Influence of temperature and carbon content on the cyclic deformation and fatigue behavior of {alpha}-iron. Part 2: Crack initiation and fatigue life
- Univ. Erlangen-Nuernberg, Erlangen (Germany). Inst. fuer Werkstoffwissenschaften
The crack initiation mechanisms and the fatigue life of {alpha}-iron polycrystals have been characterized in plastic-strain-controlled tests with small to intermediate plastic strain ranges {Delta}{epsilon}{sub pl} in the temperature range from 220 to 400 K. The fatigue life of pure decarburized {alpha}-iron cannot be described generally by means of a Manson-Coffin law, except under conditions under which distinct cyclic hardening occurs. A Basquin law is found to be valid, when the effective stress component {sigma}{sup *} dominates (i.e. at low temperatures and small {delta}{epsilon}{sub pl}). At low temperatures and up to room temperature, intergranular crack initiation is observed. At higher temperatures, mostly transgranular cracks develop in decarburized {alpha}-iron in the valleys of the surface rumpling, while in {alpha}-iron with small carbon contents persistent slip bands form which then act as sites of transgranular crack initiation. Crack initiation rates and crack growth rates are evaluated in a semi-quantitative manner from crack depth distributions.
- OSTI ID:
- 616385
- Journal Information:
- Acta Materialia, Vol. 46, Issue 5; Other Information: PBD: 2 Mar 1998
- Country of Publication:
- United States
- Language:
- English
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