Digital Repository, ICF12, Ottawa 2009

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Fatigue Life Calculation of Metastable Austenitic Steels
M. Smaga, F. Walther, D. Eifler

Last modified: 2013-05-03


Monotonic and cyclic Plastic deformation of metastable austenitic steels can lead
to a phase transformation from paramagnetic austenite to ferromagnetic α´-
martensite. The deformation-induced changes of the magnetic properties are
directly related to the accumulated plastic strain and therefore to the actual fatigue
state. This paper includes a detailed characterization of the deformation-induced
austenite-martensite-transformation in the metastable austenitic steels AISI 304,
AISI 321 and AISI 348. The cyclic deformation behavior is evaluated by
mechanical stress-strain hysteresis as well as high-precision temperature
measurements. With in-situ ferritescope magnetic measurements, the
development of the α´-martensite and the change in the magnetic induction due to
the Villari effect were investigated. On the basis of far-reaching cross effects of
mechanical and magnetic properties, measurements of magnetic-mechanical
hysteresis loops were performed. Hence, a method for fatigue life calculation
based on the change in magnetic properties has been developed.

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