5. The die-cast component according to claim 1, wherein the temperable aluminum alloy has up to 0.05 wt % manganese (Mn) and/or up to 0.05 wt % copper (Cu).

6. A body component for a motor vehicle with a die-cast component according to claim 1.

7. The body component according to claim 6, with at least one punch rivet and with another component, wherein the die-cast component is firmly connected to the other component by the punch rivet.

8. A motor vehicle with a body component according to claim 6.

9. A method for producing a die-cast component according to claim 1, wherein the method comprises a heat treatment with the following steps in the indicated sequence: at least a two-stage annealing, comprising at least a first annealing at a temperature in a range from 320° C. to 450° C. for a duration of from 20 minutes to 75 minutes and a second annealing at a temperature in a range from 510° C. to 540° C. for a duration of from 5 minutes to 35 minutes, quenching with a temperature gradient in a range of greater than 4 K/s and at least a three-stage artificial aging, comprising at least a first artificial aging at a temperature in a range from 100° C. to 180° C. for a duration of from 40 minutes to 150 minutes, a second artificial aging at a temperature a the range from 180° C. to 300° C. for a duration of from 30 minutes to 100 minutes, and a third artificial aging at a temperature in a range from 230° C. to 300° C. for a duration of from 5 minutes to 120 minutes.

10. The method according to claim 9, wherein the first annealing takes place at a temperature in a range from 390° C. to 410° C. and/or for a duration of from 50 minutes to 70 minutes.

11. The method according to claim 9, wherein the second annealing takes place at a temperature in a range from 520° C. to 535° C. and/or for a duration of from 25 to 30 minutes.

12. The method according to claim 11, wherein the second annealing takes place at a temperature in a range from 525° C. to 535° C.

13. The method according to claim 9, wherein the quenching takes place with a temperature gradient in a range from 7 K/s to 20 K/s.

14. The method according to claim 9, wherein the first artificial aging takes place at a temperature in a range from 140° C. to 160° C. and/or for a duration of from 110 minutes to 130 minutes.

15. The method according to claim 9, wherein the second artificial aging takes place at a temperature in a range from 190° C. to 210° C. and/or for a duration of from 50 minutes to 70 minutes.

16. The method according to claim 9, wherein the third artificial aging takes place at a temperature in a range from 230° C. to 270° C. and/or for a duration of from 10 minutes to 30 minutes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] To prove the achieved effects, thin-walled die-cast components were produced from different casting alloys in the die-casting process. The subject matter of the invention is depicted by way of example in the figures. In the drawings

[0058] FIG. 1 shows a view of the sequence of the heat treatment according to the invention,

[0059] FIG. 2a is a cutaway polished cross-section of two punch-riveted components, with the lower component being a die-cast component according to the prior art,

[0060] FIG. 2b shows a three-dimensional view of FIG. 2a from the die plate side,

[0061] FIG. 3a is a cutaway polished cross-section of two punch-riveted components, with the lower component being the die-cast component according to the invention, and

[0062] FIG. 3b shows a three-dimensional view of FIG. 3a from the die plate side.

WAYS TO IMPLEMENT THE INVENTION

[0063] The compositions of the tested alloys are listed in Table 1; the alloying elements listed in this table are accompanied by residual aluminum as well as inevitable production-related impurities, containing at most 0.05 wt % of each and at most 0.15 wt % collectively.

TABLE-US-00001 TABLE 1 Overview of the aluminum alloys Si Mg Mn Fe Zn Zr Ti Sr Alloys wt % wt % wt % wt % wt % wt % wt % wt % AlSi10Mg0.4Mn 10.5 0.4 0.61 <0.22 0.2 0.15 0.06 0.02 AlSi7Mg0.4 7 0.4 0.05 <0.15 0.2 0.15 0.06 0.02

[0064] The alloy AlSi7Mg0.4 ranges within the content limits according to the independent claims. The alloy AlSi10Mg0.4Mn, in comparison to the alloy AlSi7Mg0.4, has a significantly higher Si content—and in this connection, therefore lies outside the content limits according to the invention.

