Copper and its alloys are extremely common in our day-to-day use, from wires to home decorations.
Yet, some people have a bit of a hard time figuring out the difference between copper, bronze, and brass.
In this article, we go over the composition, main stand-out features, and applications of each one. Let’s jump right in!
The Difference Between Copper, Bronze, and Brass: Overview
First things first, let’s take a look at the composition and basic nature of copper and its alloys:
What Is Copper?
Copper is a reddish-brown elemental metal that’s found in nature as a part of ores. However, for industrial reasons, the metal is extracted from iron sulfide ores like chalcopyrite and bornite.
The extraction and purification processes typically rely on smelting, leaching, or electrolysis, which all depend on the metal’s chemical and physical characteristics.
A notable characteristic of copper is its response to magnets.
While magnets are metallic, not all metals are magnetic, and copper is one of those nonmagnetic exceptions.
Yet, it exhibits a flux reaction to strong metals that turns out to be the basis of electric generator coils.
What Is Bronze?
Unlike copper, bronze isn’t an element on its own. Instead, it’s a blend of 88% copper with 12% tin.
Depending on the intended application, the ratio can be shifted a bit more in favor of more copper up to 90% of the full weight.
This mixture turns the usually raw copper malleable and soft copper into a hardened yellowish-brown alloy.
In some cases, you might find other elements added to the alloy to get to certain desirable characteristics.
For instance, trace phosphorus in around 0.01 to 0.35% can enhance the alloy’s resistance to rust and corrosion. This is commonly called phosphor bronze.
On the other hand, aluminum can be added in 9-14% with a smaller portion of iron to replace tin as the main alloying metal. You’ll find this commercially sold as Wearite 411, one of the more wear-resistant alloys out there.
What Is Brass?
Much like bronze, brass is a copper-based alloy. Both are substitutional alloys, meaning that the added metal replaced a few copper atoms in its own crystalline form.
However, in the case of brass, zinc is the main alloying metal added to copper instead of tin. The copper to zinc ratio is usually 6:4 in most brass alloys.
The defining criteria to call a certain copper-zinc blend brass is that it should have no less than 15% zinc. This limit is called red brass or gunmetal.
Meanwhile, alloys with higher zinc content are called medal brass, which is the most common type with the gold-like hue we all know.
The more zinc you add to the alloy, the more unyielding it gets, and vice versa. That means that red brass is softer than medal brass.
All in all, it’s harder than both gold and pure copper.
The Difference Between Copper, Bronze, and Brass: 4 Distinguishing Points
On the surface level, copper, bronze, and brass can all seem similar. While they do have a lot in common, there are a few distinctions worth noting.
Let’s take a deeper look at four of those:
- Melting Point
Melting points make all the difference when it comes to metallurgy.
That’s because every step from the identification and extraction to the molding depends on how much heat the metal can take before liquifying.
In brass, the zinc portion is responsible for bringing down the melting point of the entire alloy. That’s why red brass (with a maximum of 15% zinc) melts at 1880°F, while yellow brass (with up to 39-40% zinc) metals at 1700°F.
Tin has an even lower melting point at only 449°F. As a result, bronze’s melting point is much lower than copper. Usually, it’s somewhere around 1675°F, depending on the alloy’s purity.
Copper is one of the best electric and thermal conductors — it’s such a good conductor that other metals and alloys are compared to it on a perfect scale where copper is a full 100%.
On the other hand, just because an alloy is copper-based doesn’t mean that it’ll have an equally high conduction rate.
It all depends on the alloying metal and the mixing ratio between the two.
Zinc, for instance, is 27% conductive, while tin is only 15%. This means that brass is an overall better conductor than phosphor bronze and nickel aluminum bronze.
In layman’s terms, you need a thicker sheet of bronze to get an equivalent heat and thermal conductivity compared to copper.
- Market Cost
Cost-wise, elemental copper is more expensive than any of the alloying metals, including tin and zinc.
However, since brass uses a smaller portion of copper when compared to bronze, it’s a cheaper alloy. The more zinc the alloy contains, the less it’s going to sell for.
In fact, bronze can come with a price tag that’s up to four times more expensive than the typical 6:4 brass blend.
- Practical Applications
Copper is most commonly used to make electric wires. Besides being a good conductor, copper also has antibacterial properties. For this reason, it’s often used to make pipes and pipe fittings with reduced contamination.
Meanwhile, bronze’s high corrosion resistance makes it a great fit for marine industries. For instance, the propellers and fittings usually have bronze frames to increase their longevity.
Although it’s easily cast, brass is rarely used for such intense applications since it’s susceptible to cracking under stress.
Since brass is very visually appealing with a gold-like sheen, it’s often used to make ornamental pieces. Yet, it can also be used to build musical instruments like guitars.
Knowing the difference between copper, bronze, and brass all comes down to identifying an elemental metal and an alloy.
At their core, brass and bronze are similar in a lot of ways. They’re both copper-based substitution alloys.
However, the zinc addition in brass makes all the difference from the tin in bronze. Even the ratio variation between copper and zinc can result in drastic changes in characteristics from color to hardness!