Some common types of weld defects:

• Incomplete fusion
• Incomplete penetration
• Porosity
• Slag inclusion
• Lack of sidewall fusion
• Undercut
• Overlap
• Cold lap
• Hot lap
• Inadequate reinforcement
• Lack of fusion at the root
• Excessive penetration
• Cracks
• Distortion
• Warping
• Buckling
• Shrinkage
• Spatter
• Blisters
• Burn-through
• Tungsten inclusions
• Solidification cracking
• Hydrogen cracking
• Stress corrosion cracking
• Fatigue cracking
• Creep
• Brittle fracture
• Ductile fracture
• Corrosion
• Erosion
• Cavitation
• Hydrogen damage
• Intergranular corrosion
• Erosion-corrosion
• Galvanic corrosion
• Microbiologically influenced corrosion
• Environmental cracking
• Impact damage
• Chemical attack
• Deformation
• Dimensional inaccuracies
• Misalignment
• Misorientation
• Poor fit-up
• Poor profile
• Inconsistent weld size
• Inconsistent weld shape
• Inconsistent weld spacing
• Inconsistent weld penetration
• Inconsistent weld reinforcement
• Inconsistent weld finish
• Inconsistent weld quality.