Friction and surface behavior of selected titanium alloys during reciprocating-sliding motion

The frictional behavior of selected orthopaedic titanium alloys during reci procating-sliding against hardened steel was found to be function of cyclic count, sliding velocity, contact stress, and alloy phase structure (metast able-beta versus alpha + beta). Surface observations have shown that the ev olution of the frictional response involves localized asperity deformation and fracture, surface plowing with formation of small debris, adhesive wear with formation of larger surface debris, and transfer between titanium and the steel counterpart. Surfaces of the metastable-beta alloys exhibited gr eater surface deformation and transfer than did Ti-6Al-4V pins. plowing bei ng representative of surface damage for the two-phase alpha + beta. The amo unt of titanium transfer increased with increasing contact stress, transfer being always greater for the metastable-beta alloys. Additionally wear deb ris collected at the end of the tests were a mixture of titanium and steel alloy constituents. The extensive plastic deformation, plowing and galling, transfer, and mechanical alloying observed all indicate that the dynamic f riction behavior of titanium alloys is controlled by their surface deformat ion behavior and transfer characteristics. (C) 2001 Elsevier Science B.V. A ll rights reserved.