Process involving heating and cooling under the controlled conditions of a material to obtain certain desirable properties is known as heat treatment.
1. Laser surface alloying
The different types of heat treatment process using laser are shown in the picture. In the process of annealing there is no zone affected by the heat and melting takes place only in the level of picometer thickness.
In hardening process there is a zone in the form of hemisphere which is affected by the heat. In this surface alloying method there is a coating of alloying or cladding materials deposited on the substrate surface.
A controlled amount of melting of work piece surface to the desired thickness using laser beam with the addition of powdered alloying elements in equal interval of time is called as laser surface alloying.
2. Laser cladding
A very thin layer of work piece melts when the beam of laser is applied on the surface. This thin layer of metal mixes with the cladding alloy and forms a metallurgical bonding in between the cladding and subtracts by freezes.
1. Using laser radiation and doing heat treatment is very fast.
2. Comparing to other heat treatment process, lasers are able to do heat treatment in a particular spot where other process are inaccessible.
3. LASER WELDING
Welding is a process of joining or combining two or more metal pieces into a single unit.
If we consider welding of two metal plates, the metal plates will be held in contact at their edges and the laser beam will be allowed to move along the line of contact of the two plates.
The laser beam will heat the edges of the two plates to their melting point and it will join them together.
1. Impurities will not be present between the joints, because it is a contact- less process.
2. Because of rapid cooling the heat affected zone is relatively small.
3. Laser welding can be done without any difficulties even in small places.
4. This welding is usually done in very high rates.
5. Even different types of metals can be welded.
6. The work piece will not get distorted, so the total amount of input is very small when compared to other welding processes.
4. LASER CUTTING
Laser cutting means evaporation or vaporization of the material at a point by focusing the laser beam.
The laser cutting setup is shown in the figure. The exothermal reaction between the metal and the gas provides the required energy for cutting. Gas jet helps in removing the vaporized materials.
The cut metal’s adjacent edges are also cooled with the help of gas jet. Hence, the gas blow reduces the requirement of laser power, it also increases the depth and speed of cutting and a high quality cut will be provided.
1. Laser cutting can be done at room temperature and pressure without preheating and vacuum condition.
2. The microstructure of surrounding layers are not affected since heat affected zone is very small.
3. High cutting speed can be obtained.