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Screwdriver Failure
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 called martinsite. The presence of
this brittle phase of steel called martinsite (and the
small cracks in the martinsitic structure on the shaft) is proof that the
screwdriver had been altered, misused, and abused
after it was originally
manufactured.
Photograph A: Overall view of failed screwdriver.
Photograph B: Close-up view of the
fractured screwdriver shaft.
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Hand Tool Accidents
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Dr.
R. Craig Jerner, Ph.D., PE specializes in accident
investigation and metallurgical failure analysis,
with over 30 years experience as a metallurgical
consultant and accident investigator. He has
testified as a metallurgical expert in over 250
depositions and more than 70 court appearances. If you or someone you know should need the services of Dr. Jerner and J.E.I. Metallurgical, please visit our web site at the buttons below, or e-mail Dr. Jerner --- 