Lead-free brass alloy and machine element made therefrom

Abstract

The present invention relates to a lead-free brass alloy comprising: 55 to 59% by weight of Cu, 2.0 to 2.5% by weight of Mn, 0.65 to 1.5% by weight of Si, less than 0.1% by weight of Pb, the remainder being Zn and unavoidable impurities. The invention further relates to a machine element which is produced from the lead-free brass alloy.

Description

Technical Field

[0001] The invention relates to a lead-free brass alloy. Background Art

[0002] In the past, up to 4 wt. % Pb was added to improve the machinability of brass alloys. However, due to foreseeable legal regulations, the amount of Pb added will be strictly limited in the future.

[0003] Therefore, a lead-free brass alloy is needed. Such alloys are known per se, for example, refer to the following documents: EP 2009 122 A1, EP 3 272 888 A1, WO 2016 / 045770 A1 and EP 3 269 835 A1. However, the lack of lead affects the cutting performance of such brass alloys. Summary of the invention

[0004] The object of the present invention is therefore to provide a lead-free brass alloy which can be machined well.

[0005] To achieve this object, a lead-free brass alloy having the features of claim 1 is provided.

[0006] The brass alloy according to the present invention contains 55 to 59 wt % Cu, 2.0 to 2.5 wt % Mn, 0.65 to 1.5 wt % Si, less than 0.1 wt % Pb, and the balance is Zn and inevitable impurities.

[0007] The brass alloy according to the invention has less than 0.1 wt. % Pb and is therefore considered lead-free. It has been shown that, despite a lead content of less than 0.1 wt. %, the brass alloy according to the invention exhibits satisfactory cutting properties. In particular, no undesirable long spiral chips are formed during cutting. Furthermore, the tribological properties of the lead-free brass alloy according to the invention are comparable to those of lead-containing brass alloys.

[0008] An advantageous embodiment of the invention provides that the weight percentage ratio of Mn to Si satisfies the inequality 2.0≤Mn / Si≤2.9. It has been found that this ratio of manganese to silicon achieves an optimal chemical composition and promotes the formation of manganese silicide.

[0009] In the lead-free brass alloy according to the present invention, the copper equivalent is between 53% and 66%.

[0010] Preferably, less than 0.2 wt. % Fe is contained in the lead-free brass alloy according to the present invention.

[0011] Preferably, less than 0.5 wt. % Sn is contained in the lead-free brass alloy according to the present invention.

[0012] Preferably, 1.5 to 2.6 wt % of Ni is contained in the lead-free brass alloy according to the present invention.

[0013] The following composition of the lead-free brass alloy according to the present invention is particularly preferred: 57 wt. % Cu, 2.3 wt. % Mn, 1.0 wt. % Si, 0.1 wt. % Fe, 0.1 wt. % Sn, 2.0 wt. % Ni, less than 0.1 wt. % Pb, the remainder being Zn and unavoidable impurities.

[0014] A preferred embodiment of the present invention provides that the lead-free brass alloy contains less than 0.1 wt % Al.

[0015] It can also be provided that the lead-free brass alloy contains less than 0.25 wt. % Cr and / or less than 0.25 wt. % Ti and / or less than 0.25 wt. % Co.

[0016] Furthermore, the invention relates to a machine element which is produced from the lead-free brass alloy according to the invention. Due to their good tribological properties, the lead-free brass alloy is optimally suitable for producing machine elements for use with lubricants.

[0017] The invention is explained below with the aid of exemplary embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are schematic illustrations and in which:

[0019] Figure 1 shows the chip pattern produced by cutting a control alloy; and

[0020] Figure 2 The chip pattern produced by cutting a lead-free brass alloy according to the present invention is shown. DETAILED DESCRIPTION

[0021] One embodiment of the lead-free brass alloy has the following composition: 57 wt % Cu, 2.3 wt % Mn, 1.0 wt % Si, 0.1 wt % Fe, 0.1 wt % Sn, 2.0 wt % Ni, less than 0.1 wt % Pb, and the balance being Zn and inevitable impurities.

