An arc-tenon attachment for nickel-based single crystal turbine blade with improved high-temperature fretting fatigue performance

Abstract

Nickel-based single crystal (NBSC) turbine blade tenon is prone to fretting fatigue failure. In this study, an arc-tenon attachment was proposed and its fretting fatigue life increased by up to 408.18 % at 600 ℃ compared with the plane-tenon structure under the applied peak stress of 65 MPa. The arc-tenon attachment could effectively reduce the maximum von-Mises stresses and resolved shear stresses near the contact region, regulating the stress distribution and reducing the stress gradient, which was beneficial to alleviating the activation of octahedral slip systems and delaying crack initiation, thereby improving the fretting fatigue life at high temperature. Meanwhile, high temperature promoted the formation of oxide layer on the contact surface, providing low coefficient of friction and further reducing the contact stress. The large resolved shear stress near the contact leading edge region facilitated the activation of octahedral slip systems, then the resultant multiple slip lines sheared both the γ matrix phase and γ′ precipitates. The further growth of the slip lines accelerated the fretting fatigue crack initiation and propagation. The arc-tenon attachment could provide long fretting fatigue life and showed great potential in engineering application.