Dave

- Creep is plastic ( not reversible ) deformation behaviour where a material deforms continuously if a constant load is applied. This means there is no direct connection between load and deformation as in elastic deformation. This deformation is time dependent. The longer you wait the bigger the deformation. And this again is the difference between creep and plastic deformation due to a stress bigger than the yield stress where the plastic deformation occurs instantaneous.

- Grain boundary sliding ( GBS ) is a deformation mechanism where the grains of a crystalline material slide above each other. With low stress at high temperature GBS is the dominant deformation mechanism in creep deformation. Another deformation mechanism in creep deformation is dislocation climb DC where the atom layers in the crystals slide above each other. 

Best regards, have a nice weekend

Guenter

Guenter Grossmann
Swiss Federal Institute for Materials Testing and Research EMPA
Centre for Reliability
8600 Duebendorf
Switzerland

Phone: xx41 1 823 4279
Fax :      xx41 1823 4054
mail:     [log in to unmask]

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