Lead- and antimony-free brass alloy

Abstract

To provide a lead- and antimony-free brass alloy that shows little hot embrittlement and can be processed by hot forming, particularly a continuous casting process.SOLUTION: A brass alloy that is lead- and antimony-free contains following elements: Cu: 56% or more and 66% or less, Mg: 0.1% or more and 1.5% or less, Pb: less than 0.1%, and Zn and inevitable impurities: a balance. The brass alloy may contain less than 0.15% of As, and / or less than 0.15% of P, and / or less than 0.1% of Al, and / or less than 0.1% of Sn.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to lead-free, antimony-free brass alloys. [Background technology]

[0002] Traditionally, the machinability of brass alloys has been improved by adding up to 4% lead by weight. Due to legal restrictions, the addition of Pb is no longer permitted.

[0003] It has been found that the addition of Pb can be replaced by the addition of Bi. However, it has been found that the addition of Bi leads to hot embrittlement of the brass alloy. This type of brass alloy limits the hot forming ability. Therefore, this type of brass alloy is not used for compression molding parts.

[0004] EP3320122B1 discloses a brass alloy containing neither Pb nor Bi. It proposes adding 0.005% to 1.0% by weight of In to the brass alloy to improve machinability. While the proposed addition of In improves machinability, machining involves the formation of relatively long, spiral-shaped chips, which can lead to clogging and tool breakage during transport.

[0005] EP 2913415 A1 further discloses a lead-free, bismuth-free brass alloy that is free of Si. This known alloy contains 60 to 65% by weight of Cu and 0.01 to 0.15% by weight of Sb.

[0006] The addition of Sb causes hot shortness. EP2913415A1 also proposes adding 0.005 to 0.3 wt% P instead. The proposed P addition makes processing by continuous casting more difficult.

[0007] EP2467507B1 discloses a lead-free brass alloy containing Fe, Ni and Sn.

[0008] EP2133437B1 discloses a lead-free free-cutting brass alloy containing 0.6 to 2.5 wt. % Mg and 0.15 to 0.4 wt. % P. The addition of P makes processing by continuous casting more difficult. Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to overcome the drawbacks of the prior art. More particularly, the object is to provide a lead-free, antimony-free brass alloy having improved machinability. According to a further object of the present invention, the brass alloy exhibits little hot shortness and can be processed by hot forming. [Means for solving the problem]

[0010] This object is achieved by the features of claim 1. Preferred embodiments are evident from the features of the dependent claims. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a pictorial representation of chips after longitudinal turning of the first example alloy. [Figure 2] FIG. 2 is a pictorial representation of chips after longitudinal turning of the second example alloy. [Figure 3] FIG. 3 is a pictorial representation of chips after longitudinal turning of the third example alloy. [Figure 4] FIG. 4 is a pictorial representation of chips after longitudinal turning of the fourth example alloy. DETAILED DESCRIPTION OF THE INVENTION

[0012] According to the invention, the following elements are proposed: Cu:56% or more and 66% or less Mg: 0.1% or more and 1.5% or less Pb: Less than 0.1% Zn and unavoidable impurities: balance A lead-free, antimony-free brass alloy comprising:

[0013] For the purposes of the present invention, [%] is understood to be percent by weight.

[0014] Surprisingly, it has been found that through the addition of 0.1% to 1.5% Mg proposed in the present invention, the Pb content can be set to less than 0.1% without undesirably forming long spiral chips during machining. It is noteworthy that the proposed brass alloy not only improves chip breaking but also shows almost no hot shortness, which can be processed by hot forming.

[0015] The present invention understands "lead-free antimony-free brass alloy" to be an alloy containing less than 0.1% Pb and less than 0.001% Sb.

[0016] According to an 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 improves the corrosion resistance of the alloy, and in particular As counteracts the removal of zinc. The addition of P improves the machinability of the alloy.

[0017] According to another advantageous embodiment, there is present ≧57% and less than 60%, preferably ≧57.5% and less than 58.5% Cu. The proposed alloy is more cost-effective due to the relatively low Cu content.

