#weld defects

Burn through and melt through occur when a welder melts through the metal they are trying to weld. Burn through creates an unsightly hole or gap. Melt through causes a raised area along the back of the material being welded. Both defects are particularly troublesome with sheet metal and thin plates. It is generally a result of too much penetration caused by having too much heat input in the weld zone. This problem can be corrected, with MIG, by reducing the wire-feed speed, which, in turn lowers the welding amperage. Travel speed may also be increased. Excessive penetration often causes burn through. While melt through is not necessarily bad, it is unsightly and the welded part may be rejected.

As stick process (also named as shield metal arc welding), is used where an arc is produced between piece and coated electrode. There may be possibility of several weld defects like: partial point penetration, undercuts, crater cracks, inclusion of slag, hydrogen induced cracking due to incorrect usage of stick rods. In order to avoid this re qualify the welders and build up are the common practices to make completely fused welds. 

Like other joint types, there are also some critical weld defects that ought to be avoid in case of T-joints. Common weld imperfections are lack of fusion, blow holes, burn through etc.