SYMPOSIA PAPER Published: 01 January 1998

Co-Cr-Mo Alloys Used in Metal-Metal Bearing Surfaces


The microstructure, crystallography, mechanical properties and tribological properties of an ASTM Standard Specification for Thermomechanically Processed Cobalt-Chromium-Molybdenum Alloy for Surgical Implants (F1537-94) were studied in this work. The effects of room temperature compression and carbon content on the above characteristics were also analyzed. Increasing amounts of deformation resulted in a decrease in the number of annealing twins in the microstructure. Also observed was an increase in the volume fraction of the hexagonal-closed-packed phase from the metastable face-centered cubic phase due to a strain-induced transformation. The higher carbon alloy had a lower volume fraction of this strain-induced phase. When subjected to mechanical testing, the low carbon and high carbon alloys exhibited an increase in both the yield strength and ultimate tensile strength with increasing amounts of deformation. In addition, the low carbon alloy experienced higher amounts of work hardening in comparison to the high carbon alloy. Friction studies conducted on these alloys revealed a higher coefficient of friction for the higher carbon alloy and no significant effect of strain-induced transformation on the friction characteristics.

Author Information

Varano, R
McGill University, Montreal, Quebec, Canada
Yue, S
McGill University, Montreal, Quebec, Canada
Bobyn, JD
Jo Miller Orthopaedic Research Laboratory, Montreal General Hospital, Montreal, Quebec, Canada
Medley, JB
University of Waterloo, Waterloo, Ontario, Canada
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Developed by Committee: F04
Pages: 55–68
DOI: 10.1520/STP12830S
ISBN-EB: 978-0-8031-5391-2
ISBN-13: 978-0-8031-2490-5