Effect of ECAP on fracture toughness and fatigue endurance of DED-processed Ti-6Al-4V investigated on miniaturized specimens

• Published in: Journal of alloys and compounds Vol. 968; p. 172167
• Main Authors: Rzepa, Sylwia, Trojanová, Zuzanka, Melzer, Daniel, Procházka, Radek, Koukolíková, Martina, Podaný, Pavel, Džugan, Ján
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2023
• Subjects: Additive manufacturing; Directed energy deposition; Equal channel angular pressing; Fatigue endurance; Fracture surfaces; Fracture toughness; Titanium alloy; Titanium alloy; Fracture surfaces; Fatigue endurance; Additive manufacturing; Equal channel angular pressing; Directed energy deposition; Fracture toughness
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2023.172167

Additive manufacturing (AM) has revolutionised the production of complex components with custom mechanical properties. However, as-deposited AM-ed materials often exhibit inferior mechanical behaviour compared to conventionally manufactured counterparts because of defects generated during the deposition. In this study, the effects of equal channel angular pressing (ECAP) on fracture toughness and fatigue endurance of Ti-6Al-4V titanium alloy manufactured by direct energy deposition (DED) are investigated. The aim of this study is to compare the mechanical performance of the material in the as-deposited and ECAP-ed states, exploiting the potential benefits of ECAP in improving the properties of additively manufactured components. ECAP processing is used to induce severe plastic deformation (SPD) and create a unique microstructure in Ti-6Al-4V specimens. As-deposited and ECAP-ed specimens were evaluated using stress intensity factor (SIF) analysis, fatigue crack growth, and high cycle fatigue tests using miniaturized specimens. Fractographic analysis was performed using scanning electron microscopy (SEM) to examine the fracture surfaces and identify the underlying failure mechanisms. The results revealed that while ECAP led to a slight increase in porosity, it significantly reduced fracture toughness and had a negligible effect on the rate of propagation of fatigue cracks. In addition, the ECAP-ed specimens showed reduced fatigue endurance of the material. ●Significant reduction in fracture toughness is observed in Ti-6Al-4 V specimens subjected to ECAP.●ECAP has minimal impact on fatigue crack propagation.●Fatigue endurance does not show significant improvement with ECAP.●ECAP-ed specimens display a slight increase in porosity.