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ProfilometryâBased Indentation Plastometry at High Temperature
This is a first report on profilometryâbased indentation plastometry (PIP) at high temperature (HT), covering both thermal characterization and issues for obtaining stressâstrain curves. The heating system has a relatively low thermal inertia, reaching 800 °C within about 10 min, while both indentation (â20 s) and cooling (â20 min) are also quick. This capability is useful in terms of limiting exposure of the sample to prolonged periods at HT, and hence avoiding the formation of thick oxide layers (which can affect indent profiles and hence inferred stressâstrain curves). There is good general consistency between stressâstrain curves obtained via HTâPIP and those from tensile testing. However, the possibility of creep (timeâdependent deformation) affecting the outcomes (of both types of test), particularly at higher temperatures, should be borne in mind. Creep has a characteristic effect on tensile curves, which can often be confirmed and investigated by changing the imposed strain rate. It can also be revealed by carrying out the HTâPIP testing with different penetration velocities or by monitoring the shape of the loadâdisplacement plot