Micron Scale Measurement of a Crack Origin in a Metal Brittle Fracture

The goal of this research is to develop a micron scale measurement method, which, based on computer vision technology, gauges the crack origin and its extensions in a metal brittle fracture. It is performed by analyzing SEM, or Scanning Electron Microscope, images. Here, a brittle fracture is a kind of fractures, which accompanies little or no plastic deformations of the metal. On the surface of a brittle fracture, many short stripe patterns, which are called 'cleavage steps,' spread radially from the origin point towards outside; consequently, by analyzing them, the crack origin and extensions can be measured. The cleavage steps typically have higher brightness than the background in a SEM image; therefore, they can be extracted and their positions and orientations can be calculated using image processing techniques. By experiments with both smooth and notched specimens, our method is proved to work accurately. It is expected that our proposed method will enable non-experts to analyze metal fractures accurately in micron scale.