Method for producing a component

Abstract

A method for producing a component from an aluminum alloy using a semisolid method is provided. The alloy contains less than 1.3% by weight of iron and no more than 0.2% by weight of silicon, and the component has sufficient ductility such that the component can be joined to other components by self-piercing riveting, flow drilling, high-speed tack setting, friction welding and/or weld riveting.

Claims

1. A method for producing a component, the method comprising: preparing an alloy based on aluminum and converting the alloy into a semisolid state including solid particles of pure aluminum suspended in a liquid metal, the semisolid state free of solid aluminum-iron particles; and forming the component with a semisolid method, wherein the alloy contains less than 1.3% by weight of iron and no more than 0.2% by weight of silicon.

2. The method according to claim 1, wherein the component is produced by rheocasting by introducing the alloy in the semisolid state into a predominantly closed mold cavity via at least one transfer opening and solidifying the alloy in the mold cavity.

3. The method according to claim 1, wherein the alloy contains no more than 0.05% by weight of silicon.

4. The method according to claim 1, wherein the alloy contains no more than 1.0% by weight of iron.

5. The method according to claim 1, wherein the alloy contains at least 0.1% by weight of iron and no more than 1.0% by weight iron.

6. The method according to claim 1, wherein the alloy contains magnesium.

7. The method according to claim 6, wherein the alloy contains 3.0-4.6% by weight of magnesium.

8. The method according to claim 1, wherein the alloy contains no more than 1.0% by weight of additional elements which differ from aluminum, magnesium, iron and silicon.

9. The method according to claim 1, wherein the alloy contains no more than 0.05% by weight of silicon, at least 0.1% and no more than 1.0% by weight of iron, and 3.0-4.6% by weight of magnesium.

10. The method according to claim 9, wherein the alloy contains about 4.3% by weight of magnesium, about 1.0% by weight of iron, about 0.1% by weight of copper, and about 0.075% by weight of manganese.

11. The method according claim 1, wherein the component is a motor vehicle component.

12. The method according to claim 11, wherein the alloy contains no more than 1.0% by weight of additional elements which differ from aluminum, magnesium, iron and silicon.

13. The method according to claim 1, further comprising heating the alloy to a liquid state having a temperature below 655 degrees Celsius to prevent formation of the solid aluminum-iron particles and then cooling the liquid alloy to convert the liquid alloy to the semisolid state.

14. The method according to claim 1, further comprising heating the alloy to a temperature exceeding 620 degrees Celsius and below 633 degrees Celsius to form the solid aluminum particles suspended in the liquid metal and to prevent formation of solid aluminum-iron particles before formation of the solid aluminum particles.

15. A method for producing a component, the method comprising: rheocasting an aluminum alloy containing less than 1.3% by weight of iron and no more than 0.2% by weight of silicon and forming the component, the aluminum alloy including solid particles of pure aluminum suspended in a liquid metal and free of solid aluminum-iron particles suspended in the liquid metal.

16. The method according to claim 15, wherein the alloy contains no more than 0.05% by weight of silicon.

17. The method according to claim 15, wherein the alloy contains no more than 1.0% by weight of iron.

18. The method according to claim 15, wherein the alloy contains at least 0.1% by weight of iron and no more than 1.0% by weight iron.

19. The method according to claim 15, wherein the alloy contains no more than 0.05% by weight of silicon, at least 0.1% and no more than 1.0% by weight of iron, and 3.0-4.6% by weight of magnesium.

20. The method according to claim 19, wherein the alloy contains about 4.3% by weight of magnesium, about 1.0% by weight of iron, about 0.1% by weight of copper, and about 0.075% by weight of manganese.

Description

DRAWINGS

(1) In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

(2) FIG. 1 shows a schematic illustration of a first stage of a method according to the teachings of the present disclosure;

(3) FIG. 2 shows a schematic illustration of a second stage of the method according to the teachings of the present disclosure;

(4) FIG. 3 shows a phase diagram that shows the dependence of various phases on the proportion of iron in an aluminum alloy;

(5) FIG. 4 shows a diagram which illustrates the temperature-dependent formation of individual phases in an aluminum alloy suitable for diecasting;

(6) FIG. 5 shows a diagram which illustrates the temperature-dependent formation of individual phases in an aluminum alloy suitable for the method according to the teachings of the present disclosure; and

(7) FIGS. 6A-6E show various stages of a joining process using a component produced according to the teachings of the present disclosure.

(8) The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

(9) The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

(10) In the various figures, identical parts are in all cases provided with the same reference signs, for which reason said parts are generally also described only once.

(11) FIG. 1 shows a device 1 for carrying out a method according to the teachings of the present disclosure. Here, the intention is to produce a component by rheocasting from an alloy 20 based on aluminum. As can be seen, a mold 2 having a first mold half 2.1 and a second mold half 2.2, which, when joined together, define between them a mold cavity 3. On one side, the mold cavity 3 is connected to a transfer opening 4, which, in turn, is connected to a container 5. The container 5 has a filling opening 6, through which the alloy 20 can be introduced in liquid form. Within the container 5, the alloy 20 is converted to a semisolid state, wherein the desired temperature of the alloy 20 is established by a temperature control device 10, which can both cool and heat. Arranged adjoining the container 5 there is furthermore a mixing device 9, which can be designed, for example, to produce electromagnetic fields. These act on the alloy 20 and bring about improved mixing of the individual components, at least in the liquid state of said alloy. Arranged within the container 5 there is, on the one hand, a movable piston 7 and, on the other hand, a transfer hatch 8. The alloy 20 is initially enclosed between the piston 7 and the transfer hatch 8 (see FIG. 1).

