In submerged arc welding process (SAW welding process), there are various parameters that determine the quality of weld.
The quality of weld depends upon the type of flux used, grade of electrode wire, as well as few other parameters.
To get the perfect weld using submerged arc welding, following parameters are necessary to control.
Submerged Arc Welding Parameters
There are 5 main parameters of Submerged Arc Welding that decides the quality of the weld.
Let’s discuss each of these parameters one by one.
#1) Welding current
Welding current controls the melting of the electrode. If the welding current is more, then the melting of electrode will be more.
And if the melting rate is more, the metal deposition rate will also be more.
Hence welding current determines the rate of metal deposition.
- If the welding current is very high, then it will cause excessive weld reinforcement. It also produces a high narrow bead and undercut.
- If the welding current is very low, then it will give an unstable arc which leads to incomplete penetration of the weld.
#2) Arc voltage
Generally the arc voltage does not affect the melting of electrode, but it determines the profile and appearance of the weld bead.
- If the arc voltage is higher, then it will create a wider weld bead and the weld penetration also decreases.
- If the arc voltage is reduced little bit, then it produces a stiffer arc which penetrates deep in the weld groove.
- If the arc voltage is very low, then it will produce a narrow bead with poor slag.
#3) Arc travel speed
- For a particular current and voltage settings, if the arc travel speed is increased, then the penetration reduces, weld reinforcement reduces as well as it also lowers the heat input per unit length of weld.
- If the arc travel speed is decreased, the weld penetration as well as weld reinforcement increases.
#4) Electrode size
In Submerged Arc Welding, the size of electrode is selected on the basis of metal thickness as well as size of weld.
To get deeper penetration and higher deposition rate, larger size electrodes are used with higher current.
#5) Heat input rate
Heat input rate (also known as arc energy) is calculated by following formula;
Heat input rate (HIR) = (V×A×time) / (S×1000)
V = arc voltage
A = current
S = distance travelled
- If the heat input rate is higher, then the cooling rate of parent metal and HAZ will be lower.
- And if the heat input rate is lower, then the cooling rate of parent metal and HAZ will be higher.
Heat input rate is a very important parameter for Submerged Arc Welding that determines the microstructure of the weld metal.