Austenite nucleation and growth observed on the level of individual grains by three-dimensional X-ray diffraction microscopy

Austenite nucleation and growth observed on the level of individual grains by three-dimensional X-ray diffraction microscopy

Savran, V.I.
Offerman, S.E.
Sietsma, J.

Mechanical, Maritime and Materials Engineering

Materials Science and Engineering

2010-01-12

Austenite nucleation and growth is studied during continuous heating using three-dimensional X-ray diffraction (3-D XRD) microscopy at the European Synchrotron Radiation Facility (ESRF) (Grenoble, France). Unique in-situ observations of austenite nucleation and growth kinetics were made for two commercial medium-carbon low-alloy steels (0.21 and 0.35 wt pct carbon with an initial microstructure of ferrite and pearlite). The measured austenite volume fraction as a function of temperature shows a two-step behavior for both steel grades: it starts with a rather fast pearlite-to-austenite transformation, which is followed by a more gradual ferrite-to-austenite transformation. The austenite nucleus density exhibits similar behavior, with a sharp increase during the first stage of the transformation and a more gradual increase in the nucleus density in the second stage for the 0.21 wt pct carbon alloy. For the 0.35 wt pct carbon alloy, no new nuclei form during the second stage. Three different types of growth of austenite grains in the ferrite/pearlite matrix were observed. The combination of detailed separate observations of both nucleation and growth provides unique quantitative information on the phase transformation kinetics during heating, i.e., austenite formation from ferrite and pearlite.

http://resolver.tudelft.nl/uuid:ca15da07-ded7-4894-8966-699b4ca6874b

https://doi.org/10.1007/s11661-009-0142-5

Springer

1073-5623

Metallurgical and Materials Transactions A, 41 (3), 2010

Institutional Repository

journal article

(c) 2010 The Author(s). This article is published with open access at Springerlink.com