Microstructure and mechanical properties of Co-29Cr-6Mo alloy aged at 1023 K

Mechanical properties of Co-29Cr-6Mo alloys consisting of ε phase and σ phase were examined at room temperature. Solution treatment at 1523 K for 7.2 ks was carried out for cast Co-29Cr-6Mo alloy, followed by various aging treatments at 1023 K for up to 21.6 ks. The area fraction of the a phase in the aged alloys increases with the aging time at 1023 K and reaches 0.6% after aging at 1023K for 21.6ks. However, mechanical properties such as 0.2% proof strength, ultimate tensile strength and plastic elongation of the aged alloys do not depend on the aging time. It is found that the σ phase less than 0.6% does not cause the deterioration of mechanical properties of the aged Co-29Cr-6Mo alloy.