DE102022122831A1 - Lead-free brass alloy and machine element made therefrom - Google Patents

Abstract

Lead-free brass alloy, containing: 55 to 59% by weight Cu, 2.0 to 2.5% by weight Mn, 0.65 to 1.5% by weight Si, less than 0.1% by weight Pb, the balance Zn and unavoidable contamination. In addition, a machine element is proposed that is made of lead-free brass alloy.

Description

The invention relates to a lead-free brass alloy.

In the past, Pb was added to an extent of up to 4% by weight to improve the machining of brass alloys. However, the addition of Pb will be severely restricted in the future due to foreseeable legal requirements.

There is therefore a need for a lead-free brass alloy. Such alloys are known per se; reference is made, for example, to the following publications: EP 2 009 122 A1 , EP 3 272 888 A1 , WO 2016/045770 A1 and EP 3 269 835 A1 . However, the lack of lead impairs the machinability of such brass alloys.

The invention is therefore based on the object of providing a lead-free brass alloy that is easy to machine.

To solve this problem, a lead-free brass alloy with the features of claim 1 is provided.

The brass alloy according to the invention contains: 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 balance Zn and unavoidable contamination.

The brass alloy according to the invention has less than 0.1% by weight of Pb and is therefore considered lead-free. It has been shown that the brass alloy according to the invention shows satisfactory machinability despite the low lead content of less than 0.1% by weight. In particular, no unwanted long spiral chips are formed during machining. In addition, the friction properties of the lead-free brass alloy according to the invention are comparable to those of a lead-containing brass alloy.

An advantageous embodiment of the invention provides that the ratio of the weight percent of Mn to Si corresponds to the inequality 2.0 ≤ Mn/Si ≤ 2.9. It has been found that this ratio between manganese and silicon leads to an optimal chemical composition and the formation of manganese silicides.

In the lead-free brass alloy according to the invention, the copper equivalent is 53 to 66%.

The lead-free brass alloy according to the invention preferably contains less than 0.2% by weight of Fe.

The lead-free brass alloy according to the invention preferably contains less than 0.5% by weight of Sn.

The lead-free brass alloy according to the invention preferably contains 1.5 to 2.6% by weight of Ni.

The following composition of the lead-free brass alloy according to the invention is particularly preferred: 57% by weight Cu, 2.3% by weight Mn, 1.0% by weight Si, 0.1% by weight Fe, 0.1% by weight Sn, 2 .0% by weight Ni, less than 0.1% by weight Pb, balance Zn and unavoidable impurities.

A preferred embodiment of the invention provides that the lead-free brass alloy contains less than 0.1% by weight of Al.

The lead-free brass alloy can also contain less than 0.25% by weight of Cr and/or less than 0.25% by weight of Ti and/or less than 0.25% by weight of Co.

In addition, the invention relates to a machine element which is made from the lead-free brass alloy according to the invention. Due to its good friction properties, the lead-free brass alloy is ideal for the production of machine elements that are used with a lubricant.

• 1 ein durch Zerspanen einer Referenzlegierung erzeugtes Spanbild; und
• 2 ein durch Zerspanen einer erfindungsgemäßen bleifreien Messinglegierung erzeugtes Spanbild.

The invention is explained below using an exemplary embodiment with reference to the drawings. The drawings are schematic representations and show:

• 1 a chip image produced by machining a reference alloy; and
• 2 a chip image produced by machining a lead-free brass alloy according to the invention.

An embodiment of the lead-free brass alloy has the following composition: 57% by weight Cu; 2.3% by weight Mn; 1.0% by weight Si; 0.1% by weight Fe; 0.1% by weight Sn; 2.0% by weight Ni; less than 0.1% by weight Pb; Rest of Zn and unavoidable impurities.

1. 1) Wenn: Si_frei = Si·3,26 - (Fe+Mn) < 0 und Si_frei2 = Si·3,26 - (Fe+Mn+Ni) < 0 dann $$Cu\ddot{A}q=\frac{Cu}{\left[\frac{100-Fe-Mn-Si-Ni+\left(\left|S{i}_{frei}\right|\times \mathrm{0,7}\right)+\left[Ni\times \left(-\mathrm{1,9}\right)\right]}{100}\right]}$$
   
2. 2) Wenn Si_frei = Si·3,26 - (Fe+Mn) > 0 und Si_frei2 = Si·3,26 - (Fe+Mn+Ni) < 0 $$Cu\ddot{A}q=\frac{Cu}{\left[\frac{100-Fe-Mn-Si-Ni+\left[S{i}_{frei2}\right]\times \left(-\mathrm{1,9}\right)}{100}\right]}$$
   
3. 3) Wenn Si_frei = Si·3,26 - (Fe+Mn) > 0 und Si_frei2 = Si·3,26 - (Fe+Mn+Ni) > 0 $$Cu\ddot{A}q=\frac{Cu}{\left[\frac{100-Fe-Mn-Si-Ni+\left(\frac{\left|S{i}_{frei2}\right|}{\mathrm{3,26}}\times 10\right)}{100}\right]}$$
   

