I guess you’re talking about a fillet weld.
Welds are not commonly drawn, because they’re highly variable in appearance and are typically controlled by a weld symbol, possibly supplemented by a weld specification. A drawn weld bead is generally considered “unnecessary artistry.”
If you apply a concave curved extrusion as @wawoodman did (aside from the issues at the ends), you come up with a completrely unrealistic representation of a weld bead, which is lumpy and uneven looking–more like a series of overlapped blobs. If you take the time to model the weld bead realistically, you have invested a lot of time on a non-technical definition that gives virtually no information.
It would be much more important to first make sure its identified as a weld and secondly provide some basis for sizing the bead.