Fatigue Crack Paths 2003

recrystallized equiaxed grain structure). An unambiguous relation between striation

spacing and macroscopic crack growth rate was not found because both types of

striation facets occur only irregularly on fracture surfaces. It means that fatigue cracks

in studied alloy are propagated by several failure mechanisms. Character of fracture

micromorphology proved that main failure mechanism is transgranular cleavage and

growth by the striation mechanisms is localized only in several areas along crack front.

In some areas it was found that local directions of fatigue crack growth determined from

striation arrangement were opposite to the macroscopic crack growth direction, i. e.

local fatigue cracks may originate ahead of the main crack front.

Acknowledgements

Financial assistance from the Grant Agency of the Czech Republic (Project

‘Improvement of properties of Fe3Al based intermetallics by thermomechanical

treatment and by modified compositions‘ – G AC R 106/02/0687) is gratefully

acknowledged.

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