Deciding on Ferrous or Non-Ferrous Metals

Definition: First, let’s define “ferrous.” Ferrous metal is any metal that contains a significant amount of iron – the name comes from iron’s chemical symbol of “Fe,” from the Latin “ferrum.”

Properties of Ferrous Metals

Iron has a number of signature attributes that make it great for a wide variety of different purposes. It is:

• Dense – Iron is extremely dense, which can be beneficial for some applications where heat retention is important.
• Strong, especially when mixed with carbon – Iron is strong on its own, but extremely strong when mixed with carbon to make steel.
• Inexpensive, plentiful, easy to refine – Iron makes up approximately 5% of the Earth’s crust, and is the second most-common metal, behind aluminum, which is 8.1% of the Earth’s crust. Despite being less common, iron is much easier to refine and work with, making it cheaper than aluminum.
• Magnetic – Iron is the most widespread magnetic element, making it highly valuable for applications which require magnetism.

However, one negative property of iron is that it is extremely prone to corrosion.

As a rule, a ferrous metal – which consists of iron and one or more other metals to create an alloy – is meant to enhance or mitigate one of the above properties of iron. Stainless steel, for example, uses chromium to fight back against corrosion.

Common Types of Ferrous Metals

While there are hundreds of different ferrous metals in use, the below-mentioned metals and alloys are the most common types.

• Cast iron – Cast iron is inexpensive and easy to cast thanks to its flowability but is quite brittle and prone to chipping and cracking.
• Gray iron – Gray iron contains about 2.5-4% carbon, and also usually uses a silicon additive to help stabilize the graphite. While it’s still inflexible, it is not as brittle as cast iron.
• Ductile iron – Ductile iron incorporates both carbon as well as silicon and a few other elements to give it high tensile strength and impact resistance.
• Carbon steel – Carbon steel usually contains up to 2.1% carbon by weight, which is harder and stronger than iron, but less ductile.
• Stainless steel – Stainless steel contains up to 10.5% chromium and 1.2% carbon, which helps resist corrosion, a common issue with most ferrous metals.

Depending on the amount of iron and other elements, ferrous metals can exhibit extremely diverse properties, ideal for an enormous variety of applications.

Definition: Non-ferrous metals are, as you may have guessed, any metal that does not contain a large amount of iron.

Properties of Non-Ferrous Metals

Because non-ferrous metals (except aluminum) are less common in Earth’s crust compared to iron, they are usually chosen for their unique properties – rather than their ability to behave similarly to iron or steel.

For example, a metal like copper exhibits extremely high conductivity – making it a much better choice than iron or steel for electrical wire, for example, despite its higher overall cost. A few properties that non-ferrous metals may be chosen for include:

• A lighter weight, compared to steel or iron (aluminum or titanium, for example)
• Differing conductivity
• Corrosion resistance
• Non-magnetic properties
• Luxury or tradition

Depending on the particular needs of a project, a non-ferrous metal may be a better choice. For example, titanium may be used where strength is important, but the density and weight of steel or iron make it a sub-par choice.

Common Types of Non-Ferrous Metals

Naturally, there is a very large list of non-ferrous metals – every metal that does not include iron. So let’s just go over a few of the most common types of non-ferrous metals below.

• Precious metals – Precious metals like silver, platinum, and gold are often used for decorative applications, but also has uses in manufacturing. Gold is an excellent conductor and often used in small quantities in electronic devices and circuit boards.
• Aluminum – Aluminum is very strong and lightweight, compared to a ferrous alloy, and resists corrosion, making it a great option for applications where weight is important, like aerospace applications.
• Copper – Due to its ductility and high conductivity, copper is an extremely common type of non-ferrous metal used for things like pipes, electrical connectors and more.
• Bronze and brass – Bronze is an alloy of copper and tin, and brass is an alloy of copper and zinc. Bronze and brass were first developed as far back as the 5th millennium BC. Brass is durable yet ductile, while bronze is very dense and a good conductor.
• Titanium – Titanium is very expensive, but extremely strong despite its low density, making it ideal for applications where low weight and high strength are both required. It’s commonly alloyed with other metals like iron, vanadium, aluminum, and molybdenum.

While there are many other types of non-ferrous metals, these are some of the most well-known and commonly-used types.