Publication detail

Near-threshold propagation of mode II and mode III fatigue cracks in ferrite and austenite

VOJTEK, T. PIPPAN, R. HOHENWARTER, A. HOLÁŇ, L. POKLUDA, J.

Original Title

Near-threshold propagation of mode II and mode III fatigue cracks in ferrite and austenite

English Title

Near-threshold propagation of mode II and mode III fatigue cracks in ferrite and austenite

Type

journal article in Web of Science

Language

en

Original Abstract

The near-threshold behavior of mode II and mode III long fatigue cracks in ferritic (ARMCO iron) and austenitic (X5CrNi18-10) steel were experimentally studied using various samples specially prepared to obtain the effective threshold values deltaKIIeff,th and deltaKIIIeff,th. In both investigated materials, the effective thresholds for mode III were about 1.7 times higher than those for mode II. 3D topological data obtained by the examination of fracture surfaces using stereophotogrammetry were utilized to identify crack growth micromechanisms. In austenite, mode I branching of both the mode II and mode III cracks started at the very onset of crack growth. On the other hand, all cracks in ferrite propagated in crystallographically-assisted local mixed mode I + II + III with mode II dominance. These experimental results can be understood in terms of crack growth micromechanisms according to a deformation model in ferrite and a decohesion model in austenite. The dissimilarity of growth mechanisms in ferrite and austenite may be attributed to a different number of available slip systems in bcc and fcc metals

English abstract

The near-threshold behavior of mode II and mode III long fatigue cracks in ferritic (ARMCO iron) and austenitic (X5CrNi18-10) steel were experimentally studied using various samples specially prepared to obtain the effective threshold values deltaKIIeff,th and deltaKIIIeff,th. In both investigated materials, the effective thresholds for mode III were about 1.7 times higher than those for mode II. 3D topological data obtained by the examination of fracture surfaces using stereophotogrammetry were utilized to identify crack growth micromechanisms. In austenite, mode I branching of both the mode II and mode III cracks started at the very onset of crack growth. On the other hand, all cracks in ferrite propagated in crystallographically-assisted local mixed mode I + II + III with mode II dominance. These experimental results can be understood in terms of crack growth micromechanisms according to a deformation model in ferrite and a decohesion model in austenite. The dissimilarity of growth mechanisms in ferrite and austenite may be attributed to a different number of available slip systems in bcc and fcc metals

Keywords

effective threshold, shear-mode fatigue cracks, ferrite, austenite, dislocation crack growth models, stereophotogrammetry

RIV year

2013

Released

01.07.2013

Publisher

Elsevier

ISBN

1359-6454

Periodical

Acta materialia

Year of study

61

Number

12

State

US

Pages from

4625

Pages to

4635

Pages count

11

Documents

BibTex


@article{BUT99307,
  author="Tomáš {Vojtek} and Reinhard {Pippan} and Anton {Hohenwarter} and Libor {Holáň} and Jaroslav {Pokluda}",
  title="Near-threshold propagation of mode II and mode III fatigue cracks in ferrite and austenite",
  annote="The near-threshold behavior of mode II and mode III long fatigue cracks in ferritic (ARMCO iron) and austenitic (X5CrNi18-10) steel were experimentally studied using various samples specially prepared to obtain the effective threshold values deltaKIIeff,th and deltaKIIIeff,th. In both investigated materials, the effective thresholds for mode III were about 1.7 times higher than those for mode II. 3D topological data obtained by the examination of fracture surfaces using stereophotogrammetry were utilized to identify crack growth micromechanisms. In austenite, mode I branching of both the mode II and mode III cracks started at the very onset of crack growth. On the other hand, all cracks in ferrite propagated in crystallographically-assisted local mixed mode I + II + III with mode II dominance. These experimental results can be understood in terms of crack growth micromechanisms according to a deformation model in ferrite and a decohesion model in austenite. The dissimilarity of growth mechanisms in ferrite and austenite may be attributed to a different number of available slip systems in bcc and fcc metals",
  address="Elsevier",
  chapter="99307",
  doi="10.1016/j.actamat.2013.04.033",
  institution="Elsevier",
  number="12",
  volume="61",
  year="2013",
  month="july",
  pages="4625--4635",
  publisher="Elsevier",
  type="journal article in Web of Science"
}