A new approach to correlate the defect population with the fatigue life of selective laser melted Ti-6Al-4V alloy

Hu Y., Wu S., Wu Z., Zhong X., Ahmed S., Karabal S., ...More

International Journal of Fatigue, vol.136, 2020 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 136
  • Publication Date: 2020
  • Doi Number: 10.1016/j.ijfatigue.2020.105584
  • Journal Name: International Journal of Fatigue
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Communication Abstracts, Compendex, INSPEC, Metadex, zbMATH, Civil Engineering Abstracts
  • Keywords: Additive manufacturing, Chapetti model, Defect tolerance assessment, Fatigue crack initiation and propagation, High cycle fatigue (HCF)
  • Abdullah Gül University Affiliated: No

Abstract

Microstructural features and defects arising from selective laser melting (SLM) determine the in-service performance of additively manufactured near-net-shape components. Here the grain type, shape, size and distribution were characterized using electron backscattered diffraction (EBSD). High-resolution synchrotron radiation X-ray computed tomography (CT) was used to quantify the population, morphology and dimensions of porosity and lack of fusion defects. For SLM Ti-6Al-4V alloy, the larger-sized defects in comparison with the α grains are more important for crack initiation, typically leading to poor fatigue resistance and a pronounced variation in fatigue life. The fatigue strength was then evaluated in terms of the defect population using a combination of the statistics of extremes and the Murakami model. Finally, an extended Kitagawa-Takahashi fatigue diagram was established within the framework of defect-tolerant design, which includes a classical safe-life region and the defect-determined lifetime in the finite life region.