High temperature LCF life prediction of notched DS Ni-based superalloy using critical distance concept

This study investigated the method of estimating the LCF strength of notched DS superalloy specimen using the critical distance concept. Fatigue tests of four types of single-edge notch machined with DS superalloy DZ125 were conducted at 850 °C with load ratio R = 0.1. Smooth bar specimen fatigue tests were also carried out. It was found that a close correlation exists between the product of critical distance and linear-elastic stress concentration factor Kt and the fracture life Nf of notched specimens. Predictions based upon the reformulated critical distance in combination with SWT parameters gave estimates falling within a scatter factor of about two.

► The critical distance determined by the conventional TCD is not a constant for DZ125.
► The relationship between the product of critical distance and Kt and Nf is constructed.
► The notched specimens LCF life prediction results falls within a scatter factor of about two using the reformulated TCD.