Which statement best contrasts ductile failure and brittle fracture?

• A. Ductile failure shows substantial plastic deformation and shear lips; brittle fracture occurs suddenly with little deformation
• B. Both failures show identical deformation
• C. Ductile failure occurs without deformation
• D. Brittle fracture involves extensive necking before failure

Answer: (A)

Understanding how ductile failure and brittle fracture differ in deformation and failure behavior. Ductile failure is characterized by substantial plastic deformation before rupture, including necking and the formation of shear lips as the material yields and redistributes stress. Brittle fracture, in contrast, occurs abruptly with little or no plastic deformation; cracks propagate rapidly with minimal warning. This is why the statement describing ductile failure as showing substantial plastic deformation and shear lips while brittle fracture occurs suddenly with little deformation best captures the contrast. The other ideas—identical deformation in both, ductile failure without deformation, or brittle fracture with extensive necking before failure—do not fit the observed behaviors: necking is a feature of ductile failure, not brittle, and ductile failure must involve some plastic deformation.