High-tensile brass alloy and alloy product

Abstract

The invention relates to a high-tensile brass alloy comprising 58-66 wt % Cu; 1.6-7 wt % Mn; 0.2-6 wt % Ni; 0.2-5.1 wt % Al; 0.1-3 wt % Si; 1.5 wt % Fe; 0.5 wt % Sn; 0.5 wt % Pb; and the remainder Zn together with unavoidable impurities. Also described are a high-tensile brass product with such an alloy composition, and a method for manufacturing such a product made of a high-tensile brass alloy.

Claims

1. A high-tensile brass alloy comprising 60-62 wt % Cu; 2.1-2.5 wt % Mn; 0.2-0.6 wt % Ni; 2.9-3.1 wt % Al; 0.35-0.65 wt % Si; <0.1 wt % Fe; <0.1 wt % Sn; <0.1 wt % Pb; and the remainder Zn together with unavoidable impurities.

2. A high-tensile brass alloy product having an alloy composition according to claim 1, wherein the high-tensile brass alloy product is adjusted by hot forming, annealing, and cold drawing in such a way that the 0.2% yield strength R.sub.P0.2 is in the range of 570-770 MPa, the tensile strength R.sub.m is in the range of 750-800 MPa, and the elongation at break A.sub.5 is in the range of 7.5-12%.

3. The high-tensile brass alloy product of claim 2, wherein the high-tensile brass alloy product is a component that is designed for a friction load that is variable over time.

4. The high-tensile brass alloy product of claim 3, wherein the high-tensile brass alloy product is a bearing bush, a slide shoe, a worm gear, or an axial bearing for a turbocharger.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 1: shows a light micrograph of the extrusion state of a first embodiment of the high-tensile brass according to the invention, in cross section with a 100 magnification,

(3) FIG. 2: shows a light micrograph of the extrusion state from FIG. 1, with a 500 magnification,

(4) FIG. 3: shows a light micrograph of the first embodiment of after soft annealing at 450 C., in cross section with a 50 magnification,

(5) FIG. 4: shows a light micrograph of the soft annealing state of the first embodiment from FIG. 3, in cross section with a 500 magnification,

(6) FIG. 5: shows a scanning electron micrograph with secondary electron contrast of the first embodiment, in the extrusion state with a 6000 magnification,

(7) FIG. 6: further shows a scanning electron micrograph with secondary electron contrast of the first embodiment, in the extrusion state with a 6000 magnification,

(8) FIG. 7: shows a light micrograph of the extrusion state of a second embodiment of the high-tensile brass according to the invention, in cross section with a 50 magnification,

(9) FIG. 8: shows the extrusion state of the second embodiment from FIG. 7, as a light micrograph with a 500 magnification,

(10) FIG. 9: shows a light micrograph of the second embodiment after soft annealing at 450 C., in cross section with a 50 magnification,

(11) FIG. 10: shows a light micrograph of the soft annealing state of the second embodiment from FIG. 9, in cross section with a 500 magnification,

(12) FIG. 11: shows a scanning electron micrograph with secondary electron contrast of the second embodiment, in the alloy end state with a 7000 magnification,

(13) FIG. 12: further shows a scanning electron micrograph with secondary electron contrast of the second embodiment, in the alloy end state with a 7000 magnification,

(14) FIG. 13: shows a light micrograph of the extrusion state of a third embodiment of the high-tensile brass according to the invention, in cross section with a 100 magnification,

(15) FIG. 14: shows the extrusion state of the third embodiment from FIG. 13, as a light micrograph with a 500 magnification,

(16) FIG. 15: shows a light micrograph of the third embodiment after soft annealing at 450 C., in cross section with a 50 magnification,

(17) FIG. 16: shows a light micrograph of the soft annealing state of the third embodiment from FIG. 15, in cross section with a 500 magnification,

(18) FIG. 17: shows a scanning electron micrograph with secondary electron contrast of the extrusion state of the third embodiment, with a 7000 magnification,

(19) FIG. 18: shows a scanning electron micrograph with secondary electron contrast of the alloy end state of the third embodiment, with a 2000 magnification,

(20) FIG. 19: shows a light micrograph of the extrusion state of a fourth embodiment of the high-tensile brass alloy according to the invention, in cross section with a 100 magnification,

