SYMPOSIA PAPER Published: 01 January 1985
STP36238S

Biaxial Fatigue of Inconel 718 Including Mean Stress Effects

Source

Biaxial fatigue tests were conducted on Inconel 718 specimens at room temperature. Thin-walled tubular specimens were subjected to tension, torsion, and combined tension and torsion loading in strain control. Two strain ratio's Rε = 0 and Rε = −1.0, were investigated. Effective strain amplitudes of 1.0 and 0.5% were employed and resulted in fatigue lives ranging from 103 to 104 cycles. Fatigue lives were determined in terms of life to 0.1 and 1.0-mm cracks as well as specimen failure. Fatigue lives were correlated in terms of the Lohr and Ellison parameter for plastic strain which is based on the plane of maximum shear strain that causes the crack to grow into the thickness of the specimen and the normal strain to that plane. Good correlation was also obtained for the Kandel, Brown, and Miller parameter which is based on maximum shear strain and the normal strain to the maximum shear plane. Mean stress effects for the Rε = 0 tests were observed. These data could be correlated with the Rε = −1 data by introducing a mean stress term in the parameters which were then combined with the Coffin-Manson equation for estimating fatigue lives. Data on 24 tests correlated within a factor of 1.5 on life when fatigue lives were determined on the basis of 1-mm cracks.

Author Information

Socie, DF
University of Illinois at Urbana-Champaign, Urbana, IL
Waill, LA
University of Illinois at Urbana-Champaign, Urbana, IL
Dittmer, DF
University of Illinois at Urbana-Champaign, Urbana, IL
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Details
Developed by Committee: E08
Pages: 463–481
DOI: 10.1520/STP36238S
ISBN-EB: 978-0-8031-4921-2
ISBN-13: 978-0-8031-0444-0