Heat treatment processes are necessary for various operations for glass and metals. Among these processes, the most commonly used is annealing, which helps test the material and strengthen its durability. This process also makes the material more pliable, making it easier to forge into the shape you need. 

You can also use different annealing methods, but the most efficient way involves heat treatment furnaces. Read this guide to learn how to anneal using a lab furnace.

What is Annealing?

The annealing process alters a material's physical properties by exposing it to high temperatures and allowing it to cool slowly. Sometimes, annealing can also change chemical properties, improving the material's elasticity and making it easier to use.

Metal fabricators and other businesses typically use this heat treatment method to mold different types of materials into new products across the automotive, aerospace, construction, and other similar industries.

The Annealing Process

The annealing process follows three steps: recovery, recrystallization, and grain growth.

1. Recovery Stage

In the recovery stage, heat treatment equipment raises the temperature of a material. They also heat the substance and recover its physical properties, which include thermal expansion, internal energy, and electrical conductivity.

This step aims to soften the metal into a workable state and relieve its internal stresses, which can cause cracks and other mechanical complications.

2. Recrystallization Stage

The second stage focuses on maintaining the temperature of the material above its recrystallization point but below melting temperature. This step usually applies to cold-worked metal to help gain nucleation and cause new grains to form without any pre-existing tension.

Recrystallization also helps remove the effects of heavy plastic deformation on highly shaped, cold-form metal parts. 

3. Grain Growth Stage

After the recrystallization stage, the material cools at a specific rate to cause new grains to develop while the recrystallized grains grow in size. The cooling rate is important because it controls the growth of the grains.

Completing these three steps will give the material more flexibility and less hardness. Occasionally, a subsequent process may be necessary to change the material's mechanical properties. 

How to Perform Annealing Using a Heat Treatment Furnace