Failure analysis of Co–Cr hip resurfacing prosthesis during solidification

In this study a failure originated during solidification process into the femoral stem component of Hip Resurfacing prosthesis was investigated. Visual inspection, optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and a commercial software simulation ProCAST were carried out in order to determine the cause and solution of this failure. The results exhibited hot tearing, shrinkage porosity and metal oxide films due to inadequate heat dissipation during solidification process, as a consequence of poor investment casting ceramic mold configuration. Also in this paper was improved the casting design solving this kind of defects.

► Co–Cr casting hip resurfacing prosthesis is susceptible to produce hot tearing due to it complex geometry.
► Cracks in this prosthetic device can result in a catastrophic fatigue failure in service.
► The hot tearing in stem of hip resurfacing can result in a fracture failure during machining process.
► Appropriated heat dissipation and control process casting design can eliminate hot tearing in hip resurfacing prostheses.