Copper-zinc alloy

Abstract

To provide a lead-free brass alloy with improved dezincification resistance that can be produced cost-effectively indeed.SOLUTION: A copper-zinc alloy contains 66.0 to 73.0 wt.% of Cu, 1.5 to 2.5 wt.% of Si, 0.01 to 0.15 wt.% of P, at most 0.1 wt.% of Pb, and balance zinc and unavoidable impurities.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a copper-zinc alloy, and more particularly to a lead-free copper-zinc alloy. [Background technology]

[0002] Copper-zinc and brass alloys are used, for example, to manufacture components in the sanitary sector. The addition of significant amounts of elements harmful to health, such as Pb and As, to these alloys is nowadays no longer permitted. These brass alloys are required to be "lead-free", i.e. with a maximum lead content of 0.1% by weight.

[0003] Previously, the addition of lead was permitted to improve the machining properties of brass alloys. Currently, attempts are being made to find lead-free brass alloys that have similar good machining properties as lead-containing brass alloys.

[0004] European Patent EP3099832B1 (Patent Document 1) discloses a conventional lead-containing brass alloy, in which the essential lead content is 0.02 to 1.00% by weight.

[0005] European Patent EP1790742B1 (Patent Document 2) discloses a lead-free brass alloy containing 0.5 to 2.5 wt% Bi and 0.02 to 0.10 wt% Sb. This known brass alloy is characterized by a relatively low copper content of 61.0 to 63.0 wt%, and a relatively low dezincification corrosion depth of 10 to 25 μm.

[0006] Japanese Patent Publication No. 58-038500 (Patent Document 3) also discloses a zinc corrosion-resistant special brass. To improve zinc corrosion resistance, this alloy also contains Sb. Sb is toxic like Pb. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] European patent EP3099832B1 [Patent Document 2] European Patent EP1790742B1 [Patent Document 3] Special Publication No. 58-038500 Summary of the Invention [Problem to be solved by the invention]

[0008] It is an object of the present invention to provide a lead-free brass alloy which can be produced very cost-effectively and has improved dezincification corrosion resistance. According to a further object of the present invention, the brass alloy has good machinability. Furthermore, the alloy according to the present invention can also be processed by continuous casting and hot forming. [Means for solving the problem]

[0009] This object is achieved by a copper-zinc alloy as set forth in the claims. Practical configurations of the invention are evident from the features of the dependent claims.

[0010] According to the present invention, 66.0-73.0 wt.% Cu, 1.5 to 2.5% by weight of Si, 0.01 to 0.15% by weight of P, up to 0.1% by weight Pb, The balance is zinc, and unavoidable impurities, A copper-zinc alloy containing Effect of the Invention

[0011] The Cu-Zn alloy of the present invention is used with a relatively low Cu content of at most 73.0 wt. %. It can be produced cost-effectively. The proposed addition of P results in improved dezincification corrosion resistance. As a result of the mandatory addition of Si, the Cu-Zn alloy of the present invention has improved machinability. At the same time, surprisingly, the alloy of the present invention can be processed by continuous casting and hot forming. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a reflected light micrograph of a copper-zinc alloy of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The copper-zinc alloy of the present invention may selectively contain one or more of the following elements. Less than 0.15% by weight As Less than 0.10% by weight Al Less than 0.25% by weight Sn

[0014] The selective addition of As contributes to improving the dezincification corrosion resistance, similar to the addition of P. The optional addition of Al also contributes to improving the dezincification corrosion resistance, since it promotes the formation of an outer layer. The further optional addition of Sn improves the strength and dezincification corrosion resistance of the Cu-Zn alloy of the present invention.

[0015] The Cu content may be preferably 68.0 to 72.5 wt %, more preferably 68.5 to 71.0 wt %. The lower the Cu content, the more efficiently the copper-zinc alloy can be produced in terms of cost.

[0016] The Si content is 1.6-2.3 wt%, preferably 2.0-2.3 wt%. The proposed Si content contributes to improving the machinability of the Cu-Zn alloy.

[0017] The content of P is preferably 0.05 to 0.07% by weight, which achieves sufficiently good dezincification corrosion resistance.

[0018] The copper-zinc alloy of the present invention is useful when it is composed of 0-3% β phase, 12-28% γ phase, and the remainder α phase. The content of the γ phase is preferably set to 25-27%.

[0019] The proposed phase composition achieves the excellent workability of the Cu-Zn alloy of the present invention.

[0020] The copper-zinc alloy of the present invention preferably has a dezincification corrosion depth of a maximum of 200 μm, preferably 70 μm or less.

[0021] The lead-free copper-zinc alloy of the present invention is particularly suitable for the manufacture of components for the sanitary engineering sector in general and for drinking water applications in particular. EXAMPLES

[0022] alloy 1 Cu:70.0wt% Si: 2.2% by weight P: 0.06% by weight Pb:0.08wt% Zn: remainder

[0023] alloy 2 Cu:69.62wt% Si: 2.26% by weight P: 0.054% by weight Pb: 0.1% by weight or less Zn: remainder

[0024] The following table gives a summary of the maximum dezincification corrosion depth (DD) in [μm] and composition in [wt. %] of two exemplary alloys numbered 2986 and 2987 compared to the Cu-Zn alloys of the present invention (2988, 2991, 2992, 2995 and 2996), where "bal." stands for balance.

[0025] [Table 1]

[0026] Figure 1 is a reflected light micrograph of the copper-zinc alloy of the present invention, which shows that the maximum dezincification corrosion depth was 66 μm.

Claims

1. 66.0 to 73.0 wt.% Cu, 1.5 to 2.5 wt.% Si, 0.01 to 0.15 wt.-% P, maximum 0.1% by weight Pb, The balance is zinc, and unavoidable impurities, Copper-zinc alloy containing

2. 2. The copper-zinc alloy of claim 1 containing less than 0.15 wt.% As.

3. 3. The copper-zinc alloy of claim 1 or 2, containing less than 0.10 wt.% Al.

4. A copper-zinc alloy according to any one of claims 1 to 3, containing less than 0.25 wt.% Sn.

5. The copper-zinc alloy according to any one of claims 1 to 4, wherein the Cu content is 68.0 to 72.5 wt%, preferably 68.5 to 71.0 wt%.

6. The copper-zinc alloy according to any one of claims 1 to 5, wherein the Si content is 1.6 to 2.3 wt%, preferably 2.0 to 2.3 wt%.

7. The copper-zinc alloy according to any one of claims 1 to 6, wherein the P content is 0.05 to 0.07 wt%.

8. A copper-zinc alloy according to any one of claims 1 to 7, comprising 0-3% β phase, 12-28% γ phase, and the balance α phase.

9. The copper-zinc alloy according to claim 8, wherein the proportion of the gamma phase is 25 to 27%.

10. A copper-zinc alloy according to any one of the preceding claims, having a dezincification corrosion depth of up to 200 μm.

11. Use of a copper-zinc alloy according to any one of claims 1 to 10 for the manufacture of parts for drinking water applications.

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