Aluminium bronze alloy, method for the production thereof and product made from aluminium bronze

Abstract

An aluminum bronze alloy containing 7.0-10.0% by weight Al; 3.0-6.0% by weight Fe; 3.0-5.0% by weight Zn; 3.0-5.0% by weight Ni; 0.5-1.5% by weight Sn; ?0.2% by weight Si; ?0.1% by weight Pb; and the remainder Cu in addition to unavoidable impurities. Also described is an aluminum bronze product having such an alloy composition, and a method for producing such a product from an aluminum bronze alloy.

Claims

1. An aluminum bronze product having an alloy composition containing 7.0-10.0% by weight Al; 3.0-6.0% by weight Fe; 3.0-5.0% by weight Zn; 3.0-5.0% by weight Ni; 0.5-1.5% by weight Sn; ?0.2% by weight Si; ?0.1% by weight Pb; and the remainder Cu in addition to unavoidable impurities; wherein the aluminum bronze product is adjusted by cold forming, followed by final annealing below a solution heat treatment temperature in a temperature range of 300-500? C., resulting in an alloy end state with a 0.2% yield strength R.sub.P0,2 of 650-1000 MPa, a tensile strength Rm of 850-1050 MPa, and an elongation at break A5 of 2-8%; wherein intermetallic KII and/or KIV phases containing iron and/or nickel aluminides are present in the alloy end state.

2. The aluminum bronze product of claim 1, wherein the alloy composition contains 7.0-7.8% by weight Al; 4.0-5.0% by weight Fe; 3.8-4.8% by weight Zn; 3.8-4.1% by weight Ni; 0.8-1.3% by weight Sn; ?0.2% by weight Si; ?0.1% by weight Pb; and the remainder Cu in addition to unavoidable impurities.

3. The aluminum bronze product of claim 1, wherein the ratio of aluminum to zinc is in a range of 1.4-3.0 based on weight proportions in the alloy composition.

4. The aluminum bronze product of claim 1, wherein the alloy end state has a yield strength to tensile strength ratio of 85-97%.

5. The aluminum bronze product of claim 1, wherein the alloy end state has a hardness of 250-300 HB 2.5/62.5.

6. The aluminum bronze product of claim 1, wherein an ? matrix with a maximum ? phase proportion of 1% by volume is present in the alloy end state.

7. The aluminum bronze product of claim 6, wherein average grain size of the ? matrix is ?50 ?m in the alloy end state.

8. The aluminum bronze product of claim 1, wherein the intermetallic KII and/or KIV phases have an elongated shape with an average length of ?10 ?m, and an average volume of ?1.5 ?m2.

9. The aluminum bronze product of claim 8, wherein an additional aluminide deposition having a rounded shape and an average size of ?0.2 ?m is present in the alloy end state.

10. The aluminum bronze product of claim 1, wherein the aluminum bronze product is a component that is acted on by a friction load that is variable over time.

11. A method for producing a product made from an alloy, comprising the steps: producing a casting blank from a melt containing 7.0-10.0% by weight Al; 3.0-6.0% by weight Fe; 3.0-5.0% by weight Zn; 3.0-5.0% by weight Ni; ?0.2% by weight Si; ?0.1% by weight Pb; and the remainder Cu in addition to unavoidable impurities; heat forming the casting blank to form an intermediate product; cold forming the intermediate product, wherein the step of cold forming is carried out as cold drawing with a rate of deformation of 5-30%; and final annealing of the product below a solution heat treatment temperature in a temperature range of 300-500? C., wherein after final annealing, a 0.2% yield strength R.sub.P0,2 is between 650-1000 MPa, a tensile strength R.sub.m is between 850-1050 MPa, and an elongation at break A.sub.5 is between 2-8%.

12. The method of claim 11, wherein the melt for producing the casting blank contains: 7.0-7.8% by weight Al; 4.0-5.0% by weight Fe; 3.8-4.8% by weight Zn; 3.8-4.1% by weight Ni; 0.8-1.3% by weight Sn; ?0.2% by weight Si; ?0.1% by weight Pb; and the remainder Cu in addition to unavoidable impurities.

13. The aluminum bronze product of claim 3, further wherein the ratio of aluminum to zinc is in a range of 1.5-2.0 based on weight proportions in the alloy composition.

14. The aluminum bronze product of claim 1, wherein the elongation at break A5 is 4-7%.

15. The aluminum bronze product of claim 10, wherein the component is a bearing bush, a slide shoe, a worm gear, or an axial bearing for a turbocharger.

16. The method of claim 11, wherein the elongation at break A5 is 4-7%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is further explained below based on one exemplary embodiment with reference to the following figures:

(2) FIG. 1: shows a scanning electron micrograph of the aluminum bronze alloy according to the present disclosure with a 3000? magnification,

(3) FIG. 2: shows a scanning electron micrograph of the aluminum bronze alloy of FIG. 1 with a 6000? magnification, and

(4) FIG. 3: shows a scanning electron micrograph of the aluminum bronze alloy of FIG. 1 with a 9000? magnification.

