Page 444 - Failure Analysis Case Studies II

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Fig. 2. Photograph of the failed shaft and chromium-plated sleeve.

part shows a bright and flat band on the top, typical of the chromium plating, while the rest of its
surface is matte with many heterogeneous grooves. This last appearance, matte, with grooves and
mechanical damage signs, is the appearance of the external surface of the lower part of the sleeve.
However, in this case the grooves are positioned almost exclusively close to the fracture area.
Also seen in Fig. 2 is the irregular shape of the fracture surface in the lower sleeve part, this
fracture surface being located in some areas below the fracture surface of the shaft. In contrast, in
the upper sleeve part, the fracture surface of the shaft is totally obscured by the sleeve. In addition,
in this part, the sleeve does not show the typical and irregular appearance of a fracture surface. Its
edge is completely regular and homogeneous, as if machined. These facts may indicate that after
the failure the fracture surface of the upper part of the sleeve was rubbing against the casing while