Gas tungsten arc welding is an arc welding process that uses a
nonconsumable tungsten electrode to produce the weld. The weld area
is
protected from atmospheric contamination by a shielding gas (usually
an inert gas such as argon), and a filler metal is normally used,
though some welds, known as autogenous welds, do not require it. A
constant-current welding power supply produces energy which is
conducted across the arc through a column of highly ionized gas and
metal vapors known as a plasma. GTAW is most commonly used to weld
thin sections of stainless steel and light metals such as aluminum,
magnesium, and copper alloys. The process grants the operator
greater
control over the weld than competing procedures such as shielded
metal
arc welding and gas metal arc welding, allowing for stronger, higher
quality welds. However, GTAW is comparatively more complex and
difficult to master, and furthermore, it is significantly slower than
most other welding techniques. A related process, plasma arc
welding,
uses a slightly different welding torch to create a more focused
welding arc and as a result is often automated.
Read the rest of this article:
http://en.wikipedia.org/wiki/Gas_tungsten_arc_welding
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Today's selected anniversaries:
105 BC:
The Cimbri and the Teutons inflicted a major defeat on the Roman
Republic in the Battle of Arausio.
(
http://en.wikipedia.org/wiki/Battle_of_Arausio)
1927:
The first successful talking movie The Jazz Singer, starring Al
Jolson, was released.
(
http://en.wikipedia.org/wiki/The_Jazz_Singer_(1927_film))
1976:
Premier Hua Guofeng ordered the arrest of the Gang of Four and their
associates, putting an end to the Cultural Revolution in China.
(
http://en.wikipedia.org/wiki/Gang_of_Four_(China))
1981:
Egyptian President Mohamed Anwar el-Sadat was assassinated while
attending a parade in Cairo to mark the eighth anniversary of the
Crossing of the Bar Lev Line at the start of the 1973 Arab-Israeli
War.
(
http://en.wikipedia.org/wiki/Anwar_Sadat)
1995:
An article in the journal Nature reported the discovery of a planet
orbiting 51 Pegasi as the first known extrasolar planet around a
main-sequence star.
(
http://en.wikipedia.org/wiki/51_Pegasi)
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Wikiquote of the day:
Behold, we know not anything; I can but trust that good shall fall At
last — far off — at last, to all, And every winter change to spring.
So runs my dream; but what am I? An infant crying in the night; An
infant crying for the light, And with no language but a cry. --
Alfred, Lord Tennyson
(
http://en.wikiquote.org/wiki/Alfred_Tennyson)