Lead-free free-cutting silicon brass alloy

Abstract

The present invention supplies a lead-free free-cutting silicon brass alloy with high zinc which preferably comprises 35.0 to 42.0 wt % Zn, 0.1 to 1.5 wt % Si, 0.03 to 0.3 wt % Al, 0.01 to 0.36 wt % P, 0.01 to 0.1 wt % Ti, 0.001 to 0.05 wt % rare earth metals selected from the group consisting of La and Ce, 0.05 to 0.5 wt % Sn, and / or 0.05 to 0.2 wt % Ni, and the balance being Cu and unavoidable impurities. The invented alloy is excellent in castability, weldability, cuttability, electroplating properties, corrosion resistance, mechanical properties. The alloy is especially applicable in castings which need cutting and welding under low pressure die casting, such as castings for faucet bodies in the water supply system. The alloy is also suitable for use in components which are produced from casting ingots by die forging.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]Not applicable.FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]Not applicable.FIELD OF THE INVENTION[0003]The present invention generally relates to a lead-free free-cutting silicon brass alloy, in particular a lead-free free-cutting silicon brass alloy with high zinc which is applicable in low pressure die castings and forgings.BACKGROUND OF THE INVENTION[0004]Currently, several series of casting brass alloys are in widespread use, for example, the Cu—Zn series, Cu—Zn—Si series, Cu—Zn—Al series. Each series includes lead-containing alloys. Lead-containing casting brass alloys have excellent cuttability, castability and low cost. However, these alloys harm the environment and the human body in the process of their production and usage. Furthermore, lead-containing brass alloys have poor weldability.[0005]The harmfulness of lead to the environment and the human body is of great concern. Over the past 15 years, many patents for lead-free o...

AI Technical Summary

Benefits of technology

[0012]One object of the present invention is to provide a free-cutting silicon brass alloy with high zinc which is excellent in castability, forging performance, cuttability, weldability, mechanical properties, corrosion resistance and electroplatability and whose cost is rather lower, especially a free-cutting and weldable silicon brass alloy with high zinc which is applicable in low pressure die casting and forging. This alloy will solve the limitations of conventional brass alloys discussed above especially the problem of lead contamination.

Problems solved by technology

However, these alloys harm the environment and the human body in the process of their production and usage.

Furthermore, lead-containing brass alloys have poor weldability.

The bismuth brass alloys disclosed by some references add expensive Se and Sn and even more expensive Te and In to change the dispersion of Bi in the grain boundary from continuous film to discontinuous particle.

One disadvantage of prior art bismuth-brass alloys is that the metals Bi, Sn, Ni, Se, Te and In are relatively expensive.

Another disadvantage of prior art bismuth brass alloys is that they have poor castability and weldability.

Accordingly, castings made of bismuth brass alloys by low pressure die casting are prone to cracking, resulting in a low overall yield.

Also, castings made of bismuth brass alloys by brazing are also prone to cracking in weld and heat-affected zones.

Furthermore, the forging temperature range is narrow.

These are some of the obstacles presented by bismuth brass alloys.

Since bismuth is relatively rare and expensive, and requires improvements in technological properties such as castability and weldability beyond what is currently known in the art, the application and development potential of bismuth brass alloy is limited.

These alloys are highly prone to be hot cracked in the process of low pressure die casting.

This approach sacrifices the plasticity of the alloy and is detrimental to casting formings and process formings.

Furthermore, as the content of Cu is high, the cost of materials is high.

But Zhang et al. do not discuss or disclose the castability of the alloy, particularly the castability applied on low pressure die casting.

Furthermore, the Sb release of these alloys into the water may exceed the NSF / ANSI61-2007 standard and should not be used for drinking water supply system applications.

The internal construction of faucet bodies is very complex.

Thus, some antimony brass alloys are not suitable for use in drinking water system installations.

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