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In situ observations on the austenite stability in TRIP‐steel during tensile testing
Author(s) -
Kruijver Suzelotte,
Zhao Lie,
Sietsma Jilt,
Offerman Erik,
Dijk Niels,
Margulies Lawrence,
Lauridsen Erik,
Grigull Stephan,
Poulsen Henning,
Zwaag Sybrand
Publication year - 2002
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.200200202
Subject(s) - austenite , trip steel , materials science , martensite , ultimate tensile strength , diffraction , deformation (meteorology) , plasticity , metallurgy , stress (linguistics) , diffusionless transformation , tensile testing , synchrotron radiation , phase (matter) , electron backscatter diffraction , composite material , microstructure , optics , chemistry , physics , linguistics , organic chemistry , philosophy
In‐situ deformation tests have been performed on a steel displaying the transformation‐induced plasticity (TRIP) effect, while monitoring the phase transformation by means of X‐ray diffraction. A tensile stress is applied to 0.4 mm thick samples of this steel with mass contents of 0.26 % Si, 1.5 % Mn, and 1.8 % Al in a transmission geometry for a synchrotron‐radiation beam of 25 μm · 25 μm. On the diffraction patterns every grain appears as a discrete spot. The austenite {200} reflections are analysed during this investigation. The diffraction patterns are treated like a powder pattern for five different η‐angles, with η representing the angle between the tensile direction and the normal direction of the diffracting {200} planes. The results of the analysis show that η = 0° and η = 90° are the preferential orientations for the transformation to martensite. The Ludwigson and Burger model [9] is used to gain more information about the stress dependence of the deformation induced martensite formation. The microdiffraction patterns also reveal the changes in carbon concentration in austenite at each retained austenite fraction.