Brass is widely known as one of the most versatile alloys, perfect for several engineering and decorative applications. The pure copper+zinc alloy called “brass” has three types based on different crystal structures, as discussed in a previous post. But the versatility of brass is largely due to the myriad of possible combinations with other metals that change its characteristics based on what you need from it — the brass alloys.
A few characteristics that can be manipulated by adding small percentages of other metals to brass are:
- Resistance to corrosion;
Below we’ll present some examples of brass alloys:
Naval brass is a high-strength and especially corrosion-resistant brass alloy, which makes it, as its name implies, perfect for usage in marine environments. Naval brass is generally composed of:
- 59% copper
- 40% zinc
- 1% tin
The addition of tin gives Naval Brass a high resistance to dezincification, which is the progressive removal of zinc from the alloy in certain environments, leaving a porous metal, which is not ideal for mechanisms of ships.
Brass alloys are commonly used as alternatives to more expensive metals, because they maintain the most important characteristics of said metals. Nordic gold, for example, despite its name, is not gold — it’s brass. Here’s its composition:
- 89% copper
- 5% zinc
- 5% aluminum
- 1% tin
Nordic Gold is widely used to make coins in several currencies, because, in addition to its gold-like color, it is antimicrobial, non-allergenic, and resistant to tarnish.
Another example of a brass alloy used as an alternative to a more expensive metal is the Muntz metal, a form of alpha-beta brass patented in 1832 as a replacement for copper sheathing on the bottom of boats.
- 60% copper
- 40% zinc
- Traces of iron
It became the material of choice for that usage (among others), as it was not only less expensive than pure copper, but it maintained its characteristics that were required for those uses. It is hard when cold, but can be easily worked hot, and it prevented unwanted sea organisms from destroying the metal.
Adding a maximum of 3% lead to brass is a safe way to increase malleability. Also known as C360 brass, Free-Machining Brass is an improved 60/40 brass, with the following composition:
- 61.5% copper
- 35.5% zinc
- 3% lead
It is a highly machinable material that can be easily cut and shaped into whatever you need.
This alloy has become the machining standard by which all other metals are compared. It is typically used for plumbing products, fittings, adapters, shafts, valves, screw parts, machine parts, couplings, electrical components, circuit boards, and industrial hardware. It is also corrosion-resistant, has a smooth finish, and accepts plating easily.
Affoltergroup, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
Those are just a few examples of the possibilities allowed by this incredibly useful copper+zinc alloy. If you find the right combination, you will have the perfect material for anything between musical instruments, decorative handles, ammunition, and industrial hardware. Add a small percentage of lead and you will have extremely malleable brass. If you want to decorate your house, arsenic, manganese, and nickel are some of the possible choices to determine the perfect color for the alloy. And if it is resistance that you want, tin can help you with that! All in all, it is undeniable that brass is one of the most versatile materials out there.