Influence of Duplex USSP/Nitriding Surface Treatments on the Dry Sliding Behavior of Ti6Al4V/AISI 316L Tribopairs.
Résumé
This contribution gives the first results of an ongoing research aiming at determining the effect of duplex USSP/Nitriding surface treatments on the dry sliding behavior of an AISI 316L steel against a Ti6Al4V counterpart under quasi-static and dynamic conditions. While the nitriding process, carried out solely, leads to a 8μm thick layer of hard (850 HV) expanded austenite, the effect of the additional USSP pretreatment is also to harden the sub-surface over about 300μm and raise the hardness of the top surface to about 1200 HV. After a quasi-static friction test against the fairly soft Ti6Al4V, the 8μm thick nitrided layer was not worn but was significantly modified. A 1μm thick layer of heavily plastically deformed material was observed at the top surface within which some transverse cracks formed and could sometimes extend throughout the entire nitrided layer. Comparatively, after a dynamic friction test, some additional recrystallization took place in the sub-surface of the USSP + nitrided treated 316L steel at the sliding output located at the end of the pads; indicating thereby that the temperature could reach values above 600°C during friction.