Fatigue crack growth rate and fractography of Ti6Al4V(ELI) specimens produced through direct metal laser sintering

¹ Department of Mechanical and Mechatronics Engineering, Faculty of Engineering, Built Environment and Information Technology, Central University of Technology, Free State, Bloemfontein 9300, South Africa
² Centre for Rapid Prototyping and Manufacturing, Faculty of Engineering, Built Environment and Information Technology, Central University of Technology, Free State, Bloemfontein 9300, South Africa
³ School of Mechanical, Industrial and Aeronautical Engineering, University of the Witwatersrand, Johannesburg 2050, South Africa
⁴ ARUA Centre of Excellence in Materials, Energy and Nanotechnology, University of the Witwatersrand, Johannesburg 2050, South Africa

^* Corresponding author: lmonaheng@cut.ac.za

Abstract

Fractographic analysis was conducted on Ti6Al4V(ELI) fatigue crack growth rate (FCGR) specimens produced via direct metal laser sintering (DMLS) to determine their failure mechanism and to generate data required for qualification of DMLS as a manufacturing technology for aircraft structural components. The specimens were built in three orientations and subsequently subjected to a two-stage heat treatment. All specimens were then tested in compliance with the ASTM E647-23a standard for FCGR measurement. Scanning electron microscopy (SEM) was used to examine the fracture surfaces and identify the underlying failure mechanisms. The observed fracture surfaces exhibited tortuous features with fibrous and lamellar tearing, characteristic of strong metallurgical bonding between the DMLS layers. The findings confirm that Ti6Al4V(ELI) aircraft components can indeed be successfully manufactured using DMLS.