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Metal hardening is a process where metal is heated to a specific temperature before being rapidly cooled down in order to significantly improve the metal’s hardness and strength.

Keep reading our blog to discover exactly what different metal hardening techniques there are, why it’s done and what hardened steel and other metals are used for.

How Do You Harden Steel and Other Metals?

The most common metal hardening technique involves heating the metal to a specific temperature and holding it there for a amount of time before being rapidly cooled down. By heating the metal above its ‘critical transformation temperature’ and then submerging it in a cool liquid like water, this locks in a hardened microstructure within the cellular structure of the metal. This method is mostly used for steel hardening, as well as in volume hardening and through hardening with slightly different steps.

Metal Hardening Techniques

There are three main types of metal hardening techniques, including:

Volume Hardening

Volume hardening and tempering is a heat treatment metal hardening technique that involves heating the entire volume of a metal object to a specific temperature, and then rapidly cooling it down. This is the most common metal hardening technique that results in hardening all the way through the object.

Surface Hardening

Surface hardening, sometimes known as case hardening, is a metal hardening technique that uses a few different ways to harden the outside of a metal object while keeping the inside softer.

• Laser hardening introduces a small amount of heat into the surrounding material.
• Induction hardening uses an alternating magnetic field to heat the object before immediately submerging it.
• Shock hardening uses a pulsed laser to generate a high-strength shockwave on the surface of the object.

Through Hardening

Similarly to volume hardening, through hardening involves heating a metal object to high temperature before cooling it rapidly – except this metal hardening method is followed by tempering. The object is heated again slightly at a lower temperature to adjust the final level of hardness. This achieves a uniform hardness throughout the entire structure, an equally hard core and surface.

What Is the Purpose of Metal Hardening?

The purpose of metal hardening is to make the material stronger and more resistant to wear. The many metal hardening techniques can improve durability, strength, hardness and mechanical properties for different applications, essentially changing the cellular microstructure of the metal to change its softness either on the outside, through the inside or both.

What Is Hardened Steel Used For?

Strong hardened steel is used to make durable metal objects that need to be able to withstand heavy loads and regular wear and tear. This includes different objects across industries:

• Hardened steel is used to make parts like gears, bolts and cardan shafts in the automotive industry.
• Excavator buckets, bulldozer blades and wear plates are made with hardened steel in the construction industry.
• In the manufacturing industry, hardened steel is used in moulds and dyes.
• Hardened steel is used to make hand-held tools and drill parts that you may have in your toolbox.
• Hardened steel is commonly used for kitchen knives.
• Military vehicles are generally armoured with hardened steel.

Take a look at our blog for more information about metal hardening techniques. Get in touch with our team at Dorsetware via our online contact form to find out more about metal hardening and de-embrittlement services or call us on 01202 677 939.