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Non-consumable Electrode Arc welding

As a non-consumable electrodes tungsten or carbon electrodes can be used. In gas-tungsten arc welding a tungsten electrode is used in place of the metal electrode used in shielded metal-arc welding. A chemicallyinertgas, such as argon, helium, orcarbon dioxideis used to shield the metal from oxidation. The heat from the arc formed between the electrode and the metal melts theedges of the metal. Metal for the weld may be added by placing abare wire in the arc or the point of the weld. This process can be used with nearly all metals and pro­duces a high-quality weld. However, therate of welding isconsiderably slower than in other processes.

Gas-Metal Arc

In gas-metal welding, a bare electrode is shielded from the air bysurrounding it with argon orcarbon dioxidegas and sometimes by coating the electrode with flux. The electrode isfed into the electric arc, and melts off in droplets that enter theliquid metal of the weld seam. Most metals can be joined by this process.

Submerged Arc

Submerged-arc welding is similar to gas-metal arc welding, but in this process no gas is used to shield the weld.Instead of that, the arc and tip of the wireare sub­merged beneath a layer of granular, fusible material that covers theweld seam. This process is also called electroslag welding. It is very efficient but can be used only with steels.

Resistance Welding

In resistance welding, heat is obtained from the re­sistance of metal to the flow of an electric current. Elec­trodes areclamped on each side of the parts to be welded, the parts are subjected to great pressure, and a heavy current is applied for a short period of time. The point where the two metals touch creates resistance to the flow of current. This resistance causes heat, which melts the metals and creates the weld. Resistance welding is widely employed in many fields ofsheet metal or wire manufac­turing and is often used for welds made by automaticor semi-automatic machines especially in automobile industry.

Читайте також:

1. Diffusion Welding
2. Gas Welding

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