Lack of Sidewall Fusion

Incomplete fusion at the flank means: the weld bead only sticks superficially to the flank but is not properly fused with the base material. This usually happens when you weld too cold, travel too fast, or hold the torch incorrectly. The weld often looks good but has no real bond – the part won't hold what it promises. Make sure the flank is clean and you put enough heat in so the pool properly 'wets' and bonds with the base material. If you don't see the flank melting properly, add more heat or slow down.