Statistical analysis of the Portevin-Le Chatelier effect in Inconel 718 at high temperature

The Portevin-Le Chatelier effect manifests itself as an unstable plastic flow which occurs during tensile tests of some dilute materials in a certain range of temperatures and strain rates. This phenomenon is also exceptionally intense in nickel based superalloys used in the aerospace industry. The aim of this research was to investigate the Portevin-Le Chatelier effect in Inconel 718 solution strengthened superalloy. The tested material was subjected to tensile tests carried out within the temperature range 250-600 degrees C with three different strain rates 2 x 10(-3) s(-1),10(-2) s(-1) and 5 x 10(-2) s(-1). The strain curves were analyzed in terms of intensity and statistical behavior. A quantitative method to describe the phenomenon was used in the study. The results indicate the presence of clear trends with temperature and strain rates. Additional optical observations were carried out to assess the changes of the microstructure. (C) 2014 Elsevier B.V. All rights reserved.