Marker load method for durability testing of additively manufactured Ti–6Al–4V under random load spectra: Marker load method for LDED Ti-6Al-4V under random spectra

This study investigates a marker load method suitable for durability testing of Laser-Directed Energy Deposition (LDED) Ti-6Al-4V material. By evaluating the Equivalent Initial Damage Size (EIDS) associated with pore-induced failures and incorporating crack growth simulation methods that account for the effects of both air and pseudo-vacuum environments, a systematic approach for determining marker load parameters is established. After fatigue tests, distinct marker lines are observed on both SEM and optical images of the fracture surfaces. After extracting the (a, T) data, the influence of initial defects on marker load parameter determination is analyzed. A comparison is made between the Murakami model and the EIDS derived from durability testing, and the causes of missing marker lines during the small crack growth stage are discussed.