ANALYSIS AND COMPARISON OF DISLOCATION STRUCTURES IN COLD AND HOT DEFORMATION

摘要

Studies of dislocation structures are relevant for both cold and hot deformation as the dislocation structure is an important factor controlling mechanical properties. Furthermore the structure is the environment in which recovery and recrystallisation processes take place. Detailed studies of dislocation structures in deformed metals have mostly been carried out for cold deformation. Characterisation of cold deformed structures, mainly by TEM, has now reached a state where the understanding of the physical processes leading to these structures is well under way. In particular strain and crystallographic slip have been identified as controlling factors. These studies have established that a number of structural parameters, e.g. boundary spacing and misorientation and boundary planes, can be linked to the processing conditions. Structural characterisation along these lines is more elaborate than that normally carried out for hot deformation. The general framework established for cold deformation is applied to hot deformation. Analysis of cold and hot deformation microstructures in the same framework gives a better basis for assessment of temperature-induced similarities and differences in the physical mechanisms behind structure evolution during deformation.