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

1. 1) If: Si _free = Si·3.26 - (Fe+Mn) < 0 and Si _free2 = Si·3.26 - (Fe+Mn+Ni) < 0 then $$Cu\ddot{A}q=\frac{Cu}{\left[\frac{100-Fe-Mn-Si-Ni+\left(\left|S{i}_{frei}\right|\times 0.7\right)+\left[Ni\times \left(-1.9\right)\right]}{100}\right]}$$
   
2. 2) If Si _free = Si·3.26 - (Fe+Mn) > 0 and Si _free2 = Si·3.26 - (Fe+Mn+Ni) < 0 $$Cu\ddot{A}q=\frac{Cu}{\left[\frac{100-Fe-Mn-Si-Ni+\left[S{i}_{frei2}\right]\times \left(-1.9\right)}{100}\right]}$$
   
3. 3) If Si _free = Si·3.26 - (Fe+Mn) > 0 and Si _free2 = Si·3.26 - (Fe+Mn+Ni) > 0 $$Cu\ddot{A}q=\frac{Cu}{\left[\frac{100-Fe-Mn-Si-Ni+\left(\frac{\left|S{i}_{frei2}\right|}{3.26}\times 10\right)}{100}\right]}$$
   

• Cu: Gew.-% Kupfer
• Fe: Gew.-% Eisen
• Mn: Gew.-% Mangan
• Si: Gew-% Silizium
• Ni: Gew-% Nickel

The abbreviations mean:

• Cu: wt.% copper
• Fe: wt.% iron
• Mn: wt.% manganese
• Si: wt% silicon
• Ni: wt% nickel

The lead-free brass alloy can be made into semi-finished products such as plates, pipes or bars, which can be used to make machine elements that are used with a lubricant. An example of this are components of axial piston pumps subjected to friction. The lead-free brass alloy contains manganese silicides, which are responsible for the good friction properties.

The machinability of the lead-free brass alloy is compared with a reference alloy. The table below shows the compositions of the lead-free brass alloy and the reference alloy: Lead-free brass alloy (chip pattern 2 ) Reference alloy (chip image 1 ) 57.2% by weight Cu, 57.2% by weight Cu, 2.3% by weight of Mn, 2.2% by weight of Mn, 1.0% by weight Si, 1.0% by weight Si, 0.1% by weight Fe, 0% by weight Fe, 0.05% by weight Sn, 0% by weight Sn, 0% by weight Pb, 0.66% by weight Pb,

An indexable insert type CNMG120404FP HC5010 was used in the machining test, the speed was 3,000 rpm, the feed per revolution was 0.25 mm, and the cutting depth was 1.25 mm. 1 shows the chip pattern of the lead-containing reference alloy, 2 In comparison, shows the chip pattern of the lead-free brass alloy. It can be seen that both alloys produce chips of approximately the same size and type. The chip quality of the lead-free brass alloy is therefore okay.

The coefficient of friction was determined in identical tests for both alloys. It was found that both the lead-free brass alloy and the lead-containing reference alloy have almost identical coefficients of friction. The coefficient of friction is approximately 0.012.

These tests have shown that the lead-free brass alloy can be used as a replacement for the lead-containing reference alloy without any restrictions.

The lead-free brass alloy can be used for the production of various machine elements, especially machine elements that are subjected to friction and are used with a lubricant. An example of this are components of axial piston pumps or sliding shoes.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2009122 A1 [0003]
• EP 3272888 A1 [0003]
• WO 2016045770 A1 [0003]
• EP 3269835 A1 [0003]

Claims (10)

Lead-free brass alloy containing: 55 to 59% by weight Cu, 2.0 to 2.5% by weight of Mn, 0.65 to 1.5% by weight Si, <0.1% by weight Pb, Rest of Zn and unavoidable impurities. Lead-free brass alloy Claim 1 , where the ratio of the weight percent of Mn to Si corresponds to the following inequality: $$2.0\le \text{Mn}/\text{Si}\le \mathrm{2.9.}$$

Lead-free brass alloy Claim 1 or 2 , with the copper equivalent being between 53 and 66%. Lead-free brass alloy according to one of the preceding claims, containing less than 0.2% by weight of Fe. Lead-free brass alloy according to one of the preceding claims, containing less than 0.5% by weight of Sn. Lead-free brass alloy according to one of the preceding claims, wherein 1.5 to 2.6% by weight of Ni is contained. Lead-free brass alloy according to one of the preceding claims, containing: 57% by weight Cu, 2.3% by weight of Mn, 1.0% by weight Si, 0.1% by weight Fe, 0.1% by weight Sn, 2.0% by weight Ni, <0.1% by weight Pb, Rest of Zn and unavoidable impurities. Lead-free brass alloy according to one of the preceding claims, containing less than 0.1% by weight of Al. Lead-free brass alloy according to one of the preceding claims, containing less than 0.25% by weight of Cr and/or less than 0.25% by weight of Ti and/or less than 0.25% by weight of Co. Machine element made from a lead-free brass alloy according to one of the Claims 1 until 9 .

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