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Joining Materials by Welding

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One can connect parts together in different ways. Commonly this can be done by fasten them with rivets or bolts, solder or weld them together. Welding is a process that creates a continuous joint on large materials surfaces. This advantage of welding used to make boilers or other enclosed containers.

The design of joint, filler, base material and flux influence the quality of the weld. The welding method and concentration of energy input, weldability of the base material and type of the filler and flux influence the strength of weld and material. The heat-affected zone has also effect on weld quality. To test the quality of the weld either destructive or nondestructive methods are used. Gas and non-metallic inclusions, cracks, incomplete penetration, distortions, lack of fusion and lamellar tearing are common defects of welds.

Welding is a fabrication that joins materials by causing fusion, which usually melts the base material. In addition, filler materials are typically added to the joint. They form a pool of molten material that creates a joint after cooling. As a rule, a base material is not as strong as a joint. In addition, welded parts can be pressurized.

There are different ways the parts can be geometrically prepared for welding. V-butt joint, lap joint butt joint, and T-joint are the basic types of weld joints. There are many other types of joints existing. The particular joint design can be required for many welding techniques. Resistance, laser, and electron-beam welding are most frequently performed on the lap joints.

The original fusion technique is known from the earliest uses of iron. The process of joining small pieces of iron to larger ones was through heating to welding temperature and hammering or pressing together. The most common today’s welding techniques are arc welding (see also best welding caps), oxyacetylene welding, resistance, electron-beam, friction, laser welding and other. The largest total volume of welding is shielded metal-arc welding. An electric arc is created between materials leading to electrode’s metal melting and transferring it to the joint in this process. Another technique is gas (usually oxyacetylene) welding. The source of heat in this process is acetylene burned in the atmosphere of oxygen. For the resistance welding, the main source of heat is the electrical resistance of the joint. Such welds are made using low-voltage and high current power source with pressure applied. Electron-beam welding is based on a dense stream of high-velocity electrons bombarding the joint. If you use the friction of moving parts, this is called the friction welding. Laser welding is accomplished when materials are fused together by heat generated from a laser source.

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