Portevin–Le Châtelier type plastic instabilities in depth sensing macro-indentation

Abstract

Depth-sensing indentation at constant loading rate was applied to investigate the Portevin–Le Châtelier effect. Comparison of the different testing methods was achieved using representative strain and stress quantities. The depth of the dynamic strain ageing shows a good coincidence for Vickers and conical indentations, and for the large strain region of the tension tests. Tests with cylindrical indenters and tension experiments show a transient and a stationary behaviour for small and for large strains, respectively. The transient part can be interpreted by taking into account the free-flight time of dislocations in the Kubin–Estrin model.