Microstructural evolution and hardening parameters

The evolution of dislocation structures in polycrystals with increasing strain is described within a framework of grain subdivision by dislocation boundaries and high angle boundaries. The evolving microstructures are characterized with emphasis on morphology and the changes in the misorientation angle across and spacing between deformation induced boundaries. Also the relationship between the slip pattern and the deformation microstructure is analyzed based on experimental observations showing a correlation between grain orientation in a polycrystal and the deformation microstructure. Next the changes in structural parameters are analyzed over a large strain range using a scaling hypothesis and the principle of similitude. The observations and analyses lead to a discussion of the effect of microstructural parameters on the flow stress behavior. Plastic deformation of metals has been a long lasting interest of Ali Argon and we are very glad on this occasion to thank him for many inspiring papers, scientific discussions and friendly companionship.