[0018] According to another embodiment, more than 0.5% Mg is present. The proposed Mg content contributes to improving the machinability.

[0019] The Pb content is judiciously between 0.05% and 0.09%. The In content is less than 0.005%.

[0020] Finally, according to an advantageous embodiment, it is proposed that the Zn content is between 40% and 42.5%. Alloys with the proposed Zn content exhibit good machinability properties.

[0021] The proposed lead-free and antimony-free brass alloy further allows good processing quality in the continuous casting process.

[0022] Exemplary embodiments of the invention are explained in more detail below by means of the drawings. FIG. 1 shows a chip depiction after longitudinal turning of the first example alloy. FIG. 2 shows a chip depiction after longitudinal turning of the second example alloy. FIG. 3 shows a chip depiction after longitudinal turning of the third example alloy. FIG. 4 shows a chip depiction after longitudinal turning of the fourth example alloy.

[0023] The chip depictions in Figures 1 to 4 were produced by longitudinal turning of the alloy at a rotational speed of 850 rpm in each case. An indexable cutting insert with the identification number KNMX160405-R8IC907 was used. The scale bar included in Figures 1 to 4 is 5 mm in each case.

[0024] Figure 1 shows a chip diagram after longitudinal turning of Example Alloy 1. Example Alloy 1 is a reference alloy. Example Alloy 1 contains 58% Cu and 42% Zn, meaning that Example Alloy 1 does not contain any Mg additions.

[0025] As can be seen from Figure 1, longitudinal turning of the alloy of Example 1 generates long spiral chips. Such spiral chips are undesirable during machining. They can cause jamming during transport and breakage of the tool.

[0026] Figure 2 shows a depiction of the chips after longitudinal turning of Example 2 alloy, which contains 58% Cu, 41.5% Zn, and 0.5% Mg. It is clear that the chips generated during longitudinal turning are shorter than those shown in Figure 1.

[0027] Figure 3 shows a depiction of the chips after longitudinal turning of Example 3 alloy, which is composed of 58% Cu, 41% Zn, and 1% Mg. It is clear that the chips generated are much shorter than those generated by longitudinal turning of Example 2 alloy.

[0028] Figure 4 shows a depiction of the chips after longitudinal turning of Example 4 alloy. Example 4 alloy is composed of 58% Cu, 40.5% Zn, and 1.5% Mg. The chips generated when turning Example 4 alloy are even shorter than the chips generated by longitudinal turning of Example 3 alloy.

[0029] Therefore, by adding 0.1-1.5% Mg to the proposed lead-free and antimony-free brass alloy, significantly improved chip breakage can be achieved. Furthermore, the proposed brass alloy is characterized by almost no hot shortness, which can be processed by hot forming, especially continuous casting processes.

Claims

1. The following elements: Cu: 56% or more and 66% or less Mg: 0.1% or more and 1.5% or less Pb: less than 0.1% Zn and inevitable impurities: the balance A lead-free and antimony-free brass alloy containing the above.

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

3. The lead-free and antimony-free brass alloy according to Claim 1 or 2, containing less than 0.15% of P.

4. The lead-free and antimony-free brass alloy according to Claim 1 or 2, containing less than 0.1% of Al.

5. The lead-free and antimony-free brass alloy according to Claim 1 or 2, containing less than 0.1% of Sn.

6. The lead-free and antimony-free brass alloy according to Claim 1 or 2, containing 57% or more and less than 60% of Cu.

7. The lead-free and antimony-free brass alloy according to Claim 6, containing 57.5% or more and 58.5% or less of Cu.

8. The lead-free and antimony-free brass alloy according to Claim 1 or 2, containing more than 0.5% of Mg.

9. The lead-free and antimony-free brass alloy according to Claim 1 or 2, containing 0.05% or more and 0.09% or less of Pb.

10. The lead-free and antimony-free brass alloy according to Claim 1 or 2, containing less than 0.005% of In.

11. The lead-free and antimony-free brass alloy according to Claim 1 or 2, containing 40% or more and 42.5% or less of Zn.

Images