When exploring the many alloys available to you for the manufacturing processes, it can sometimes be challenging to keep everything straight amid materials that physically look and act similarly.
Of two metallic materials that usually come to mind and may be confused for each other, we have bronze and brass, which both undergo machining, processing, and are found in similar applications, but impart different properties, which we will discuss in further detail below.
What Is Bronze?
Bronze alloy is one of many out there, but it is made up of a specific composition of copper and tin, and often less than 7% of some other elements, including phosphorus, silicon, zinc, arsenic, aluminium, and manganese.
Bronze provides a fairly good balance of excellent corrosion resistance, relatively low metal-to-metal friction, and reasonable ductility.
Bronze often has a metallic surface in a reddish-brown colour, one example of which is shown below.
Although known for its oxidation properties, you may also find bronze products or structures which are a deeper brown and developing a greenish blue patina.
Advantages and Disadvantages
There are a few perks to working with bronze:
- Bronze has better corrosion resistance, even in seawater, when compared to brass.
- It is also hard and strong and can be more so than pure copper and iron.
- It can also be more fatigue resistant than many steels.
That said, there are also some downsides to be aware of with bronze:
- Bronze is indeed more difficult to work with because it is hard, so there is a little more effort in changing its shape compared to brass or copper.
- It is able to be susceptible to bronze disease, which is a corrosion that just ruins the bronze and cannot be reversed.
- Its resistance to ammonia, cyanides, and ferritic compounds is not great.
- It tarnishes more readily than copper.
- Usually bronze is much more expensive than brass.
What Is Brass?
Brass is also an alloy, like bronze, but while bronze incorporates tin in its alloy, brass contains a mixture of copper and zinc. Brass also typically has other elements and metals; for example: silicon, iron, aluminum, and manganese, that will affect its color and properties.
For example, if your brass has higher levels of zinc, the brass will likely have increased ductility and strength; if your brass had higher levels of manganese, the brass will have greater corrosion resistance. Often to assist in workability, some brass includes lead.
Brass typically has a yellow or gold color, as seen in the brass rod image below, but that will differ based on which elements you actually have and in what concentration. In general, more zinc, and you end up with a silvery finish; more copper provides a reddish tint.
Advantages and Disadvantages
You’ll find that brass has its own advantages as a material:
- Brass championed over bronze in workability, machinability, and malleability, compared to bronze in each of these categories, brass is a better choice.
- Brass is antibacterial property can be beneficial in certain industries.
- Brass typically has a gold color that is superior in looks to other metals and alloys.
You’ll also want to note the disadvantages that usually come with using brass:
- Brass is susceptible to cracking when exposed to harsh chemicals, including ammonia.
- Although some materials tarnish less than others, brass is more subjective to tarnishing.
- Brass has a slightly lower melting point than bronze -970 °C compared to 950 °C.
How They Are Made
The processes for making brass and bronze are generally the same, the only real difference is the concentration of elements and what metals are added. In bronze, we mostly see around 88% copper and about 12% tin.
In brass, we look at a range of around 55-95% copper to about 5% – 45% zinc. Once the mixture is correct, they are melted down and then into molds. The molds are cooled and set, then sent for processing which will involve prepping the materials for all kinds of products and processes.
As for costs, you will see that bronze is more expensive as it will cost more to make (tin costs more than zinc).
Copper costs more than zinc too, and since bronze has more copper than brass does, bronze is more expensive for that reason too. You will see that making and buying bronze can be up to 4 times the cost of brass.
Properties of Bronze and Brass
This table will give you a quick rundown of how bronze and brass compare when it comes to how they look and their properties and uses.
| Property | Bronze | Brass |
|---|---|---|
| Color | Reddish-brown | Goldish |
| Alloying elements | Copper and tin | Copper and Zinc |
| Melting point | 950 °C | 900 °C |
| Corrosion resistance | Excellent (even in saltwater) | Good |
| Brittle/ductile | More brittle | More ductile |
| Magnetic | No | No |
| Applications | Instruments and things like cymbals, bells, guitar strings, sculptures and architectural sculptures, outside sculptures, bearings, bushings, springs, machine parts that are precision graded, submerged bearings and ship props. | Instruments like tuba, trumpet, saxophones, harmonicas, french horns, jewelry, coins, statues, decorative, bearings, gears, locks, doorknobs, valves. |
FAQs About Bronze and Brass
These are answers to some of the most common questions that crop up when you’re working with or deciding between bronze and brass.
Does copper turn to bronze?
Not at all, while copper is part of the makeup of bronze, bronze contains various other elements to formulate an alloy. So over time you will not see copper become bronze, unless tin and other element traces are alloys along with copper.
Are bronze and brass weldable?
Yes, both bronze and brass can be welded although it can be challenging weling due to their fairly great thermal conductivity. Just as we have done with brass, using a larger tip (i.e. a size larger than that which you would use to weld steel of similar thickness) will be advisable.
Is bronze or brass more malleable?
Brass tends to be more malleable than bronze. Because bronze has tin in its makeup, it tends to have more hardness than its counterpart.
Are bronze and brass magnetic?
No, bronze or brass are not magnetic. This is because the bronze and brass is made of non-magnetic elements and metals (eg. copper, tin, and zinc) and it may be true that nickel is included in the bronze alloy and makes it slightly magnetic, but otherwise they are non-magnetic they are not magnetic metals or alloys.