Deformation mechanism maps

A deformation mechanism map is a way of determining the expected failure mode of a material loaded under a given set of conditions. Typical deformation mechanism maps consist of some kind of stress plotted against some kind of temperature axis. For a given set of operating conditions calculations are undergone and experiments performed to determine the predominant failure method for a given material.

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Constructing the Map

Repeated experiments are performed to characterize the mechanism by which deformation failure occurs in various materials. The dominant mechanism is the one by which the material will fail, however at any given level of stress and temperature, all of the creep and plasticity mechanisms are active. It is left to scientific experiment to determine which controls the failure of the material.

Reading the Map

For a given stress profile and temperature, the point lies in a particular "deformation field". If the values place the point near the center of a field, it is likely that the primary mechanism by which the material will fail, ie: the type and rate of failure expected, grain boundary diffusion, plasticity, nabarro-herring creep, etc... If however, the stress and temperature conditions place the point near the boundary between two failure mechanism regions then the dominating mechanism is less clear. Near the boundary there are likely more than one effect that are of sufficient magnitude to affect the failure of the material. Deformation mechanism maps are only as accurate as the number of experiments and calculations undertaken in their creation.

See also

• continuum mechanics