What is a Ferrous Metal?

Metals are among the most versatile materials and are used in a wide range of industries, from construction and manufacturing to electronics and transportation. There are many different categories into which metals can be placed. Some metals may be ductile, while some may be brittle. Other metals could be magnetic, and some have no magnetism at all. Some types of alloys can be precipitation hardened, and others cannot.

These classifications help determine the suitability of metals for specific purposes and projects, guiding engineers, designers, and manufacturers in selecting the right material for their needs. However, when categorizing metals, one of the most important differences is whether the metal in question is ferrous or non-ferrous. So, what is ferrous metal? Let’s learn more.

What is a Ferrous Metal?

A metal with the descriptor “ferrous” means that it has iron in its composition. When the term ferrous metal is used, it also usually implies that iron is a large percentage of the elemental composition. If it’s not the most abundant element, it would probably be the second or third most prolific. If a metal only contains trace amounts of iron, as many metals do, then that small amount is not considered enough to declare the metal ferrous because the minimal presence of iron does not influence their properties enough to classify them in this category.

What are the Common Properties of Ferrous Metals?

It is difficult to assign common properties to ferrous metals since they can have a wide variety of alloying elements that greatly change their characteristics. For instance, many ferrous metals are magnetic; however, this is not true for all ferrous metals. Austenitic stainless steel, while considered a ferrous metal, is not magnetic because the large amount of nickel allows it to have a crystal structure that is predominantly austenite at room temperature. Austenite is not magnetic, although it does contain iron. Some ferrous metals, such as cast iron, are extremely strong and brittle. However, low carbon steel, another type of ferrous metal, can be quite soft and ductile because it does not contain as much carbon as cast iron.

While it is difficult to place the properties of all ferrous materials under one umbrella, there are some generalizations that can be made with some accuracy. Ferrous metals often have relatively high strength, especially when compared with copper, tin, and lead alloys. Ferrous metals are also generally hard, and if they’re not alloyed with many other elements or coated, they can be subject to rust. Most ferrous metals, with the exception of austenitic stainless steel and some other grades, are magnetic.

Examples of Ferrous Metals

Ferrous metals are primarily composed of iron, but their specific characteristics can vary depending on the other elements alloyed with them. As mentioned earlier in the article, there are many different types of ferrous metals.

The following are some examples of ferrous metals:

• Carbon Steel
• Stainless Steel
• Cast Iron
• Alloy Steel

Carbon Steel

Carbon steels are possibly the most widely used type of ferrous metal. Their popularity stems from their excellent balance of strength, affordability, and adaptability, making them a go-to material for a wide range of products and projects. They are primarily made up of iron, with over 90% of their chemical composition being that element. The only other major alloying element in carbon steel is carbon. There are only trace amounts of other elements.

Thanks to its versatility, carbon steel can be found in numerous everyday and industrial applications. Common applications of carbon steels include structures, furniture, and automotive components.

Stainless Steel

Stainless steel is another group of ferrous metals that are commonly used. In general, stainless steels have a high amount of chromium that helps them to resist corrosion better than carbon steels. The addition of chromium forms a passive layer on the surface, which protects the metal from rust and oxidation, even in harsh environments.

Stainless steels can be further broken down into subgroups. Austenitic stainless steels have the most corrosion resistance, with high amounts of nickel and chromium. These are commonly used in settings where there is frequent exposure to corrosive substances like acids or saltwater. There are also ferritic, martensitic, and duplex stainless steels. Each has its advantages and disadvantages, depending on the application.

Common applications of stainless steels include appliances, pharmaceutical and medical equipment, food-grade equipment, and knives.

Cast Iron

Cast iron is a type of ferrous metal that has more carbon than most other types. This gives it a high amount of strength. Although high in strength, it is quite brittle, meaning it can fracture under sudden impact or excessive stress. This limits its use in applications requiring flexibility or ductility but does not detract from its utility in static or low-impact settings. The lack of other alloying elements outside of iron and carbon makes it a relatively affordable ferrous metal.

Common applications of cast iron include cookware, such as skillets and Dutch ovens, which benefit from its excellent heat retention properties. It is also used in small components subject to wear, such as gears, rods, pins, and mining equipment.

Alloy Steel

Alloy steels are a type of ferrous metal specially formulated to serve specific purposes, making them highly versatile and useful across a variety of industries. Their adaptability lies in the ability to modify their chemical composition by adding different alloying elements, which allows for precise control over their mechanical and physical properties. While composed primarily of iron, differing amounts of copper, vanadium, tungsten, manganese, and other elements can be used to tailor an alloy steel to have higher toughness, ductility, tensile strength, hardness, and other properties.

The capacity for customization makes alloy steels particularly valuable for demanding applications where standard carbon steels may fall short. By carefully selecting and balancing the alloying elements, manufacturers can create steels with enhanced wear resistance, improved machinability, or greater ability to withstand extreme temperatures and pressures. These properties make alloy steel an indispensable material for tools and machinery that require high durability and reliability.

Common applications of alloy steels include tools, dies, and machining equipment.