Engineering estimation of the fatigue limit of wrought and defective additively manufactured metals for different load ratios

An empirical bi-parametric model based on the Vickers hardness HV and a proper microstructural length parameter, l, was proposed to estimate the fully reversed threshold-Stress Intensity Factor for long cracks of wrought and additively manufactured (AM) alloys. In this paper, the model has been extended to positive load ratios (R ≅ 0 and ≅ 0.5). Afterwards, experimental results generated from testing AM specimens containing natural defects were taken from the literature and were compared successfully with the estimation based on the El Haddad Smith Topper and the Atzori Lazzarin Meneghetti models defined solely on the basis of the HV and l.