Application Cases | The application of scanning electron microscope in metal fracture analysis
What is a metal fracture? When a metal breaks under external forces, it leaves behind two matching surfaces called "fracture surfaces" or "fracture faces." The shape and appearance of these surfaces contain important information about the fracture process. By observing and studying the morphology of the fracture surface, we can analyze the causes, properties, modes, and mechanisms of the fracture. It also provides insights into the stress conditions and crack propagation rates during the fracture. Similar to an "on-site" investigation, the fracture surface preserves the entire process of fracture. Therefore, examining and analyzing the fracture surface is a crucial step and method in studying metal fractures. Scanning electron microscope, with its large depth of field and high resolution, has been widely used in the field of fracture analysis. The application of scanning electron microscope in metal fracture analysis Metal fractures can occur in various failure modes. Based on the deformation level before fracture, they can be classified as brittle fracture, ductile fracture, or a mixture of both. Different fracture modes exhibit characteristic microscopic morphologies, and CIQTEK scanning electron microscope characterization can help researchers quickly analyze fracture surfaces. Ductile fracture Ductile fracture refers to the fracture that occurs after a significant amount of deformation in the component, and its main feature is the occurrence of obvious macroscopic plastic deformation. The macroscopic appearance is cup-cone or shear with a fibrous fracture surface, characterized by dimples. As shown in Figure 1, at the microscale, the fracture surface consists of small cup-shaped micropores called dimples. Dimples are microvoids formed by localized plastic deformation in the material. They nucleate, grow, and coalesce, eventually leading to fracture, and leaving traces on the fracture surface. Figure 1: Ductile fracture surface of metal / 10kV / Inlens Brittle fracture Brittle fracture refers to the fracture that occurs without significant plastic deformation in the component. The material undergoes little or no plastic deformation before fracture. Macroscopically, it appears crystalline, and microscopically, it can exhibit intergranular fracture, cleavage fracture, or quasi-cleavage fracture. As shown in Figure 2, it is a mixed brittle-ductile fracture surface of metal. In the ductile fracture region, noticeable dimples can be observed. In the brittle fracture region, intergranular brittle fracture occurs along different crystallographic orientations. At the microscale, the fracture surface exhibits multiple facets of the grains, with clear grain boundaries and a three-dimensional appearance. Smooth and featureless morphology is often observed on the grain boundaries. When the grains are coarse, the fracture surface appears crystalline, also known as a crystalline fracture; when the...
