Many welding beginners asks what is the right current, do you know the triangle relationship between welding current, voltage and base metal? Let's explore together today: For beginners, all beginners know the welding current should be higher as the welding rods dia. get bigger. For welding pros, the welding pros knows from experience that the right current is decided by welding rods dia., weld piece thickness, welding position and layers of welding.
① what is the reference current range for welding rods dia. & base metal thickness?
Here comes the standards:
Notes: above are guide values, they can be different according to different welding process and welder’s habit
Relationship between welding rods dia. and welding current 
Notes: above are guide values, they can be different according to different welding process and welder’s habit
And here is an example:
Qustion: To weld 5mm thickness low carbon steel (ASTM 36 for example), what should be the correct welding parameters?
Answer: According to the relationship between weld piece thickness & welding rods dia., 3.2mm welding rods will match with 5mm weld piece.
According to the relationship between welding rods dia. & welding current, 100-130A will be suitable for 3.2mm welding rods.
But they are not always right in common practice as we also need to consider some other factors:
②Welding positions
- In flat welding, higher current can be chosen
- In horizontal / vertical / overhead position welding, the current should be lower
- In fillet welding, the current should be higher
③Layers & passes of welding
- In root welding, especial one-side welding with back formation, we should use lower welding current
- In filling welding passes, higher welding current can be chosen for higher efficiency
- In cosmetic welding, lower current should be chosen to achieve better bead and prevent undercut.