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Need for Heat Treatment - Part 1

written by: kkaarthic • edited by: Lamar Stonecypher • updated: 12/14/2008

This is the first in series of articles dealing with heat treatment of steels. The basics for the requirement of heat treatment in steels, the advantages derived from doing so are discussed in this article.

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    Steel, the wonder material in the life of mankind. Just look around and you will feel that you have been engulfed by this material. From the safety pin we use, the cars we drive, the airplanes we travel in to the latest space station hovering above the earth, everything has steel in it.

    We use this material a lot, abuse it to, yet it tends to serve the purpose it has been meant for. In application, steel is various forms and shapes are subjected to wear and tear, bending, twisting, impact and shock loadings. Whatever be the application, the material steel has no comparison.

    Well all steels we look at are somewhat similar chemically, but tend to vary in their mechanical properties. All the steel coming of the steel mills may or may not have the desired mechanical properties i.e. tensile strength, corrosion resistance, etc. So how are the various properties induced in Steel? There are two methodologies

    1. By adding chemical elements to the steel which tend to improve the properties of steel directly.

    2. By adding chemical elements to the steel which tend to improve the properties of steel when they are heat treated.

    Improvement of the properties of steel by heat treatment of steel clearly stands above the rest in enhancing the properties of steel. The basic heat treatment process of steel involves the following procedure normally.

    1. Heating of the material to the specific temperature.

    2. Maintaining the material at the specific temperature until the microstructure of the material becomes uniform throughout the material.

    3. Cooling the material at a particular rate so that a required microstructure of the material can be formed.

    The properties in steel are basically altered due to the change in microstructure of the steel. Further the microstructure of the steel depends basically on the following constituents of the steel

    · Carbon content of the steel

    · Heat treatment temperature maintained for the material.

    · The rate of heating or cooling the material.

    We will look into the other aspects and methodologies of the heat treatment of steel in the forthcoming articles.