METHOD FOR PRODUCING AN ENGINE COMPONENT, ENGINE COMPONENT, AND USE OF AN ALUMINUM ALLOY

Abstract

The invention relates to a method for producing an engine component, in particular a piston for an internal combustion engine, wherein an aluminum alloy is cast in the gravity die casting process and wherein the aluminum alloy has 7 to <14.5 wt % silicon, >1.2 to ≦4 wt % nickel, >3.7 to <10 wt % copper, <1 wt % cobalt, 0.1 to 1.5 wt % magnesium, 0.1 to ≦0.7 wt % iron, 0.1 to ≦0.7 wt % manganese, >0.1 to <0.5 wt % zirconium, ≧0.1 to ≦0.3 wt % vanadium, 0.05 to 0.5 wt % titanium, and 0.004 to ≦0.05 wt % phosphorus as alloying elements and aluminum and unavoidable contaminants as the remainder. The aluminum alloy can optionally comprise beryllium, wherein the calcium content is limited to a low level. The invention further relates to an engine component, in particular a piston for an internal combustion engine, wherein the engine component is composed at least partially of an aluminum alloy, and to the use of an aluminum alloy to produce an engine component, in particular a piston of an internal combustion engine.

Claims

1-20. (canceled)

21. A method for producing an engine component, wherein an aluminum alloy is cast in a gravity die casting process, said aluminum alloy including the following alloying elements; TABLE-US-00002 silicon: 7 wt. % to <14.5 wt %, nickel: >1.2 wt % to ≦4 wt %, copper: >3.7 wt % to <10 wt %, cobalt: up to <1 wt %, magnesium: 0.1 wt % to 1.5 wt %, iron: 0.1 wt % to ≦0.7 wt %, manganese: 0.1 wt % to ≦0.7 wt %, zirconium: >0.1 wt % to <0.5 wt % vanadium: ≧0.1 wt % to ≦0.3 wt % titanium: 0.05 wt % to 0.5 wt % phosphorus: 0.004 wt % to ≦0.05 wt % optionally beryllium: 0.0005 wt % to 0.5 wt %, and optionally calcium: up to ≦0.0005 wt %, and the remainder aluminum and unavoidable impurities.

22. The method according to claim 21, wherein the aluminum alloy further includes: TABLE-US-00003 beryllium: 0.0005 wt. % to 0.5 wt %, and calcium: up to ≦0.0005 wt %.

23. The method according to claim 21, wherein the aluminum alloy includes: TABLE-US-00004 silicon: 9 wt. % to <10.5 wt %, nickel: >2 wt % to <3.5 wt %, copper: >5.2 wt % to <10 wt %, cobalt: up to <1 wt %, magnesium: 0.5 wt % to 1.5 wt %, iron: 0.1 wt % to 0.7 wt %, manganese: 0.1 wt % to 0.4 wt %, zirconium: 0.2 wt % to <0.4 wt % vanadium: >0.1 wt % to <0.2 wt % titanium: 0.05 wt % to <0.2 wt % phosphorus: 0.004 wt % to 0.008 wt %, and the remainder aluminum and unavoidable impurities.

24. The method according to claim 21, wherein the aluminum alloy includes: TABLE-US-00005 silicon: 9 wt. % to <10.5 wt %, nickel: >1.2 wt % to <2.0 wt %, copper: >5.2 wt % to <10 wt %, cobalt: up to <1 wt %, magnesium: 0.5 wt % to 1.5 wt %, iron: 0.1 wt % to 0.7 wt %, manganese: 0.1 wt % to 0.4 wt %, zirconium: 0.2 wt % to <0.4 wt % vanadium: >0.1 wt % to <0.2 wt % titanium: 0.05 wt % to <0.2 wt % phosphorus: 0.004 wt % to 0.008 wt %, and the remainder aluminum and unavoidable impurities.

