The structure of adiabatic shear bands in metals: A critical review

Abstract

A review of the structure of adiabatic shear bands in metals is presented. Shear bands are redefined as being either “transformed” or “deformed” according to how the prior shear deformation is partitioned between two discrete zones in metallographic section. Metals are then classified by their general tendency to form these two types of shear zone during adiabatic shear deformation, based on available literature. Metals of low thermal diffusivity and of low resistance to adiabatic shear localization tend more readily to form “transformed” shear bands; these metals are also capable of transforming to other phases at elevated temperature (and pressure), and forming martensite on rapid cooling to room température. Shear bands of “transformed” appearance can also form in other metals during extremely localized adiabatic shear deformation resulting from the effect of localized plastic flow and elevated temperature alone. The role of phase transformations themselves in promoting the formation of “transformed” shear bands cannot be isolated using the arguments presented in this work, and may even by incidental.