noramlizing process on heated object

What is Normalizing?

Normalizing is the process of heating ferrous or non-ferrous metals at recyclization temperature above the austenite, is stable, holding at temperature for a short period and, allowing them to cool at room temperature. Heating at recrystallization temperature forms a new grain structure in the material without any stresses. Cooling of metal at room temperature changes the microstructure to increase its ductility.

Normalizing produce microstructure consisting of ferrite and perlite for hypo-eutectic steel and perlite and cementite for hypereutectoid steels.

Steel containing 0.8% carbon is eutectoid steel. Steel containing less than 0.8% carbon is hypo eutectoid steel, and steel containing above 0.8% carbon is hypereutectoid steel. 

It is a final heat treatment process given to a product that is subject to relatively high stresses.

Read More- What is Hot Working Process?

The objective of the Normalizing

  1. Refine the grain structure of the metal or non-metal to improve the mechanical properties of the material.
  2. To remove strain caused due to cold working processes like hammering, rolling, and bending process makes the material brittle and unreliable.
  3. To remove dislocations in the internal structure of the metal or non-metal caused due to hot working process.
  4. Improve toughness and machinability of the material.
  5. Reduce hardness.

How Normalizing Process Works?

There are three stages of the normalizing process.

  • Recovery stage

In this stage, the furnace and other mediums are using to increase the temperature of the metal at recrystallization temperature. This heating reduces internal stresses.

  • Recrystallization stage

Due to the heating of metal at recrystallization temperature, it forms a new and fine grain structure.

  • Grain Growth

In this stage, fully developed new grains are cooled at room temperature to increase their ductility and reduce hardness.

What Materials Can Be Normalized?

Many materials are suitable for the normalizing process.

  1. Ferrite material alloys (stainless steel, carbon steel, and tool steel)
  2. Nickel-based alloys
  3. Aluminum
  4. Copper
  5. Brass

Benefits of Normalizing

  1. It gives a strong and uniform grain structure to improve the mechanical properties of the material.
  2. It is a less expensive process due to cooling happens at room temperature.
  3. Normalizing raises the yield point, ultimate tensile strength, and impact strength in steels. 
  4. Normalized steel is hard and strong than annealed steel for the same composition but less ductile.

Applications

Normalizing process is using in various industries like aerospace, Nuclear, Automobile, Oil & Energy, Heavy Equipment, Agriculture, etc.