Abstract: The self-developed high-temperature friction tester was used to simulate the high-temperature friction process of uncoated 22MnB5 steel under actual hot stamping process. The influence of initial friction temperature, sliding speed and normal load on the friction behavior were analyzed. The results indicated that since the oxide layers formed on the surface of the specimen during transfer process had the same protective and lubricating effect on friction, the initial friction temperature had little effect on the friction coefficient. When the sliding speed was low, the oxides on the specimen surface would form small accumulation blocks with non-uniform thickness, which made the specimen surface uneven. And the oxides could not support the friction interface well, resulted in high coefficient of friction. As the normal load increased, the friction coefficient increased due to the spalling of the oxide layers and the exposure of the metal substrate.

Key words: hot stamping; uncoated 22MnB5 steel; extra cooling; oxides