Notch along the toe where the arc melted base metal that weld metal did not refill, usually from too much current, too long an arc, a poor angle or too fast travel. It thins the section and creates a sharp stress raiser, so codes limit its depth, commonly to about 1/32 inch on statically loaded structures and less on cyclically loaded work. Repairs usually add a small stringer bead along the toe.
Inspector flagged undercut on the top toe of every horizontal fillet, drop your amps and slow your travel.
In thermal spray and machine shops an undercut is a groove cut on purpose; in welding it is always a flaw to be measured.
Also heard as
- undercutting
Related terms
Toe
The edge of a weld bead, where weld metal blends into the surface of the base metal.
Cap
Shop word for the final layer of passes on the face of a groove weld, the cover pass in code language.
Fillet weld
Weld with a triangular profile laid in the corner where two members meet, the usual weld on T, lap and corner joints.
Discontinuity
Any break in the normal makeup of a weld, such as a pore or inclusion, that becomes a defect only when it exceeds code limits.
Same word, different worlds
A recess deliberately machined below finished size so the coating can fill it to full thickness.
Gear EngineeringA notch cut into the base of small-pinion teeth when the generating tool removes part of the working involute.
GeosyntheticsDigging out soft or unsuitable subgrade below grade and replacing it with better fill.