Shielded Metal Arc Welding - SMAW welding process and SMAW electrode specification

Submitted by engineer on Mon, 02/15/2021 - 20:58
SMAW electrodes

 

 

 

 

 

The SMAW welding process (Shielded Metal Arc Welding) which is also called Electric Arc Welding is a welding process that uses heat to melt the base material or the parent metal and electrodes (filler material). The heat is generated by a jump of electric ions that occur between the cathode and anode (the tip of the electrode and the surface of the plate to be welded). The amount of heat generated from this jump of electric ions can reach 4,000 degrees C to 4,500 degrees C. There are two kinds of voltage sources used in SMAW welding, namely AC (alternating current) and DC (Direct Current).

SMAW electrode


The process of this welding occurs due to contact between the tip of the electrode and the base material so that a short circuit occurs, when the short circuit occurs, the welder must pull the electrode so that an electric arc is formed, namely a jump of ions which causes heat. The heat will melt the electrode and the base material so that the electrode fluid and the base material fluid will unite to form the weld metal. The amount of electric current for welding depends on the diameter and the variety of welding electrodes. The following table shows the welding amperage for various sizes of electrode diameters and several types of electrodes.

SMAW Electrode specification

When welding takes place, the weld is a metal that melts when it comes in contact with the surrounding air, so the oxygen and nitrogen present in the air will react with the molten metal. This oxidation reaction can cause the quality of the weld to decrease, namely the presence of air voids in the weld or the occurrence of porous joints. In electric arc welding, to avoid the occurrence of porous joints and to strengthen the quality of the welded joints, various ways are sought to protect the weld from the influence of the air or the atmosphere, namely by using welding slag as a protection or using additional materials / electrodes that are filmed / wrapped. made of materials that can protect the weld from the influence of the atmosphere.

Mild steel and low alloy steel electrodes for electric arc welding according to the AWS (American Welding Society) clarification are indicated by the mark EXXXX which means as follows. E represents the electrode,  XX (two numbers) after E represents the tensile strength of the weld deposit in thousands of lb / 𝑖𝑛2, see the following table:

SMAW electrode tensile strength


X (third number) represents the welding position.
a. Number 1 for all-position welding ( flat, overhead, vertical, horizontal )
b. Number 2 for welding position : flat and horizontal only

X (fourth number) states the type of coating and the type of current suitable for welding, see the following table:

SMAW electrode coating specification

 

for example, the SMAW electrode specification E6013 means:
a. 60 - the minimum tensile strength of the weld deposit is 60,000 lb / 𝑖𝑛2 or 42 Kg / 𝑚𝑚2
b. 1 - can be used for welding in all positions
c. 3 - type of electrode coating is Titania potassium and welding with AC or DC (+) or DC (-)

another example, the SMAW electrode specification E7018 means:
a. 70 - the minimum tensile strength of the weld deposit is 70,000 lb / 𝑖𝑛2 or 49 Kg / 𝑚𝑚2
b. 1 - can be used for welding in all positions
c. 8 - type of electrode coating is iron powder low hydrogen and welding with AC or DC (+).

your turn, what is the meaning of E8012?