(5) In addition to the aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the accompanying drawings and the detailed description forming a part of this specification.

DETAILED DESCRIPTION

(6) For one exemplary embodiment, the alloy composition was melted and hot-formed by means of vertical continuous casting at a casting temperature of 1170? C. and a casting speed of 60 mm/min at a pressing temperature of 900? C.

(7) The alloy in question has the following composition:

(8) TABLE-US-00001 Cu Zn Pb Sn Fe Mn Ni Al Remainder 4.64 0.01 1.01 4.08 0.03 3.90 7.30

(9) The test alloy present after cooling in the extrusion state was characterized by means of scanning electron micrographs and energy-dispersive analyses (EDX); after cooling, the material state shown in FIGS. 1 and 2 was present. The micrographs depicted in FIGS. 1 and 2, with secondary electron contrast at magnifications of 3000? and 6000?, show an ? phase, which forms the alloy matrix, and hard phase depositions in the form of K.sub.II and K.sub.IV phases which are composed of iron and nickel aluminides and which deposit primarily at the grain boundaries. In addition, the micrograph shown in FIG. 3 with a 9000? magnification shows that hard phase depositions with an average size of ?0.2 ?m are additionally present.

(10) For the ? phase, EDX measurements showed on average a chemical composition of 84.2% by weight Cu, 5.0% by weight Zn, 4.4% by weight Fe, 3.4% by weight Ni, 2.8% by weight Al, and 0.1% by weight Si. For the K.sub.II phases investigated, in the extrusion state an average composition of 15.2% by weight Cu, 2.4% by weight Zn, 67.6% by weight Fe, 9.4% by weight Ni, 4.7% by weight Al, and 0.7% by weight Si was found. In addition, the proportion of intermetallic phases was determined to be 7% by volume, while the ? phase proportion in the extrusion state was less than 1% by volume. Measurements of the material states which resulted after the cold forming and heat treatment steps described below showed no change in the phase composition.

(11) For setting the mechanical properties, starting from the extrusion state determined essentially by the chemical composition of the aluminum bronze alloy, soft annealing was carried out at 550? C., followed by cold forming in the form of stretch forming. The soft-annealed intermediate products were prepared for the cold drawing in a soaping bath at 50? C. Different reductions in cross section of 8-25% were selected as process parameters for the stretch forming. In a final treatment step, final annealing of the formed aluminum bronze products was carried out at 380? C. for 5 hours; Table 1 summarizes the average mechanical properties for the 0.2% yield strength R.sub.P0,2, the tensile strength R.sub.m, the elongation at break A.sub.5, the Brinell hardness HB, and the yield strength to tensile strength ratio:

(12) TABLE-US-00002 Yield strength to tensile R.sub.P0.2 R.sub.m A.sub.5 HB strength ratio State [MPa] [MPa] [%] 2.5/62.5 [%] Extrusion state 360 690 26 176 48.8 Cold forming 700 810 9.6 211 85.7 8% reduction in cross section Cold forming 840 840 6.1 225 86.9 15% reduction in cross section Cold forming 850 930 5.5 233 91.2 20% reduction in cross section Cold forming 830 950 3.9 242 87.0 25% reduction in cross section Final annealing 830 870 5.9 250 95.1 380? C./5 h (after 8% reduction in cross section) Final annealing 810 900 6.5 260 90.3 380? C./5 h (after 15% reduction in cross section) Final annealing 850 930 5.5 275 91.2 380? C./5 h (after 20% reduction in cross section) Final annealing 940 1000 2.5 291 94.1 380? C./5 h (after 25% reduction in cross section)

(13) For further measurement series, the final annealing for setting the alloy end state of the aluminum bronze products was carried out below the soft annealing or solution heat treatment temperature. Final annealing temperatures in the range of 300-400? C. were preferably selected for the tests; in combination with a variation in the withdrawal rates of the prior cold forming, a wide range is settable for the mechanical properties of the final alloy state without using complicated measures for temperature-controlled cooling.

(14) It is apparent from this description that the special positive properties of the claimed invention in the narrowly claimed range of the elements involved in the alloy were not expected against the background of the disclosures in the prior art. It was therefore surprising for the inventors to find that by adjusting the alloy parameters in the claimed interval, the data is improved compared to the previously known alloys. This also applies to the surprisingly robust processability of this alloy for setting the desired strength properties.

(15) While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations therefore. It is therefore intended that the following appended claims hereinafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations are within their true spirit and scope. Each apparatus embodiment described herein has numerous equivalents.

(16) The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims. Whenever a range is given in the specification, all intermediate ranges and subranges, as well as all individual values included in the ranges given are intended to be included in the disclosure. When a Markush group or other grouping is used herein, all individual members of the group and all combinations and sub-combinations possible of the group are intended to be individually included in the disclosure.

(17) In general, the terms and phrases used herein have their art-recognized meaning, which can be found by reference to standard texts, journal references and contexts known to those skilled in the art. The above definitions are provided to clarify their specific use in the context of the invention.