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MICROSTRUCTURAL STUDY OF CYCLIC STRAIN HARDENING BEHAVIOUR IN BIAXIAL STRESS STATES AT ELEVATED TEMPERATURE
Author(s) -
Nishino Seiichi,
Hamada Naomi,
Sakane Masao,
Ohnami Masateru,
Matsumura Naomi,
Tokizane Masaharu
Publication year - 1986
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.1986.tb01212.x
Subject(s) - materials science , torsion (gastropod) , hardening (computing) , isotropy , composite material , amplitude , cyclic stress , push pull , von mises yield criterion , structural engineering , anisotropy , finite element method , engineering , electrical engineering , physics , optics , medicine , surgery , layer (electronics)
This paper describes the cyclic strain hardening behaviour and dislocation structures of material in biaxial low cycle fatigue at elevated temperatures. In this study, push‐pull, reversed torsion and combined push‐pull/reversed torsion tests were carried out using a type 304 stainless steel in air. While there was no significant difference between the cyclic stress amplitudes in the push‐pull and reversed torsion tests on a von Mises' base, combination tests exhibited a 40% increase in stress amplitude. Most of the dislocations in the first two types of test adopted ladder or maze structures, while in the later case cells were found. Changing the loading mode at a certain cycle, for example, from push‐pull to reversed torsion, revealed that stress amplitude depended mainly on the concurrent applied strain mode and furthermore, that the strain mode before the interchange had little or no effect on the stress amplitude after the interchange. Tests were also performed in order to examine how prestrained material hardened in the three different loading modes, with the following results: prestrained material in push‐pull or in reversed torsion exhibited an anisotropic stress response, while the material in the combined tests exhibited an isotropic response. These cyclic responses are discussed in connection with the dislocation structure.