What is meaning of Under Cut in Welding? |

What is meaning of Under Cut in Welding?

  1. UNDER CUT –

 “A defect that appears as a groove formed in the BM adjacent to the toe of a weld along the edge of the weld & left unfilled by the weld metal”.



  • Generally located parallel to the junction of weld metal & base metal at the toe or root of the weld
  • Reduces the cross-sectional thickness of the base metal
  • Acts as stress raiser in fatigue loading

Cause and prevention of undercut:

Cause – 

  • High welding current & arc voltage
  • Too large electrode dia
  • Incorrect electrode angle
  • Longer arc length


  • Use prescribed welding current for electrode size.
  • Adjust electrode angle to fill undercut area.
  • Correct travel speed, arc length, etc.


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