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:
- 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.