(12) When the alloy 20 has been converted to the semisolid state, the actual shaping process begins, for which purpose the transfer hatch 8 is opened (see FIG. 2), while the piston 7 is moved in the direction of the mold 2. The alloy 20 is thereby moved through the container 5 and forced onward, via the transfer opening 4, into the mold cavity 3, while it continues in the semisolid state. Within the mold cavity 3, the alloy 20 hardens and forms the desired component.

(13) The component produced could be, in particular, a body component which is subsequently connected by self-piercing riveting (SPR) to another component, which is made of steel, for example. In this method, the enhanced ductility which is established according to the teachings of the present disclosure is advantageous.

(14) The alloy 20 used in this example has the following components:

(15) Magnesium: 4.3% by weight

(16) Iron: 1.0% by weight

(17) Silicon: 0.1% by weight

(18) Copper: 0.1% by weight

(19) Manganese: 0.075% by weight

(20) Aluminum: remainder

(21) The significance of the proportion of iron being less than 1.3% by weight (in this case 1.0% by weight) becomes clear from the phase diagram in FIG. 3, which illustrates the formation of various phases as a function of the proportion of iron. In this case, it can be seen that a mixed phase comprising solid aluminum in a liquid phase can only be achieved if the proportion of iron is restricted as described and is thus below the value of 1.3% by weight for the eutectic. Otherwise, formation of solid Al13Fe4 takes place first, before the pure aluminum phase is formed. This would be the case, for example, with alloys that can be used for diecasting in the prior art, which usually have a proportion of iron between 1.5% by weight and 1.7% by weight. One example of this would be Castaduct®-42, which differs from the alloy used according to the present disclosure, in particular, by having a proportion of iron of 1.6% by weight.

(22) This state of affairs is clear once again from the diagrams in FIGS. 4 and 5, which each illustrate the temperature-dependent formation of individual phases. FIG. 4 shows a corresponding diagram for an alloy that cannot be used according to the teachings of the present disclosure, having the following components:

(23) Magnesium: 4.3% by weight

(24) Iron: 1.3% by weight

(25) Silicon: 0.1% by weight

(26) Copper: 0.1% by weight

(27) Manganese: 0.075% by weight

(28) Aluminum: remainder

(29) It can be seen that the formation of Al13Fe4 is already beginning at about 655° C., while the formation of the Al phase begins only below about 633° C. FIG. 5 shows a diagram for the above-described alloy that can be used according to the teachings of the present disclosure. The reduction of the proportion of iron to 1.0% by weight suppresses the formation of the Al13Fe4-phase, with the result that it starts only below about 631° C., while the formation of the Al phase is once again already beginning below about 633° C.

(30) In the case of the alloy according to the present disclosure used here, the proportion of silicon is 0.1% by weight. This proportion can be further reduced without prejudicing the advantageous properties described above, e.g. to 0.05% by weight, 0.01% by weight or 0.001% by weight.

(31) FIGS. 6A-6E show various phases of a method in which a component is produced according to the present disclosure, where an aluminum part 11 is connected to a steel part 12 by self-piercing riveting. Here, both parts 11, 12 are illustrated as flat plates, but this should not be interpreted restrictively. The aluminum part 11 is laid on a die 13, wherein the steel part 12 rests on the component 11. A semi-tubular rivet 14 is accommodated in a setting unit 15 (see FIG. 6A). The setting unit 15 is placed on the steel part 12, thereby fixing the joining location envisaged. At the same time, the semi-tubular rivet 14 is pushed forward and placed in contact (FIG. 6B). By means of a further forward motion, there is first of all a plastic deformation of the steel part 12 and of the aluminum part 11 into the die 13, while the semi-tubular rivet 14 still retains its original shape (FIG. 6C). Subsequently, the semi-tubular rivet 14 punches only through the steel part 12 situated at the top and forms the underlying aluminum part 11 plastically to form a closing head 11.1 (FIGS. 6D and 6E). At the same time, the stem of the semi-tubular rivet 14 is spread apart, thereby completing the positive connection. It is self-evident that a high degree of forming takes place in the region of the closing head 11.1, wherein particularly high ductility is desired to avoid cracks or tears. It has been found that components which have been produced according to the present disclosure have a particularly low tendency to form or do not form cracks in this method.

(32) Apart from the self-piercing riveting process shown here by way of example, the aluminum part 11 can also advantageously be used with other connection methods, among which there are, in particular, screw-joining by flow drilling, high-speed tack setting, friction welding and weld riveting.

(33) Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word “about” or “approximately” in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.

(34) As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

(35) The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.