The Science Behind Hardening Steel

Steel – as incredible a medium as it is – is simply too soft to be used for many applications. Think about tools, machine parts and dies which need to be a good deal harder than the products that they are drilling, forming or shaping. It’s for this reason that various treatments and metals are used for the hardening of steel to make it fit for a multitude of purposes.

The process of hardening steel is a fascinating process which changes the structure of carbon steel at a molecular level to produce a strong, tough product.

There’s No Shortcut to Hardening Steel

When we talk about hardening steel, we refer to carbon steel, as it’s the percentage of carbon present with the iron which allows the for the process of hardening as the crystalline structure within is broken down and altered.

Heating the steel slowly to approximately +700°C causes the metal to glow red and starts to change the structure of the metal. Once at the desired temperature, depending on the makeup of the metal and its desired use, the steel is quenched in oil, brine or a sodium hydroxide solution. This quenching process allows the carbon to fuse within the steel creating a hard, tough product.

This product, as strong as it is, can be very brittle at this point. So further processes need to be applied to make sure that the steel is hard, tough and durable. This involves tempering – reheating the steel, usually at temperatures from 180°C or more, and then quenching to fix the metal at the desired hardness.

In this state, the steel is now fit for purpose, being both tough and strong.

Hardening steel is a skill and a science and requires the talents of seasoned metalworkers to produce consistently good results.

What are your steel needs? Why not call Steelmor today and let us assist you with your next project.