ABSTRACT

Investigations showed that deformation proceeded without twinning, beginning with

a rise to a certain temperature. A l so , increase of the deformation temperature promoted

block formation. The latter process consisted of dividing of the grains into a few large

blocks within a grain and simultaneously of a great number of fine blocks formed along the

grain boundaries. After the fine block formation, the grain boundaries became of serrated

appearance. Another process which became more important with temperature increase was

sliding along the grain boundaries. This process was recognised to be a cycl ic one with

alternate grain boundary migration in every cycle. Decrease of the deformation rate

promoted the high temperature mechanisms of deformation to act at lower temperatures.