Effects of strain amplitude, cycle number and orientation on low cycle fatigue microstructures in austenitic stainless steel and aluminum
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Beschreibung
The combined influence of grain orientation, cycle number and local strain amplitude on the dislocation structures during low cycle fatigue of austenitic stainless steel (AISI 316L) and aluminum single- and bi-crystals is studied.
To this aim a novel approach which combines electron backscatter diffraction, digital image correlation and electron channeling contrast imaging is applied. This approach enables to systematically probe a large matrix of different parameters.
Polycrystalline steel samples with three different double-slip orientations (〈1 ̅12〉 // LD, 〈1 ̅22〉 // LD, 〈012〉 // LD) and three different multiple-slip orientations (〈1 ̅11〉 // LD, 〈011〉 // LD, 〈001〉 // LD) are cyclically deformed for 5, 30, 50 and 100 cycles. The dislocation structures are investigated for three local strain amplitudes of 0.35%, 0.65% and 0.95%. Three double-slip oriented aluminum single crystals (〈2 ̅32〉 // LD, 〈3 ̅3 ̅2〉 // LD, 〈130〉 // LD) are cycled for 50 and 100 cycles with a constant strain amplitude of 0.3-0.4%. The dislocation structures formed after 50 cycles in two aluminum bi-crystals are studied.
It is observed that the local strain amplitude differs significantly from the average global strain amplitude in polycrystalline stainless steel samples, having a high influence on the formation of dislocation structures. A significant orientation-dependence of the dislocation structure evolution in cyclically deformed polycrystalline stainless steel samples is observed.
Aluminum single- and bi-crystals form dislocation cell structures during LCF. Analysis of dislocation structures formed in cyclically deformed Al bi-crystals reveals that the respective grain orientations are of higher importance for dislocation structure formation than the grain boundary character.
Autor*in
Jens Arne Nellessen
Themen in »Effects of strain amplitude, cycle number and orientation on low cycle fatigue microstructures in austenitic stainless steel and aluminum«
Dislocations ECCI Low Cycle Fatigue