Thermal and mechanical stability of retained austenite in high carbon steel: An in-situ investigation

Abstract

High carbon multiphase steels have attracted a lot of interest in industrial applications due to their high resistance against abrasion. The structure of these steels comprises of mixed martensitic structure, plates and laths, and retained austenite. The presence of retained austenite phase plays a very important role in properties of these steels. In this paper, two in-situ approaches have been used to study thermal and mechanical stability of retained austenite. By in-situ x-ray diffraction, the start and end of phase transformation temperatures of retained austenite were identified. For the sample with higher retained austenite percentage, phase transformation started at lower temperature because by increasing the percentage, required barrier energy for phase transformation will be reduced. Also, different stages of phase transformation were investigated using a nano-indentation method. Phase transformation from austenite to martensite was identified in the mechanical stress range of 60–70mN.