Unique corrosion and wear resistant identification tags via LISI™ laser marking

A method of marking metal items with unique corrosion and wear resistant identification tags has been developed at the Center for Laser Applications (CLA) at the University of Tennessee Space Institute (UTSI). The method, coined LISI™ laser marking, uses a laser beam to melt a pre-placed powder mix of alloying compounds into the surface of the part in a desired pattern. The formulation of the powder mix is designed to enhance the surface properties of the laser processed areas and protect the identification tags from the specific corrosion and aggressive wear during transportation, operation and overhaul. The specific marking preparation steps, typical processing conditions and a representative set of results are presented for LISI™ laser marking of AISI 4340 steel with Cr-CrB₂, and 2024 aluminum with WC. Results include transverse cross-sectional views and hardness measurements of the marked material, and data on the concentration of alloying compounds within the laser melted layer. The corrosion and wear resistance of LISI™ data matrix marks was also investigated.