Bursts, laps, and cracks are discontinuities found in which category of manufactured parts?

• A. Castings
• B. Welds
• C. Forgings
• D. Extrusions

Answer: (C)

Discontinuities like bursts, laps, and cracks come from how metal behaves under forging. In forging, metal is forced to flow and fill die cavities under high pressure and temperature. If gas or inclusions are trapped and the metal is squeezed too hard, surface ruptures can occur, called bursts. As metal flows, it can fail to fill smoothly and fold over itself, producing a lap — an overlapping seam that weakens the piece. If the deformation and cooling aren’t controlled, residual stresses and brittle behavior can cause cracks to form. These flaw types are characteristic of forging processes, reflecting problems with metal flow, pressure, and heat during deformation.