Cracks in a powder vibrating sieve disc

A case study of cracks in a powder vibrating sieve disc is presented in this paper. An evaluation of the failed disc was undertaken to assess its integrity that included a visual examination, photo documentation, chemical analysis, micro-hardness measurement, tensile testing, and metallographic examination. The fracture surfaces were examined with the help of a scanning electron microscope equipped with energy-dispersive X-ray (EDX) facility. In addition, the deposits scraped from the inner surface of the bolt holes were subjected to X-ray diffraction. Spectrum analysis and EDX results identified the material of the disc as zinc-coated (galvanized) silicon-killed structural steel. Results indicate that cracks initiated from bolt holes in the disc and propagated in a peripheral direction and a radial direction with different lengths. The cracks are fretting fatigue cracks from high vibration stress. The reason why cracks initiated at holes is that there were fretting wear scars the inner surface of the bolt holes.