Defect-related strain-controlled high-temperature fatigue behavior in additive manufacturing Hastelloy X assisted with ultrasonic micro-forging treatment

Due to the defects, the performance of laser directed energy deposition (LDED) parts was restricted. This work investigated the strain-controlled high-temperature fatigue behavior of LDED Hastelloy X after ultrasonic micro-forging treatment (UMFT). Results showed that UMFT significantly increased the fatigue life twice; mathematical statistical analysis showed that the size of the fatigue source (defect) and the fatigue loading conditions accounted for the fatigue lifetime of the LDED Hastelloy X; based on the organic combination of Smith-Watson-Topper (SWT) and Stress intensity factor (SIF) models, a new defect-related strain-controlled fatigue life pre-diction model was proposed with the correlation coefficient of 0.93.