A flat head screwdriver failure injured the user and prompted a metallurgical failure examination. Failure analysis included visual examination, microscopic and stereomicroscopic examinations.
Physical evidence and identification of the fracture origin during this metallurgical failure examination revealed that the screwdriver had been subjected to a bending force at the time of failure. Failure analysis of the screwdriver also revealed that it had been used to make electrical contact between two electrodes (i.e. jumping a battery). This action, jumping a battery, resulted in small arc marks on the surface of the screwdriver shaft. The arcing process created a metallurgical microstructure component inside the screwdriver shank called martensite. The presence of this brittle phase of steel called martensite (and the small cracks in the martensitic structure on the shaft) is proof that the screwdriver had been altered, misused, and abused after it was originally manufactured.
Photograph A Failed screwdriver.
Photograph B Fractured screwdriver shaft.