Heat treating is field that many of us are unfamiliar with, but it is a very important part of creating items we use every day. The process has played a part in our military, influenced industry and makes our lives easier thanks to the tools created because of this process. Altering the properties of any metal needs the application of some heat, or removal of heat using the technique of quenching. Treating the metal with heating and cooling can change the following properties to different levels :- ductility, hardness, softness, stress and tensile strength. To attain these properties, one or the other of the following treatments can be used – tempering, hardening, stress relieving, annealing, normalizing and quenching. Cooling rates from the high furnace temperature are also an important part of this type of treatment. Leaving the heat treated part in furnace to cool at a controlled rate is the slowest general cooling rate.
Generally, fast cooling involves some type of liquid and is known as Quenching. Each liquid provides a different cooling rate, so it is important that the correct quenching liquid is used to achieve proper heat treating cooling levels to avoid breaking. The other methods of cooling include forced air or gases such as nitrogen. A combination of heating and cooling operations applied to an alloy or a metal in solid state to obtain the required conditions and properties. Heating for the hot working is excluded from the meaning of definition here. The first method of the heat treating process normally suits for low carbon steel and is mainly passed on cold rolled steel such as the wire drawn steel. This method tends to improve the properties such as ductility and hardness which otherwise makes the process difficult. Heat treating a material can change the size of the crystals to grow or shrink.
Additionally, the heat treating process can cause different phases to become more common - that is, different arrangements of the molecule. Ultimately, heat treatment achieves the desired metallic characteristics by growing the different phases to required grain and concentration size. Generally, in the carbon steels, different phases are characterized by the presence and concentration of carbon. Generally, the term heat treatment is used for increasing the strength of materials like steel and alloys as it greatly affects the mechanical properties such as ductility, strength, hardness, toughness and wear resistance of the materials. Anyhow, it can also be used to change some manufacturing defects such as it can help in improving machining, improving the permeability, restoring ductility of alloys after a very difficult working procedure. So, it can be considered as a permissive manufacturing process that not only helps the other manufacturing processes, but also improves the performance of product by increasing it's strength and other required properties of the product or metal.
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