How to harden steel?
What is steel?
Steel is hardened by a repeated process of heating, quenching and cleaning. If you repeat the process many times, you can harden the steel. The number of times you repeat the process, the more will be the hardened of the steel.
Steel is basically an alloy of iron which is used in construction activities, manufacturing of metal tools, making knives, type of nuts and many more.
First, while selecting the steel, make sure that you have the steel with more carbon content. Diamonds are caused due to the high pressure from the ground we stand on and high heat present in the earth. The combination of both high pressure and high temperature causes the carbon content materials like coal and graphite to convert into diamond. Make sure that you select the steel which has the carbon capacity of more than 1% (more than 0.6% or higher is enough).
Steels are classified into three types depending on the carbon content present. They are as follows-
1. High-carbon steel
2. Medium-carbon steel
3. Mild-carbon steel
If the carbon content is more than 0.6 %, it is known as High-carbon steel.
If the carbon content is in between 0.4 % to 0.55 %, it is known as Medium-carbon steel.
If the carbon content is less than 0.4 %, it is known as Mild-carbon steel.
All the steels can be used for hardening, but must be coated with other materials and this process is known as hardening.
Heating the steel slowly makes the initial step. Make sure to heat every other piece of steel part and after it gets enough heat, concentrate the heat where the steel need to be hardened. You need to heat until the maximum heat is applied from your side, i.e., even until the steel turns to glowing red in color.
After heating the steel, do not make it to cool down by air. Bring it to a liquid or gas which rapidly cools the heat of the steel. Normal cooling of hot steel does not affect the steel to be hardened or softened. Always remember to cool the hot metal as quickly as you can. Oil can be used to cool down the temperature of the steel and the commonly used oils are vegetable oil, cotton seed oil, whale oil and many more. Never agitate to create bubbles. When bubbles are created, the place near the bubble gets softened. Even when the bubbles appear, slow down the process of cooling so that air bubbles does not form. The process of cooling down the hot steel by using a liquid or oil or gas is known as Quenching. Salt water is preferred when compared to normal water for quenching of hot red steel.
After the quenching of steel, if the metal is quenched with oil or any other type of fluid, we need to clean the metal with water so that complete dust gets removed from the metal. If the metal is quenched with water itself, just clean the steel with an emery cloth or with a light abrasive so that any dust particles attached to it gets removed.
Heating, cooling and cleaning can be applied in small amounts to harden the steel. All these steps can be repeated so as to harden the steel as much as we can.