Heat treatment is a method by which we can change the physical properties of a metal.We heat a metal above a certain critical temperature and keep for a certain time, and then allow it to cool at different rates in order to obtain the mechanical properties we required. This is called as heat treatment of steel.
Heat treatment take place during the various shaping operations. We can relieve internal stresses, refine the plasticity and cutting property, improve comprehensive mechanical property which exist in the metal.
There are four main operations in the heat treatment, as below,
1. Normalized. We heat steel above a critical temperature(30-50℃) and keep for a due time, cool it at room temperature.This is a natural cooling method.
2. Annealing. We heat the steel above the critical temperature and permit it to cool very slowly. So that it becomes softer than before, and much easier to process.
Compared with annealing,normalizing has some advantages. Not only is the cooling rate of normalizing faster than annealing, but also the lead time of normalizing is much shorter than annealing. therefore, it is very economical for us that normalizing instead of annealing when the normalizing and annealing all can reach our requirements at the same time.
3. Quenched.We heat metal up beyond the critical temperature, make it harder by rapid cooling and the quench it in water or some other liquid.This is a method which we cool the metal at the most quickly rate in all methods.The faster temperature drops, the harder metal becomes.
4. Tempered. Tempered is usually followed after quenched. Tempered together with quenched are called thermal refining. The metal which cools slowly is less liable to have internal stress than metal which cools quickly. In other words,the plasticity and mechanical properties of the metal decreases during quenching, the purpose of tempering is to eliminate internal stresses and improve its comprehensive properties.
As has been noted, our understanding of heat treatment as the above, welcome to contact and communicate with me if you are interested in our products and service.
