Investigation on high cycle fatigue performance of additively manufactured Alloys: Synergistic effects of surface finishing and Post-Heat treatment

The high-cycle fatigue (HCF) behavior of additively manufactured (AM) materials in structural applications remains insufficiently explored when contrasted with conventionally fabricated alloys. Addressing this research gap, we systematically investigate the potential to enhance HCF performance in AM alloys through a strategic interplay of surface finishing and post-heat treatment design. Concentrating on laser powder bed fusion, we evaluate surface roughness and post-heat treatment effects on HCF life across a300to1000 MPa stress range. Findings show that, at700to1000 MPa, surface finishing significantly extends HCF life by mitigating crack initiation. Paradoxically, at300to700 MPa, it shortens HCF life due to induced local residual stress on the sample surface. Additionally, post-aging finishing moderately enhances HCF life compared to pre-aging. This underscores the crucial role of sequence in surface finishing and heat treatment, emphasizing their collective impact on fatigue properties. Our study advances the understanding of post-processing factors influencing AM alloy fatigue properties, providing valuable insights for enhancing mechanical performance.