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Abstract. In the last years, the use of High Strength Steels (HSS) as structural parts in car bodyin-white manufacturing has rapidly increased thanks to their favourable strength-to-weight ratio and stiffness, which allow a reduction of the fuel consumption to accommodate the new restricted regulations for CO2 emissions control. The survey of the technical and scientific literature shows a large interest in the development of different coatings for the blanks from the traditional Al-Si up to new Zn-based coatings and on the analysis of hard PVD, CVD coatings and plasma nitriding applied on the tools. By contrast, fewer investigations have been focused on the development and test of new tools steels grades capable to improve the wear resistance and the thermal properties that are required for the in-die quenching during forming. On this base, the paper deals with the analysis and comparison the tribological performances in terms of wear, friction and heat transfer of new tool steel grades for high-temperature applications, characterized by a higher thermal conductivity than the commonly used tools. Testing equipment, procedures as well as measurements analyses to evaluate the friction coefficient, the wear and heat transfer phenomena are presented. Emphasis is given on the physical simulation techniques that were specifically developed to reproduce the thermal and mechanical cycles on the metal sheets and dies as in the industrial practice. The reference industrial process is the direct hot stamping of the 22MnB5 HSS coated with the common Al-Si coating for automotive applications. IntroductionThe increasing demand for fuel-efficient vehicles, improved safety, and crashworthiness [1], has led automotive industry to introduce new alloys in car manufacturing, characterized by a high stiffness and strength-to-weight ratio. To meet the need to form these new materials, hot stamping has been widely applied in the automotive industry [2] to produce car body-in-white parts with a high strength-to-weight ratio, which allows a reduction of the fuel consumption [3] and preserves the passengers' safety. Despite the advantages that the hot stamping leads in terms of (i) shorter process chain, especially in the case of direct hot stamping, (ii) increase of mechanical properties just after the deformation process and without the need of additional heat treatments, (iii) reduction of the total weight of the vehicles thanks to thinner components maintaining the frame stiffness, (iv) high shape precision [4], (v) absence of lubricants that are often hazardous for the environment and require expensive cleaning operations [5], friction and wear become particularly critical for the sheet sliding in the dies cavities and their service life [6] and the heating phase, with the subsequent inevitable contact with air during transport and forming, causes the oxidation and decarburization of the metal sheets [7]. For these reasons, the 22MnB5 steel sheets that

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