[0022] The copper equivalent (CuEq) of the lead-free brass alloy is between 53% and 66% and can be calculated based on the alloy composition as follows:

[0023] 1) If Si 无 =Si·3.26-(Fe+Mn)<0 and Si 无2 =Si·3.26-(Fe+Mn+Ni)<0, then

[0024]

[0025] 2) If Si 无 =Si·3.26-(Fe+Mn)>0 and Si 无2 =Si·3.26-(Fe+Mn+Ni)<0,

[0026]

[0027] 3) If Si 无 =Si·3.26-(Fe+Mn)>0 and Si 无2 =Si·3.26-(Fe+Mn+Ni)>0

[0028]

[0029] The meanings of the abbreviations are as follows:

[0030] Cu: weight % of copper

[0031] Fe: Iron by weight

[0032] Mn: weight % of magnesium

[0033] Si: weight % of silicon

[0034] Ni: Nickel weight %

[0035] The lead-free brass alloy can be processed into semi-finished products such as plates, tubes or rods, from which machine elements for use with lubricants can then be made. An example is a component in an axial piston pump that is subject to friction. The lead-free brass alloy contains manganese silicide, which is responsible for its good friction properties.

[0036] The cutting performance of the lead-free brass alloy was compared with that of the control alloy. The compositions of the lead-free brass alloy and the control alloy are shown in the table below:

[0037]

[0038] In the cutting test, an indexable insert of type CNMG120404FP HC5010 was used, the rotation speed was 3000 rpm, the feed per rotation was 0.25 mm, and the cutting depth was 1.25 mm. Figure 1 The chip pattern of the leaded control alloy is shown. Figure 2 The chip pattern of the lead-free brass alloy is shown in comparison. It can be seen that the two alloys produce chips of approximately the same size and type. Therefore, the cutting quality of the lead-free brass alloy is acceptable.

[0039] The coefficient of friction was determined for both alloys in the same test. It was found that the lead-free brass alloy and the lead-containing control alloy had almost the same coefficient of friction. The coefficient of friction was about 0.012.

[0040] These tests have shown that the lead-free brass alloy can be used without restriction as a replacement for the lead-containing control alloy.

[0041] The lead-free brass alloy can be used, for example, to produce various machine elements, in particular machine elements that are subject to friction and are used with lubricants, for example, parts of axial piston pumps or sliding blocks.

Claims

1. A lead-free brass alloy comprising: 55 to 59 wt% Cu, 2.0 to 2.5 wt.% Mn, 0.65 to 1.5 wt% Si, <0.1 wt% Pb, The balance is Zn and inevitable impurities.

2. The lead-free brass alloy according to claim 1, wherein the weight percentage ratio of Mn to Si satisfies the following inequality: 2.0≤Mn / Si≤2.

9.

3. The lead-free brass alloy according to claim 1 or 2, wherein the copper equivalent is between 53% and 66%.

4. A lead-free brass alloy according to any one of the preceding claims, comprising less than 0.2 wt. % Fe.

5. A lead-free brass alloy according to any one of the preceding claims, comprising less than 0.5 wt. % Sn.

6. A lead-free brass alloy according to any one of the preceding claims, comprising 1.5 to 2.6 wt. % Ni.

7. A lead-free brass alloy according to any one of the preceding claims, comprising: 57 wt% Cu, 2.3 wt% Mn, 1.0 wt% Si, 0.1 wt% Fe, 0.1 wt% Sn, 2.0 wt% Ni, <0.1 wt% Pb, The balance is Zn and inevitable impurities.

8. A lead-free brass alloy according to any one of the preceding claims, comprising less than 0.1 wt. % Al.

9. The lead-free brass alloy according to any one of the preceding claims, comprising less than 0.25 wt. % Cr and / or less than 0.25 wt. % Ti and / or less than 0.25 wt. % Co.

10. A machine component made of the lead-free brass alloy according to any one of claims 1 to 9.

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