Shielded Metal Arc Welding (SMAW)

Shielded Metal Arc Welding (SMAW)

Date 06/05/2019

Welding rods are the method of applying heat energy generated by arc welding between the coated electrode and the welding surface. The lagoon is formed from a part of the base metal and the embankment will solidify to form the weld.

Characteristics:

The whole process is done manually so it requires high skill of the welder.

The advantages of the method are simple, flexible and versatile and can be welded on most metals so this is a widely applicable method.

The weld metal process is performed through the addition of solder elements so it is very effective in the welding, surface repair and surface welding.

Equipment and consumables are cheaper than other welding methods.

Versatile - a wide variety of welding rods that meet requirements from simple to complex.

Mobility, less dependent on weather, easy to deploy on the site, where the wind is still weld.

Disadvantages:

Requires high skill of the welder. Welder must be trained and tested regularly. Low productivity. The possibility of other welding defects is high. Low welding efficiency due to time consuming guan sticks, slag, weld clean.

Factors influencing the shielded welding method

Welding power: can be AC or DC source with constant CC characteristics.
Welding Coatings: it has an important impact on weld quality:
-Create an atmosphere that protects the lagoon

-Maintain a steady burning of arc welding

-Supply welding alloys

-Cover, protect and help the solidified lattice to cool properly

Most carbon steel and low alloy steel use the same cores. Based on the type of wrapper, the mechanical properties and welding characteristics will be different.
The role of shielded welding coating:
Protection: Generate gas (CO2) and slag cover and metal droplets shift.
Deoxidizing: Slag has the effect of reducing the oxide through oxidation-reduction, whereby the weld metal is refined.
Metallisation: The ferro-metal components in the solding will enhance the mechanics of the alloy and prevent adverse effects when the solder metal is heated and freeze-dried.
Insulation: Weld slag after coagulation will cover the weld and act as a heat-shrink layer to control the curing and cooling speed of the weld.
Characteristics of groups of welding rods
Technological features

AWS electrodes specification


Read the stick symbol



AWS Badge Rules



Low alloy steel welding rod E 8018 - B1



Grouping of welding rods F No



OCV & VI characteristics of the welding machine

Experience calculating welding parameters:

A = 15 ÷ 20V

B = 15.7 V / cm

Ignore the last limit, then:

Uh = 20 + 15.7Lh

Example:

Ф 3.2 then Lh = 3.2 mm

Uh = 20 +15.7 x 0.32 = 25V

Ih = 5V / 0.04 = 125A

Polar solder



Welding properties

Weldability is the ability to successfully weld easily or difficultly.

Welded joints are not cracked, ensure mechanical, minimum hnaf defects.

Factors influencing welding properties: Weld configuration; Chemical base material; Accessibility (sanitation / observation / repair).

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