MICROSTRUCTURAL CHANGES DURING ISOTHERMAL FORGING OF A Co-Cr-Mo ALLOY.

The response of as-cast Vinertia to isothermal forging is examined by means of isothermal and isostrain-rate compression testing. The interaction between the carbide phase and the recrystallization induced during hot working governs the degree of homogeneity that can be achieved. Control of carbide volume fraction, size, and distribution by prior processing can lead to a fine grain equiaxed structure with uniformly distributed carbides. The potential offered by isothermal forging for control of microstructure is discussed as well as the limits imposed by the starting material and strain gradients expected during the forging of surgical implants.