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In heat treatments, not all are for hardening metals, there are also methods to soften them and to rectify their internal structure.

What is annealing?

Annealing is a method of modifying the internal structure of the steel by heating it to a specific temperature depending on the purpose of the process.

Annealing types

  • The best known use is to soften the steel after it has been tempered.
    In annealing, the temperature of the steel rises above the tempering temperature, it is kept for a certain time so that its internal structure changes slowly, and it is allowed to cool very slowly until it reaches room temperature.
  • It can also be performed to remove stresses that may have occurred inside due to cold bending, welding, or the like.
    The temperature you need to correct these deformations is less than what is needed to soften the material after tempering.

The temperatures at which the steel rises depend on the amount of carbon they carry. They are usually between 550º and 980º.


  • One option, and the most common, is to raise its temperature in an oven and once reached, turn it off so that it cools very slowly inside. Thus we get a slow and progressive cooling. This process takes hours, which makes it quite expensive.
  • Another way to do it is by applying electric current to raise its temperature just like the oven does.

In any case, most of the times it is more affordable to manufacture a part again than to do the annealing process, especially the simpler it is.

As you can see, not all processes are for hardening metal. If you want to discover more, subscribe to our newsletter. A greeting plasmador!