Abstract
Crack growth rate da/dN in Alloy 718 at 650°C, compared on the conventional ΔK basis, increased with increase in R (Kmin/Kmax) and also generally with inclusion of hold time at Kmax and Kmin. An exception, however, was that a 1-min hold at a Kmin just below the threshold K for creep crack growth caused retardation of crack growth. Correlation of da/dN for various R levels was better with Kmax than with other parameters such as Kmin, ΔK, and Δ J-integral. Fatigue crack growth in the alloy was found to be time dependent and Kmax controlled under these test conditions and consequently the best overall correlation was given by da/dt with Kmax. An unusual observation was that the addition of hold time to the loading cycle at near zero Kmin (R = 0.05) caused an increase in da/dN, as the result of an environmental interaction.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
