Tribological performances of Zn-based coating in direct hot stamping

• Application of hot-dip galvanized Zn coating to direct hot stamping applications.
• Tribological behavior of Zn coating applied to boron steel sheets in hot stamping.
• Comparison of frictional and wear performances of Zn and conventional Al–Si coatings.
• Innovative experimental approaches and machines to test the coatings up to 900 °C.
• Investigation of the main parameters: temperature, pressure and sliding speed.

In hot stamping of High Strength Steels, the severe tribological conditions make the metal sheet coating one of the most critical choices for the technical and economical success of the process. This paper presents the approach and the results in evaluating a Zinc-based coating applied to boron steel sheets in hot stamping operations. Thermal and physical-simulation experiments were carried out to evaluate the chemical interactions between the coating and the metal sheet and the tribological performances during the process. The coating proved to overcome most of the drawbacks of the currently utilized Al–Si coating.