25. The method according to claim 21, wherein the aluminum alloy includes: TABLE-US-00006 silicon: 9 wt. % to <12 wt %, nickel: 2 wt % to <3.5 wt %, copper: >3.7 wt % to 5.2 wt %, cobalt: up to <1 wt %, magnesium: 0.5 wt % to 1.5 wt %, iron: 0.1 wt % to 0.7 wt %, manganese: 0.1 wt % to 0.4 wt %, zirconium: 0.2 wt % to 0.4 wt % vanadium: 0.1 wt % to 0.3 wt % titanium: 0.1 wt % to 0.5 wt % phosphorus: 0.004 wt % to 0.008 wt %, and the remainder aluminum and unavoidable impurities.

26. The method according to claim 21, wherein the aluminum alloy includes: TABLE-US-00007 silicon: 7 wt. % to <14.5 wt %, nickel: >1.2 wt % to ≦4 wt %, copper: >3.7 wt % to ≦5.5 wt %, cobalt: up to <1 wt %, magnesium: 0.1 wt % to 1.2 wt %, iron: 0.1 wt % to ≦0.7 wt %, manganese: 0.1 wt % to ≦0.7 wt %, zirconium: >0.1 wt % to <0.5 wt % vanadium: ≧0.1 wt % to ≦0.3 wt % titanium: 0.05 wt % to ≦0.2 wt % phosphorus: 0.004 wt % to ≦0.05 wt %, beryllium: 0.0005 wt % to 0.5 wt %, calcium: up to ≦0.0005 wt %, and the remainder aluminum and unavoidable impurities.

27. The method according to claim 21, wherein in the aluminum alloy a weight ratio of iron to manganese is no more than about 5:1.

28. The method according to claim 21, wherein a sum of nickel and cobalt is preferably >2.0 wt % and <3.8 wt %.

29. The method according to claim 22, wherein the aluminum alloy has a fine microstructure with a low content of pores and inclusions and/or few and small primary silicon, particularly in a bowl rim area of the engine component, wherein the porosity is <0.01% and/or the content of primary silicon is <1%, said primary silicon having lengths of <5 μm on average and/or maximum lengths of <10 μm, and the intermetallic phases and/or primary precipitates having lengths of <30 μm on average and or maximum lengths of <50 μm.

30. An engine component which consists, at least in part, of an aluminum alloy, said aluminum alloy including the following alloying elements: TABLE-US-00008 silicon: 7 wt. % to <14.5 wt %, nickel: >1.2 wt % to ≦4 wt %, copper: >3.7 wt % to <10 wt %, cobalt: up to <1 wt %, magnesium: 0.1 wt % to 1.5 wt %, iron: 0.1 wt % to ≦0.7 wt %, manganese: 0.1 wt % to ≦0.7 wt %, zirconium: >0.1 wt % to <0.5 wt % vanadium: ≧0.1 wt % to ≦0.3 wt % titanium: 0.05 wt % to 0.5 wt % phosphorus: 0.004 wt % to ≦0.05 wt %, optionally beryllium: 0.0005 wt % to 0.5 wt %, and optionally calcium: up to ≦0.0005 wt %, and the remainder aluminum and unavoidable impurities.

31. The engine component according to claim 30, wherein the aluminum alloy further includes: TABLE-US-00009 beryllium: 0.0005 wt % to 0.5 wt %, and calcium: up to ≦0.0005 wt %.

32. The engine component according to claim 30 wherein the aluminum alloy includes: TABLE-US-00010 silicon: 9 wt. % to <10.5 wt %, nickel: >2 wt % to <3.5 wt %, copper: >5.2 wt % to <10 wt %, cobalt: up to <1 wt %, magnesium: 0.5 wt % to 1.5 wt %, iron: 0.1 wt % to 0.7 wt %, manganese: 0.1 wt % to 0.4 wt %, zirconium: 0.2 wt % to <0.4 wt % vanadium: >0.1 wt % to <0.2 wt % titanium: 0.05 wt % to <0.2 wt % phosphorus: 0.004 wt % to 0.008 wt %, and the remainder aluminum and unavoidable impurities.

