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Types of welds



TIG Welding

TIG Welding Principle

TIG welding means Tungsten Inert Gas welding is the special designed welding system. In arc welding we have seen coated electrodes are used, a protective enveloped gases formed around the weld zone from attack the atmosphere oxygen and nitrogen . In the TIG welding there inert gasses are used . The arc is maintained between the tip of tungsten which worked as a electrode and work piece. A special type electrode holder is made for the inert gases spread on the weld bid concentrically. The tungsten non-consumable electrodes  are used for tig weld. The filler rod is additionally added to the weld joint.

In this process Alternating current (AC) or Direct Current (DC) may be used, which depends upon the type of metal to be welded. The Direct Current with straight polarity is used for welding copper or its alloys, stainless steel and reverse polarity used for magnesium. The Alternating Current or AC is used for welding steel, cast iron, aluminium and magnesium. This Tungsten Inert Gas or TIG weld is best suited for the thin cross-section metals. It may be operated in

manual or automatic controlling system. This welding process can be used for continuous, spot or intermittent weld joints. This method is suitable of most metals and alloys except lead and zinc, because due to their lower melting point temperature, they are vaporized early and make dull the electrode. It has specific welding metals to be welded like– copper alloys, aluminium alloys, magnesium alloys, nickel alloys, zirconium alloys, beryllium alloys, titanium alloys, carbon steels, alloy steels, stainless steels and refractory metals.

TIG Welding Image

The inert gas for TIG welding:

Helium and Argon gas is most suitable gas for TIG welding. Argon has much use in this welding than Helium. Both are color and odor less gas. Helium is the very light gas and its atomic weight is 4 and its melting point is –2720C. This is lowest of all known melting temperature substance. It is mostly found only in USA in concentration only 2%. It reduced the weld temperature, so minimizing the distortion as well as facilitating penetration. The helium gas shielded the welded zone as well as refined the grain structure. The only disadvantage is due to its lightness properties  the much amount of gas is required to complete the welding and outside of United States its cost is very high, so it not easily available.

The atomic weight of Argon is 39.94 and melting point is –1880C. The density is 10 times more than Helium. It is comparatively easily obtained from air and liquefied it then distilled. It has better electrical properties than Helium. It produced stable arc when using alternating current due to lower ionization voltage.

Applications of TIG welding:

1. Welding the sheet and thinner section metals.

2. Space ship vehicles motor chamber welding.

3. It can be weld the copper, aluminum, nickel and their alloys, zirconium, titanium etc.

4. Weld the bellows, instruments diaphragms, transistor cases joints.

5. Precision instrument weld by TIG welding process.

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TIG Welding Principle