Which item is considered a welding defect?

• A. Slight misalignment of fit-up.
• B. Spatter and noise.
• C. Cracking caused by overheating.
• D. Porosity in the weld metal.

Answer: (D)

Gas being trapped in the molten weld as it solidifies creates pores in the weld metal. Those voids disrupt the continuity of the deposited metal, weaken the joint, and can act as starting points for cracks or fatigue failure. Porosity is a classic internal defect because it directly compromises the strength and integrity of the weld, making it the primary concern when evaluating weld quality.

Slight misalignment of fit-up is a joint preparation issue rather than a flaw inside the weld metal itself, so it’s not classified as a weld defect in the deposited metal. Spatter and noise are process or cosmetic issues on the surface, not internal weaknesses of the weld itself. Cracking caused by overheating is indeed a serious defect, but the question highlights porosity as the defect-focused weld metal imperfection often emphasized in practice, as porosity directly affects the weld’s integrity.