For the development of processing maps for various magnesium alloys from the flow stress data, a simple instability condition based on Ziegler's continuum principles as applied to large plastic flow is extended to delineate the regions of unstable metal flow or the occurrence of fractures or defects. The measured flow stress data is fitted to a constitutive equation. The applicability of the processing maps developed has been examined by comparing with reported microstructural observations of deformed compression specimens of various magnesium alloys. Optimum hot working conditions for the material are suggested, based on the maximum values of the strain rate sensitivity index.

A simple instability condition based on Ziegler's continuum principles as applied to large plastic flow is extended to define the deformation processing maps that delineate 'safe' and 'non-safe' hot working conditions. Processing maps were developed utilising the measured flow stress data of nickel based powder metallurgy superalloys in a constitutive equation. The applicability of the processing maps developed has been examined by comparing with the reported microstructural observations of deformed compression specimens. Optimum hot working conditions for the materials are suggested, based on the maximum values of the strain rate sensitivity index.