(21) FIG. 20: shows the extrusion state of the fourth embodiment from FIG. 19, as a light micrograph with a 500 magnification,

(22) FIG. 21: shows a light micrograph of the fourth embodiment after soft annealing at 450 C., in cross section with a 50 magnification,

(23) FIG. 22: shows a light micrograph of the soft annealing state of the fourth embodiment from FIG. 21, in cross section with a 500 magnification,

(24) FIG. 23: shows a scanning electron micrograph with secondary electron contrast of the alloy end state of the fourth embodiment, with a 3000 magnification, and

(25) FIG. 24: shows a scanning electron micrograph with secondary electron contrast of the alloy end state of the fourth embodiment of, with a 6500 magnification.

(26) Before further explaining the disclosed embodiments of the present invention, it is to be understood that the invention is not limited in its application to the details of the particular arrangements shown, since the invention is capable of other embodiments. While exemplary embodiments are illustrated in reference to the figures, it is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than limiting. Also, the terminology used herein is for the purpose of description and not of limitation.

DETAILED DESCRIPTION

(27) As described above, a first embodiment of the high-tensile brass according to the invention comprises 58-64 wt % Cu; 5-7 wt % Mn; 3-5 wt % Ni; 4-6 wt % Al; 0.5-2.5 wt % Si; 0.1-1.5 wt % Fe; 0.3 wt % Sn; 0.5 wt % Pb; and the remainder Zn together with unavoidable impurities. In the cast state, intermetallic phases (IMP) which are embedded in a fine brass matrix structure are present in the high-tensile brass according to the first embodiment. In addition, the cast structure has no significant structural variation, either in the cross section or over the longitudinal extent of the cast strand. The investigated sample of high-tensile brass alloy according to this first embodiment has the following composition (data in wt %):

(28) TABLE-US-00001 Cu Zn Pb Sn Fe Mn Ni Al Si As Sb P Cr 61.0 Remainder 0.005 0.005 1.0 5.9 4.5 5.0 1.5 0.02 0.005 0.03

(29) The aluminum content for the first embodiment of the high-tensile brass according to the invention, which is selected to be relatively high, suppresses the conversion of the phase to the phase during cooling of the alloy in the cast state, so that, despite the relatively high zinc proportion that is selected, a dominant phase, not an / mixed phase, results.

(30) Due to the extrusion which follows the casting, an extrusion state is achieved, shown as light micrographs in FIGS. 1 and 2 with cross section magnifications of 100 and 500, respectively. The structure, which is significantly refined compared to the casting, has a matrix with a uniform phase in which intermetallic phases, which are divided into two average sizes, are intercalated. The larger intermetallic phases are present at the grain boundaries and also in the interior of the grains, while the smaller intermetallic phases are present only at the grain boundaries. Based on longitudinal sections, not illustrated in detail, it was possible to determine that the brass matrix as well as the intermetallic phases have only a relatively weak orientation in the extrusion direction.

(31) The alloy according to the first embodiment was characterized in the extrusion state by scanning electron micrographs and EDX analyses. FIGS. 5 and 6 show examples of scanning electron microscopy images with secondary electron contrast, with a 6000 magnification; the contrasting dark region demonstrates flat intermetallic phases having two different average sizes. The EDX measurements showed that the chemical composition of the intermetallic phases is (Fe, Mn, Ni) mixed silicides, predominantly manganese mixed silicides Mn.sub.5Si.sub.3, Mn.sub.5Si.sub.2, Mn.sub.6Si, or Mn.sub.44.1Si.sub.8.9.

(32) For setting the mechanical properties, the extrusion product of the high-tensile brass alloy according to the first embodiment may be subjected to heat treatment in the form of soft annealing at a temperature of 450 C., whereby a maximum phase proportion of 14% is achievable. The soft annealing state is illustrated by the cross-sectional light micrographs shown in FIGS. 3 and 4. Reduced solubility of the phase is shown at lower and higher annealing temperatures. It was also found that the phase which forms during soft annealing at 450 C. is present primarily at the grain boundaries.

(33) With regard to the mechanical properties, high-tensile brass according to the first embodiment in the extrusion state has a 0.2% yield strength of 760-810 MPa, a tensile strength R.sub.m of 780-920 MPa, and an elongation at break of 1.5-3%. An adjustment may be made to the required mechanical properties of a high-tensile brass product as a function of the selected temperature control during the annealing and an optional final annealing. In the alloy end state, which is set without cold forming subsequent to the heat treatment, the high-tensile brass alloy according to the first embodiment achieves high mechanical strength.

