WHAT IS A FERROUS METAL?

There are many different categories into which metals can be placed. Some metals may be ductile, 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. The aforementioned are important distinctions; however, when categorizing metals, one of the most important differences worth noting is whether the metal in question is ferrous or non-ferrous.

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.

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, it 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 high of an amount of 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 amounts of 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, can be subject to rust. Most ferrous materials, with the exception of austenitic stainless steel and some other grades, are magnetic.

Examples of Ferrous Metals

As was 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. 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. 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. Stainless steels can be further broken down into subgroups. Austenitic stainless steels have the most corrosion resistance, with high amounts of nickel and chromium. There are also ferritic, martensitic, and duplex stainless steels. Each has their own 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. The lack of other alloying elements outside of iron and carbon make it a relatively affordable ferrous metal. Common applications of cast iron include cookware, small components subject to wear such as gears, rods, and pins, and mining equipment.

Alloy Steel

Alloy steels are a type of ferrous metal specially formulated to serve specific purposes. 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. Common applications of alloy steels include tools, dies, and machining equipment.