Tribological Conditions in Hot Bending of 22MnB5 Tubes

Thanks to the high stiffness-to-weight ratio given by the closed-section geometry, tubular components are particularly suitable for automotive applications that require extreme lightness to reduce energy consumption and increase crashworthiness. Tube bending processes are traditionally performed in cold conditions, but to overcome the dramatic problems of accuracy and formability that the new high-strength steels present, a novel draw bending set at high temperature has been proposed. This paper presents the results of the investigations carried out on the tribological conditions of the hot draw bending of 22MnB5 tubes to obtain tubular parts with tailored mechanical properties. Investigation about the process thermal cycle has been performed with focus on the influence of the contact pressure on the heat transfer. The results show the practicability of the new process chain to obtain hot stamped tubular parts.