Abstract The ideal scenario for failure analysts is when the stress situation of a damaged component is precisely known. Ambiguous findings from fractography and microstructure analysis can then be reliably evaluated and classified. This article describes the failure of a threaded hexagonal bolt installed in a medium-voltage switch. It was tested in the manufacturer’s test laboratory with up to 10,000 switching cycles. As it was clearly a fatigue fracture, it must have been a low-cycle fatigue fracture, since there are no high-cycle stresses in the switch test. It was only through this reliable classification of the damage mechanism based on the stress situation that the fractography, which was not straightforward in this case, could be understood.
Giller et al. (Thu,) studied this question.