(34) As described above, a second embodiment of the high-tensile brass according to the invention comprises 60-66 wt % Cu; 1-2.5 wt % Mn; 4-6 wt % Ni; 1-2.5 wt % Al; 1-3 wt % Si; 0.1-1 wt % Fe; 0.5 wt % Sn; 0.5 wt % Pb; and the remainder Zn together with unavoidable impurities. For the second embodiment, intermetallic phases (IMP) occur in the cast state. In the extrusion state, illustrated in the light micrographs in FIGS. 7 and 8, a predominant phase with a phase portion having an island-like distribution results. The intermetallic phase is present in the and portions of the matrix; a wide-ranging size distribution of the hard phases having a rounded shape has been determined. Specifically, the investigated sample according to the second embodiment of the high-tensile brass alloy has the following composition (data in wt %):

(35) TABLE-US-00002 Cu Zn Pb Sn Fe Mn Ni Al Si As Sb P Cr 64.0 Remainder 0.1 0.1 0.3 2.0 5.0 2.0 2.2 0.03

(36) Longitudinal sections, not illustrated in detail, have shown that the brass matrix has only a relatively weak orientation, and the intermetallic phases have no orientation, in the extrusion direction.

(37) The extrusion product of the high-tensile brass alloy according to the second embodiment is treated by soft annealing in a subsequent process step; the soft annealing state is illustrated by the cross-sectional light micrographs shown in FIGS. 9 and 10. The structure after the soft annealing at an annealing temperature of 450 C.-550 C. is dominated by the phase, and has island-like phase portions.

(38) The soft annealing is followed by cold forming, the degree of deformation typically being selected in the range of a 5-15% reduction in cross section. Lastly, a final annealing is carried out; for an annealing temperature of 450 C.-550 C., a predominant phase portion, together with a phase portion that is increased compared to the soft annealing state, results.

(39) The alloy according to the second embodiment was characterized in the alloy end state by scanning electron micrographs and EDX analyses. FIGS. 11 and 12 show examples of scanning electron microscopy images of the / mixed matrix and the intermetallic phases. The EDX measurements showed that the chemical composition of the intermetallic phases is (Fe, Mn, Ni) mixed silicides, predominantly manganese mixed silicides Mn.sub.5Si.sub.3, Mn.sub.5Si.sub.2, Mn.sub.6Si, or Mn.sub.44.1Si.sub.8.9.

(40) With regard to the mechanical properties, high-tensile brass according to the second embodiment in the extrusion state has a 0.2% yield strength of 280-300 MPa, a tensile strength R.sub.m of 590-630 MPa, and an elongation at break of 9-14%. In the end alloy state, a 0.2% yield strength of 450-650 MPa, a tensile strength R.sub.m of 570-770 MPa, and an elongation at break of 4-9.4% are present.

(41) As described above, a third embodiment of the high-tensile brass according to the invention comprises 58-64 wt % Cu; 1.5-3.5 wt % Mn; 0.1-1 wt % Ni; 2-4 wt % Al; 0.1-1 wt % Si; 0.5 wt % Fe; 0.5 wt % Sn; 0.5 wt % Pb; and the remainder Zn together with unavoidable impurities. In the cast state for the third embodiment, intermetallic phases are present which in the extrusion state have been determined as rounded, elongated hard phases inside the grain. The alloy matrix in the extrusion state is formed by a phase. The extrusion state is illustrated in the light micrographs of FIGS. 13 and 14. Specifically, the investigated sample according to the third embodiment of the high-tensile brass alloy has the following composition (data in wt %):

(42) TABLE-US-00003 Cu Zn Pb Sn Fe Mn Ni Al Si As Sb P Cr 61.0 Remainder 0.05 0.005 0.05 2.3 0.4 3.0 0.6 0.02 0.013

(43) It is apparent from longitudinal sections, not illustrated in detail, that the brass matrix has only a relatively weak orientation in the extrusion direction. In contrast, there is a distinct orientation of intermetallic phases in parallel to the extrusion direction.

