What is A Ferrous Metal?
The term ferrous comes from the Latin word Ferrum, which means “iron-containing metal compound.” Ferrous metals are those that contain only small amounts of iron in their composition. Ferrous metals are magnetic and have high strength and hardness due to their iron content.
Ferrous metal is any metal that is primarily composed of iron and has magnetic properties. Ferrous metal is known for its hardness, durability, and tensile strength. Some common ferrous metals include alloy steel, carbon steel, cast iron, and wrought iron. Ferrous metals are known and used for their strength.
Ferrous metals are highly vulnerable to corrosion when exposed to moisture or an acidic or corrosive environment due to their high carbon molecule content. As such, they are typically mixed with many different alloying elements to obtain the desired properties.
Some examples of alloying elements used include chromium, vanadium, nickel, and manganese. These elements can give ferrous steels the material properties that make them widely used in various engineering industries.
Some desirable ferrous metal properties include durability, great tensile strength, magneticity, low resistance to corrosion, silver color, the ability to be recycled, and electrical conduction. That said, it is difficult to assign common properties among ferrous metals overall due to the wide variety of alloying elements that are used to change their characteristics.
The properties that they possess make them perfect to be used in both the industrial and architectural sectors for projects like skyscrapers, bridges, railroad projects, and vehicles. Due to their magnetic properties, ferrous metals are also widely used in various appliances and engines.
Ferrous metals, however, have high carbon content, which generally makes them more likely to rust; stainless steel is an exception due to its chromium content, as is wrought iron, due to the purity of its iron content. Ferrous metals are widely used in almost all industries such as in the manufacturing of shipping containers, industrial piping, automobiles, railroad tracks, ships, and many commercial and domestic tools.
What is Ferrous?
In chemistry, the adjective Ferrous indicates a compound that contains iron (II), meaning iron in its +2-oxidation state, possibly as the divalent cation Fe2+. It is opposed to “ferric” or iron (III), meaning iron in its +3-oxidation state, such as the trivalent cation Fe3+.
This usage has been largely replaced by the IUPAC nomenclature, which calls for the oxidation state is indicated by Roman numerals in parentheses, such as iron (II) oxide for ferrous oxide (FeO), iron (III) oxide for ferric oxide (Fe2O3), and iron (II, III) oxide for the oxide Fe3O4 that contains both forms of iron.
Outside chemistry, “ferrous” means generally “containing iron”. The word is derived from the Latin word Ferrum (“iron”). Ferrous metals include steel and pig iron (with a carbon content of a few percent) and alloys of iron with other metals (such as stainless steel). “Non-ferrous” is used to describe metals and alloys that do not contain an appreciable amount of iron.
The term “ferrous” is usually applied only to metals and alloys. The adjective ferruginous is used instead to refer to non-metallic substances that contain iron, such as “ferruginous water”; or to an orangish-brown color resembling that of rust.
Properties of Ferrous Metals
Ferrous metals share some basic properties, including being prone to rust and being magnetic. The list of common ferrous metal properties includes:
- Good tensile strength
- Good electrical conductivity
- Low corrosion resistance
- Silver in color
- Usually, magnetic
Ferrous metals can include a wide range of different alloying elements, including chromium, nickel, manganese, molybdenum, and vanadium, manganese. These alloying elements give ferrous materials different properties that allow them to be used in a variety of engineering and other applications including tools, pipelines, containers, cutlery, and larger fabrications like skyscrapers.
List of Ferrous Metals
Some common ferrous metals include alloy steel, carbon steel, cast iron, and wrought iron, let’s discuss each of them one by one.
Steel is made by adding iron to carbon which hardens the iron. Alloy steel becomes even tougher as other elements like chromium and nickel are introduced. Steel is made by heating and melting iron ore in furnaces. The steel can is tapped from the furnaces and poured into molds to form steel bars. Steel is widely used in the construction and manufacturing industries.
2. Carbon Steel
Carbon steel has higher carbon content in comparison to other types of steel making it exceptionally hard. It is commonly used in the manufacturing of machine tools, drills, blades, taps, and springs. It can keep a sharp cutting edge.
