In-Situ SEM Investigation of the Fatigue Behavior of Additive Manufactured Titanium Alloys

Additive manufacturing of large-scale metal components has a great potential to be applied in the field of equipment manufacturing, repairing, and remanufacturing. The wire and arc additive manufacturing (WAAM) technology has become the preferred additive manufacturing technology for the production of large parts due to its higher deposition rate and better flexibility. The WAAM procedure may lead to a significant periodicity and inhomogeneity in material deposition layers, affecting mechanical properties of materials. The in-situ fatigue testing of Ti-6Al-4V specimens made by WAAM is performed to study fatigue performance based on in-situ observations with scanning electron microscope (SEM). The crack initiation and growth behaviors can be monitored during the fatigue testing of the specimens. The microstructure effect on crack growth rate and path are observed. The uncertainty of fatigue crack growth rate due to these factors is quantified using the experimental data with Paris’ model.