Metal fracture surfaces are a key basis for determining failure modes. Metal specimens with good electrical conductivity can be directly observed by secondary electron (SE) imaging without coating, clearly revealing the shape and distribution of crystal grains, precipitates, and fracture surface features. By identifying microscopic characteristics such as dimples, fatigue striations, and intergranular fracture, the fracture type can be determined as ductile, brittle, fatigue, or stress corrosion cracking. The magnification of a desktop SEM is sufficient to resolve these fine features indicative of specific failure mechanisms. EDS can further analyze the composition of inclusions or corrosion products at the fracture initiation site, helping trace the root cause of fracture. A typical procedure includes cleaning the fracture surface, polishing if necessary, selecting an appropriate accelerating voltage and imaging mode, and progressively observing and recording features from low to high magnification.
