What type of defect can be identified during a visual inspection of welds?

A visual inspection of welds is primarily focused on identifying defects that are apparent to the naked eye. Cracks and porosity are defects that can be easily detected just by observing the weld surface.

Cracks are visible discontinuities that can appear on the surface of the weld bead, which may indicate structural problems or a failure in the welding process. Porosity refers to small holes or voids within the weld metal that may occur due to trapped gases. Both of these defects can compromise the integrity of the weld and affect the overall performance of the welded joint.

Though color variations, thickness discrepancies, and alignment issues can also be assessed during visual inspections, they do not specifically fall under the category of defects that impact the mechanical properties of the weld as directly as cracks and porosity do. Color variations may indicate changes in temperature or material but do not always signify a defect. Thickness discrepancies can be identified, but they typically require precise measurements rather than a visual inspection. Alignment issues may also be noticed, but they relate more to the fit-up of the pieces being welded rather than the quality of the weld itself. Thus, identifying cracks and porosity is the strongest focus of a visual inspection, making this the correct choice.