Which visual sign does brittle fracture lack?

Which visual sign does brittle fracture lack?

• A. Necking
• B. Ductility
• C. Shear lips
• D. Dimpled surface

Answer: (C)

Visual signs reveal how the material failed. Brittle fracture happens with almost no plastic deformation, so you typically see a flat fracture surface, sometimes with cleavage facets, and little to no signs of ductile flow. Features that come from plastic deformation, like necking before fracture and a dimpled surface from microvoid coalescence, point to ductile behavior. Shear lips are a feature formed by plastic shear around the crack in ductile fracture. Because brittle fracture lacks this plastic flow, you wouldn’t see a shear lip there. So the visual sign brittle fracture lacks is the shear lip. The other signs—necking and a dimpled surface—are associated with ductile failure, and ductility is a material property rather than a surface feature.

Visual signs reveal how the material failed. Brittle fracture happens with almost no plastic deformation, so you typically see a flat fracture surface, sometimes with cleavage facets, and little to no signs of ductile flow. Features that come from plastic deformation, like necking before fracture and a dimpled surface from microvoid coalescence, point to ductile behavior. Shear lips are a feature formed by plastic shear around the crack in ductile fracture. Because brittle fracture lacks this plastic flow, you wouldn’t see a shear lip there. So the visual sign brittle fracture lacks is the shear lip. The other signs—necking and a dimpled surface—are associated with ductile failure, and ductility is a material property rather than a surface feature.