Laser Implantation of Titanium-Based Particles into Hot Stamping Tools for Improving the Tribological Performance During Hot Sheet Metal Forming

Over the last decades, the application of ultra-high strength steel (UHSS) has constantly increased within the automotive industry due to its favorable strength-to-weight ratio. In this regard, hot stamping is used to manufacture such steel grades to geometrical complex car body components with high shape accuracy. Hot stamped parts are commonly made out of boron-manganese steel sheets, which are initially austenitized and subsequently formed and quenched simultaneously. During forming, however, high thermo-mechanical tool stresses appear, which in turn promote the occurrence of severe wear and high friction at the blank-die interface. After short time production, the quality of the parts as well as the operating time of the tool is negatively affected. To counter this, an innovative surface engineering technology named laser implantation process has been investigated, in order to improve the tribological performance of hot stamping tools. Within prior studies, the effectiveness of this technology has already been proven in laboratory scale by means of modified pin-on-disk and quenching tests. However, the tribological impact under industrial-related contact pressure has not been analyzed so far. Furthermore, the transferability of this technology to a deep drawing process has not been investigated in detail. To counter this, hot strip drawing tests with surface pressures ≥ 20 MPa have been performed to evaluate the tribological behavior. Furthermore, a locally modified as well as a conventional die were utilized for hot stamping rectangular cups, in order to compare their tribological impact.