(44) The intermetallic phases inside the grain represent a single phase; an average length of 10 m was measured. The chemical composition of the intermetallic phases was determined from EDX measurements, and showed mixed silicides, primarily manganese silicides in the form of Mn.sub.5Si.sub.3 and Mn.sub.5Si.sub.2.

(45) Starting from the extrusion state, the high-tensile brass alloy according to the third embodiment is treated by soft annealing in a subsequent process step; the soft annealing state is illustrated by the cross-sectional light micrographs shown in FIGS. 15 and 16. A predominant phase results for a soft annealing temperature of 450 C.; phase portions with a random distribution are present in the region of the grain boundaries and inside the grains. Increasing the soft annealing temperature to 550 C. results in a uniform phase.

(46) The soft annealing is followed by cold forming, the degree of deformation typically having been selected in the range of a 5-15% reduction in cross section. Lastly, a final annealing is carried out; for an annealing temperature of 450 C., a continued predominant phase portion and an phase portion that is greatly increased compared to the soft annealing state are present. In comparison, at a final annealing temperature of 550 C. no significant change in the alloy structure occurs compared to the soft-annealed state.

(47) With regard to the mechanical properties, high-tensile brass according to the third embodiment in the extrusion state has a 0.2% yield strength of 480-550 MPa, a tensile strength R.sub.m of 720-770 MPa, and an elongation at break of 9.3-29%. In the end alloy state, a 0.2% yield strength of 570-770 MPa, a tensile strength R.sub.m of 750-800 MPa, and an elongation at break of 7.5-12% are present.

(48) As described above, a fourth embodiment of the high-tensile brass according to the invention comprises 58-64 wt % Cu; 1-3 wt % Mn; 1-3 wt % Ni; 0.1-1 wt % Al; 0.2-1.5 wt % Si; 0.1-1.5 wt % Fe; 0.5 wt % Sn; 0.5 wt % Pb; and the remainder Zn together with unavoidable impurities. For this fourth embodiment, in the cast state intermetallic phases form which in the extrusion state have been determined as rounded hard phases present inside the grain of an phase. In the extrusion state, illustrated in the light micrographs in FIGS. 19 and 20, a predominant phase was found, with additional phase portions present at the grain boundaries of the phase. Based on longitudinal sections, not illustrated in detail, for the brass matrix this results in a distinct orientation in the extrusion direction, while the intermetallic phases are only weakly oriented. Specifically, the investigated sample according to the fourth embodiment of the high-tensile brass alloy has the following composition (data in wt %):

(49) TABLE-US-00004 Cu Zn Pb Sn Fe Mn Ni Al Si As Sb P Cr 61.0 Re- 0.02 0.05 0.5 1.8 2.0 0.3 0.8 mainder

(50) The extrusion product of the high-tensile brass alloy according to the fourth embodiment is treated by soft annealing in a subsequent process step; the soft annealing state is illustrated by the cross-sectional light micrographs shown in FIGS. 21 and 22. For a soft annealing temperature of 450 C., a dominant phase with island-like phase portions results. An increased soft annealing temperature in the range of 550 C. results in a uniform phase, with decreased island-like phase portions compared to the lower soft annealing temperature.

(51) The soft annealing is followed by cold forming, the degree of deformation typically having been selected in the range of a 5-15% reduction in cross section. Lastly, a final annealing is carried out; the alloy structure is not significantly different from the soft-annealed state.

(52) For the alloy end state, the intermetallic phases inside the grains of the base matrix have single-phase structures with an average length of 7 m; a polycrystalline structure was demonstrated. Based on the EDX measurements, with regard to the chemical composition of the intermetallic phases it was shown that in addition to (Fe, Mn, Ni) mixed silicides, in particular iron silicides of the form Fe.sub.5Ni.sub.3Si.sub.2 and Fe.sub.3Si are present. In addition, hard phase deposits having an average size 0.2 m were found at the grain boundaries and in the phase.

(53) With regard to the mechanical properties, high-tensile brass according to the fourth embodiment in the extrusion state has a 0.2% yield strength of 480-550 MPa, a tensile strength R.sub.m of 430-470 MPa, and an elongation at break of 22-42%. In the end alloy state, a 0.2% yield strength of 350-590 MPa, a tensile strength R.sub.m of 400-650 MPa, and an elongation at break of 3-19% are present.

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

(55) 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.

(56) 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.