VHCF life of AM1 Ni-based single crystal superalloy after pre-deformation
Résumé
VHCF properties of the Ni-based single crystal superalloy AM1 with pre-deformation have been investigated at 1000 °C. Pre-deformed material did not present life debit under fully reversed conditions (R =-1). Pre-deformation decreased VHCF lifetime under high mean stress conditions (R = 0.5) with a presence mode I surface crack initiation. The pre-deformed material has microstructure coarsened bands lying on the former {111} slip planes, facilitating microstructure shearing during VHCF at R = 0.5. Slip traces increased surface roughness, causing surface recrystallization and fatal surface crack. Rejuvenation heat treatment after pre-deformation can restore the microstructure and the fatigue life. Highlights VHCF life of pre-deformed Ni-based single crystal superalloy at 1000 °C. Pre-deformation has no effect on the VHCF life at R =-1. Pre-deformation induces VHCF life debit at R = 0.5 and high mean stress. Rejuvenation heat treatment restores VHCF life.
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