Ranges of the Stress-Strain Curve for Aluminium (135) and (113) Single Crystals in View of Heterogeneous Deformation.

The aim of these investigations was a thorough analysis of the course of strain hardening during tensile tests of aluminum single crystals deformed by slip in the single system (orientation left bracket 1 Bar 35 right bracket ) and in two systems (orientation left bracket 1 Bar 13 right bracket ). It has been stated that in the parabolic stage of strain hardening for each orientation two regions of deformation occur. On basis of investigations concerning the changes in the orientation of the axis and the structure of slip markings in the deformation process, the influence of the heterogeneity of deformation upon the course of the stress-strain curve has been determined in the stated regions of deformation. It has been proved that the regions of an easy slip and of the linear hardening in case of orientation left bracket 1 Bar 35 right bracket are subjected to modifications due to the occurrence of narrow bands of lattice curvature. The local rotation in the kink bands opposes the initial variation in the orientation of the tension axis. The initial deformation region of monocrystals of left bracket 1 Bar 13 right bracket orientation is characterized by the occurrence of wide lattice curvatures, this process is in connection with the alternating slip in the primary and conjugate slip systems. The slip in the critical system is always located in the kink bands of the tested monocrystals. The mechanism of deformation and the structure of slip markings in regions preceding the moment of stability loss of the specimen are independent on the initial orientation of the tension axis.