Welding is one of the methods of connecting materials (metal, non-metal, composite, etc.) to each other. two pieces are placed together; They heat them until they melt. After cooling and taking the slag, the parts are welded together. Welding is very different from soldering (both hard soldering and soft soldering). In connecting materials with the help of welding, the base material melts due to high heat; But in soldering, there is no melting of the base metal. Also, in the method of joining with the help of welding, a material called "filler" is used to create molten material. After cooling the weld and removing the slag, you will have a stronger joint than the base metal joint. In welding, in addition to heat, we also need pressure in special conditions. To generate heat, we can use gas flame, electric arc, friction, ultrasound waves, etc. Welding occurs in various industrial environments; For example, underwater, outside the atmosphere, etc. While doing this, try to observe all safety precautions.
Arc in welding
Electric current arises from the flow of electrons in a conductive body. Whenever there is a gap consisting of air (gas) in this path, the artery and the transfer of electrons will stop for a moment, as a result, the electric current will be zero. If the air gap is very narrow; The potential difference and high current intensity cause the gases present in the gap to ionize and the electric arc process occurs. This process is used to generate the necessary energy to melt the electrode. Arc welding methods include: welding with a covered manual electrode, sub-powder welding, welding with shielding gas (argon welding), welding with shielding gas and tungsten electrode, and plasma welding.
Resistive welding processes
In this type, a high electric current passes through the object, and heat is generated due to the electrical resistance and the force applied from the side of the copper rods. When a current of about 1000 to 10000 amperes passes through the metal, a small chamber of melt is formed at the boiling point. This method has very little pollution and is very practical. On the other hand, the application of this type of welding is very limited. Also, the cost of preparing tools for this method is very high. Resistance welding methods include spot welding, seam welding, butt welding and welding using a template.
Solid state welding process
In this process, there is no melting of materials and the materials are connected to each other under pressure and heat (sometimes without heat). The processes of this method include: friction welding, penetration welding and welding with the help of ultrasonic waves. Friction welding: In this method, mechanical energy (friction) is used to generate heat. Also, one of the parts is rotating at high speed and the other part is fixed. Now, this part is being called to another part. The friction created between these two parts causes high heat in the connection area. In this step, two pieces are connected to each other under pressure. Penetration welding and ultrasonic welding (welding with the help of ultrasound waves) are among the solid state welding processes.
Gas welding process In this type, welding is done with the help of different gases such as acetylene, propane, etc. This work is usually done with the help of special lasers (carbon dioxide). Also, be careful that the energy of the beam is not too high because it destroys the metal. Welding with the help of electron beam
In this method, electrons are accelerated with the help of high voltage and are thrown out in the form of very narrow beams. The high energy density in the welded area makes the welding quality very favorable. This method is used in the construction of fighter bodies.
