Hardening and tempering steel is done through a process of heating, quenching and reheating steel. The purpose is to increase the level of hardness and the strength of the steel.Continue Reading
Steel contains carbon, and the amount of carbon determines whether or not it can be hardened. Steel with low concentrations of carbon cannot be hardened because there is insufficient carbon to change the crystalline structure. However, high carbon steel can be hardened and tempered.
To harden the steel, the metal is heated to very high temperatures. After heating the steel higher than its critical temperature, the metal is cooled fast through a process called quenching. This involves dipping the heated metal into water, oil, or any other liquid to rapidly lower its temperature.
Since steel contains carbon along with other metals, the heating of the alloy above its critical temperature causes the carbon and the metals to go into solid solution together. When this solid solution is cooled rapidly through quenching, the solution “freezes” and preserves the micro structure obtained during the heating process, thus making the steel harder. This also makes the steel more brittle, which is why it has to be tempered to maintain the strength of the alloy.
Tempering is the process of reheating the steel to a relatively lower temperature compared to the temperature used for hardening. The reheating allows for the precipitation of the carbon in the steel. Depending on the strength desired in the final product, the temperature and duration for which the steel is tempered can be controlled.Learn more about States of Matter
Common examples of solids are wood, sand, ice, bricks and steel. Examples of liquids include water, blood, wine, coffee and rubbing alcohol. Some common gases are hydrogen, helium, propane, water vapor and gaseous nitrogen.Full Answer >
The melting point of mild steel, or low carbon steel, is usually 2,600 degrees Fahrenheit, or 1,427 degrees Celsius. Mild steel is one of the most commonly used types of industrial steel, and it consists of an alloy of steel and carbon.Full Answer >
The specific heat capacity of steel is 452 Joules per kilogram Kelvin, or 0.108 calories per gram Kelvin. This value is based on room temperature and atmospheric pressure. Specific heat capacity is defined as the heat energy needed to raise the temperature of one kilogram of a material by 1 degree Kelvin.Full Answer >
Convection does not occur in solids because the particles within are too tightly packed to facilitate the process. Convection requires actual movement between the particles within a substance in order to transfer heat which is only possible in a fluid state of matter such as liquid or gas.Full Answer >