On the fatigue thresholds and the fatigue crack growth behaviour of two ferrite-pearlite microalloyed steels

Sarma, V. S. ; Padmanabhan, K. A. ; Jaeger, G. ; Koethe, A. ; Schaper, M. (2000) On the fatigue thresholds and the fatigue crack growth behaviour of two ferrite-pearlite microalloyed steels Transactions of the Indian Institute of Metals, 53 (3). pp. 303-314. ISSN 0019-493X

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Abstract

In this paper the fatigue thresholds ( Delta K sub th ), crack closure and fatigue crack growth (FCG) behaviour of two microalloyed (MA) ferrite-pearlite HSLA steels are reported. The Delta K sub th , crack closure and FCG rates were measured using the dynamic compliance measurement technique. The fatigue thresholds decreased with increasing load ratio, R. This is attributed to the crack closure phenomenon. The theoretically computed crack closure stress intensity K sub clth and Delta K sub effth were compared with the experimental values. The estimated K sub cl was significantly lower than the experimentally measured value in the low carbon MA steel E-38 (ferrite dominant) but marginally higher in the medium carbon MA steel 49MnVS3 (pearlite dominant). The estimated Delta K sub effth correlated reasonably well with the experimental values in both the steels. The predicted FCG rates in the Paris region compared well with the experimental results with the Paris exponent m was taken as equal to 2(2n'+1). Transmission electron microscopy in the near threshold region showed dislocation pile ups near the ferrite grain boundary in the low carbon MA steel.

Item Type:Article
Source:Copyright of this article belongs to Indian Institute of Metals.
ID Code:66418
Deposited On:22 Oct 2011 12:00
Last Modified:22 Oct 2011 12:00

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