In fatigue crack growth, crack tip blunting and resharpening occur within every cycle. Thus the first requisite for fatigue threshold may be considered as fulfillment of the condition of dislocation group emission from the crack tip. On the other hand, it has been experimentally observed that fatigue threshold stress intensity depends on the ferrite grain size. Therefore, the second requisite for fatigue threshold may be to satisfy the mechanical relation between the emitted dislocation group and the grain boundary. A mathematical formula for fatigue threshold has been derived based on the first requisite as the rate determining process. The criterion for fatigue threshold is proposed based on the condition of fulfillment of both the first and the second requisites. The fatigue threshold is considered as the stress intensity required to let the lead dislocation, after emitted from the source, reach the grain boundary.
|Number of pages||5|
|Journal||Zairyo/Journal of the Society of Materials Science, Japan|
|Publication status||Published - 1982 May|
ASJC Scopus subject areas
- Chemical Engineering (miscellaneous)
- Metals and Alloys
- Polymers and Plastics