What type of hole defect is indicated by discoloration around the edge of the drilled hole?

Discoloration around the edge of a drilled hole typically indicates a burned or overheated surface. When drilling materials, especially metals, excessive heat can accumulate due to high friction, poor tool conditions, or incorrect feed rates. This heat can cause thermal degradation of the material, leading to discoloration, which might appear as a tint or shading around the drilled area.

The presence of this discoloration suggests that the material has been exposed to temperatures that compromise its integrity, which could affect its performance or lead to subsequent failure if not addressed. Recognizing this type of defect is crucial in aerospace assembly, as ensuring structural integrity and quality hinges on the condition of drilled holes and the absence of overheating symptoms.

Other options, while related to defects, do not correctly describe the scenario of discoloration caused by heat.