Welding Processes

Gas metal-arc welding (GMAW) also called as metal inert-gas (MIG) welding, In Gas metal-arc welding process the weld area is shielded by an effectively inert atmosphere of argon, helium, carbon dioxide or various other gas mixtures. The consumable bare wire is fed automatically through a nozzle into the weld arc by a wire-feed drive motor. In addition to using inert…

In Submerged-arc Welding (SAW), the weld arc is shielded by a granular flux consisting of lime, silica, manganese oxide, calcium fluoride and other compounds. The flux is fed into the weld zone from a hopper by gravity flow through a nozzle. The thick layer of flux completely covers the molten metal. Covered flux prevents spatter and sparks…

Brazing: Brazing is a metal joining processes, which is done by using the filler metal. It is heated above the melting point and distributed between two or more fitting parts by capillary action. Types of brazing: Torch brazing: In this technique filler material is melted by using oxyacetylene flame Dip Brazing: By creating molten liquid bath of…

Shielded metal arc welding (SMAW), also known as manual metal arc (MMA) welding or informally as stick welding, is a manual arc welding process that uses a consumable electrode coated in flux to lay the weld. An electric current, in the form of either alternating current or direct current from a welding power supply, is used to form an electric arc between the electrode and the metals to be…

Defects in welding joints can be classified into two types as external and internal defects. ·         External Defects in Welding ·         Internal Defects in Welding   1. External Defects in welding: External defects of welding includes overlap, undercut, spatter, crater, excessive convexity, excessive concavity, surface porosity, surface cracks. 1.1 Overlap: Reasons: §  Magnetic arc  blow. §  Excessive size of electrodes….

Electrogas welding (EGW) is an vertical positioned arc welding process, is used for welding the edges of sections vertically and in one pass with the pieces placed edge to edge (butt joint). It is classified as a machine-welding process, because for its operation requires special equipment. The weld metal is deposited into a weld cavity between the two…

The flux-cored arc welding process is shown in image below is similar to Gas Metal-arc Welding, except that the electrode is tubular in shape and is filled with flux. Cored electrodes produce a more stable arc, improve weld contour and produce better mechanical properties of the weld metal. The flux in these electrodes is much more flexible…

In Plasma-arc Welding (PAW) is an arc welding process, a concentrated plasma arc is produced and directed towards the weld area. The arc is stable and reaches temperatures as high as 33,000°C. A plasma is an ionised very hot gas composed of nearly same numbers of electrons and ions. The plasma starts between the tungsten…

Electroslag welding (ESW) applications are similar to electrogas welding. The main difference is that the arc is started between the electrode tip and the bottom of the part to be welded. Flux is added, which then melts by the heat of the arc. After the molten slag reaches the tip of the electrode, the arc is extinguished. Heat is produced continuously…

Gas Tungsten-arc Welding (GTAW) formerly known as TIG (Tungsten Inert Gas) welding, the filler metal is supplied from a filler wire as shown in the figure below. The tungsten electrode is not used during this welding operation, a constant and stable arc gap is maintained at a constant current level. The filler metals are similar to the…