3. Alloy Steel
Alloy steels incorporate elements such as chromium, nickel, and titanium to impart greater strength and durability without increasing weight. Stainless steel is important alloy steel made using chromium. Alloy steels are used in construction, machine tools, and electrical components.
4. Cast Iron
Cast iron is an alloy made from iron, carbon, and silicon. Cast iron is brittle and hard and resistant to wear. It’s used in water pipes, machine tools, automobile engines, and stoves.
Cast iron is produced when a carbon content of 1.5-4% is alloyed with iron. Other elements including silicon, manganese, Sulphur, and phosphorus will be present, but only in small quantities. Cast iron is brittle but has a good wear resistance due to its hardness. It is also easy to cast, relatively cheap, has high compressive strength, and has a low melting point.
5. Wrought Iron
Wrought iron is an alloy with so little carbon content it’s almost pure iron. During the manufacturing process, some slag is added which gives wrought iron excellent resistance to corrosion and oxidation, however, it is low in hardness and fatigue strength. Wrought iron is used for fencing and railings, agricultural implements, nails, barbed wire, chains, and various ornaments.
Examples and Uses of Each one
Due to the different properties of ferrous materials, they have a variety of applications that differ depending on the metal being used:
Also known as carbon steels, non-alloy steels use carbon as the alloying element. These steels do include other elements, such as manganese, silicon, Sulphur, and phosphorus, but the content of these elements is so low that they do not impact the material properties.
Non-alloy steels are classified as having either a low, medium, or high carbon content, and each has different characteristics and treatment methods:
1. Low Carbon Steel
Low-carbon steels, also called mild steels, contain just 0.05-0.25% carbon. Low-cost and malleable, these steels are widely used for items such as nuts and bolts or forgings. The surface hardness of these steels can be increased by carburizing.
2. Medium Carbon Steel
Medium carbon steels contain 0.25-0.6% of carbon. This higher carbon content provides an increase in strength and hardness over low-carbon steels. However, these steels have reduced ductility compared to low-carbon steels.
Increased levels of carbon and manganese in medium-carbon steels mean that they can be tempered and quenched. These steels are widely used for making components for the automotive industry, such as gears, axles, and shafts, but are also suitable for use on railway applications.
3. High Carbon Steel
High carbon steels contain 0.6-1% carbon and are the strongest of the non-alloyed steels. This strength makes them ideal for applications requiring resistance to mechanical wear, while they are also good at maintaining their shape.
On the negative side, these steels are inferior to lower carbon steels when it comes to weldability, ductility, and impact toughness. High carbon steel is used for springs, blades, rail steels, wire rope, wear-resistant plates, tools, and more.
Alloy Steels and the Alloying Elements
Alloy steels make up another subgroup of ferrous metals, with each alloying element having its own effect on the material properties. These alloying elements include chrome, copper, nickel, silicon, and titanium, but can be combined to provide a range of properties. Here are the properties of the most common of these alloying elements:
Chromium is used to make stainless steel, with chromium levels of over 11% making metals corrosion-resistant. An oxidized chromium layer on top of the metal will prevent the underlying metal from coming into contact with oxygen, thereby greatly reducing the chance of corrosion. Chromium also increases the hardness, tensile strength, toughness, and wear resistance of a metal.
Manganese can be used as an alloying element to prevent iron sulfides from forming, as well as increasing strength at high temperatures, improving ductility and wear resistance. Manganese can also improve hardenability through quenching, reducing the danger of defect formation and making the metal more stable.
Nickel, when used with other elements, can increase ductility and corrosion resistance. For example, a mix of 18% chromium and 8% nickel creates extremely durable stainless steel.
Silicon can be used to increase the magnetic properties of metal as well as improve strength and provide elasticity for applications like springs.
Titanium can be used to improve the strength and corrosion resistance of a metal, as well as limit the austenite grain size.
Vanadium carbides also limit the grain size of a metal, increasing the ductility of the alloyed material. Vanadium also improves the strength, hardness, wear and shock impact resistance. However, if used in quantities that are too high it can have a negative impact on material properties.
Molybdenum offers a good effect on steel alloys operating at high temperatures. It not only improves mechanical properties, but also provides higher resistance to rust and corrosion, and amplifies the effects of other alloying elements.