Gopinath, K. ; Gogia, A. K. ; Kamat, S. V. ; Balamuralikrishnan, R. ; Ramamurty, U. (2009) Low cycle fatigue behaviour of a low interstitial Ni-base superalloy Acta Materialia, 57 (12). pp. 3450-3459. ISSN 1359-6454
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Official URL: http://www.sciencedirect.com/science/article/pii/S...
Related URL: http://dx.doi.org/10.1016/j.actamat.2009.03.046
Abstract
The low cycle fatigue behaviour of precipitation strengthened nickel-base superalloy 720Li containing a low concentration of interstitial carbon and boron was studied at 25, 400 and 650 ° C. Cyclic stress response at all temperatures was stable under fully reversed constant total strain amplitude (Δ ε /2) when Δ ε /2 ≤ 0.6%. At Δ ε /2 > 0.6%, cyclic hardening was followed by softening, until fracture at 25 and 650 °C. At 400 °C, however, cyclic stress plateaued after initial hardening. Dislocation-dislocation interactions and precipitate shearing were the micromechanisms responsible for the cyclic hardening and softening, respectively. The number of reversals to failure vs. plastic strain amplitude plot exhibits a bilinear Coffin-Manson relation. Transmission electron microscopy substructures revealed that planar slip was the major deformation mode under the conditions examined. However, differences in its distribution were observed to be the cause for the bilinearity in fatigue lives. The presence of fine deformation twins at low Δε/2 at 650 °C suggests the role of twinning in homogenization of cyclic deformation.
Item Type: | Article |
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Source: | Copyright of this article belongs to Elsevier Science. |
Keywords: | 720Li; LCF; Planar Slip |
ID Code: | 62525 |
Deposited On: | 22 Sep 2011 03:12 |
Last Modified: | 22 Sep 2011 03:12 |
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