Classifying Brasses by Their Crystal Structure—Muntz Metal and Other Brass Types

Copper is valued for its numerous useful properties. Apart from being extensively used for electrical and electronic applications, it also boasts of health benefits. Amazing as it is in pure form, this metal becomes even more useful when combined with other equally prized metals. For instance, when alloyed with zinc, it produces brass, which also has its fair share of great merits, including its high tensile strength and machinability.

Brass can be formed in an array of types by manipulating its zinc content. Each type has unique properties required for specific applications. Currently, there are at least 60 different types of brass. These are further classified into smaller groups based on their crystal structure. 

Alpha Brasses

All brasses that contain less than 37 percent zinc are classified as alpha. This small amount of zinc is evenly distributed within the alloy to form a homogenous alpha grain structure, thus the name. Because there are fewer atoms of zinc held between the molecules of copper in this structure, there’s not enough strength to resist even light pressure. Consequently, the resulting brass is softer and more ductile than other types, making it very easy to work with.

Alpha-Beta Brasses

Adding more zinc to the mixture allows for the creation of a beta grain structure. This is why brasses with 37 to 45 percent zinc content are classified as alpha-beta brasses. Having a beta grain structure, the resulting brass becomes tougher and less ductile, which makes it difficult to work with at room temperature. This is why alpha-beta brasses are usually hot worked by extrusion, stamping, or die-casting. One example of this type of brass is Muntz metal, which has about 60% copper, 40% zinc, and a trace amount of iron.

Beta Brasses

With more than 45 percent zinc, beta brasses are the hardest of all types of brass so much so that they can only be hot-worked or cast. Their hardness makes them suitable for making faucet handles, sprinkler heads, window and door fittings, and other fixtures that are constantly subjected to pressures. Other elements, such as aluminum and iron, are added into the alloy to achieve even better properties that are necessary for complex and aggressive applications.

Apart from differentiating crystal structures, there are other ways brasses can be classified to identify the type that can work best for certain applications. Specifically, they can be classified by their mechanical properties and color, although each property used as basis is related to the rest of the properties.

Using brass with the right characteristics can improve the quality of your project’s output, and possibly reduce the cost. This is why it is important to consult with an expert in metals before shopping around for brass supplies. Top suppliers like Rotax Metals have experts ready to guide you through the choosing and buying process. Also, because they have a huge selection of brass products with different grades and zinc content, you can easily find the most suitable type for your project.

About Rotax Metals. When it comes to copper and brass, you should settle only for the best, and that’s what we at Rotax Metals offer. Established in 1947, we’ve been providing the highest quality copper supplies to professionals and businesses across North America. We even customize metal parts for manufacturers that need specific designs for their machinery. Whether you are a designer or a metal supplier, you need us to provide you with topnotch metal solutions for your projects.

Sources:

Brass Alloys and Their Chemical Composition, thoughtco.com

Brass, britannica.com