The Initiation Mechanism of Plastic Strain Localization Bands and Acoustic Anisotropy

摘要

The plastic strain localization in metals takes place, as a rule, at large strains and therefore it can be considered as an important indicator of failure. Detection of plastic strain localization allows us to improve technical diagnostics. However, there is no consensus on the leading mechanism of such localization. There are two approaches: a dislocation model and a model of the dynamic instability of plastic deformation associated with the descending branch of the stress-strain curve. Both models do not allow us to predict the parameters of the plastic strain localization bands, since they use characteristics that are difficult to determine experimentally (for example the density of dislocations et al.). The method of acoustic anisotropy is used as an experimental method for the precise determination of plastic strain localization zones. As the main mechanism of localization, it is proposed to consider the probability distribution of the characteristics of individual grains in polycrystalline material. The experimental results are described in the article and a new three-dimensional model of the localization effect of plastic deformations is given, which is an important indicator of the material failure.