Intrinsic fingerprint detects tampered steel parts

Magnetic ‘fingerprints’ within steel could be used to identify the provenance of metal components, says researchers.

A phenomenon known as magnetic Barkhausen noise – introduced into ferromagnetic items as a result of the manufacturing process – could be used to verify weapons treaties and help to reduce the use of counterfeit bolts in the construction industry, says the team from Los Alamos National Laboratory in the US.

“Magnetic signals provide a wide range of possible national security applications,” according to David Mascareñas, a research and development engineer at Los Alamos and lead author of the study published in the journal Smart Materials and Structures.

“It's a promising phenomenon that we hope to leverage to uniquely identify different pieces of artillery,” he says.

All materials typically display some variation in their microstructure simply as a result of the manufacturing process, such as rolling, heat treating, welding, and grinding. This means Barkhausen noise measurements between nominally similar components are unique, and could be used to detect instances where steel goods have been subjected to clandestine repairs and tampering.

In the research, researchers applied Barkhausen noise to two types of steel; conventional steel and an abrasive-resistant type of steel used in mining equipment.

A sensor measured electromagnetic signals by repeatedly scanning the different kinds of steel over a period of time. Researchers compared the signals from those two sets of scanned images and found signatures that were intrinsic to each type of steel.

The variations that occur from the production of various kinds of steel are reflected as distinct fingerprints. "They seem to be repeatable," says Mascareñas.

That intrinsic signature could help to discover counterfeit or low-grade steel parts in construction by looking for differences in the electromagnetic signatures.

Future research could involve studying other types of steel and developing a handheld sensor for treaty verification.