Do You Run 7018 On AC Or DC?

The AWS A5.1 E7018 standard explicitly states that this type of welding electrode supports both AC (alternating current) and DC (direct current, including positive and negative polarity) power modes. Most mainstream 7018 products are compatible with "AC / DC + / -" usage.
Preferred Choice in Industrial Settings
Although both AC and DC can be used with 7018 electrodes, 90% of industrial welding processes recommend using DC reverse polarity (DCEP/Reverse polarity). The main reasons include:

• Arc stability: In DCEP mode, the arc is smoother and quieter (occasionally accompanied by a slight crackling sound), making it easier to operate and suitable for both beginners and demanding industrial applications.
• Welding quality: Reverse polarity welding provides better penetration, more uniform weld bead formation, and less spatter, effectively reducing porosity and cracking defects.
• Increased efficiency: Faster deposition rate and easier control of the weld pool, especially suitable for structural welding projects.

 Applicable Scenarios for AC Power
AC power is only a backup option, mainly used in the following special circumstances:
Magnetic arc blow control: When welding magnetic metals (such as steel structures exposed to magnetic fields for extended periods), AC power can counteract the effects of magnetic arc blow through polarity reversal.
Specific equipment limitations: Some older welding equipment only supports AC output; in this case, 7018 can be used, but the welding effect is slightly inferior to that of DC mode.

The typical current ranges corresponding to different electrode diameters are as follows:

Important reminder:
7018 is a low-hydrogen welding electrode and must be stored in a strictly dry environment. If it becomes damp, it must be re-dried at 250°C for 2 hours before use; otherwise, it will increase the risk of hydrogen-induced cracking in the weld.