Stainless steel made with built-in anti-counterfeiting

Researchers in Germany say they have developed a method of  protecting technical-grade steel from counterfeiting using magnetic signatures intrinsic to the material.

The team from the Technische Universität Kaiserslautern have applied the technique – described as a “hidden fingerprint” – to austenitic stainless steel, an alloy that contains high levels of chromium and nickel and low levels of carbon and is widely used in industrial applications that require strength and resistance to corrosion.

They note that using features that are contained within the steel rather than those that are applied later, such as RFID tags, nanomagnets or random patterns of nanowires, keeps the anti-counterfeit feature covert and also avoids a production step, potentially reducing costs.

Their approach involves applying a technique known as hammer peening – in essence repeatedly beating the surface of the steel to apply mechanical stress – in order to create microstructures within it consisting of martensite, a higher carbon form of stainless steel that is harder and more brittle.

These structures can form hidden fingerprints that can be shaped into patterns – for example into a logo, serial number or even a 2D bar code – but are invisible to the naked eye. They can be detected with a magnetic sensor, without having to take a sample from the steel.

“This gives the original equipment manufacturer a technological advantage over counterfeiters, who do not know that such a hidden information exists,” write the researchers in the journal Materials Letters.

They go on: “If at some point hidden fingerprints on specific components are detected by counterfeiters, their replication is still challenging due to the required manufacturing and measurement technology as well as the process specific know-how.

“These requirements increase the effort and the costs for counterfeiters, which makes replicating the product less desirable.”

Image by Mohit Maurya from Pixabay