What is Heat Treatment in Welding?

Heat treatment is a process that alters the physical and sometimes chemical properties of a material.

What is heat treatment and what is its purpose?

The most common application of heat treatment is in the manufacturing of metals and alloys, where it is used:

to change the microstructure of the material to improve its strength,
ductility,
or hardness.

Heat treatment can also be used to change the surface properties of a material, such as increasing its wear resistance or making it easier to weld.

In welding, heat treatment is often used to pre-heat or post-heat the materials being joined:

Pre-heating helps to reduce the risk of cold cracking and can also make the materials easier to weld.
Post-heating can be used to relieve weld stress and improve the properties of the weld.

Heat treatment is also used to heat treat welding consumables, such as electrodes, to improve their performance.

Which heat treatment is required after welding?

The type of heat treatment required after welding depends on the materials being welded and the application. For most ferrous metals, such as steel and cast iron, a process called annealing is often used. This involves heating the material to a high temperature and then slowly cooling it. This process relieves stress in the material and makes it more ductile.

For some applications, such as welding pressure vessels or pipelines, a process called normalizing may be used. This involves heating the material to a high temperature and then cooling it in the air. Normalizing increases the strength of the material by changing its microstructure.

Dehydrogenation heat treatment

It is a process that is used to remove hydrogen from the material. This is often done after welding to prevent hydrogen embrittlement, which can make the welded joint susceptible to failure.

Heat treatment is an important process in welding and must be carefully controlled to ensure that the desired results are achieved. Improper heat treatment can lead to problems such as:

cracking,
warping,
and loss of strength in the welded joint.

Welding heat-treated steel

Heat-treated steels are commonly used in applications where high strength and low weight are required, such as in the automotive and aerospace industries. These materials are often difficult to weld due to their high strength and low ductility.

Annealing in welding

Annealing is a heat treatment process that is used to relieve stress in the material and make it more ductile. It is often used after welding to prevent cracking and warping.