Numéro |
J. Phys. IV France
Volume 112, October 2003
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Page(s) | 349 - 352 | |
DOI | https://doi.org/10.1051/jp4:2003899 |
J. Phys. IV France 112 (2003) 349
DOI: 10.1051/jp4:2003899
Effects of high magnetic field on martensitic transformation and its reverse transformation in Fe-based alloys
H. Ohtsuka and H. WadaNational Institute for Materials Science, 3-13 Sakura, Tsukuba, Ibaraki 305-0003, Japan
Abstract
Effects of high magnetic field on martensitic transformation and its reverse transformation from lath martensite to austenite
have been investigated in Fe-based alloys. An Fe-0.4C alloy was solution treated at 900 °C for 15 min and water-quenched without
magnetic field, which produces the lath martensite single phase structure. Then this specimen was reheated to 750 °C (ferrite
and austenite two phase region) with or without magnetic field and held for 20 min and then rapidly cooled to room temperature
by He gas. In this heat treatment, austenite is formed by the reverse transformation and then transformed to lath martensite
again during the cooling to room temperature, making the final structure of ferrite and lath martensite. Without magnetic
field, equiaxed ferrite grains are formed and both ferrite and lath martensite are distributed homogeneously.
With magnetic field, lath martensite, that is, austenite grains in the two phase region, and ferrite grains are aligned along
the direction of magnetic field. On the contrary, neither martensite nor ferrite phases are aligned along the direction of
magnetic field when the reheating temperature is rather high such as 770 °C or the prior austenite grain size is rather large.
In both specimens, austenite is not necessarily aligned along the direction of magnetic field, and rather formed along the
packet or block boundaries. Effects of high magnetic field on austenite to lath martensite transformation behavior was also
studied, but no structural alignment along the magnetic field was observed.
© EDP Sciences 2003