The method of heating materials such as glass slows, and metal is known as tempering. In case of metals, this process is carried out to harden the metal and to modify brittle bainite or martensite to a mixture of cementite and ferrite.
Precipitation hardening alloys such as aluminum super alloys and inter metallic particles that harden the metal. Tempering is done by a regulated reheating of temperature to maintain under critical temperature.
Temperer
Characteristics of Process
The features of process are follows.
• This method enhances toughness and ductility
• It reduces cracking and improves machinability
• Improves impact resistance and malleability
• And, decreases hardness
Working of a Temperer
The working procedure includes Quenching and Austenizing, and tempering the steel. Let us discuss the working procedure briefly.
Quenching and Austenizing
Austenizing
The first step in process is austenizing. In this step, steel is heated at 1,200 degrees Fahrenheit to make a solid mixture of iron and carbon. This process takes place due to chemical modifications happening in the steel alloy at a high temperature. Once the steel is austenized, it should be quenched for next modification. Due to quenching, the metal cools very quickly and hardens due to its crystalline structure. Once the crystalline quality is achieved in the steel, the major tempering process will start.
Tempering the steel
After the process of austenizing and quenching, a crystalline structure in the steel will be created. Then the steel has to be heated again to tamper it. The metal can be tampered in two temperature ranges-
a. 700 to 1,200 degrees Fahrenheit, and
b. 300 to 500 degrees Fahrenheit.
c.
Generally, the range among 500 and 700 degrees is avoided, as this generates more brittle metal. The steel is subjected to tempering temperature to permit the carbon within the metal to break down a little, scattering the crystalline structure of the steel so that it may be reinforced later.
Some metals are quenched and tempered multiple times, utilizing various temperature ranges to guide the steel to the precise toughness for its further use. The steel is austenized again and permitted to cool very slowly before being quenched to generate certain types of tempered steel. Care should be taken when the steel is subjected to austenizing or tempering to avoid brittleness of steel.
Chocolate Tempering
With the help of tampering, chocolate is prepared by using micro oven. To take a look at visual demonstration, see this video clip: