Correlation Between Martensitic Transformation and Strain Burst in Retained Austenite Grains During Nanoindentation Investigation

Abstract

In general, the martensitic transformation in metastable austenite grain in steels during nanoindentation investigation will induce strain burst, also commonly referred as pop-in. However, it is found that the occurrence of pop-in depends on the position of transformed martensite. Different from the martensite transformed beneath the indenter, the martensite transformed adjacent to the indenter may not necessarily lead to an obvious pop-in. Nevertheless, the formation of martensite adjacent to the indenter can alter the mechanical behavior of the austenite phase. Thus, the present work demonstrates that in addition to the detection of pop-in, an investigation on the change of mechanical behavior of austenite phase is necessary to characterize the martensitic transformation during nanoindentation investigation.