Yeswelder CT2050 Operator's Manual page 42

BASIC KNOWLEDGE OF WELDING
Since argon is a kind of inert gas and it does not react with metals, the alloying elements in the weld metal will not be burned out
and the metal molten pool can be fully protected from oxidation. Besides, because argon is insoluble in liquid metal at high tempera-
tures, air holes can be avoided in the weld bead. Therefore, the protective effect of argon is effective and reliable, and better weld-
ing quality can be obtained.
Characteristics of Argon Arc Welding
Compared with other arc welding methods, argon arc welding has the following features.
1. Argon has excellent protective performance, so corresponding flux is not needed when welding. It is basically a simple process of
metal melting and crystallization, and pure weld beads of high quality can be obtained.
2. Due to the compression and cooling effect of argon flow, the heat of the arc is concentrated at a high temperature. Therefore, the
heat-affected zone is very narrow, and there is little welding deformation stress and crack tendency. Thus, argon arc welding is es-
pecially suitable for thin plate welding.
3. Argon arc welding is a kind of open flame welding and is easy to operate and observe, so the mechanization and automation of
the welding process can be achieved easily. Besides, welding at various spatial locations can be carried out under certain condi-
tions.
4. Argon arc welding can be applied to welding a wide range of welding materials. Almost all metal materials can be welded by ar-
gon arc welding, and it is especially suitable for welding chemically active metals and alloys. Generally, it is used in the welding of
aluminum, titanium, copper, low alloy steel, stainless steel, refractory steel, etc.
With the increase in product structure of non-ferrous metals, high alloy steel, and rare metals, common gas welding methods and
arc welding methods are difficult to obtain the required welding quality. However, argon arc welding is being more and more widely
used due to its remarkable characteristics above.
Gas Tungsten Arc Welding (GTAW)
a) Welding Torch
The function of the welding torch for GTAW is to clamp the electrode, conduct current, and carry argon flow. For manual welding,
the ON/OFF button is mounted on the handle of the welding torch. Generally, welding torches can be divided into three categories,
large-type, medium-type, and small-type. For small-type welding torches, the maximum welding current is 100A. And the welding
current can reach up to 400~600A for a large-type welding torch with water cooling. The torch body is pressed from nylon, so it is
light, small-sized, insulated, and heat-resistant.
The torch nozzle plays an important part in the protective performance of argon. The common nozzle shapes are shown in Fig 18.
Cylindrical nozzle with a cone-shaped or spherical end has the best protective effect, since the argon flow speed is uniform, and lam-
inar flow is easy to hold. The protective effect of the coniform nozzle is worse because the argon flow speeds up. However, this kind
of nozzle is easy to operate and the visibility of the molten pool is good, so it is also commonly used in welding.
(1) Cylindrical nozzle with
cone-shaped end
Molten pool
Filler wire
Fig 24 Sketch Map of Argon Arc Welding
(2) Cylindrical nozzle with
spherical end
Nozzle
Tungsten electrode
Shield gas
39
Weld bead
(3) Coniform nozzle