VERY HIGH-CYCLE FATIGUE BEHAVIOR OF ADDITIVELY MANUFACTURED TI-6AL-4V USING ULTRASONIC FATIGUE MACHINE AND SELF-HEATING TESTING.

Accelerated characterization of high-cycle fatigue properties is necessary in order to enable the optimization of parameters of additive manufacturing processes such as LPBF (Laser Powder Bed Fusion). Therefore, two accelerated characterization methods are applied and compared on Ti-6Al-4V samples produced using the LPBF process. The first method uses an ultrasonic fatigue machine and the second one determines the fatigue limit using self-heating testing. To study the interactions between the material and the accelerated testing methods, fatigue tests are carried out on different grades of Ti-6Al-4V-LPBF differing by their microstructure or their porosity. Three grades have the same microstructure but different porosity levels and three grades have different microstructures with the same porosity. Both properties showed a strong impact on VHCF strength and affected the mechanisms at fatigue crack initiation.
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