33. The engine component according to claim 30, wherein the aluminum alloy includes: TABLE-US-00011 silicon: 9 wt. % to <10.5 wt %, nickel: >1.2 wt % to <2.0 wt %, copper: >5.2 wt % to <10 wt %, cobalt: up to <1 wt %, magnesium: 0.5 wt % to 1.5 wt %, iron: 0.1 wt % to 0.7 wt %, manganese: 0.1 wt % to 0.4 wt %, zirconium: 0.2 wt % to <0.4 wt % vanadium: >0.1 wt % to <0.2 wt % titanium: 0.05 wt % to <0.2 wt % phosphorus: 0.004 wt % to 0.008 wt %, and the remainder aluminum and unavoidable impurities.

34. The engine component according to claim 30, wherein the aluminum alloy includes: TABLE-US-00012 silicon: 9 wt. % to <12 wt %, nickel: 2 wt % to <3.5 wt %, copper: >3.7 wt % to 5.2 wt %, cobalt: up to <1 wt %, magnesium: 0.5 wt % to 1.5 wt %, iron: 0.1 wt % to 0.7 wt %, manganese: 0.1 wt % to 0.4 wt %, zirconium: 0.2 wt % to 0.4 wt % vanadium: 0.1 wt % to 0.3 wt % titanium: 0.1 wt % to 0.5 wt % phosphorus: 0.004 wt % to 0.008 wt %, and the remainder aluminum and unavoidable impurities.

35. The engine component according to claim 30, wherein the alloy includes: TABLE-US-00013 silicon: 7 wt. % to <14.5 wt %, nickel: >1.2 wt % to ≦4 wt %, copper: >3.7 wt % to ≦5.5 wt %, cobalt: up to <1 wt %, magnesium: 0.1 wt % to 1.2 wt %, iron: 0.1 wt % to ≦0.7 wt %, manganese: 0.1 wt % to ≦0.7 wt %, zirconium: >0.1 wt % to <0.5 wt % vanadium: ≧0.1 wt % to ≦0.3 wt % titanium: 0.05 wt % to ≦0.2 wt % phosphorus: 0.004 wt % to ≦0.05 wt %, beryllium: 0.0005 wt % to 0.5 wt %, calcium: up to ≦0.0005 wt %, and the remainder aluminum and unavoidable impurities.

36. The engine component according to claim 30, wherein in the aluminum alloy a weight ratio of iron to manganese is no more than 5:1.

37. The engine component according to claim 30, wherein a sum of nickel and cobalt is preferably >2.0 wt % and <3.8 wt %.

38. The engine component according to claim 30, wherein the aluminum alloy has a fine microstructure with a low content of pores and inclusions and/or few and small primary silicon, particularly in a bowl rim area of the component, wherein the porosity is <0.01% and/or the content of primary silicon is <1%, said primary silicon having lengths of <5 μm on average and/or maximum lengths of <10 μm, and the intermetallic phases and/or primary precipitates having lengths of <30 μm on average and/or maximum lengths of <50 μm.

39. Use of an aluminum alloy to produce an engine component, in particular a piston of an internal combustion engine, wherein said aluminum alloy includes the following alloying elements: TABLE-US-00014 silicon: 7 wt. % to <14.5 wt %, nickel: >1.2 wt % to ≦4 wt %, copper: >3.7 wt % to <10 wt %, cobalt: up to <1 wt %, magnesium: 0.1 wt % to 1.5 wt %, iron: 0.1 wt % to ≦0.7 wt %, manganese: 0.1 wt % to ≦0.7 wt %, zirconium: >0.1 wt % to <0.5 wt % vanadium: ≧0.1 wt % to ≦0.3 wt % titanium: 0.05 wt % to 0.5 wt % phosphorus: 0.004 wt % to ≦0.05 wt %, optionally beryllium: 0.0005 wt % to 0.5 wt %, and optionally calcium: up to ≦0.0005 wt %, and the remainder aluminum and unavoidable impurities.

