Heat treatment is a industrial and metalworking processes.
They are also used in the manufacture of many other materials. To make the materials hardened or soft. Hence process can be include hardening, strengthening, tempering, normalizing and quenching.
It has three basic steps: Heating, soaking, and cooling.
Metallic items consist of a micro structure of small crystals called “grains”. The nature of the grains is one of the most effective factors. The temperature of metals are heated, and the rate of cooling after heat treatment can change properties of metal. The most common reasons that metals undergo in heat treatment is to improve their strength, hardness, toughness, and corrosion resistance.
It is a process of heat treating. Hence is used to increase the toughness of iron. It is usually performed after hardening. To reduce some of the excess hardness, which is done by heating the metal at low temperature and then make it to cool in the air. It depends on both the specific composition of the alloy and the finished product. At low temperatures hard tools are tempered. Because springs are tempered at much high temperatures.