Very-high-cycle fatigue behavior of Ti-6Al-4V manufactured by selective laser melting: Effect of build orientation

The effect of building orientation on the very-high-cycle fatigue (VHCF) response of Ti-6Al-4V specimens produced through selective laser melting (SLM) process with three different building orientations (0 degrees, 45 degrees and 90 degrees) has been experimentally assessed. The fatigue performance decreases with different building orientations from 0 degrees to 90 degrees. The fatigue crack origin has been found to be always an internal defect both at high-cycle fatigue and VHCF regime independent of building orientations. Size of defects induced fatigue failures and the stress intensity factor range decrease with the number of cycles to failure. By considering the VHCF strength at 109 cycles, the median value decreases from 217 MPa (0 degrees) to 201 MPa (45 degrees) and finally to 155 MPa (90 degrees), with a 40% reduction from 0 degrees to 90 degrees. The building orientation significantly influences both the defect size and the resulting VHCF response.