40. Use according to claim 39, wherein the aluminum alloy further includes: TABLE-US-00015 beryllium: 0.0005 wt % to 0.5 wt %, and calcium: up to ≦0.0005 wt %.

41. The method according to claim 27, wherein the weight ratio of iron to manganese is about 2.5 to 1.

42. The method according to claim 21, wherein the engine component is a piston.

43. The engine component of claim 30, comprising a piston.

44. The engine component of claim 30, wherein the weight ratio of iron to manganese is about 2.5 to 1.

Description

SUMMARY OF THE INVENTION

[0015] It is an object of the present invention to provide a method for producing an engine component, in particular a piston for an internal combustion engine, wherein an aluminum alloy is cast in the gravity die casting process, such that a highly heat-resistant engine component can be produced in the gravity die casting process.

[0016] The solution to this object is provided by the method according to claim 1. Further preferred embodiments of the invention can be seen from the corresponding sub-claims.

[0017] Another object of the invention is to provide an engine component, in particular a piston for an internal combustion engine, which is highly heat-resistant while being composed, at least in part, of an aluminum alloy.

[0018] This object is achieved by the subject matter of claim 10, and further preferred embodiments can be seen from the corresponding sub-claims.

[0019] In a method according to the invention, the aluminum alloy includes the following alloying elements:

[0020] silicon (Si) from about 7, preferably from about 9 wt %, to <about 14.5, preferably to <about 12, more preferably to <about 10.5, and even more preferably to <about 10 wt %; nickel (Ni) from >about 1.2, preferably from >about 2 wt %, to ≦about 4, preferably to <about 3.5, and more preferably to <about 2 wt %;

[0021] copper (Cu) from >about 3.7, preferably from >about 5.2, and more preferably from >5.5 wt %, to <about 10, preferably to <about 8, more preferably to ≦about 5.5, and even more preferably to about 5.2 wt %;

[0022] cobalt (Co) of up to <about 1 wt %, preferably from >about 0.2 wt % to <about 1 wt %;

[0023] magnesium (Mg) from about 0.1, preferably from about 0.5, more preferably from about 0.6, even more preferably from >about 0.65, and particularly preferred ≧about 1.2, to about 1.5, preferably to about 1.2 wt %, and more preferably to ≦about 0.8 wt. %;

[0024] iron (Fe) from about 0.1, preferably from about 0.4 wt %, to ≦about 0.7, preferably to about 0.6 wt %;

[0025] manganese (Mn) from about 0.1 wt % to ≦about 0.7, and preferably to about 0.4 wt. %;

[0026] zirconium (Zr) from >about 0.1, preferably from about >0.2 wt %, to <about 0.5, preferably to ≦about 0.4, and more preferably to <about 0.2 wt %;

[0027] vanadium (V) from ≧about 0.1 wt % to ≦about 0.3, preferably to <about 0.2 wt %;

[0028] titanium (Ti) from about 0.05, preferably from about 0.1 wt %, to about 0.5, preferably to ≦about 0.2 wt %;

[0029] phosphorus (P) from about 0.004 wt % to about ≦0.05, preferably to about 0.008 wt %,

[0030] and the remainder aluminum and unavoidable impurities. Other elements not mentioned above can also be considered as impurities. The impurity level may, for example, amount to 0.01 wt % per impurity element or 0.2 wt % in total.

[0031] The selected aluminum alloy makes it possible to produce an engine component in the gravity die casting process which has a high content of finely dispersed, highly heat-resistant, thermally stable phases as well as a fine microstructure. The selection of the alloy according to the invention reduces susceptibility to crack initiation and crack propagation, for example on oxides or primary phases, and the TMF-HCF service life as compared to hitherto known processes for producing pistons and similar engine components.

