What is A Ferrous Metal? – A Complete Guide

What is A Ferrous Metal?

When a metal has the label “ferrous”, it means that it contains iron. When the word ferrous metal is used, it also usually means that iron is a substantial share of the elemental composition.

If it is not the most prevalent element it is probably the second or third most prevalent. If a metal only consists of trace amounts of iron, as many metals contain, then that amount is too small to classify the metal as ferrous.

Ferrous metals, as mentioned, have iron so it possesses magnetic characteristics. Iron gives ferrous metals high strength and hardness attributes which are useful for architectural and structural purposes, including the tallest skyscrapers, bridges, railways, etc.

Ferrous metals have magnetic characteristics that is why you can pin some things with magnets to your refrigerator door, however, ferrous metals often rust given their high carbon content.

The exception to that is stainless steel due to the chromium which makes it non-rusting and wrought iron which has a high pure iron content making it non-rusting.

Some examples of ferrous metals include alloy steel, carbon steel, cast iron, and wrought iron. Ferrous metals have become known and accepted as strong metals because they possess strength.

What is Ferrous?

In chemistry, ferrous refers to a substance which contains iron (II), which means it contains iron in the +2-oxidation state and possibly as the divalent cation Fe2+.

The term ferrous is the opposite of ferric, or iron (III), which means it contains iron in the +3-oxidation state, and may be as the trivalent cation Fe3+.

Ferrous has almost entirely fallen out of use in favor of the IUPAC nomenclature that uses Roman numerals in parentheses to indicate oxidation state, e.g., iron (II) oxide for ferrous oxide (FeO), iron (III) oxide for ferric oxide (Fe2O3) and iron (II, III) oxide for the oxide that contains both forms of iron, Fe3O4.

Outside of chemistry, ferrous means it is generally containing iron. Ferrous comes from the Latin Ferrum (iron). Ferrous metals includes steel and pig iron (which contains a few percent carbon) and iron-alloyed with other metals (e.g., stainless steel). The word non-ferrous is used to describe metals and alloys that do not have any appreciable iron within it.

Ferrous is generally applied to metals and alloys only. The word ferruginous is generally used instead to describe non-metallic substances that contain iron, for example, ferruginous water; or to describe an orangish-brown colour that resembles rust.

Properties of Ferrous Metals

Ferrous materials have a few primary properties in common, in addition to being rust-prone and often magnetic as mentioned above. The list of properties that ferrous metals share includes:

• Durable
• Good tensile strength
• Good electrical conductivity
• Low corrosion resistance
• Silver in color
• Recyclable
• Usually, magnetic

Ferrous metals can include a diversity of different alloying elements such as chromium, nickel, manganese, molybdenum, and vanadium, manganese.

The addition of these alloying elements gives ferrous materials different properties that allow for their many engineering and other uses such as in tools, pipelines, containers, cutlery, and larger applications such as skyscrapers.

Examples 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.

1. Steel

Steel is formed by artificially carbonising iron; this change, allows hardened iron. Alloy steel is hardened by using elements such as nickel and chrome.

To create steel we start out by applying heat and melting iron ore in a furnace. The iron or steel is then tapped out of the furnace, and poured into moulds to create steel bars. Steel is used without fail in construction, and manufacturing.

2. Carbon Steel

Due to its higher carbon content than other steels, its also very hard. Typically, it is used for drill bits and machine tools, blades taps and springs as well as meaning it keeps its sharp cutting edge.

3. Alloy Steel

Alloy steels, which have automotive and mechanical applications, contain additional elements (for example: chromium, nickel, titanium, etc.) to yield more strength and toughness without the subsequent increase in weight.

A major form of alloy steel is stainless steel, which contains a minimum 10.5 wt % chromium. Alloy steels are often used for structural applications, machine tools, and electrical components.

4. Stainless Steel

Stainless steel is another family of ferrous metals to which there are many common uses and generalizations. Generally speaking, stainless steels have a significant quantity of chromium, which provides better resistance to corrosion than carbon steels. Stainless steels may be sectioned again into sub-groups.

Austenitic stainless steels have the highest corrosion resistance, due to a high quantity of nickel and chromium. There are also some ferritic, martensitic, and duplex stainless steels. Each family of stainless steels has important pros and cons based on application.

Stainless steels are commonly found in household appliances, pharmaceutical/medical equipment, food-grade equipment and knives.

5. Cast Iron

Cast iron is an iron-carbon-silicon alloy. Cast iron is hard and brittle and is wear resistant. Cast iron can be used in water pipes, machine tools, automobile engines and stoves.

Cast iron is made when carbon is alloyed with iron in the ratio of 1.5% to 4%. Some other elements including silicon, manganese, sulphur and phosphorus will be present in small amounts.

Also, cast iron is brittle but has good wear resistance due to its hardness. Cast iron is easy to cast, relatively cheap, and has high compressive strength and a low melting point.

6. Wrought Iron

Wrought iron is an alloy that contains very little carbon so as to be almost pure iron. Some slag was added during manufacture, which gave wrought iron good resistance to corrosion and oxidation, however, it has low hardness and fatigue strength.

Wrought iron is used to manufacture fencing and railings, agricultural tools, nails, barbed wire, chains, and many ornamental items.

Alloy Steels and the Alloying Elements

Alloy steels are another subgroup of ferrous metals, and each of the alloying elements has its own effect on the properties of alloy steels.

The alloying elements range from chrome, copper, nickel, silicon, and titanium but they can also be combined to give a number of properties. The following are properties of the most common of the alloying elements:

1. Chromium

Chromium is an important alloying element for stainless steels, as chromium levels over 11 % can produce corrosion resistant metals.

When chromium is oxidized, it provides a layer to the surface area of the metal which decreases the exposure of the underlying metal to oxygen, one of the conditions for corrosion to initiate.

In addition to providing corrosion resistance, chromium enhances the hardness, tensile strength, toughness, and wear resistance of metals.

2. Manganese

Manganese can act as an alloying component used to prevent the formation of iron sulfides, and also increase strength at elevated temperatures, improve ductility, wear resistance, and increase hardenability by using quenching methods, which mitigate the possibility of defects occurring and make the metal more stable.

3. Nickel

Nickel can improve ductility and corrosion resistance when added to other metal types. A mixture of 18% chromium and 8% nickel makes a very strong stainless steel.

4. Silicon

Silicon is used to enhance the electrical and magnetic properties of metals and the strength and elasticity needed for applications like springs.

5. Titanium

Titanium is often used to increase the strength and corrosion resistance of a metal, and for the purpose of size refinement of the austenite grain.

6. Vanadium

Vanadium carbides also influence the grain size of a metal, improving the ductility of the alloyed material. Vanadium also provides greater strength, hardness, wear resistance, and shock impact resistance. However, at certain concentrations, it can negatively affect material properties.

7. Molybdenum

Molybdenum is beneficial to steel alloys for high-temperature uses because it provides all of the benefits of mechanical properties, added resistance to rust and corrosion, and the benefits of other alloying elements.

Applications of Ferrous Metals

Ferrous metals are used in a variety of applications. Listed below are its major uses:

• Sturdy crushing machinery.
• Nuts, bolts girders, and plates.
• Car cylinder blocks and gear wheels.
• Machine tool parts, machine handles, and engine parts.
• Vices, brake drums, and plumbing fittings.
• Gears and shafts.
• Cutting equipment for lathes.
• Kitchen draining boards and cutlery.
• Aircraft and pipes.
• Chisels, files, and lathe tools.
• Garden tools, hammers, drills, dies, and taps.
• Metal ropes, springs, and wire.

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