THERMAL FRICTION PROCESS IN STEEL 28NCDV1 0 OXIDIZED IN AIR AND STEAMAT 850-DEGREES-C

The industrial tools are subjected to thermal, mechanical and tribolog ical stresses, during the Mannessmann piercing process. So, the purpos e of this work is to investigate the influence of the pre-existent oxi de film on friction process between the forming tool and the tube, dur ing the piercing in hot metal forming. A wear behaviour of a low alloy steel (28NCDV10) is studied on a cylinder-disc tribometer. Two differ ent atmospheres, which are air and steam, are employed for oxidizing t he discs at 850-degrees-C. The experimental results of non oxidized di scs exhibit a severe oxidation wear and metal transfer from the cylind er to the disc. While, the oxidation of the discs, notably in the case of steam, shows a decreasing in the wear rate.