Annealing furnaces & ovens

Carbolite Gero offers a wide range of annealing furnace and annealing oven solutions, from standard to fully custom designed units. Below you will find suitable products sorted by atmosphere as well as a general introduction.

Please choose air atmosphere, inert atmosphere or vacuum to view a list of suitable annealing furnace and oven solutions:
 

Introduction to annealing with furnaces and ovens

Annealing is a heat treatment process that alters the physical properties of a metal in order to increase its ductility and make it easier to work with.

Metals are heated above their recrystallisation temperature and are kept at a steady temperature for a required length of time, before being allowed to cool. This method changes the internal microstructure of the metal as the atoms diffuse through the solid material, reducing the number of dislocations (linear defects within the metal's crystalline structure), increasing the size of the grains within the structure, and reducing stresses, resulting in a more workable material.

There are three stages to the process: recovery, recrystallization, and grain growth.

Stage 1: Recovery

The recovery stage involves heating the metal to soften it and remove dislocations and internal stresses. The process of heating provides the energy required to break bonds and increases the rate at which atoms diffuse through the solid material.

Stage 2: Recrystallization

During the recrystallization stage new “strain-free” grains will nucleate (form) and replace those deformed by dislocations and internal stresses. If the process is allowed to progress to the “grain growth” stage, the grains will continue to increase in size.

Stage 3: Grain Growth

If the annealing process continues beyond the recrystallization stage, the grain growth stage occurs. A piece of metal with large grains has higher ductility and machinability, but lower yield strength than a piece of the same material with smaller grains. The size of the resulting grains depends on both the temperature and processing time. Once the annealed metal has been worked, it is possible to increase its strength by subjecting it to other processes such as hardening and tempering.

Removing dislocations via annealing processes

When stress is applied to a metal, plastic deformation can occur, which generates defects in the crystalline structure, known as “dislocations”. The higher the number of dislocations within the material structure, and the more they move against each other, the harder the material becomes. Thus the aim of annealing is to prevent this by reducing the number of dislocations.

Annealing temperatures required for different metals

Different metals have different annealing temperatures. The table below shows examples of metals commonly used within manufacturing and jewellery making, alongside both their anneal and melting ranges.

_{*Please note that the values shown are approximate, and exact values are wholly dependent on the individual composition of the alloy.}

Annealing with Mesh Belt Furnaces

Continuous Mesh Belt Furnaces can be adapted for annealing processes under both hydrogen and inert atmospheres.

We offer custom systems with a maximum operating temperature of 1100°C, which can be designed for single or multi-zone operation.

Annealing furnaces & ovens - FAQ