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Title: A comparison of dilatometry and in-situ neutron diffraction in tracking bulk phase transformations in a martensitic stainless steel

Phase transformations in the 17-4PH martensitic stainless steel have been studied using different in-situ techniques, including dilatometry and high resolution neutron diffraction. Neutron diffraction patterns were quantitatively processed using the Rietveld refinement method, allowing the determination of the temperature-dependence of martensite (α′, bcc) and austenite (γ, fcc) phase fractions and lattice parameters on heating to 1000 °C and then cooling to room temperature. It is demonstrated in this work that dilatometry doesn't permit an accurate determination of the end temperature (Ac3) of the α′ → γ transformation which occurs upon heating to high temperature. The analysis of neutron diffraction data has shown that the respective volumes of the two phases become very close to each other at high temperature, thus making the dilatometric technique almost insensitive in that temperature range. However, there is a very good agreement between neutron diffraction and dilatometry at lower temperature. The martensitic transformation occurring upon cooling has been analysed using the Koistinen–Marburger equation. The thermal expansion coefficients of the two phases have been determined in addition. A comparison of the results obtained in this work with data from literature is presented. - Highlights: • Martensite is still present at very high temperature (> 930 °C)more » upon heating. • The end of austenitisation cannot be accurately monitored by dilatometry. • The martensite and austenite volumes become similar at high temperature (> ∼ 850 °C)« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [3]
  1. Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, Rue Christian Pauc, BP 50609, 44306 Nantes Cedex 3 (France)
  2. ISIS Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX (United Kingdom)
  3. (United Kingdom)
Publication Date:
OSTI Identifier:
22285066
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 82; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AUSTENITE; BCC LATTICES; DILATOMETRY; FCC LATTICES; LATTICE PARAMETERS; MARTENSITE; MARTENSITIC STEELS; NEUTRON DIFFRACTION; PHASE TRANSFORMATIONS; STAINLESS STEELS; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0400-1000 K; THERMAL EXPANSION