Grain Nucleation and Growth of Individual Austenite and Ferrite Grains Studied by 3DXRD Microscopy at the ESRF

Abstract

The mechanical properties of steel strongly depend on the microstructure, which is formed during the production and processing of steel. Understanding the underlying mechanisms of the nucleation and growth kinetics during solid-state phase transformations in steel is of vital importance to control the microstructure of steel. The kinetics of individual grains in the bulk of steel can be measured in situ with the three-dimensional X-ray diffraction microscopy (3DXRD) at the European synchrotron radiation facility (ESRF). Simultaneously the fraction transformed, the nucleation rate, and the growth rate of individual grains can be measured. A furnace was developed to match with the 3DXRD-technology with the aim to map the three-dimensional microstructure of steel at elevated temperatures and to follow the kinetics of individual grains in more detail. Unique in situ measurements of nucleation and growth rates of individual austenite and ferrite grains are presented.