Toshiba performs failure analyses to determine the root cause of failures of many types of industrial equipment. The tools that are used to provide the necessary information for these analyses may include photography, both at low and high magnification, scanning electron microscopy (SEM), optical microscopy (OM), chemical analysis, both laboratory and x-ray fluorescence positive material identification (PMI), mechanical properties testing, hardness testing (both macro and micro), as well as finite element analysis (FEA).
A major cause of industrial equipment failures is fatigue due to cyclic stresses, both low cycle and high cycle. Examinations of fracture surfaces at high magnifications on the SEM are often necessary to reveal the fine features associated with this mode of crack propagation and to locate the initiation sites of the cracking that caused the failure.
In addition, deposits on the fracture surfaces can be chemically analyzed to determine if corrosive species played a part in cracks propagation. The optical microscope is used to determine whether microstructural anomalies were present at fracture's origin and to determine whether crack propagation was transgranular, intergranular, or a mix of both. This tells the analyst whether there were material weaknesses between grains and whether corrosion may have played a part in crack propagation.