What is arc strike?

• A. A deliberate arc used to start a weld.
• B. A defect caused by improper filler metal.
• C. An arc that travels under the base metal.
• D. An unintended arc on the base metal surface causing a localized burn or damage.

Answer: (D)

Arc strike is an unintended arc that touches and heats the base metal surface, leaving a localized burn or damage. It isn’t part of forming the weld bead and shows up as a small burn, crater, or discoloration on the metal away from the weld area. This happens when energy from the arc is transferred to the base metal rather than through the filler metal into the joint. It’s not a deliberate arc used to start a weld, and it’s not an arc traveling under the base metal; rather, it’s a stray arc that causes surface damage. In inspection, arc strikes are treated as surface defects that may require cleaning or rework if the damage is significant, since the heat-affected surface can alter hardness or appearance.