Characterization of the microstructure obtained by the quenching and partitioning process in a low-carbon steel

The "quenching and partitioning" process is a new heat treatment for the development of multiphase steels with improved mechanical properties. In this work, a partial austenitization followed by Q&P paths, at which the partitioning step is effectuated at a temperature equal to the quenching temperature, has been applied to a low-carbon steel. The resulting multiphase microstructures have been investigated by optical microscopy using bright field and differential interference contrast, electron backscatter diffraction, Xray diffraction and magnetic measurements. This group of techniques has led to a complete identification of the microstructural constituents: ferrite present during the partial austenitization, epitaxial ferrite formed during cooling, martensite and retained austenite. The analysis of the results has shown a significant relevance of the epitaxial ferrite in the retention of austenite, whereas the carbon partitioning from martensite to austenite has played a minor role. (C) 2008 Elsevier Inc. All rights reserved.