Influence of temperature and carbon content on the cyclic deformation and fatigue behavior of {alpha}-iron. Part 2: Crack initiation and fatigue life

Journal Article · Mon Mar 02 04:00:00 EST 1998 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(97)00363-7· OSTI ID:616385

Sommer, C; Mughrabi, H; Lochner, D ^[1]

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1. 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, Journal Name: Acta Materialia Journal Issue: 5 Vol. 46; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CARBURIZATION
CRACK PROPAGATION
DECARBURIZATION
FATIGUE
IRON-ALPHA
TEMPERATURE DEPENDENCE