An acoustic emission study of martensitic and bainitic transformations in carbon steel

Abstract

Steel is one of the most commonly used materials today, especially in industrial sectors such as ship building and the automotive industry. In order to meet the requirements for steel applications, new multi-phase steels are being developed. The microstructure of these steels consists of a variety of different phases, which leads to superior material properties - a combination of high strength with good formability. For the development of such steels research is required to gain more insight into the underlying microstructure and the mechanisms by which it is formed. This thesis describes unique acoustic emission experiments during martensitic and bainitic transformations in steel. The main objective of this work is to obtain a better understanding of the growth mechanism and kinetics of these solid-state phase transformations that can occur in carbon steel. In view of fact that acoustic emission is an unexplored technique in this kind of steel research, this study also aims to give a good overview of the possibilities and limitations of acoustic emission as a real-time monitoring technique for the evolution of bainite and martensite formation.Applied Science