Chicken wire failure analysis and accident reconstruction

Chicken Wire Analysis by Metallurgy

A schoolteacher stopped off at a local restaurant on his way home to purchase some take out chicken. Shortly after he began eating the chicken at home, something lodged in his throat and he had to be taken to the emergency room where the doctors removed a piece of wire from his throat (see photo).

There seemed to be little doubt that the wire had come from the chicken he was eating. The main question was whether the wire contaminated the chicken at the restaurant or at the poultry farm before arriving at the restaurant.
Several wire brushes were identified in the restaurant supply catalog used by the restaurant in question.

subject wire
Scale in Centimeters

One wire brush in particular stood out as a potential match for the subject wire. There were eleven features of the brush wire that were identical or nearly identical to the subject wire:

• Length – nearly identical
• Diameter – identical at .014”
• Stiffness – nearly identical behavior
• Elemental Alloy Composition – identical
• Striations from wire drawing – nearly identical
• Niobium and Molybdenum (drawing lubricant) – inside striations
• Wire Fracture Surface at working end – nearly identical
• Wire Fracture Surface at brush handle end – nearly identical
• Unusual Magnetic Properties – identical
• Cross Sectional Metallography – identical
• Longitudinal Metallography – identical

For example, the photo below illustrates a comparison of the drawing striations of the subject wire to the exemplar brush wire.

Subject wire on the left. Exemplar brush wire on the right.

The most notable feature was that both the subject wire and the brush wire were slightly magnetic and could be picked up by non-magnetized iron. From the fracture surfaces it appeared that the wire failed by fatigue at the wire-handle interface. Given the eleven matching features between the exemplar brush wire and the subject wire, and the fact that there were no dissimilar features, it was fairly certain that the subject wire came from the restaurant and not the poultry farm.

Dr. Fox is a nationally recognized metallurgy expert, corrosion expert and failure analysis expert who has published numerous peer-reviewed, scientific papers in these fields. He worked for years as a bench scientist and a research manager in the fields of corrosion, metallurgy and failure analysis of materials in nuclear reactors.

Chicken Wire Analysis

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Chicken Wire Analysis by Metallurgy

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