Tribological Behavior of a Heat-Treated Cobalt-Based Alloy

The present study reviews the tribological behavior of a Co-Cr-Mo alloy regarding to microstructural changes caused by solution and aged heat treatments. The influence of microstructure on wear resistance was assessed in a pin-on-disk configuration. It was found that after a long solution heat treatment of 6 h at 1200 degrees C, most of the carbides were dissolved into the matrix, and coarse grain size was obtained. Solution treatment for 1 h presented fine grains and globular carbides along the matrix. Aging at 850 degrees C resulted in a quantity of phase transformation which was different from austenite face cubic centered to martensite hexagonal close packed (HCP); 35% of HCP was reached during 8 h of treatment and 60% for 15 h. As-cast condition and 6-h solution heat treatment exhibited the greatest wear loss, while 1-h solution treatment and samples containing HCP phase showed a threefold lower wear.