It's not really welding since the base metal is not melted, more
soldering. The tensile strength of the joint is not very high. I.e.,
don't count on it holding 2 pieces in tension together. But it is good
for filling in. E.g., a hole that's been wallowed out can be filled and
redrilled (and tapped). It's best used on aluminum, using it on pot
metal is tricky since the melting points are so close. You can wind up
making a puddle out the part that you are trying to fix.

Bob