[0032] At least in a piston produced according to the invention, the alloy according to the invention, and more particularly the comparatively low silicon content, also allows comparatively less and finer primary silicon to be present in the bowl rim area of the piston, which is subject to high thermal load, such that the alloy results in particularly good properties of a piston produced according to the invention. Thus, a highly heat-resistant engine component can be produced in the gravity die casting process. The amounts according to the invention of copper, zirconium, vanadium and titanium, and more particularly the comparatively high zirconium, vanadium and titanium content, result in an advantageous proportion of strength-increasing precipitates, without, however, giving rise to large, plate-like intermetallic phases. It is possible, for example, to optimize the alloy properties for a specific application by targetedly selecting the Cu content within the range according to the invention. Higher Cu contents particularly improve the heat resistance of the alloy. Lower contents, on the other hand, allow the heat conductivity to be increased and the density of the alloy to be reduced. Furthermore, the amounts according to the invention of cobalt and phosphorus are advantageous in that cobalt increases the hardness and (thermal) strength of the alloy, and phosphorus, as a nucleating agent for primary silicon precipitates, contributes to these being precipitated in a particularly fine and uniformly dispersed manner. Zirconium and cobalt moreover contribute to an increase in strength at elevated temperatures, particularly in the bowl rim area.

[0033] In an advantageous manner, the aforementioned aluminum alloys preferably include 0.6 wt % to 0.8 wt. % magnesium which, in the preferred concentration range, particularly contributes to the efficient formation of secondary, strength-increasing phases, without there being an excessive formation of oxides. Alternatively or additionally, the alloy preferably further includes 0.4 wt % to 0.6 wt % iron which advantageously reduces the tendency of the alloy to stick in the casting die, with the formation of plate-like phases being limited in the aforementioned concentration range.

[0034] The aluminum alloys described above may further contain from about 0.0005, preferably from >about 0.006, and more preferably from about 0.01 wt %, to about 0.5, preferably to about <0.1 wt % beryllium (Be), with the calcium content being limited to ≦about 0.0005 wt %. The addition of beryllium results in a particularly good castability of the alloy. The addition thereof to the melt produces a thick oxide skin on the melt which functions as a diffusion barrier and reduces oxidation and hydrogen uptake of the melt. Also, it is possible therewith to prevent the diffusion of aluminum and magnesium to the outside. The above effects are particularly relevant when holding furnaces are used. In addition, a fine/thin oxide layer which improves fluidity is formed at the solidification front during casting, for example in a die. As a whole, therefore, thin walls and finely shaped structures can be filled better and without any additional auxiliary measures. The addition of beryllium additionally improves the strength characteristics of the alloy as a whole. During aging, a higher density can be achieved on strength-increasing precipitates. The addition of beryllium supplements the advantageous effects of the present aluminum alloys by decreasing the oxidation of the melt, and contributes to improved castability, particularly in the gravity die casting procedure, and improves the strength of the alloy. At the same time, it is preferred that the calcium content be limited to the above low level. The simultaneous presence of higher amounts of calcium may counteract the advantageous effects of beryllium and may enhance oxidation. The lowest possible calcium content is advantageous in this regard.

[0035] Particularly preferred aluminum alloys A, B, C and D of the present invention can be seen from the following table (figures in wt %):

TABLE-US-00001 Composition A B C D Si min 9 9 9 7 max <10.5 <10.5 <12 <14.5 Ni min >2.0 >1.2 2 max <3.5 <2.0 <3.5 ≦4 Cu min >5.2 >5.2 >3.7 max <10 <10 5.2 ≦5.5 Co min max <1 <1 <1 <1 Mg min 0.5 0.5 0.5 0.1 max 1.5 1.5 1.5 1.2 Fe min 0.1 0.1 0.1 max 0.7 0.7 0.7 ≦0.7 Mn min 0.1 0.1 0.1 max 0.4 0.4 0.4 ≦0.7 Zr min 0.2 0.2 0.2 >0.1 max <0.4 <0.4 0.4 <0.5 V min >0.1 >0.1 0.1 max <0.2 <0.2 0.3 ≦0.3 Ti min 0.05 0.05 0.1 max <0.2 <0.2 0.5 ≦0.2 P min 0.004 0.004 0.004 max 0.008 0.008 0.008 ≦0.05 Be min — — — 0.0005 max — — — 0.5 Ca min — — — max — — — ≦0.0005 Remainder Al and unavoidable impurities

