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The process of heat treatment involves several thermal, industrial, and metal processing which is used to change the physical properties of certain materials. In some cases, heat treatment can even change the chemical properties of a material, too. Metallurgy is one of the most common applications of heat treatment. In heat treatment, materials are put under extreme conditions for manufacturing. Heating and cooling are both included in the heat treatment. Case hardening, annealing, tempering, precipitation strengthening, quenching, and normalizing are a few of the techniques in the process of heat treatment. Glass is one of the most common things which go through heat treatment.
The first exposure of heat treatment was developed in the 1950s. At that point, it was used in heat treatment furnaces, while in the 1970s it was used in vacuum furnaces. Heat treatment has been going on since the old civilizations. Even though its first proper exposure was there in the 1950s, the first working was first discovered around 1200 B.C. Louis Pasteur, a French Scientist, was the first person who paved the road for heat treatment through pasteurization.
Definition of heat treatment
Heat treatment can be referred to as the controlled process of cooling and heating of metals and altering the physical or mechanical properties, or both, without altering the product structure. Sometimes, heat treatment is done accidentally due to the processes involved in manufacturing. It can be either through welding or forming of metals. Metallic structures are formed of crystallites, which are small crystals. These crystallites form the basic changes that take place during heat treatment. Through the rate of cooling and rate of diffusion among the crystallites, the manipulation done by heat treatment takes place.
Induction Hardening
The process of induction heating a metal surface and then quenching is known as induction hardening. In simpler words, induction hardening is a type of surface hardening. The metal develops brittleness and gets hardened after undergoing a martensitic transformation, after quenching. Induction hardening is the common process of hardening the portion that the users need to harden without altering the other parts or properties of the metal. The process of electromagnetic induction is used, which follows a non-contact heating way. Induction heating was first discovered by Michael Faraday in 1831. Induction heating used nowadays uses electrical power, ranging between 1 kW to several megawatts.
Heat treatment of steel
There are four processes involved in the heat treatment of steel. They are as follows:
Annealing – Annealing is the opposite of hardening. The process of hardening involves the hardening of metal surfaces, while annealing is used as a stress reliever, softening of metals, the grain structure is improved, and the ductility increases. Inappropriate heating can sometimes cause damage to the metals causing uneven temperatures in different parts. Annealing is the one-stop solution to this problem.
Normalizing – Most of the time, metals undergo internal stresses from heat treatment, welding, forming, or casting. To overcome this problem, normalizing is used. Before any type of metal hardening, normalizing should be practiced to guarantee the success of the work.
Hardening – Lots of metal surfaces are hard, but that does not mean that it is strong. Hardening makes the metal both hard and strong. There is a certain disadvantage to hardening. Even though it makes the metal stronger, it reduces the ductility of the metal. The metal should be tempered after hardening to reduce brittleness to some extent.
Tempering – As mentioned above, after hardening, the metal may undergo a few changes. It does not matter whether it is by flame or case, the result remains the same in most situations. Internal stressing and brittleness can be avoided by tempering the steel. Tempering includes heating steel below the hardening temperature for some time, before cooling it in still air.
Benefits of heat treatment
The heat treatment offers us several benefits or advantages. The benefits are as follows:
Heat treatment can help in altering the mechanical or chemical properties of metals, which may help in the manufacturing of certain products.
Machining and welders become comparatively used by stress relieving through heat treatment.
From strengthening, flexibility, to making the metal more ductile, everything is achieved through heat treatment.
The metal is introduced to hardness either throughout the metal or just the surface of the metal.
Compatibility with other metals can be formed through magnetic and electrical properties by heat treatment.
Some of the metals are quite brittle and can break down if exposed to certain environments. To overcome this, heat treatment can be done.
Conclusion
Heat treatment is one of the most complex processes in the industrial sector. It includes several difficult processes, and all of them are sophisticated. Induction heating, heat treatment of steel, tempering heat treatment, etc., are concepts from heat treatment.
