Embedding hidden information in additively manufactured metals via magnetic property grading for traceability

Abstract

Use of counterfeit goods has a large negative impact on manufacturing industry. Recently, counterfeiting of additively manufactured parts is being facilitated by advances in 3D scanning methods, which enable users to retrieve high resolution models and improve reverse engineering approaches. The present study develops and validates a methodology for encoding part authentication information within additively manufactured hardware during part fabrication which is based on embedding a ferromagnetic physical tag within a non-magnetic product. To demonstrate the applicability of this technique, non-magnetic 316 stainless steel was fabricated via laser direct energy deposition with embedded ferromagnetic 430 or 17-4PH stainless steels regions for local control of the magnetic response. The magnetic flux normal to the surface was recorded using a custom built 3-axis magnetic sensor to obtain magnetic flux intensity maps, revealing the embedded magnetic regions. The distribution of the magnetic regions, also characterized using scanning electron microscopy evaluations, can be retrieved from this map revealing the features of the physical tag. Magnetic response of the composites is explained as a function of local composition changes and crystalline structure. The methodology introduced here can be used to embed several traceability tools such as magnetic barcodes and Quick Response (QR) codes away from the surface, which can be detected on demand, in 3-D printed parts.