INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
artículos
Título:
Growth of short cracks during low and high cycle fatigue in a duplex stainless steel
Autor/es:
I. ALVAREZ-ARMAS; U. KRUPP; M. BALBI; S. HEREÑÚ; M.C. MARINELLI; H. KNOBBE
Revista:
INTERNATIONAL JOURNAL OF FATIGUE
Editorial:
ELSEVIER SCI LTD
Referencias:
Lugar: Amsterdam; Año: 2012 vol. 41 p. 95 - 100
ISSN:
0142-1123
Resumen:
Damage
evolution during low- and high-cycle fatigue in an embrittled duplex stainless
steel is characterized in this paper. Moreover, scanning electron microscopy
observations (SEM) in combination with electron backscattered diffraction
(EBSD) measurements and transmission electron microscopy (TEM) were employed in
order to analyze microcracks formation and propagation. During low-cycle
fatigue, microcracks initiate
the ferrite phase either along slip planes with the highest Schmid factor (SF)
inside the grains or at the α/α grain boundary. Then, microcracks propagation
take place in ferrite or austenite grains with the highest SF. An analysis of
the dislocation structure in the near-surface and in ferritic grains in the
bulk of the specimen has shown that dislocation microbands are associated with
microcrack initiation.
In
the high-cycle fatigue regime, damage generally initiates in the austenite by
slip band formation followed by crack initiation either at an α?α boundary or
at an α?γ boundary in the intersection of slip bands in the austenite. The
microstructure in the austenite consists of a low density of dislocation pile-ups
while the ferrite is practically inactive or develops only micro-yielding at
boundaries.
Despite
the differences in both fatigue regimes, phase boundaries are an effective
barrier against crack propagation because they delay the advance of the crack
tip.