Which statement describes ductile fracture?

• A. Rapid fracture with no warning
• B. Slow crack propagation with warnings and cup-cone surface
• C. Cleavage along slip planes
• D. Immediate fracture after yielding

Answer: (B)

Ductile fracture is marked by substantial plastic deformation before the part breaks. After yielding, the material necks and the crack grows slowly, absorbing a lot of energy. This gradual process produces the cup-and-cone fracture surface, a telltale sign of ductile failure resulting from microvoid formation and coalescence under shear. This contrasts with brittle fracture, which happens rapidly with little or no warning and little to no necking. Surfaces described as cleavage along crystal planes align with brittle behavior, not ductile, and fracturing immediately after yielding would leave almost no plastic deformation, which isn’t how ductile failure behaves.