[0065] The die-cast components P1 (prior art) and I1 (according to the invention) with the relevant Al—Si aluminum alloys were subjected to a subsequent heat treatment according to Table 2:

TABLE-US-00002 TABLE 2 Overview of the heat treatment Com- Annealing Artificial aging ponent Alloy First Second Quenching First Second Third P1 AlSi10Mg0.4Mn 400° C. 510° C. 3 K/s 120° C. 230° C.  1 h  30 min  2 h  1 h I1 AlSi7Mg0.4 400° C. 530° C. 7 K/s 150° C. 200° C. 250° C.  1 h  30 min  2 h  1 h  20 min

[0066] FIG. 1 shows the sequence of the heat treatment according to the invention in greater detail: First, a two-stage annealing takes place, namely a first annealing 1.1 and subsequent second annealing 1.2, after which a quenching 2 takes place and, after a certain storage time, a three-stage artificial aging takes place with a first heating 3.1, a subsequent second heating 3.2, and a subsequent third heating 3.3. In this heat treatment, the die-cast component I1 passes through various states from T4, T6x, T6, up to T7, as indicated in FIG. 1.

[0067] FIG. 1 also shows the difference in the second annealing 1.2 between the invention I1 and the prior art P1. The second annealing in the prior art P1 takes place at a distinctly lower temperature than in the invention I1.

[0068] By contrast with the invention, the die-cast component P1 lacks a third artificial aging. There are also significant differences in the parameters of the second annealing—these differences by and large lead to the fact that after the heat treatment, the die-cast component P1 is in the T6 state.

[0069] At the end, the two die-cast components P1 and I1 were tested to ascertain their mechanical properties. For this purpose the yield strength R.sub.p0.2, ultimate tensile strength R.sub.m, elongation at break A.sub.5, and uniform elongation A.sub.g were ascertained. The measurement results obtained are compiled in Table 3. The necking elongation A.sub.z was calculated based on the elongation at break A.sub.5 and the uniform elongation A.sub.g.

TABLE-US-00003 TABLE 3 Mechanical properties Component R.sub.p0.2 [MPa] R.sub.m [MPa] A.sub.5 [%] A.sub.g [%] A.sub.z [%] = A.sub.5 − A.sub.g P1 195 277 12.8 8.7 3.7 I1 195 250 12.4 6.7 6.1

[0070] According to Table 3, the die-cast component according to the invention I1 has a distinctly higher necking elongation (A.sub.z)—as a result of which the die-cast component I1 has a particularly good punch riveting suitability and is generally suitable for a joining by means of shaping.

[0071] This suitability was tested by means of a punch riveting using a domed die plate—specifically, an aluminum sheet A of the 6xxx series was punch riveted to the die-cast component P1 on the die sheet side and to the die-cast component I1 on the die sheet side using a rivet element N. The results of this punch riveting are shown in FIGS. 2a & 2b and 3a & 3b, respectively.

[0072] In the polished cross-section of AlSi10Mg0.4Mn in the T6 state shown in FIG. 2a, several cracks R are visible, whereas in the polished cross-section of the Al—Si7Mg0.4 alloy according to the invention in the high-strength T7 state shown in FIG. 3a, no cracks are visible.

[0073] In addition, the AlSi10Mg0.4 Mn T6 shown in FIG. 2b exhibits numerous deep cracks on the die plate side whereas the cracks in the Al—Si7Mg0.4 T7 are much finer. There is in fact a larger number of them, but these are not critical because of their small width and depth. According to the invention, a riveting result is thus improved significantly compared to the prior art.

[0074] For this reason, the die-cast component according to the invention I1 also has a particularly good suitability, for example, for thin-walled shaped parts on a body of a vehicle, preferably a motor vehicle.