[0036] Alloys A, B, C and D realize the aforementioned technical advantages. In addition, the comparatively high content of Cu and Zr in alloy A proves advantageous in that it increases the level of strength-increasing precipitates. The same applies for the preferred alloy B which, due to having a reduced nickel content, moreover helps reduce the costs of the alloy. The comparatively high content of Zr, V and Ti in alloy C also additionally contributes to increasing the level of strength-increasing precipitates. An increased content of Zr generally brings about a further improvement in strength. It is particularly preferred for alloy C to have a Si content of <10.5 wt %. Alloy D is advantageous in that the addition of beryllium improves, as described above, the oxidation and flow properties of the melt as well as the strength of the alloy. This effect is enhanced even further by the comparatively low content of Mg and the content of Ca which is limited to a low level. Alloy D may, in addition, include the alloying elements in the following preferred concentration ranges: nickel (Ni) from about 2 to <about 3.5 wt %, copper (Cu) from >about 3.7 to about 5.2 wt %, magnesium (Mg) from >about 0.65 to <about 0.8 wt %, iron (Fe) from about 0.4 to about 0.6 wt %, manganese (Mn) from about 0.1 to about 0.4 wt %, and as regards beryllium, the aforementioned preferred concentration limits. The presence/addition of beryllium in/to the alloys A, B and C is optionally also possible in order to improve the oxidation, flow and strength properties. Here, the calcium content should also be limited to the specified low level in order not to counteract the advantageous effects of beryllium. As a whole, the alloys A, B, C and D can be combined to a certain extent, and therefore, the advantageous technical effects thereof can also be realized together in one single alloy.

[0037] Advantageously, the weight ratio of iron to manganese in the aforementioned aluminum alloys is no more than 5:1, preferably about 2.5:1. In this embodiment, the aluminum alloy thus contains no more than five parts of iron for one part of manganese, preferably about 2.5 parts of iron for one part of manganese. Owing to this ratio, particularly advantageous strength characteristics of the engine component are achieved.

[0038] It is particularly preferred that the nickel concentration be <3,5 wt % since otherwise excessively large, plate-shaped (primary, nickel-rich) phases may form in the structure which, owing to their notch effect, may reduce strength and/or service life. At the preferred nickel concentrations of >1.2 wt %, a thermally stable network of primary phases having connectivity and contiguity is produced.

[0039] It is furthermore preferred that the sum of nickel and cobalt in the aforementioned aluminum alloys be >2.0 wt % and <3.8 wt %. The lower limit ensures an advantageous strength of the alloy, and the upper limit advantageously guarantees a fine microstructure and avoids the formation of coarse, plate-shaped phases which would reduce strength.

[0040] The aluminum alloys advantageously exhibit a fine microstructure with a low content of pores and inclusions and/or few and small primary silicon, particularly in the highly loaded bow rim area. In this regard, a low content of pores must preferably be understood as meaning a porosity of <0.01, and few primary silicon as meaning <1%. Furthermore, the fine microstructure is advantageously described in that the average length of the primary silicon is about <5 μm and its maximum length is about <10 μm, with the intermetallic phases and/or primary precipitates having lengths of about <30 μm and no more than <50 1μm on average. The fine microstructure particularly contributes to improving the thermomechanical fatigue strength. Limiting the size of the primary phases may reduce the susceptibility to crack initiation and crack propagation and may thus significantly increase the TMF-HCF service life. Owing to the notch effect of pores and inclusions, it is moreover particularly advantageous to keep the content thereof as low as possible.

[0041] An engine component according to the invention consists, at least in part, of one of the aforementioned aluminum alloys. Another independent aspect of the invention is the use of the aforementioned aluminum alloys to produce an engine component, in particular a piston of an internal combustion engine, according to claim 19 and the corresponding sub-claim. The found aluminum alloys are processed, in particular, in the gravity die casting process.