Welding basic knowledge

In shipbuilding area,welding accounts for a large proportion.

Welding concept

Welding is the process of manufacturing non-removable structures from metals, alloys and other materials.
By hot welding it is possible to bond most metals and alloys
With any thickness. It is possible to weld metals and heterogeneous alloys.
Principle of welding: When soldering hot, the KL of the solder reaches the liquid state. The specific heat of the mixture is carried out at the edges of the grafted element. It is possible to weld by making a bundle of metallic or metallic materials and materials. The clamp, or the sheet metal, and the hot addition Kl are poured into the weld pool themselves and moistened with the solid surface of the grafting elements. By turning off the KL heater, the liquid cooled and solidified-crystallized, after the crystallization tank formed a monolithic weld with the two-component bonding structure.

II. Advantages and disadvantages of welding.


– Welding is a technology process that is widely used for fabrication and restoration of structures and details. Superiority includes:
Consume less metal, cut labor costs, get equipment, shorten production time


– In the MIG welding process or the others, it will occurs the oxidation of some elements, the absorption and dissolution of gases of the metal tank as well as changes of the heat zone influenced the heat. The results of the composition and structure of the weld differ from those of Metal. The deformation caused by residual stress can distort its size and shape and affect the durability of the joint.

III. Some concepts.

1. Arc:

– Is the discharge in the high pressure gas. It is characterized by line density
Large in conduction air and low voltage between electrodes

2. Plasma:

– In normal gas well insulation. When the source arises
Make the gas gas is the phenomenon of ion gas chemicals. If substance
The gas is heated to high temperature all the xyz ionized presents
Out simultaneously in the gas. The ionizing gas that occurs conducts electricity so-called

3. Thyritto:

– Used to stream by frequency
– Transform the alternating current into one direction

4. Inveter

– The same effect as thryrito, is the next life
– Variable current flow with frequency
– Transform the alternating current into one direction
– Aluminum welding: There are 2 modes AC, DC

IV. Classification:

*. Welding in protective gas
To receive high quality solder arc welding and hot metal zone
Not safeguard against harmful effects of air, in welding
Gas shields, arcs and hotspots are protected by gas
(Ar, He, Ar + He), not applied to metal when soldered, and gas
Active (CO2, CO2 + O2, CO2 + Ar …) works with liquid metal.
-When welding with non-hot electrodes, the arc burns between the object and the electrode
Hot, not very hot in the welding process and not go in
Weld. The arc moves along the heated weld bead
They, as they move the hot metal to hot metal, form
Welding welded joints. (Solder TIC)
– When welding with electrodes
Hot flashing arc between two consecutive electrodes is provided and the solder.
Arc heating wire and weld bead. Metal electrodes move in
Welded and formed. When the arc moves away, the cage solidifies
Solder welds the welded edges. Extremely hot wire can
Condensed, or containing alloy powder, slag and gas. Welding wire of this type
Called core or powder wire welding (MIG / MAG welding)
To save gas, the welding is performed in two separate airflows that provide focus on the arc.
The arc temperature in the soldering iron is very hot and low in temperature
5000-6500K. The arc temperature in welding electrodes is not hotter than high
much. It is low so the energy of the arc gas is reduced to one side because of
Large arc cathode, on the other hand metal wire electrode continuously transferred to the tank
Cool the arc column.

1. Welding TIC:

– The welding technology in the gas shield, using Ar gas, and not hot electrodes Vonfan.
Key features: Heat treatment of metal at the weld bead, when cold will freeze

2. MIG / MAG welding:

– welding in hot electrodes
– Use Ar + CO2,
– use the wire feeder
– Principle: Added welded wire feeder kit, together with hot-dip galvanized wire

3. CO2 welding:

– welding in hot electrodes
– Use a gas shield is CO2
– use welded wire feeder

Plasma welding technology

– The arc temperature in plasma welding is high up to 15000-200000C, unlike lakes
Optical in the free solder has an enlarged shape on the arc
In cylindrical plasma welding, it has the ability to penetrate deep into the tank
Welding, so the thick solder beads do not need to be large beveled edges
– Plasma arc welding can connect different ferrous and non-ferrous metals: aluminum and titanium alloy, low carbon steel and stainless steel, copper, brass