Ductile Cast Irons

This article presents fractographs of overload fractures in a ductile cast iron piston, tensile test bar, differential case, brake caliper, compressor crankshaft, and pivot arm. SEM images show such features as dimpled rupture at the thin metallic matrix ligatures between the graphite nodules, bull's-eye ferrite and pearlite microstructure, loose graphite nodules and dimpled rupture morphology transitioning to cleavage, cleavage morphology with river lines, and ratchet marks and beach marks.