IL295024A

IL295024A - Lead- and antimony-free brass alloy

Info

Publication number: IL295024A
Application number: IL295024A
Authority: IL
Original assignee: Diehl Brass Solutions Stiftung & Co Kg
Priority date: 2021-07-27
Filing date: 2022-07-24
Publication date: 2023-02-01
Also published as: EP4124667A1; KR20230017150A; JP2023021941A; US20230035864A1; CN115679151A; ZA202207823B; BR102022014247A2; DE102021119474A1; AU2022209210A1; MX2022009224A

Description

Lead- and antimony-free brass alloy The invention relates to a lead- and antimony-free brass alloy. In the past the machinability of brass alloys has been improved by adding Pb in an extent of up to 4 wt%. Adding Pb is no longer allowable, owing to legal stipulations. It has been found that the adding of Pb can be replaced by addition of Bi. It has emerged, however, that the addition of Bi leads to hot embrittlement of the brass alloy. Brass alloys of this kind have only limited capacity for hot forming. Brass alloys of these kinds, consequently, are not used for compression-moulded parts. EP 3 320 122 B1 discloses a brass alloy admixed with neither Pb nor Bi. For improving machinability, it is proposed that 0.005 to 1.0 wt% In be added to the brass alloy. While the proposed addition of In does improve the machinability, machining is nevertheless accompanied by formation of relatively long spiral chips, which can lead to blockages as they are transported away, and to tool breakage. EP 2 913 415 A1 discloses a further lead-free and bismuth-free brass alloy which, more over, contains no Si. The known alloy contains 60 to 65 wt% Cu and also 0.01 to 0.15 wt% Sb. The addition of Sb causes hot embrittlement. Alternatively proposed in EP 2 913 415 A1 is an addition of 0.005 to 0.3 wt% P. The proposed addition of P makes processing by continuous casting more difficult. EP 2 467 507 B1 discloses a lead-free brass alloy which contains Fe, Ni and Sn. EP 2 133 437 B1 discloses a lead-free free-cutting brass alloy which contains 0.6 to 2.5 wt% Mg and also 0.15 to 0.4 wt% P. The addition of P makes processing by continuous casting more difficult. It is an object of the invention to eliminate the disadvantages according to the prior art. The intention more particularly is to specify a lead- and antimony-free brass alloy having improved machinability. According to a further objective of the invention, the brass alloy is to exhibit little hot embrittlement, allowing it to be processed by hot forming. This objective is achieved by the features of Claim 1. Judicious embodiments are apparent from the features of the dependent claims. Proposed in accordance with the invention is a lead- and antimony-free brass alloy containing 56 to 66% Cu, 0.1 to 1.5% Mg, less than 0.1% Pb, balance Zn and also unavoidable impurities. For the purposes of the present invention, [%] is understood to be per cent by weight. It has surprisingly emerged that through the addition of 0.1 to 1.5% Mg as proposed in the invention, the Pb content can be established at less than 0.1% without undesirable formation of long spiral chips during machining. The proposed brass alloy is notable not only for improved chip breaking but also for little hot embrittlement. It may be processed by hot forming. The invention understands a "lead- and antimony-free brass alloy" to be an alloy which contains less than 0.1% Pb and less than 0.001% Sb. According to one advantageous embodiment, the alloy may contain less than 0.15% As and/or less than 0.15% P and/or less than 0.1% Al and/or less than 0.1% Sn. Sn stabilizes the β solid solution. As leads to improved corrosion resistance of the alloy, with As in particular counteracting removal of zinc. The addition of P improves the machinability of the alloy. According to another advantageous embodiment, 57 to less than 60%, preferably 57.to 58.5% of Cu is present. The proposed alloy is more cost-efficient because of the relatively lower Cu contents.

According to another embodiment there is more than 0.5% Mg. The proposed Mg content contributes to improved machinability. The Pb content is judiciously in the range from 0.05 to 0.09%. The In content is less than 0.005%. Lastly, according to one advantageous embodiment, it is proposed that the Zn content be 40 to 42.5%. An alloy having the proposed Zn content displays good machining properties. The proposed lead- and antimony-free brass alloy additionally enables good processing qualities in the continuous casting process. Exemplary embodiments of the invention are elucidated in more detail below by means of the drawings, in which: Fig. 1 shows a chip depiction after longitudinal turning of a first example alloy, Fig. 2 shows a chip depiction after longitudinal turning of a second example alloy, Fig. 3 shows a chip depiction after longitudinal turning of a third example alloy, and Fig. 4 shows a chip depiction after longitudinal turning of a fourth example alloy. The chip depictions according to Figs 1 to 4 were produced in each case by subjecting alloys to longitudinal turning at a rotary speed of 850 rpm. An indexable cutting insert was used with the identification KNMX160405-R8IC907. The scale bar included in Figs 1 to 4 is 5 mm in each case. Fig. 1 shows a chip depiction after longitudinal turning of a first example alloy. The first example alloy is a reference alloy. The first example alloy contains 58% Cu and 42% Zn, meaning that the first example alloy contains no addition of Mg. As can be seen from Fig. 1, the longitudinal turning of the example alloy 1 produces long spiral chips. Such spiral chips are unwanted when machining. They may lead to blockages when being transported away, and to tool breakage.

Fig. 2 shows a chip depiction after the longitudinal turning of a second example alloy. The second example alloy contains 58% Cu, 41.5% Zn and 0.5% Mg. It is apparent that the chips generated during longitudinal turning are shorter than the chips shown in Fig. 1. Fig. 3 shows a chip depiction after the longitudinal turning of a third example alloy. The third example alloy consists of 58% Cu, 41% Zn and 1% Mg. It is clearly apparent that the chips produced are again shorter than the chips generated by the longitudinal turning of the second example alloy. Fig. 4 shows a chip depiction after the longitudinal turning of a fourth example alloy. The fourth example alloy consists of 58% Cu, 40.5% Zn and 1.5% Mg. The chips generated during turning of the fourth example alloy are again smaller than the chips generated by the longitudinal turning of the third example alloy. Through the proposed addition of 0.1 to 1.5% Mg to a lead- and antimony-free brass alloy, therefore, considerably improved chip breaking can be achieved. The proposed brass alloy is notable, moreover, for little hot embrittlement. It may be processed by hot forming, particularly in a continuous casting process.

Claims

1.Claims 1. Lead- and antimony-free brass alloy containing to 66% Cu, 0.1 to 1.5% Mg, less than 0.1% Pb, balance Zn and also unavoidable impurities.

2. Lead- and antimony-free brass alloy according to Claim 1, containing less than 0.15% As.

3. Lead- and antimony-free brass alloy according to either of the preceding claims, containing less than 0.15% P.

4. Lead- and antimony-free brass alloy according to any of the preceding claims, containing less than 0.1% Al.

5. Lead- and antimony-free brass alloy according to any of the preceding claims, containing less than 0.1% Sn.

6. Lead- and antimony-free brass alloy according to any of the preceding claims, containing 57 to less than 60%, preferably 57.5 to 58.5% Cu.

7. Lead- and antimony-free brass alloy according to any of the preceding claims, containing more than 0.5% Mg.

8. Lead- and antimony-free brass alloy according to any of the preceding claims, containing 0.05 to 0.09% Pb.

9. Lead- and antimony-free brass alloy according to any of the preceding claims, containing less than 0.005% In.

10. Lead- and antimony-free brass alloy according to any of the preceding claims, containing 40 to 42.5% Zn.