The evaluation of hot-working characteristics of cobalt-based implant alloys

• Published in: Journal of materials science 1994-08, Vol.29 (15), p.4086-4092
• Main Authors: Tsai, Jong-Cheng, Duh, Jing-Bang, Chueh, Shan-Chang
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Forging and extrusion; Forming; Metals. Metallurgy; Production techniques
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/BF00355975

The hot-working characteristics of wrought Co-Ni-Cr-Mo implant alloy during ingot-to-billet conversion were evaluated using a Gleeble-2000A simulator. The hot tensile test at 700-1320 deg C was used to determine the optimum hot-working parameters at a strain rate equivalent to that of conventional press forging to ensure acceptable hot workability. Hot ductility and deformation resistance as a function of temperature can be clearly established. The fracture surfaces of the tensile specimens were examined to correlate them with the hot tensile ductility values at various temperatures. The poor ductility at temperatures > 1300 deg C was attributed to the incipient melting of grain boundaries. The effect of temperature and strain rate on the flow-stress behaviour and microstructures were investigated by uniaxial compression testing in the temperature range 900-1200 deg C and strain rate, epsilon , range of 0.01-10 s exp -1 . The strain-hardening and steady-state behaviour were described from the measured true stress-true strain curves.