Difference between AC and DC welding sets

May 5, 2021

AC and DC welding are arc welding types which use different currents to create an electric arc. Such kind of welding include the production of an electric arc between the metal you are welding and electrode. The arc produces heat to fuse the metal. A power supply is used to create the arc which can use a DC or an AC. The selection of power source chooses the electrical current polarity running through the electrode.

Choosing the right electrode polarity affects your weld’s quality and strength. Commonly called straight or reverse, these two kinds of current flow are also known as electrode positive and electrode negative. The AC polarity flows in one direction for some time and then in the other direction while the DC polarity is fixed.

DC Welding

Direct current is a current with fixed polarity flow in one direction. The current can be positive or negative. With DC welding, because the magnetic field and arc current as fixed, stable arcs are generated.


  • Smooth welding results in comparison to AC welding
  • Much stable arc
  • Low spatter
  • The negative of DC produces quicker deposition rates when welding thin sheet metals.
  • DC positive offers better penetration in the welding metal.


  • It cannot fix arc blow issues.
  • Equipment is costlier as DC currents need internal transformer to switch the current.


DC welding is suggested to join thinner metals and also used for sticking welding applications. It is recommended for overhead and vertical applications.

AC Welding

Alternate current is a current which changes its direction several times per second. A 60-hertz current can be seen changing its polarity 120 times per second.


  • The AC between positive and negative polarity permits to create a more stable arc for welding magnetic items.
  • Allows efficient aluminum welding
  • These welding machines are easy on pocket in comparison to DC machines.


  • Highly spatter
  • Weld quality isn’t as smooth as DC machine
  • Less reliable and tougher to handle in comparison to DC machines.


When using AC positive, it allows removal of oxide from metallic surfaces and hence it is recommended for welding aluminum.

It also majorly used in ship building especially for seam welds as it has the power to set the current more than DC. AC welding is very useful in down hand heavy plate welding.

Another major use of AC welding is that it can be used with metals which are magnetized, proving helpful in repairing machinery.

With the difference between AC and DC welding sets getting clear from above information, now you can finally pick the one feasible for you. No matter you are looking for an AC welding set or DC welding set, you can buy all types of welding sets online at Grey Eagle. Place your order for the best welding machine and use them for desired task at the best possible prices. For any further help or information on the welding machine sets, you can discuss with the customer support team. So, order now!


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Thomas P
I believe in making the impossible possible because there’s no fun in giving up. Travel, design, fashion and current trends in the field of industrial construction are topics that I enjoy writing about.


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