Lead-Free Brass Alloy

Abstract

The invention relates to brass alloys that are substantially lead-free. In the alloys of the invention, lead is replaced with tellurium resulting in alloys that exhibit excellent machinability and conductivity.

Description

TECHNICAL FIELD[0001]The present invention relates to brass compositions with extremely low to no lead content. The compositions exhibit good machinability and strength similar to that of conventional leaded brass alloy free machining brass.BACKGROUND OF THE INVENTION[0002]It has been common practice to add up to 4.5% lead to brass compositions to improve the machinability of the resulting product. Lead, however, is a toxic substance and its use in the production of alloys is surrounded by legislation and expensive control procedures. For example, California adopted legislation which limits the amount of lead in plumbing fixtures to 0.25% or less beginning in 2010.[0003]Furthermore, the lead phase in copper lead alloys can be affected by corrosive attacks with hot organic or mineral oil. For example, when temperature of such an alloy rises, it has been known that the oil can break down to form peroxides and organic gases which effect a degree of leaching on the lead phase within the...

AI Technical Summary

Benefits of technology

[0010]The resulting alloys exhibit excellent machinability and conductivity. Depending on the composition of the alloy, the tensile strength will vary between 240 MPa and 530 MPa and yield strength will vary from about 200 to about 450 MPa. Conductivity will range from about 28% to about 49% IACS. The machinability of the novel alloys of the invention is similar to that for lead containing compositions. This eliminates or reduces the amount of retooling needed to use the novel alloys to produce finished products such as plumbing fixtures.

[0011]The composition of the novel alloys also allows the end product manufacturers to recycle the scrap from the manufacturing process itself. This eliminates the need to return the scrap to the alloy manufacturer for recycling. Yet another key feature of the present invention is that the alloys containing less than about 15% zinc exhibit excellent dezincification resistance.

Problems solved by technology

Lead, however, is a toxic substance and its use in the production of alloys is surrounded by legislation and expensive control procedures.

Furthermore, the lead phase in copper lead alloys can be affected by corrosive attacks with hot organic or mineral oil.

If this leaching progresses to any appreciable extent, the component, if it is a bearing or structural component, may eventually malfunction or fail.

While the alloys described above yield substantially lead-free alloys, they do not possess the same machinability as the lead containing alloys.

This results in the need for substantial retooling of the equipment used to produce end product, such as plumbing equipment and the like.

In addition, the scrap produced during the manufacturing of the lead products often cannot be readily recycled by the end product manufacturer.

The cost of shipping the scrap back to the initial foundry increases the overall product cost of the end product.

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