Grid Laser Marking Influence on High-strength Steels Tensile Test Behavior

Automotive car companies are using AHSS (advanced high strength steels) over the last 20 years, to reduce vehicle weight and improve safety. The new steels can achieve higher strength and good fatigue resistance, but some issues related to springback and low formability are also a big concern. Thus, companies need to extend their know-how regarding material behaviour, design rules and manufacturing processes. Therefore, materials characterization laboratories are working to obtain the new formability charts of the steels. The grid laser marking of test pieces is a recent approach. However, the marking process must accomplish three main aspects: indelibility during the tensile testing procedure, precision, and of course, it must not affect the mechanical properties of studied steels. This work is focused on the laser marking of test pieces, using Ytterbium fiber laser. A dual phase steel (JFE CA 1180) is studied. Process parameter are defined. Keywords: grid marking, laser, advanced high-strength steels, AHSS, formability diagrams, mechanical properties