Abstract The influence of sliding speed and contact load on wear-resistance of cast iron in the unhardened state (cast without heat treatment) and in the state after surface hardening by electroarc plasma (GTAW method) is investigated. This method provides formation of composite hardening structure in the process of fast crystallization. It is shown, that during friction of hardened cast iron the contribution of mechanical-thermal hardening with simultaneous development of relaxation processes prevails over mechanical peening. It provides high level and stability of wear-resistanc